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60c74c43337d6cad7de27bf0 | 10.26434/chemrxiv.12453989.v1 | Computational Method for Simulating Thermoset Polymer Curing and Prediction of Thermophysical Properties | Thermoset polymers are an area of intense research due to their low cost,
ease of processing, environmental resistance, and unique physical properties. The favorable
properties of this class of polymers have many applications in aerospace, automotive, marine,
and sports equipment industries. Molecular simulations of thermosets are frequently used to
model formation of the polymer network, and to predict the thermomechanical properties. These
simulations usually require custom algorithms that are not easily accessible to non-experts and
not suited for high throughput screening. To address these issues, we have developed a robust
cross-linking algorithm that can incorporate different types of chemistries and leverage
GPU-enabled molecular dynamics simulations. Automated simulation analysis tools for
cross-linking simulations are also presented. Using four well known epoxy/amine formulations
as a foundational case study and benzoxazine as an example of how additional chemistries can
be modeled, we demonstrate the power of the algorithm to accurately predict curing and
thermophysical properties. These tools are able to streamline the thermoset simulation process,
opening up avenues to in-silico high throughput screening for advanced material development. | Jeffrey Sanders; Carla E. Estridge; Matthew B Jackson; Thomas JL Mustard; Samuel J. Tucker; David J. Giesen; Stephen Christensen; Andrea Browning; Mathew
D. Halls | Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74c43337d6cad7de27bf0/original/computational-method-for-simulating-thermoset-polymer-curing-and-prediction-of-thermophysical-properties.pdf |
65feb1b6e9ebbb4db9569a9d | 10.26434/chemrxiv-2024-nvj38 | Controlling noncollinear ferromagnetism in van der Waals metal-organic magnets | Van der Waals (vdW) magnets can be used to explore both fundamental 2D physics and offer a route to exploit magnetism in next generation information technology, but vdW magnets with complex, noncollinear spin textures are currently rare. We re- port here the syntheses, crystal structures, bulk magnetic properties and magnetic ground states of four vdW metal-organic magnets (MOMs): FeCl2(pym), FeCl2(btd), NiCl2(pym) and NiCl2(btd), pym = pyrimidine and btd = 2,1,3-benzothiadiazole. Using a combination of neutron diffraction and bulk magnetometry we show that these materials are noncollinear magnets and although only NiCl2(btd) has a ferromagnetic ground state, low-field hysteretic metamagnetic transitions also allow access to states with net magnetisation in zero-field and high coercivities for FeCl2(pym) and NiCl2(pym). By combining our bulk magnetic data with diffuse scattering analysis and broken-symmetry density-functional calculations we probe the magnetic superexchange interactions, which when combined with symmetry analysis allow us to suggest design principles for future noncollinear vdW MOMs. | Jem Pitcairn; Mario Antonio Ongkiko; Andrea Iliceto; Peter Speakman; Stuart Calder; Malcolm Cochran; Joseph Paddison; Cheng Liu; Stephen Argent; Andrew Morris; Matthew Cliffe | Physical Chemistry; Inorganic Chemistry; Coordination Chemistry (Inorg.); Magnetism; Solid State Chemistry; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-03-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65feb1b6e9ebbb4db9569a9d/original/controlling-noncollinear-ferromagnetism-in-van-der-waals-metal-organic-magnets.pdf |
61ba54a3d1f662acb83a551e | 10.26434/chemrxiv-2021-nk5cr | The molecular impact of life in an indoor environment | The chemistry of indoor surfaces, and the role of microbes in shaping and responding to that chemistry, are largely unexplored. We found that over one month, people’s presence and activities profoundly reshaped the chemistry of a house. Molecules associated with eating/cooking, bathroom use, and personal care were found throughout the entire house, while molecules associated with medications, outdoor biocides, and microbially-derived compounds were distributed in a location-dependent manner. The house, and its microbial occupants, in turn, also introduced chemical transformations such as oxidation and transformations of foodborne molecules. The awareness of and the ability to observe the molecular changes introduced by people should influence future building designs. | Alexander A. Aksenov; Rodolfo A. Salido; Alexey V. Melnik; Caitriona Brennan; Asker Brejnrod; Andrés Mauricio Caraballo-Rodríguez; Julia M. Gauglitz; Franck Lejzerowicz; Delphine K. Farmer; Marina E. Vance; Rob Knight; Pieter C. Dorrestein | Analytical Chemistry; Earth, Space, and Environmental Chemistry; Environmental Science; Environmental Analysis; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2021-12-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61ba54a3d1f662acb83a551e/original/the-molecular-impact-of-life-in-an-indoor-environment.pdf |
60c7459ef96a002ec6286bfc | 10.26434/chemrxiv.10072460.v1 | A Site-Selective Amination Catalyst Discriminates Between Nearly Identical C-H Bonds of Unsymmetrical Disubstituted Alkenes | C−H activation reactions enable chemists to unveil new retrosynthetic disconnections and streamline
conventional synthetic approaches. A longstanding challenge in C−H activation is the inability to
distinguish electronically and sterically similar C–H bonds. Although numerous synergistic combinations
of transition-metal complexes and chelating directing groups have been utilized to distinguish C−H bonds,
undirected regioselective C−H functionalization strategies remain elusive. Herein, we report a
regioselective C−H activation/amination reaction of various unsymmetrical dialkyl-substituted alkenes.
The regioselectivity of C−H activation is correlated to the electronic properties of allylic C−H bonds
indicated by the corresponding 1JCH coupling constants. A linear relationship between the difference of
1JCH coupling constants of the two competing allylic C−H bonds (Δ
1JCH) and the C−H activation barriers (Δ
ΔG
‡
) has also been determined. | Tomislav Rovis; Honghui Lei | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2019-10-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7459ef96a002ec6286bfc/original/a-site-selective-amination-catalyst-discriminates-between-nearly-identical-c-h-bonds-of-unsymmetrical-disubstituted-alkenes.pdf |
64ef58d1dd1a73847fd4ec84 | 10.26434/chemrxiv-2023-326fj | Strategies to enhance figures of merit in ICP-ToF-MS | Inductively coupled plasma with time-of-flight mass spectrometry (ICP-ToF-MS) is currently setting new benchmarks for the analysis of single particles (SP) and elemental mapping using laser ablation (LA). The rapid collection of the full elemental mass spectra promotes non-target approaches, fast imaging as well as inquiries of particle stoichiometry. However, one shortcoming often associated with ICP-ToF-MS is a lack of detection power due to lower duty cycles relative to sequentially operating mass analysers. The sensitivity of ICP-ToF-MS can be increased using two strategies, which are detailed in this study. First, instead of analysing full mass spectra, elements in the low and high mass range were excluded from analysis using a Bradbury-Nielsen gate. The resulting restricted mass range was acquired up to 5 times faster increasing duty cycles and sensitivity accordingly. Second, isotopes of polyisotopic elements recorded simultaneously were accumulated to increase signal to noise ratios.
In a proof of concept, we applied SP ICP-ToF-MS for the first time for the characterisation of upconversion nanoparticles (UCNPs) which contained Gd and Yb. Both signal amplification strategies were combined and the consequences for detection limits and signal to noise ratios were considered and compared to a standard method. Sensitivities were increased up to factor 27 when accumulating all Gd and Yb isotopes at 177 kHz, and size detection limits decreased by a factor of approximately 3. Improved figures of merit promoted more accurate investigations of UCNPs, which were characterised regarding size distributions and composition.
As second application, we demonstrated the utility of the described strategies in LA-ICP-ToF-MS. Mo and Se were targeted as relatively rare elements in rat brain tissue. Increased acquisition frequencies of 185 kHz and isotope accumulation resulted into drastically improved signal to noise ratios and enabled the mapping of both while still considering relevant neuroanatomical elements such as Fe and Zn.
| Thomas Lockwood; Raquel Gonzalez de Vega; Ziqing Du; Lukas Schlatt; Xiaoxue Xu; David Clases | Analytical Chemistry; Analytical Apparatus; Imaging; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ef58d1dd1a73847fd4ec84/original/strategies-to-enhance-figures-of-merit-in-icp-to-f-ms.pdf |
60c74d83702a9bda0018b87c | 10.26434/chemrxiv.12630230.v1 | A Model for the Simulation of the CnEm Nonionic Surfactant Family Derived from Recent Experimental Results | <div><div><div><p>Using a comprehensive set of recently published experimental results for training and validation, we have developed computational models appropriate for simulations of aqueous solutions of poly(ethylene oxide) alkyl ethers, an important class of micelle- forming nonionic surfactants, usually denoted CnEm. These models are suitable for use in simulations that employ a moderate amount of coarse graining and especially for dissipative particle dynamics (DPD), which we adopt in this work.</p><p><br /></p><p>The experimental data used for training and validation were reported earlier and produced in our laboratory using dynamic light scattering (DLS) measurements per- formed on twelve members of the CnEm compound family yielding micelle size dis- tribution functions and mass weighted mean aggregation numbers at each of several surfactant concentrations. The range of compounds and quality of the experimental results were designed to support the development of computational models. An es- sential feature of this work is that all simulation results were analysed in a way that is consistent with the experimental data. Proper account is taken of the fact that a broad distribution of micelle sizes exists, so mass weighted averages (rather than num- ber weighted averages) over this distribution are required for the proper comparison of simulation and experimental results.</p><p><br /></p><p>The resulting DPD force field reproduces several important trends seen in the exper- imental critical micelle concentrations and mass averaged mean aggregation numbers with respect to surfactant characteristics and concentration. We feel it can be used to investigate a number of open questions regarding micelle sizes and shapes and their dependence on surfactant concentration for this important class of nonionic surfactants.</p></div></div></div> | Michael Johnston; Andrew Duff; Richard L. Anderson; William Swope | Surfactants; Computational Chemistry and Modeling; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74d83702a9bda0018b87c/original/a-model-for-the-simulation-of-the-cn-em-nonionic-surfactant-family-derived-from-recent-experimental-results.pdf |
64477f5083fa35f8f6370cce | 10.26434/chemrxiv-2023-4czjx | Interfacial bonding between a crystalline metal-organic framework and an inorganic glass | The interface within a composite is critically important for the chemical and physical properties of these materials. However, experimental structural studies of the interfacial regions within metal-organic framework (MOF) composites are extremely challenging. Here, we provide the first example of a new MOF composite family, i.e. using an inorganic glass matrix host in place of the commonly used organic polymers. Crucially, we also decipher atom-atom interactions at the interface. Specifically, we dispersed ZIF-8 within a phosphate glass matrix, and identified interactions at the interface using several different analysis methods of pair distribution function (PDF) and multinuclear multidimensional magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. These demonstrated glass-ZIF atom-atom correlations. Additionally, carbon dioxide uptake and stability tests were also performed to check the increment of the surface area and the stability and durability of the material in different media. This opens up the possibility to create new composites including the intrinsic chemical properties of the constituent MOFs and inorganic glasses. | Celia Castillo; Ashleigh Chester; Ronan P. Cosquer; Adam Sapnik; Lucia Corti; Roman Sajzew; Bruno Poletto Rodrigues; Georgina Robertson; Daniel Irving; Lauren McHugh; Lothar Wondraczek; Frédéric Blanc; David A. Keen; Thomas D Bennett | Materials Science; Composites; Hybrid Organic-Inorganic Materials; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2023-04-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64477f5083fa35f8f6370cce/original/interfacial-bonding-between-a-crystalline-metal-organic-framework-and-an-inorganic-glass.pdf |
64653d17f2112b41e9b884ef | 10.26434/chemrxiv-2023-f9w32 | Tetrathiafulvalene-2,3,6,7-tetrathiolate Linker Redox-State
Elucidation via S K-edge X-ray Absorption Spectroscopy | Sulfur K-edge XAS data provide a unique tool to examine
oxidation states and covalency in electronically complex Sbased
ligands. We present sulfur K-edge X-ray absorption
spectroscopy on a discrete redox-series of Ni-based
tetrathiafulvalene tetrathiolate (TTFtt) complexes as well as on a
1D coordination polymer (CP), NiTTFtt. Experiment and theory
suggest that Ni—S covalency decreases with oxidation which
has implications for charge transport pathways. Finally, a
characteristic peak for doubly oxidized TTFtt verifies this
formal redox state in the CP, NiTTFtt. | Ningxin Jiang; Jan-Niklas Boyn; Arun Ramanathan; Henry LaPierre; John Anderson | Inorganic Chemistry; Bonding; Coordination Chemistry (Inorg.); Spectroscopy (Inorg.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64653d17f2112b41e9b884ef/original/tetrathiafulvalene-2-3-6-7-tetrathiolate-linker-redox-state-elucidation-via-s-k-edge-x-ray-absorption-spectroscopy.pdf |
63a37aeb81e4bac11355ee92 | 10.26434/chemrxiv-2022-v4zqc-v2 | Antineoplastic Properties of THCV, HHC and their anti-Proliferative effects on HPAF-II, MIA-paca2, Aspc-1, and PANC-1 PDAC Pancreatic Cell Lines | Cannabinoid receptors CB1 and CB2 are the primary endogenous receptors with which cannabinoids interact, inducing physiological and psychological effects. Although interactions with other receptors including TRPV1 and GPCR55, have been recognized in earlier studies, these interactions may play a significant role in cancer remediation through the unspecified upregulation or downregulation of specific pathways. The main active constituents within the cannabis plant are cannabidiol (CBD) and tetrahydrocannabinol (THC), which have been categorized as either non-intoxicating with benefit or intoxicating with no benefit. These categories are constantly ignored, as cannabinoids have shown efficacy in the treatment of certain diseases and ailments as single-agent compounds. Tetrahydrocannabivarin (THCV), a rare cannabinoid, is a homologue of THC, with the C5 alkyl chain having three carbons rather than the standard five carbon length. THCV has garnered attention in a clinical setting as an anti-obesity drug treating glucose issues. Hexahydrocannabinol (HHC), a hydrogenated analogue of THC, is a rare cannabinoid like THCV. These cyclic cannabinoids are considered rare, because they are typically found in minimal to trace amounts within cannabis sativa and their given C. indica, and C. ruderalis sub species. Increased popularity of these rare cannabinoids has led to proposed experimentation leading to assessing the cytotoxicity of these cannabinoids toward, cancer cells of the pancreas (MIA-PaCa2, HPAF-II, and PANC1). The data evaluated through such studies led to the proposed idea of these rare cyclic cannabinoids towards the treatment of pancreatic cancer due to the modest efficacy as single agent antineoplastics compared to common single agent antineoplastics on the market, with evidence being strongly presented when compared to commercially available anticancer agents poly(ADP-ribose) polymerase (PARP) inhibitors. | Tesfay Tesfatsion; Arianna Collins; Giovanni Ramirez; Yousef Mzannar; Husain Khan; Omar Aboukameel; Asfar Azmi; Prakash Jagtap; Kyle Ray; Westley Cruces | Biological and Medicinal Chemistry; Organic Chemistry; Natural Products; Chemical Biology; Drug Discovery and Drug Delivery Systems | CC BY 4.0 | CHEMRXIV | 2022-12-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63a37aeb81e4bac11355ee92/original/antineoplastic-properties-of-thcv-hhc-and-their-anti-proliferative-effects-on-hpaf-ii-mia-paca2-aspc-1-and-panc-1-pdac-pancreatic-cell-lines.pdf |
6671ec4bc9c6a5c07ac8adf0 | 10.26434/chemrxiv-2024-8fxfk | Transfer learning based on atomic feature extraction for the prediction of experimental ¹³C chemical shifts | Forecasting experimental chemical shifts of organic compounds is a long-standing challenge in organic chemistry. Recent advances in machine learning (ML) have led to routines that surpass the accuracy of ab initio Density Functional Theory (DFT) in estimating experimental $^{13}$C shifts. The extraction of knowledge from other models, known as transfer learning, has demonstrated remarkable improvements, particularly in scenarios with limited data availability. However, the extent to which transfer learning improves predictive accuracy in low-data regimes for experimental chemical shift predictions remains unexplored.
This study indicates that atomic features derived from a message passing neural network (MPNN) forcefield are robust descriptors for atomic properties. A dense network utilizing these descriptors to predict $^{13}$C shifts achieves a mean absolute error (MAE) of 1.68 ppm. When these features are used as node labels in a simple graph neural network (GNN), the model attains a better MAE of 1.34 ppm. On the other hand, embeddings from a self-supervised pre-trained 3D aware transformer are not sufficiently descriptive for a feedforward model but show reasonable accuracy within the GNN framework, achieving an MAE of 1.51 ppm. Under low-data conditions, all transfer-learned models show a significant improvement in predictive accuracy compared to existing literature models, regardless of the sampling strategy used to select from the pool of unlabeled examples.
We demonstrated that extracting atomic features from models trained on large and diverse datasets is an effective transfer learning strategy for predicting NMR chemical shifts, achieving results on par with existing literature models. This method provides several benefits, such as reduced training times, simpler models with fewer trainable parameters, and strong performance in low-data scenarios, without the need for costly ab initio data of the target property. This technique can be applied to other chemical tasks opening many new potential applications where the amount of data is a limiting factor. | Žarko Ivković; Jesús Jover; Jeremy Harvey | Theoretical and Computational Chemistry; Machine Learning; Artificial Intelligence | CC BY NC 4.0 | CHEMRXIV | 2024-06-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6671ec4bc9c6a5c07ac8adf0/original/transfer-learning-based-on-atomic-feature-extraction-for-the-prediction-of-experimental-13c-chemical-shifts.pdf |
6501f50799918fe537e4f79a | 10.26434/chemrxiv-2023-xsg7n | Pressure-Induced Amidine Formation via Side-Chain Polymerization in a Charge-Transfer Cocrystal | Compression of small molecules can induce solid-state reactions with products that are difficult or impossible to obtain through solution-phase synthesis. Of particular interest is the topochemical-like reaction of arenes to produce polymeric nanomaterials rich in sp3 carbon. However, high reaction onset pressures and poor control over high-pressure reaction selectivity remain significant challenges to be addressed. Herein, the incorporation of electron withdrawing/donating groups into π-stacked arenes is proposed as a strategy to reduce reaction barriers and onset pressures. Charge transfer cocrystals represent systems with optimal π-stacking and reduced energy barriers for intermolecular cycloaddition reactions, however, competing side-chain reactions between functional groups must also be considered. For the case of a diaminobenzene:tetracyanobenzene cocrystal, amidine formation between side groups is the first reaction to occur with an onset pressure near 9 GPa, as characterized using vibrational spectroscopy, X-ray diffraction, and computational studies. High-pressure reactivity is system-dependent and while functionalized arenes are predicted to exhibit reduced-barrier energy cycloaddition pathways, directed reactions between side groups can be used as a novel strategy for the formation unique polymeric materials. | Samuel Dunning; Wan Si Tang; Bo Chen; Li Zhu; George Cody; Stella Chariton; Vitali Prakapenka; Timothy Strobel | Physical Chemistry; Organic Chemistry; Physical Organic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6501f50799918fe537e4f79a/original/pressure-induced-amidine-formation-via-side-chain-polymerization-in-a-charge-transfer-cocrystal.pdf |
60c747c80f50dbfd91396670 | 10.26434/chemrxiv.11755098.v1 | Enhanced Electrospray In-source Fragmentation for Higher Sensitivity Data Independent Acquisition and Autonomous METLIN Molecular Identification | Electrospray
ionization (ESI) in-source fragmentation (ISF) has traditionally been
minimized to promote precursor molecular ion formation, and therefore its value
in molecular identification underappreciated. Recently a METLIN-guided
in-source annotation (MISA) algorithm was introduced to increase confidence in putative
identifications by using ubiquitous in-source fragments. However, MISA is
limited by ESI sources that are generally designed to minimize ISF. In this
study, enhanced ISF with MISA (eMISA) was created by tuning the ISF conditions
to generate in-source fragmentation patterns comparable with higher energy
fragments generated at higher collision energies as deposited in the METLIN
MS/MS library, without compromising the intensity of precursor ions (median
loss ≤ 10% in both positive and negative ionization modes). The analysis of 50
molecules was used to validate the approach in comparison to MS/MS spectra
produced via data dependent acquisition (DDA) and data independent acquisition
mode (DIA) with quadrupole time-of-flight mass spectrometry (QTOF-MS). Enhanced
ISF as compared to QTOF DDA, enables for higher peak intensities for the
precursor ions (median: 18 times at negative mode and 210 times at positive
mode), with the eMISA fragmentation patterns consistent with METLIN for over 90%
of the molecules with respect to fragment relative intensity and <i>m/z</i>.
eMISA also provides higher peak intensity as opposed to QTOF DIA with a median
increase of 20% at negative mode and 80% at positive mode for all precursor
ions. Metabolite identification with eMISA was also successfully validated from
the analysis of a metabolic extract from macrophages. An interesting side
benefit of enhanced ISF is that it significantly improved the compound
identification confidence with low resolution single quadrupole mass
spectrometry-based untargeted LC/MS experiments. Overall, enhanced ISF allowed
for eMISA to be used as a more sensitive alternative to other QTOF DIA and DDA
approaches, and further, it enables the acquisition of ESI TOF and ESI single
quadrupole mass spectrometry instrumentation spectra with higher sensitivity
and improved molecular identification confidence. | jingchuan xue; Xavier Domingo-Almenara; Carlos Guijas; Amelia Palermo; Markus Rinschen; H. Paul Benton; Gary Siuzdak | Analytical Chemistry - General | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c747c80f50dbfd91396670/original/enhanced-electrospray-in-source-fragmentation-for-higher-sensitivity-data-independent-acquisition-and-autonomous-metlin-molecular-identification.pdf |
62cbb9edc79aca51785b936e | 10.26434/chemrxiv-2022-wddg0 | Probing Local Environments of Oxygen Vacancies Responsible for Hydration in Sc-doped Barium Zirconates at Elevated Temperatures: In Situ X-ray Absorption Spectroscopy, Thermogravimetry, and Active Learning Ab Initio Replica Exchange Monte Carlo Simulations | Proton-conducting oxides, specifically heavily Sc-doped barium zirconate perovskite, have attracted attention as electrolytes for intermediate-temperature protonic ceramic fuel cells because of their high proton conductivity and high chemical stability against carbon dioxide in that temperature regime. Hydration is a key reaction for incorporating protons by filling oxygen vacancies, VO, with hydroxyl groups and activating proton conduction in the perovskite. However, probing the local environment of oxygen vacancies responsible for hydration is challenging because the behavior depends on the temperature and water partial pressure, which necessitates in situ observations and calculations of the local environments at elevated temperatures. To obtain such information, we combined in situ X-ray absorption spectroscopy (XAS) for both the Sc and Zr K-edges, thermogravimetry, X-ray diffractometry, and active learning ab initio replica exchange Monte Carlo (RXMC) simulations in undoped and 20–40 at% Sc-doped barium zirconates at and below 800 °C. The presence of oxygen vacancies adjacent to Sc and Zr in the dehydrated samples and the hydration of these oxygen vacancies under a wet atmosphere were probed by in situ XAS for Sc and Zr pre-edges at elevated temperatures. Here, the microscopic hydration linearly responds to the macroscopic degree of hydration. RXMC sampling further supports the presence of Sc-VO-Zr and Sc-VO-Sc environments. An initial hydration occurs in the Sc-VO-Zr environment at and above 600 °C, but the Sc-VO-Sc environment contribution is greater at higher degrees of hydration. The Zr-Vo-Zr environment is the least abundant among them for the whole temperature range examined and thus has a negligible impact. | Kenta Hoshino; Shusuke Kasamatsu; Junji Hyodo; Kentaro Yamamoto; Hiroyuki Setoyama; Toshihiro Okajima; Yoshihiro Yamazaki | Inorganic Chemistry; Solid State Chemistry | CC BY NC 4.0 | CHEMRXIV | 2022-07-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62cbb9edc79aca51785b936e/original/probing-local-environments-of-oxygen-vacancies-responsible-for-hydration-in-sc-doped-barium-zirconates-at-elevated-temperatures-in-situ-x-ray-absorption-spectroscopy-thermogravimetry-and-active-learning-ab-initio-replica-exchange-monte-carlo-simulations.pdf |
60c75582337d6c5088e28c4e | 10.26434/chemrxiv.14113427.v1 | Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites | <div>The vibrational dynamics of pure and methylammonium-doped formamidinium lead iodide perovskites</div><div>(FAPbI3) has been investigated by high-resolution neutron spectroscopy. For the ?first time, we provide an exhaustive and accurate analysis of the cation vibrations and underlying local structure around the organic moiety in these materials using ?first-principles electronic-structure</div><div>calculations validated by the neutron data. Inelastic Neutron Scattering experiments on FAPbI3</div><div>provide direct evidence of the formation of a low-temperature orientational glass, unveiling the</div><div>physico-chemical origin of phase metastability in the tetragonal structure. Further analysis of these</div><div>data provides a suitable starting point to understand and explore the stabilization of the perovskite</div><div>framework via doping with small amounts of organic cations. In particular, we ?find that hydrogen</div><div>bonds in FAPbI3 are strengthened in a synergistic manner as a result of cage deformation induced</div><div>by the dynamics of the neighbouring methylammonium cations.</div> | Kacper Druzbicki; Rasmus Laven; Jeff Armstrong; Lorenzo Malavasi; Felix Fernandez-Alonso; Maths Karlsson | Hybrid Organic-Inorganic Materials; Optical Materials; Organometallic Compounds; Computational Chemistry and Modeling; Spectroscopy (Organomet.); Theory - Organometallic; Photovoltaics; Physical and Chemical Properties; Spectroscopy (Physical Chem.); Structure; Thermodynamics (Physical Chem.); Materials Chemistry; Crystallography | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75582337d6c5088e28c4e/original/cation-dynamics-and-structural-stabilization-in-formamidinium-lead-iodide-perovskites.pdf |
61277a2b8e38a310674116af | 10.26434/chemrxiv-2021-0f96d | Development of chimeric molecules that degrade the estrogen recep-tor using decoy oligonucleotide ligands | Targeted protein degradation using chimeric small molecules, such as proteolysis-targeting chimeras (PROTACs) and specif-ic and nongenetic inhibitors of apoptosis protein [IAP]-dependent protein erasers (SNIPERs), has attracted attention as a method to degrade intracellular target proteins via the ubiquitin-proteasome system (UPS). These chimeric molecules target a variety of proteins using small molecules that can bind to the proteins. However, it is difficult to develop such degraders in the absence of suitable small molecule ligands for the target proteins, such as for transcription factors (TFs). Therefore, we constructed the chimeric molecule LCL-ER(dec), which consists of a decoy oligonucleotide that can bind to the estrogen receptor alpha (ERalpha) and an IAP ligand, LCL161 (LCL), in a click reaction. LCL-ER(dec) was found to selectively degrade ERalpha via the UPS. These findings will be applicable to the development of other oligonucleotide-type degraders that target different TFs. | Miyako Naganuma; Nobumichi Ohoka; Genichiro Tsuji; Haruna Tsujimura; Kenji Matsuno; Takao Inoue; Mikihiko Naito; Yosuke Demizu | Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61277a2b8e38a310674116af/original/development-of-chimeric-molecules-that-degrade-the-estrogen-recep-tor-using-decoy-oligonucleotide-ligands.pdf |
65bd6d7666c1381729d6d8f0 | 10.26434/chemrxiv-2024-vpstm | Linearizable Macrocyclic Peptide Libraries for Affinity Selection-Mass Spectrometry | Macrocyclic peptides are attractive for therapeutic development but have been limited in their application to combinatorial library selection from synthetic libraries. Here, we establish a synthetic approach based on split-pool chemistry to produce 100-million membered macrocyclic libraries containing natural and non-natural amino acids. Near-quantitative intramolecular disulfide formation is facilitated by rapid (<10 minute) oxidation by iodine to prepare macrocyclic synthetic libraries in solution. Treatment with dithiothreitol post-affinity selection enables near-quantitative reduction of the library members, rendering the linear analogs amenable to standard tandem mass spectrometry sequencing. We demonstrate the utility of these libraries to discover novel macrocyclic binders to cadherin-2 and the anti-hemagglutinin antibody clone 12ca5. The lead cadherin-binding peptide (CBP) is endowed with nanomolar binding affinity measured by biolayer interferometry (BLI, apparent dissociation constant KD = 53 nM). Structure-activity relationship (SAR) studies including alanine and D-amino acid scans reveal the amino acids responsible for driving affinity (hot-spots) and the positions tolerating mutagenesis (cold-spots). Informed by SAR data, two new macrocyclic libraries are designed to derivatize these positions with a variety of abiotic amino acids based on the hot- and cold-spots. Following affinity selection and experimental validation by BLI, 10 high-affinity ligands out of 10 discovered were identified from the library that derivatized the CBP cold-spots, while zero of the two peptide ligands discovered from the hot-spot library were high-affinity binders. Of these noncanonical CBPs (NCBP), NCBP-4 demonstrates improved affinity to cadherin-2 (KD = 29 nM). Overall, we expect that this work will pioneer the use of large-scale macrocyclic libraries to further catalyze therapeutic peptide discovery and development. | Michael A. Lee; Joseph S. Brown; Charlotte E. Farquhar; Andrei Loas; Bradley L. Pentelute | Biological and Medicinal Chemistry; Organic Chemistry; Organic Synthesis and Reactions; Bioengineering and Biotechnology; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65bd6d7666c1381729d6d8f0/original/linearizable-macrocyclic-peptide-libraries-for-affinity-selection-mass-spectrometry.pdf |
6424bb2f647e3dca99b8d11f | 10.26434/chemrxiv-2023-j6wt1-v2 | pyCHARMM: Embedding CHARMM Functionality in a Python Framework | CHARMM is rich in methodology and functionality as one of the first programs
addressing problems of molecular dynamics and modeling of biological macromolecules and their
partners, e.g., small molecule ligands. When combined with the highly developed CHARMM
parameters for proteins, nucleic acids, small molecules, lipids, sugars, and other biologically
relevant building blocks, and the versatile CHARMM scripting language, CHARMM has been a
trendsetting platform for modeling studies of biological macromolecules. To further enhance the
utility of accessing and using CHARMM functionality in increasingly complex workflows
associated with modeling biological systems, we introduce pyCHARMM, Python bindings,
functions, and modules to complement and extend the extensive set of modeling tools and
methods already available in CHARMM. These include access to CHARMM function-generated
variables associated with the system (psf), coordinates, velocities and forces, atom selection
variables and force field related parameters. The ability to augment CHARMM forces and
energies with energy terms or methods derived from machine learning or other sources, written
in Python, CUDA or OpenCL and expressed as Python callable routines is introduced together
with analogous functions callable during dynamics calculations. Integration of Python-based
graphical engines for visualization of simulation models and results is also accessible. Loosely
coupled parallelism is available for workflows such as free energy calculations, using MBAR/TI
approaches or high-throughput multisite 𝜆-dynamics (MSλD) free energy methods, string path
optimization calculations, replica exchange and molecular docking with a new Python-based
CDOCKER module. CHARMM accelerated platform kernels through the CHARMM/OpenMM API,
CHARMM/DOMDEC and CHARMM/BLaDE API are also readily integrated into this Python
framework. We anticipate that pyCHARMM will be a robust platform for the development of
comprehensive and complex workflows utilizing Python and its extensive functionality as well as
an optimal platform for users to learn molecular modeling methods and practices within a Pythonfriendly
environment such as Jupyter Notebooks. | Joshua Buckner; Xiaorong Liu; Arghya Chakravorty; Yujin Wu; Luis Cervantes; Thanh Lai; Charles Brooks | Theoretical and Computational Chemistry; Physical Chemistry; Biological and Medicinal Chemistry; Computational Chemistry and Modeling; Theory - Computational; Machine Learning | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6424bb2f647e3dca99b8d11f/original/py-charmm-embedding-charmm-functionality-in-a-python-framework.pdf |
646380a1f2112b41e9a7c435 | 10.26434/chemrxiv-2023-xjt55 | Molecular auxetic polymer of intrinsic microporosity via conformational switching of a cavitand crosslinker | Auxetics are materials characterized by a negative Poisson’s ratio (NPR), an uncommon mechanical behavior corresponding to a transversal deformation tendency opposite to the traditional materials. Here we present the first example of a 3D synthetic molecular auxetic polymer, obtained by embedding a conformationally expandable cavitand as crosslinker into a rigid polymer of intrinsic microporosity (PIM). The rigidity and microporosity of the polymeric matrix are pivotal to maximize the expansion effect of the cavitand that, under mechanical stress, can assume two different conformations: a compact vase one and an extended kite form. The auxetic behavior and the corresponding NPR of the proposed material is predicted by a specific micromechanical model that considers the cavitand volume expansion ratio, the fraction of the cavitand crosslinker in the polymer, and the mechanical characteristics of the polymer backbone. The reversible auxetic behavior of the material is experimentally verified via Digital Image Correlation technique (DIC) performed during the mechanical tests on films obtained by blending the auxetic crosslinked polymer with pristine PIM. Two specific control experiments prove that the mechanically driven conformational expansion of the cavitand crosslinker is the sole responsible of the observed NPR of the polymer. | Francesca Portone; Mattia Amorini; Matteo Montanari; Roberta Pinalli; Alessandro Pedrini; Roberto Verucchi; Roberto Brighenti; Enrico Dalcanale | Polymer Science; Organic Polymers; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/646380a1f2112b41e9a7c435/original/molecular-auxetic-polymer-of-intrinsic-microporosity-via-conformational-switching-of-a-cavitand-crosslinker.pdf |
61284007abeb63f610c14957 | 10.26434/chemrxiv-2021-m73zv-v2 | Protein Modification at Tyrosine with Iminoxyl Radicals | Post-translational modifications (PTMs) of proteins are a biological mechanism for reversibly controlling protein function. Synthetic protein modifications (SPMs) at specific canonical amino acids can mimic PTMs. However, reversible SPMs at hydrophobic amino acid residues in proteins are especially limited. Here we report a tyrosine (Tyr)-selective SPM utilizing persistent iminoxyl radicals, which are readily generated from sterically hindered oximes via single electron oxidation. The reactivity of iminoxyl radicals with Tyr was dependent on the steric and electronic demands of oximes; isopropyl methyl piperidinium oxime 1f formed stable adducts, whereas the reaction of tert-butyl methyl piperidinium oxime 1o was reversible. The difference in reversibility between 1f and 1o, differentiated only by one methyl group, is due to the stability of iminoxyl radicals, which is partly dictated by the bond dissociation energy of oxime O‒H groups. The Tyr-selective modifications with 1f and 1o proceeded under physiologically-relevant, mild conditions. Specifically, the stable Tyr-modification with 1f introduced functional small molecules, including an azobenzene photoswitch, to proteins, whereas the reversible modification of Tyr with 1o switched protein function on and off in an enzyme and in a monoclonal antibody by modification and deconjugation processes. | Katsuya Maruyama; Takashi Ishiyama; Yohei Seki; Kentaro Sakai; Takaya Togo; Kounosuke Oisaki; Motomu Kanai | Biological and Medicinal Chemistry; Organic Chemistry; Bioorganic Chemistry; Organic Synthesis and Reactions; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61284007abeb63f610c14957/original/protein-modification-at-tyrosine-with-iminoxyl-radicals.pdf |
67687d74fa469535b97b9833 | 10.26434/chemrxiv-2024-v73kb | Physico-chemical, rheological, and antiviral properties of poly(butylene succinate) composites with terpene-hydrophobized montmorillonites | The aim of the work was to obtain poly(butylene succinate) – PBS films with an addition of natural sodium montmorillonite (Na-MMT) modified with two selected terpenes: pinene (P) and limonene (L) or their mixture (PL) and examine their physico-chemical, rheological and antimicrobial properties. Na-MMT was effectively hydrophobized and intercalated (confirmed with FTIR, TGA and XRD analysis) with the terpenes via solventless method. The biopolymeric composites were obtained via extrusion, and the films were formed using thermo-compression molding. The addition of the fillers slightly increased mechanical properties, but barrier properties towards oxygen and water vapor were significantly improved without alternation of polymer morphology (SEM, XRD, FTIR), thermal and thermomechanical properties, despite high filler content (10 wt%) in the polymer matrix. PBS/M, PBS/M-L, and PBS/M-PL exhibited antiviral properties tested using Φ6 phage. | Magdalena Zdanowicz; Mateusz Barczewski; Małgorzata Mizielińska; Piotr Miądlicki | Physical Chemistry; Materials Science; Chemical Engineering and Industrial Chemistry; Biodegradable Materials; Composites; Geological Materials | CC BY 4.0 | CHEMRXIV | 2024-12-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67687d74fa469535b97b9833/original/physico-chemical-rheological-and-antiviral-properties-of-poly-butylene-succinate-composites-with-terpene-hydrophobized-montmorillonites.pdf |
616e694ea3d2c9b7aadbcdb0 | 10.26434/chemrxiv-2021-mq7kn | Cesium immobilization in metakaolin-based geopolymers elucidated by 133Cs solid state NMR spectroscopy | Geopolymers are promising candidates for nuclear-waste immobilization, and more specifically for the immobilization of radioactive cesium. Low-Si metakaolin-based geopolymers cured at temperatures of 40°C in the presence of Cs ions generate a mixture of amorphous and crystalline phases including a Cs-bearing zeolite F phase. Using a combination of 133Cs solid-state NMR and X-ray powder diffraction measurements we were able to show that Cs preferentially binds to zeolite F even when zeolite F is not the dominant phase in the matrix. Moreover, post-leaching NMR experiments indicate that zeolite F binds Cs more efficiently than the remaining crystalline or amorphous phases. Tailoring geopolymer formulations so that a large fraction of zeolite F is generated may therefore be a promising route for the production of immobilization matrices for cesium. | Michal Arbel Haddad; Yonatan Harnik; Yaron Schlosser; Amir Goldbourt | Physical Chemistry; Materials Science; Earth, Space, and Environmental Chemistry; Environmental Science; Wastes; Structure | CC BY NC ND 4.0 | CHEMRXIV | 2021-10-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/616e694ea3d2c9b7aadbcdb0/original/cesium-immobilization-in-metakaolin-based-geopolymers-elucidated-by-133cs-solid-state-nmr-spectroscopy.pdf |
65f335cd66c1381729fe7c40 | 10.26434/chemrxiv-2024-1mssg | Mapping hydrogen initiatives in Italy: An overview of funding and projects | The global momentum towards hydrogen has led to various initiatives aimed at leveraging hydrogen’s potential. Particularly, low-carbon hydrogen is recognized for its crucial role in reducing greenhouse gas emissions across hard-to-abate sectors such as steel, cement and heavy-duty transport.
This study focuses on presenting all the funding initiatives in Italy, providing a comprehensive overview of the diverse hydrogen-related activities and their geographical locations. The funding investigated stem from the National Recovery and Resilience Plan (PNRR), projects directly funded through the Important Projects of Common European Interest (IPCEI), and various initiatives supported by private companies or other funding sources (hydrogen valleys). Specific calls for proposals within the PNRR initiative outline the allocation of funds, emphasizing hydrogen production in brownfield areas (52 expected hydrogen production plants by 2026), hydrogen use in hard-to-abate sectors, and the establishment of hydrogen refuelling stations for road (48 refuelling stations by 2026) and railway transport (10 hydrogen-based railway lines). An in-depth description of funded initiatives covering geographical location, typology, and size (when available), as well as the funding they have received, is presented, by collecting data on about approximately 150 funded initiatives. This overview sheds lights on regions focusing on heavy-duty transport decarbonisation, particularly along cross-borders commercial routes, as evident in northern Italy. Conversely, some regions concentrate more on local transport, typically buses, or on the industrial sector, primarily steel and chemicals. Additionally, the study presents initiatives aimed to strengthen the national manufacturing capacity for hydrogen-related technologies, alongside with new regulatory and incentive schemes for hydrogen.
The ultimate goal of this analysis is to foster connections among existing and planned projects, stimulate new initiatives along the entire hydrogen value chain, grow awareness in stakeholders about hydrogen, and promote cooperation and international competitiveness.
| Marta Gandiglio; Paolo Marocco | Energy; Energy Storage; Fuels - Energy Science; Power | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65f335cd66c1381729fe7c40/original/mapping-hydrogen-initiatives-in-italy-an-overview-of-funding-and-projects.pdf |
60c74f160f50db08b2397330 | 10.26434/chemrxiv.12801164.v2 | Lanthanide Complexes with a Tripodal Nitroxyl Radical Showing Strong Magnetic Coupling | A series of isomorphous mononuclear complexes of Ln(III) ions comprising one stable
tripoidal oxazolidine nitroxyl radical were obtained in acetonitrile media
starting from nitrates. The compounds, [LnRad(NO<sub>3</sub>)<sub>3</sub>]
(Ln = Gd, Tb, Dy, Tm, Y; Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl),
have molecular structure. Their coordination
polyhedron, LnO<sub>7</sub>N<sub>2</sub>,
can be described as a tricapped trigonal prism with symmetry close to <i>D</i><sub>3h</sub>. The value of 23 cm<sup>-1</sup> for the
antiferromagnetic coupling Gd-Rad established from the <i>DC</i> magnetic and EPR data is a record strength for the complexes of
4f-elements with nitroxyl radicals. The terbium derivative displays
frequency-dependent out-of-phase signals in zero field indicating
single-molecule magnetic behavior with an effective barrier of 57 cm<sup>-1</sup>. | Mauro Perfetti; Andrea Caneschi; Taisiya S. Sukhikh; Kira E. Vostrikova | Lanthanides and Actinides; Magnetism; Transition Metal Complexes (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f160f50db08b2397330/original/lanthanide-complexes-with-a-tripodal-nitroxyl-radical-showing-strong-magnetic-coupling.pdf |
6733c043f9980725cffb80cf | 10.26434/chemrxiv-2024-nwlrm | Earth-abundant manganese nitride catalysts for mild-condition ammonia synthesis | Developing advanced catalytic materials for mild-condition ammonia (NH3) synthesis is essential for improving the energy efficiency of this key industrial process. Here, we report a ζ-phase manganese-nitride (MnN0.43) catalyst for low-temperature NH3 synthesis. The as-synthesized MnN0.43 catalyst is protected by a carbon shell, allowing for storage and processing of the air-sensitive metal nitride under ambient conditions. After activation in situ, the MnN0.43 catalyst exhibits high activity for NH3 synthesis at 250-350 °C, surpassing the conventional noble metal based Ru/MgO catalyst. A combination of kinetic, chemisorption and computational studies indicate that a nitrogen vacancy-mediated associative mechanism accounts for the catalytic enhancements. Our work highlights the great potential of earth-abundant transition metal nitrides for catalyzing mild-condition NH3 synthesis. | Weiye Qu; Pranav Roy; Canhui Wang; Fan Bu; Xinsui Zhang; Zimin He; Michael Tsapatsis; Brandon C. Bukowski; Chao Wang | Materials Science; Catalysis; Chemical Engineering and Industrial Chemistry; Catalysts; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6733c043f9980725cffb80cf/original/earth-abundant-manganese-nitride-catalysts-for-mild-condition-ammonia-synthesis.pdf |
63925182836ceb4de7795418 | 10.26434/chemrxiv-2022-3nvmg | Inkjet Printing of All Aqueous Inks to Flexible Microcapacitors for High-Energy Storage | Due to the low energy density of commercial printable dielectrics, printed capacitors occupy a significant printing area and weight in fully printed electronics. It has long remained challenging to develop novel dielectric materials with printability and high energy-storage density. Here, we present the inkjet printing of all aqueous colloidal inks to dielectric capacitors composed of carbon nanotube electrodes and polyvinylidene fluoride (PVDF)-based dielectrics. The formulated dielectric ink is composed of PVDF latex particles coated by protonated chitosan molecules. Beyond the isoelectric point, the ink demonstrates excellent printability and film-forming properties. Chitosan serves as a strong binder to largely improve the printed film quality yet it introduces charged species. To confine the transport of these mobile charges, the printed PVDF@Chitosan layer was interlayered by a boron nitride nanosheet nanolayer. This layer is perpendicular to the electric field and serves as an efficient barrier to block the transport and the avalanche of charges, eventually leading to a recoverable energy density of 15 J/cm3 at 610 MV/m. This energy density represents the highest value among the waterborne dielectrics. It is also superior to most of the state-of-the-art printed dielectric materials from solvent-based formulations. | Junjin Che; Cécile Zakri; Maxime Bronchy; Isabelle Ly; Wilfrid Neri; Philippe Poulin; Jinkai Yuan | Materials Science; Polymer Science; Energy; Composites; Materials Processing; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2022-12-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63925182836ceb4de7795418/original/inkjet-printing-of-all-aqueous-inks-to-flexible-microcapacitors-for-high-energy-storage.pdf |
65a7b2ac9138d231611f6e06 | 10.26434/chemrxiv-2023-9zj33-v2 | How much water is there within calcium silicate hydrates? Probing water dynamics by Inelastic Neutron Scattering and Molecular Dynamics Simulations | Calcium silicate hydrate (C-S-H) is a disordered, nanocrystalline material acting as the primary binding phase in Portland cement. Thin films of water are present on the surfaces and inside the nanopores of C-S-H and related phases such as calcium-aluminum-silicate-hydrate (C-A-S-H), an Al-bearing substitute present in low-CO2 C-S-H cement. These water films control many of the chemical and mechanical properties of C-S-H, including drying shrinkage, ion transport, creep, and thermal behavior. Therefore, obtaining a fundamental understanding of their properties is essential. In this work, we have applied a combination of inelastic incoherent neutron scattering and molecular dynamics simulation methods to unravel the dynamics of water in synthetic C-(A)-S-H samples conditioned at five hydration states (from dry to fully hydrated) and with three different Ca/Si ratios (0.9, 1, and 1.3). Our results converge towards a picture where the evolution from thin layers of adsorbed water to bulk capillary water is dampened by the structure of C-(A)-S-H, in particular by the availability of Ca2+ sites which tend to keep the water in the form of structured surface layers. | Zhanar Zhakiyeva; Valérie Magnin; Agnieszka Poulain; Sylvain Campillo; María Pilar Asta; Rogier Besselink; Stéphane Gaboreau; Francis Claret; Sylvain Grangeon; Svemir Rudic; Stéphane Rols; Mónica Jiménez-Ruiz ; Ian C. Bourg; Alexander E.S. Van Driessche; Gabriel J. Cuello; Alejandro Fernandez-Martinez | Physical Chemistry; Materials Science; Chemical Engineering and Industrial Chemistry; Nanostructured Materials - Materials; Interfaces; Physical and Chemical Properties | CC BY NC 4.0 | CHEMRXIV | 2024-01-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a7b2ac9138d231611f6e06/original/how-much-water-is-there-within-calcium-silicate-hydrates-probing-water-dynamics-by-inelastic-neutron-scattering-and-molecular-dynamics-simulations.pdf |
6790de246dde43c908c1ca90 | 10.26434/chemrxiv-2025-ttn8k | Functional porous carbons derived from novel alkali metal-based coordination polymers for energy storage | The application of alkali metal-based coordination polymers as precursors to novel porous materials for energy storage appears as a very promising, but yet essentially unexplored approach. We provide comprehensive investigations of the alkali metal (Li, Na, K)-based coordination polymers with 1,3,5-benzenetricarboxylate as an organic linker, which revealed a variety of 2D and 3D coordination networks accessible in mild conditions and aqueous environment. The resulting coordination polymers were applied as self-templating precursors to porous carbon materials with hierarchical porosity, which exhibited BET areas up to 1871 m2/g. Furthermore, the developed porous carbons were applied as supercapacitors and aqueous Zn-ion capacitors (AZICs), which showed promising capacity, as well as high cyclic stability and rate capability. In particular, the top-performing device, prepared using the carbon material developed from the K-based coordination polymer, achieved one of the highest performances reported for AZICs, exhibiting a remarkable specific capacity of 754.7 F g-1 at 0.1 A g-1. | Michał Leszczyński; Maria Kochaniec; Michał Terlecki; Iwona Justyniak; Selay Aydin Sahin; Busra Aydogdu; Recep Yuksel; Marcin Hołdyński; Władysław Wieczorek; Janusz Lewiński | Inorganic Chemistry; Energy; Coordination Chemistry (Inorg.); Energy Storage; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2025-01-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6790de246dde43c908c1ca90/original/functional-porous-carbons-derived-from-novel-alkali-metal-based-coordination-polymers-for-energy-storage.pdf |
67cad70081d2151a027dcfb0 | 10.26434/chemrxiv-2025-8jrzf | π-π Interactions supporting outer-sphere hydride transfer – A new direction in metal-ligand cooperativity | A series of new phosphine-free Ru(II)-CNC complexes with benzimidazolylidenes have been found to have the unique ability to operate via inner-sphere and outer-sphere mechanisms at different stages of the same catalytic cycle. All new complexes have been characterised using multinuclear NMR spectroscopy and mass analyses while the solid-state structure of 1a has been determined using single-crystal X-ray diffraction technique. The new complexes serve as excellent catalysts for α-alkylation of ketones using primary alcohols. DFT calculations reveal these systems follow an inner-sphere mechanism for the alcohol dehydrogenation step, but the subsequent hydrogenation of the enone proceeds via an outer-sphere mechanism. An unprecedented crossover between inner- and outer-sphere mechanisms was observed to occur via structural rearrangement of the Ru-hydride intermediates. The outer-sphere path is found to be supported by π-π interaction between the extended aromatic ring system of the benzimidazolylidene-based CNC-ligand and aromatic rings of the substrates in a new, unprecedented case of metal-ligand cooperativity. | Ashu Singh; Vishal Jaiswal; Shilpi Misra; Amrendra K. Singh | Theoretical and Computational Chemistry; Catalysis; Organometallic Chemistry; Homogeneous Catalysis; Kinetics and Mechanism - Organometallic Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2025-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67cad70081d2151a027dcfb0/original/interactions-supporting-outer-sphere-hydride-transfer-a-new-direction-in-metal-ligand-cooperativity.pdf |
65e9ce1f9138d23161f10e5a | 10.26434/chemrxiv-2024-76908 | Correlation Clustering Imaging: A method for Functional Mapping of Semiconductor materials and photovoltaic devices in operando | Understanding the relationship between the active material's structure and function in operational devices is key for the rational engineering of the next generation of devices. However, this has proven elusive due to the invasiveness of structural characterization methods and their inability to penetrate the multi-layered device. Here, we introduce a Correlation Clustering Imaging Method (CLIM) based on photoluminescence microscopy. CLIM offers insights into structural and functional aspects related to carrier transport, defects, and recombination losses in operational photovoltaic devices. Our study reveals the presence of "blinking" phenomena in high-quality semiconductor films and their corresponding devices. CLIM demonstrates that highly correlated clusters correspond precisely to grain structures of perovskite layer on glass observed with SEM. Importantly, we find that the perovskite layer in photovoltaic devices exhibits predominant blinking during specific operational conditions. The correlated regions within devices are notably larger than those on bare substrate, indicating different microstructures likely caused by the transport layer at the interface. CLIM's contrast opens new possibilities in optical microscopy for functional imaging of materials and in-operando device, enabling the rational design and optimization of high-efficiency photovoltaic devices. | Boris Louis; Sudipta Seth; Qingzhi An; Ran Ji; Yana Vaynzof; Johan Hofkens; Ivan Scheblykin | Materials Science; Nanoscience; Energy; Hybrid Organic-Inorganic Materials; Thin Films; Photovoltaics | CC BY 4.0 | CHEMRXIV | 2024-03-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65e9ce1f9138d23161f10e5a/original/correlation-clustering-imaging-a-method-for-functional-mapping-of-semiconductor-materials-and-photovoltaic-devices-in-operando.pdf |
60c7463fee301c49f7c794a5 | 10.26434/chemrxiv.11214914.v1 | Descriptors for Electron and Hole Charge Carriers in Metal Oxides | <div>
<div>
<div>
<p>Metal oxides can act as insulators, semiconductors or metals depending on their
chemical composition and crystal structure. Metal oxide semiconductors, which support equilibrium populations of electron and hole charge carriers, have widespread
applications including batteries, solar cells, and display technologies. It is often difficult to predict in advance whether these materials will exhibit localized or delocalized
charge carriers upon oxidation or reduction. We combine data from first-principles
calculations of the electronic structure and dielectric response of 214 metal oxides to
predict the energetic driving force for carrier localization and transport. We assess descriptors based on the carrier effective mass, static polaron binding energy, and Frohlich
electron–phonon coupling. Numerical analysis allows us to assign p and n type transport of a metal oxide to three classes: (i) band transport with high mobility; (ii) small
polaron transport with low mobility; and (iii) intermediate behaviour. The results of
this classification agree with observations regarding carrier dynamics and lifetimes and
are used to predict 10 candidate p-type oxides.
</p>
</div>
</div>
</div> | Daniel Davies; Christopher Savory; Jarvist Moore Frost; David Scanlon; Benjamin Morgan; Aron Walsh | Solid State Chemistry; Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7463fee301c49f7c794a5/original/descriptors-for-electron-and-hole-charge-carriers-in-metal-oxides.pdf |
60c758b1bdbb8972cba3adf0 | 10.26434/chemrxiv.14578497.v1 | Material Screening for Gas Sensing using an Electronic Nose: Gas Sorption Thermodynamic and Kinetic Considerations | To detect multiple gases in a mixture, one must employ an electronic nose or sensor array, composed of several materials as a single material cannot resolve all the gases in a mixture accurately. Given the many candidate materials, choosing the right combination of materials to be used in an array is a challenging task. In a sensor whose sensing mechanism depends on a change in mass upon gas adsorption, both the equilibrium and kinetic characteristics of the gas-material system dictate the performance of the array. The overarching goal of this work is two-fold. First, we aim to highlight the impact of thermodynamic characteristics of gas-material combination on array performance and to develop a graphical approach to rapidly screen materials. Second, we aim to highlight the need to incorporate the gas sorption kinetic characteristics to provide an accurate picture of the performance of a sensor array. To address these goals, we have developed a computational test bench that incorporates a sensor model and a gas composition estimator. To provide a generic study, we have chosen, as candidate materials, hypothetical materials that exhibit equilibrium characteristics similar to metal organic frameworks (MOFs). Our computational studies led to key learnings, namely: (1) exploit the shape of the sensor response as a function of gas composition for material screening purposes for gravimetric arrays; (2) incorporate both equilibrium and kinetics for gas composition estimation in a dynamic system; and (3) engineer the array by accounting for the kinetics of the materials, the feed gas flow rate, and the size of the device. | Ashwin Kumar Rajagopalan; Camille Petit | Sensors | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c758b1bdbb8972cba3adf0/original/material-screening-for-gas-sensing-using-an-electronic-nose-gas-sorption-thermodynamic-and-kinetic-considerations.pdf |
62ad062b3f333ea86a73f955 | 10.26434/chemrxiv-2022-pwtdx-v2 | Simultaneous Processing of Antagonistic Chemical Events (SPACE): An Atroposelective Dynamic Kinetic Resolution of MRTX1719 | A high-yielding protocol for atropisomeric resolution was developed by rectifying inherent incompatibilities between crystallization and epimerization via continuous processing. Application toward synthesis of MRTX1719, a densely functionalized active pharmaceutical ingredient (API), improved yield from 37% to 87%. This protocol provides a complementary means to access rotamers which challenge current asymmetric methodologies, and greatly improves sustainability by decreasing consumption of solvent and advanced synthetic intermediates. | Michal Achmatowicz; Cheng-yi Chen; David Snead | Organic Chemistry; Chemical Engineering and Industrial Chemistry; Process Chemistry; Stereochemistry; Pharmaceutical Industry | CC BY 4.0 | CHEMRXIV | 2022-06-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62ad062b3f333ea86a73f955/original/simultaneous-processing-of-antagonistic-chemical-events-space-an-atroposelective-dynamic-kinetic-resolution-of-mrtx1719.pdf |
6478611be64f843f41224869 | 10.26434/chemrxiv-2023-twzgh-v2 | Europium(III)/Terbium(III) mixed metal-organic frameworks and their application as a ratiometric thermometer | The ability to molecularly engineer luminescent metal-organic frameworks is a powerful tool for the design of better performing rational temperature sensors. Lanthanide based MOF stand out as luminescent temperature sensors due to the high luminescence intensity and sharp emission lines of the lanthanides. The use of two different lanthanide cations incorporated into the same MOF structure is supposed to allow for a rational, that is self-referencing, temperature sensing. Here, we present series of mixed EuxTb(1-x)BTC, which were designed as nanoparticles. The EuxTb(1-x)BTC series shows controllable luminescent properties, which depend on the solvation of the lanthanide. The two MOFs in the series with the lowest Eu content, i.e. Eu0.04Tb0.96BTC and Eu0.02Tb0.98BTC, are suitable candidates for rational temperature sensing in the range between 200 and 270 K and above 300 K. | Madhura Joshi; Zhuang Wang; Florian M. Wisser; Maurizio Riesner; Rebecca Reber; Marcus Fischer; Rachel Fainblat; Karl Mandel; Doris Segets; Gerd Bacher; Martin Hartmann | Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6478611be64f843f41224869/original/europium-iii-terbium-iii-mixed-metal-organic-frameworks-and-their-application-as-a-ratiometric-thermometer.pdf |
63496711e79b3f9a18e90c7b | 10.26434/chemrxiv-2022-hjx8v | Tb3+ Photophysics: Mapping the radiative and non-radiative transition probabilities of [Tb(H2O)9]3+ using molecular photophysics | The study of optical transitions in lanthanides has evolved separately from molecular photophysics. However, the forbidden transitions can be accurately described using the framework developed in molecular photophysics. In this study, a detailed photophysical characterization of the [Tb(H2O)9]3+ aqua ion was performed. The luminescence quantum yield (Φlum), excited state lifetime (τ), radiative (kr ≡ A) and non-radiative (knr) rate constant and oscillator strength (f) was determined for Tb(CF3SO3)3 in H2O/D2O mixtures in order to map the radiative and non-radiative transition probabilities. It was shown that the intense luminescence observed from Tb3+ compared to other Ln3+ is not due to a higher radiative transition probability but rather due to a lack of quenching, quantified by a contribution to knr from O-H oscillators in the aqua ion of kq(OH) = 2090 s-1 for terbium and kq(OH) = 8840 s-1 for europium. Further, the Horrocks method of determining inner-sphere solvent molecules has been revisited, and it was concluded that the coordination number of Tb3+ in aqueous solution is 9. | Nicolaj Kofod; Thomas Just Sørensen | Physical Chemistry; Inorganic Chemistry; Coordination Chemistry (Inorg.); Lanthanides and Actinides; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-10-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63496711e79b3f9a18e90c7b/original/tb3-photophysics-mapping-the-radiative-and-non-radiative-transition-probabilities-of-tb-h2o-9-3-using-molecular-photophysics.pdf |
66693103409abc034533ad26 | 10.26434/chemrxiv-2024-6l0sh | A Carrier-free Peptide Co-assembled System with Synergistic Antitumor Effect Combines Immunotherapy and Sonodynamic Therapy | Blocking programmed cell death ligand 1 (PD-L1) in tumor cells is an effective therapy strategy to achieve immune system activation for tumor therapy, however only a few patients can benefit from it. Development of synergistic therapy with checkpoint PD-L1 blockade immunotherapy is beneficial to enhance antitumor effect. Herein, we constructed a carrier-free system EH@Ag2S co-assembled by peptide nanofiber and Ag2S nsanoparticles to achieve a superadditive (1 + 1 > 2) antitumor effect. EH nanofiber can block PD-L1, and Ag2S can produce reactive oxygen species (ROS) under ultrasound irradiation and induce cell apoptosis. Further, in vivo mice experiment also confirmed the high efficiency of this carrier-free co-assembled system in successfully inducing anti-tumor response while inhibiting tumor growth. We believe that this highly bioavailable and multifunctional therapeutic system may become a promising nanoplatform for tumor therapy. | Weizhi Wang; Limin Zhang | Nanoscience; Nanostructured Materials - Nanoscience | CC BY 4.0 | CHEMRXIV | 2024-06-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66693103409abc034533ad26/original/a-carrier-free-peptide-co-assembled-system-with-synergistic-antitumor-effect-combines-immunotherapy-and-sonodynamic-therapy.pdf |
65aabbdc9138d231614d0d37 | 10.26434/chemrxiv-2024-09h35 | Tricyclononenes and Tricyclononadienes as Efficient Monomers for ROMP: Understanding Structure–Propagation Rate Relationships and Enabling Facile Post-Polymerization Modification | Grubbs 3rd-generation (G3) pre-catalyst-initiated ring-opening metathesis polymerization (ROMP) remains an indispensable tool in the polymer chemist’s toolbox. Tricyclononenes (TCN) and tricyclononadienes (TCND) represent under-explored classes of monomers for ROMP—especially for G3-initiated ROMP—that have the potential to both advance fundamental knowledge (structure-polymerization kinetics relationships) and serve as practical tools for the polymer chemist (post-polymerization functionalization). In this work, a library of TCN and TCND imides, monoesters, and diesters, along with their exo-norbornene counterparts, were synthesized to compare their behavior in G3-initiated ROMP. Real-time 1H NMR was used to study their polymerization kinetics; propagation rates were extracted for each monomer. To understand the relationship between monomer structure and ROMP propagation rate, density functional theory methods were used to calculate a variety of electronic and steric parameters for the monomers. While electronic parameters (e.g., HOMO energy levels) correlated positively with the measured kp values, steric parameters generally gave improved correlations, which indicates that monomer size and shape are better predictors for kp than electronic parameters for this data set. Furthermore, the TCND diester—which contains an electron-deficient cyclobutene that is resistant to ROMP—and its polymer p(TCND) are shown to be highly reactive toward DBU-catalyzed conjugate addition with thiols, providing a protecting/activating-group free strategy for post-polymerization modification. | Landon Kilgallon; Timothy McFadden; Matthew Sigman; Jeremiah Johnson | Organic Chemistry; Polymer Science; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-01-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65aabbdc9138d231614d0d37/original/tricyclononenes-and-tricyclononadienes-as-efficient-monomers-for-romp-understanding-structure-propagation-rate-relationships-and-enabling-facile-post-polymerization-modification.pdf |
652fdd902431cc1dacd07078 | 10.26434/chemrxiv-2023-t58lb-v3 | Quantifying and modulating protein encapsulation in guanosine-based supramolecular particles | The encapsulation of proteins is an effective way to preserve their structure and enhance their function. One exciting possibility is adjusting the protective agent to match the specific protein's characteristics to influence its properties. In a recent study, we developed a flow cytometry-based method to quantify the encapsulation of small molecule dyes in colloidal particles made from guanosine derivatives (SHS particles). We aimed to determine if this method could quantify protein encapsulation and track changes and if proteins could be tuned to bind to these particles. Our results showed that FITC-labeled proteins had apparent association constants in the micromolar range, with hydrophobicity as the dominant factor enhancing the affinities. Confocal laser scanning microscopy imaging supported these results and provided additional information about protein distribution within the particles. We also tested the feasibility of tuning avidin affinity (AVI) for SHS particles with a biotin ligand. We found that increasing the amount of biotin initially enhanced AVI binding, but then reached saturation, which we hypothesize results from non-covalent cross-linking caused by strong biotin/AVI interactions. CLSM images showed that the linker also impacted AVI distribution within the particles. Our strategy provides an advantage over other methods for quantifying protein encapsulation by being suitable for high-throughput analysis with high reproducibility. We anticipate that future efforts of using lower affinity ligands would result in better strategies for modulating protein affinity for drug-delivery applications. | Luis A. Prieto-Costas; Génesis R. Rivera-Cordero; Jose M. Rivera | Organic Chemistry; Nanoscience; Bioorganic Chemistry; Supramolecular Chemistry (Org.); Nanostructured Materials - Nanoscience; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652fdd902431cc1dacd07078/original/quantifying-and-modulating-protein-encapsulation-in-guanosine-based-supramolecular-particles.pdf |
636a8c7fb58850d7c1433d80 | 10.26434/chemrxiv-2022-lkzm9 | Anharmonic and entropic stabilisation of cubic zirconia from first principles | Finite-temperature stability of crystals is of continuous importance in solid-state chemistry with many exciting properties only emerging in high-temperature polymorphs. Currently, the discovery of new phases is largely serendipitous due to a lack of computational methods to predict crystal stability with temperature. Conventional methods use harmonic phonon theory, but this breaks down when imaginary phonon modes are present, and anharmonic methods are thus warranted to describe dynamically stabilised phases. We investigate the high-temperature tetragonal-to-cubic phase transition of zirconia based on first-principles anharmonic phonon theory and molecular dynamics simulations as an archetypical example of a phase transition involving a soft phonon mode. It is shown that the stability of cubic zirconia cannot be attributed solely to anharmonic stabilisation, and is thus absent for the pristine crystal. Instead the stabilisation is attributed to spontaneous defect formation which is also responsible for superionic conductivity at elevated temperatures. | Kasper Tolborg; Aron Walsh | Theoretical and Computational Chemistry; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2022-11-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/636a8c7fb58850d7c1433d80/original/anharmonic-and-entropic-stabilisation-of-cubic-zirconia-from-first-principles.pdf |
672cab8e7be152b1d0519fab | 10.26434/chemrxiv-2024-cd3pj | New Isostructural Family of Mixed-Metal Na-M(III)-MOFs Based on Glycolic Acid | A series of new isostructural metal–organic frameworks based on trivalent metal ions (Al, Fe, Ga), Na+ ions and glycolate ions as the linker molecules, denoted as M-CAU-64, with the framework composition [M(III)Na(H2O)2(C2H2O3)2] · x H2O were obtained using high-throughput methods. The crystal structures of the title compounds were determined from single crystal or powder X-ray diffraction data. Thermogravimetric analyses indicate a thermal stability up to 340 °C for Ga-CAU-64, while variable temperature powder X-ray diffraction (VT-PXRD) revealed various structural changes including phase transformations and a rearrangement of the inorganic building unit of CAU-64, associated with the loss of adsorbed water molecules upon thermal treatment. Water sorption measurements confirmed the porosity of the CAU-64 compounds and sorption capacities up to 360 mg/g were found. Furthermore, the synthesis of multivariate MOFs (Alx-Fe1-x-CAU-64) enabled the fine-tuning of both thermal stability and sorption characteristics. | Bastian Achenbach; Christian Näther; Norbert Stock | Inorganic Chemistry; Organometallic Chemistry; Organometallic Compounds; Coordination Chemistry (Organomet.); Materials Chemistry; Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/672cab8e7be152b1d0519fab/original/new-isostructural-family-of-mixed-metal-na-m-iii-mo-fs-based-on-glycolic-acid.pdf |
666a34ba409abc03454679fb | 10.26434/chemrxiv-2024-k0wkb | Automated Flow Synthesis of Artificial Heme Enzymes for Enantioselective Biocatalysis | The remarkable efficiency with which enzymes catalyze small molecule reactions has driven their widespread application in organic chemistry. Here, we employ automated fast-flow solid-phase synthesis to access full-length enzymes without restrictions on the number and structure of non-canonical amino acids incorporated. We demonstrate the total syntheses of Fe-dependent Bacillus subtilis myoglobin (BsMb) and sperm whale myoglobin (SwMb), which displayed excellent enantioselectivity and yield in carbene transfer reactions. Absolute control over enantioselectivity in styrene cyclopropanation was achieved using L- and D-BsMb mutants which delivered each enantiomer of cyclopropane product in identical and opposite enantiomeric enrichment. BsMb mutants outfitted with non-canonical amino acids were used to facilitate detailed structure-activity relationship studies, revealing a previously unrecognized hydrogen-bonding interaction as the primary driver of enantioselectivity in styrene cyclopropanation. | Giulio Fittolani; Dennis A. Kutateladze; Andrei Loas; Stephen L. Buchwald; Bradley L. Pentelute | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Bioengineering and Biotechnology; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/666a34ba409abc03454679fb/original/automated-flow-synthesis-of-artificial-heme-enzymes-for-enantioselective-biocatalysis.pdf |
66c65b87a4e53c48762c3c12 | 10.26434/chemrxiv-2024-n79xj-v2 | Electrochemical Kinetics of Multistep Reactions in General and the HOR/HER on Platinum in Particular | While multistep reactions in electrochemistry are ubiquitous, their analytical treatment has been incomplete and at times misleading. Several misconceptions have led to incorrect conclusions, derailing the analysis of electrochemical processes. In this work we present a rigorous application of the Butler-Volmer model and develop a coherent nomenclature and methodology on how to analyze multistep reactions. We discuss how a universal definition of the exchange current density does not exist for multistep reactions, clarify the meaning of the Tafel slope, often misinterpreted in the electrochemical literature. Eventually we discuss the classically proposed HOR/HER mechanisms on platinum, briefly discuss their origin, show how mass transport effects should be correctly analyzed by introduce a new equation that complements the Koutecký-Levich equation in the micropolarization region. We then perform a thorough experimental investigation of the HOR/HER kinetics over a wide range of combination of cations, anions, concentration, and buffers. There we reveal that buffers seem to take directly part in the HOR/HER and discuss the supposed “cation-effect”. Through the analysis of the micropolarization, Tafel region, and kinetics of the H-upd we propose a new mechanistic description of the HOR/HER with substantial experimental agreement and discuss how anions in the interface play a deciding role in the HOR/HER and H-upd on polycrystalline platinum. | Benedikt Axel Brandes; Christodoulos Chatzichristodoulou | Catalysis; Electrocatalysis | CC BY 4.0 | CHEMRXIV | 2024-08-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66c65b87a4e53c48762c3c12/original/electrochemical-kinetics-of-multistep-reactions-in-general-and-the-hor-her-on-platinum-in-particular.pdf |
66f33755cec5d6c14218886a | 10.26434/chemrxiv-2024-h08x5-v2 | Coupling online size exclusion chromatography with charge detection-mass spectrometry using Hadamard transform multiplexing | Charge detection mass spectrometry (CD-MS) is a powerful technique for the analysis of large, heterogeneous biomolecules. By directly measuring the charge states of individual ions, CD-MS can measure the masses from spectra where conventional deconvolution approaches fail due to the lack of isotopic resolution or distinguishable charge states. However, CD-MS is inherently slow because hundreds or thousands of spectra need to be collected to produce adequate ion statistics. The slower speed of CD-MS complicates efforts to couple it with online separation techniques, which limit the number of spectra that can be acquired during a chromatographic peak. Here, we present the application of Hadamard transform multiplexing to online size exclusion chromatography (SEC) coupled with Orbitrap CD-MS, with a goal of using SEC for separating complex mixtures prior to CD-MS analysis. We developed a microcontroller to deliver pulsed injections from a large sample loop onto a SEC for online CD-MS analysis. Data showed a series of peaks spaced according to the pseudo-random injection sequence, which were demultiplexed with a Hadamard transform algorithm. The demultiplexed data revealed improved CD-MS signals while preserving retention time information. This multiplexing approach provides a general solution to the inherent incompatibilities of online separations and CD-MS detection that will enable a range of applications. | James Sanders; October Owen; Brian Tran; Jeffrey Mosqueira; Michael Marty | Analytical Chemistry; Biochemical Analysis; Mass Spectrometry; Separation Science | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f33755cec5d6c14218886a/original/coupling-online-size-exclusion-chromatography-with-charge-detection-mass-spectrometry-using-hadamard-transform-multiplexing.pdf |
64db1ea569bfb8925af47f44 | 10.26434/chemrxiv-2023-pr94t | Macroscopic Approach to Cloud Droplet Growth by Condensation - A Study by a semi-real scale Experimental System | Formation and growth of water droplets were studied using a semi-real scale experimental system; the main component of the system was a 430 m vertical shaft used to perform cloud formation experiments at a spatial scale close to that of the real atmosphere. By generating an updraft with humid air, a cloud was observed to form at a height of 35 m from the bottom. The number concentration, and size distribution of water droplets were recorded. In some experiments, NaCl particles were intentionally injected into the air stream to increase the number of condensation nuclei. The effects of this on the number and size distribution of droplets were studied. The droplet growth rate was estimated on the basis of these effects. It was found that in the shaft, the humidity of the air stream was below the saturation level. Thus, macroscopically, condensation and growth proceeded without supersaturation, which is usually assumed in traditional microscopic cloud physics for water droplet growth. The growth process was considered as a chemical reaction to deal with this condition. An attempt was made to obtain information about the rate constant. | utiyama masahiro; fukuyama tsutom | Physical Chemistry; Earth, Space, and Environmental Chemistry | CC BY 4.0 | CHEMRXIV | 2023-08-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64db1ea569bfb8925af47f44/original/macroscopic-approach-to-cloud-droplet-growth-by-condensation-a-study-by-a-semi-real-scale-experimental-system.pdf |
63887b401234cb12642a1b8b | 10.26434/chemrxiv-2022-8bt8r | FeNC Oxygen Reduction Electrocatalyst with High Utilisation Penta-coordinated sites | Atomic Fe in N-doped carbon (FeNC) electrocatalysts for oxygen (O2) reduction at the cathode of proton exchange membrane fuel cells (PEMFCs) are the most promising alternative to platinum-group-metal catalysts. Despite recent progress on atomic FeNC O2 reduction, their controlled synthesis and stability for practical applications remains challenging. A two-step synthesis approach has recently led to significant advances in terms of Fe-loading and mass activity; however, the Fe utilisation remains low owing to the difficulty of building scaffolds with sufficient porosity that electrochemically exposes the active sites. Herein, we addressed this issue by coordinating Fe in a highly porous nitrogen doped carbon support (~3295 m2 g-1), prepared by pyrolysis of inexpensive 2,4,6-triaminopyrimidine and a Mg2+ salt active site template and porogen. Upon Fe coordination, a high electrochemical active site density of 2.54×10^19 sites gFeNC-1 and a record 52% FeNx electrochemical utilisation based on in situ nitrite stripping was achieved. The Fe single atoms are characterised pre- and post-electrochemical accelerated stress testing by aberration-corrected high-angle annular dark field scanning transmission electron microscopy, showing no Fe clustering. Moreover, ex situ X-ray absorption spectroscopy and low-temperature Mössbauer spectroscopy suggest the presence of penta-coordinated Fe sites, which were further studied by density functional theory calculations. | Jesus Barrio; Angus Pedersen; Saurav Ch. Sarma; Alexander Bagger; Mengjun Gong; Silvia Favero; Chang-Xin Zhao; Ricardo Garcia-Serres; Alain You Li; Qiang Zhang; Frédéric Jaouen; Frédéric Maillard; Anthony Kucernak; Ifan E. L. Stephens; Magda Titirici | Catalysis; Energy; Electrocatalysis; Fuel Cells; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2022-12-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63887b401234cb12642a1b8b/original/fe-nc-oxygen-reduction-electrocatalyst-with-high-utilisation-penta-coordinated-sites.pdf |
654fbcfedbd7c8b54b154672 | 10.26434/chemrxiv-2023-hk4dq | Amplifying the Temperature Sensitivity of Zero-Field Splitting in Mn(II) Through Ligand Tuning | Controlling the temperature response of magnetic resonance properties is an essential step toward novel molecular thermome-ters or quantum sensing platforms. To date, however, demonstrations of using molecular design to control the temperature dependence of zero-field splitting (D), a critical property that governs the electron paramagnetic resonance (EPR) response of open-shell molecules, have been absent in the literature. Herein we demonstrate that ligand design can control the temperature dependence of D. To do so, we prepared and analyzed three different encapsulated Mn2+ complexes. High-field, high-frequency EPR spectroscopy reveal EPR spectra for all complexes that vary in width as a function of temperature, indicating a change in D value. At lower temperatures, these temperature sensitivities change substantially with ligand shell and are stark, ranging from 2.2 to 9.8 MHz/K. These results are the first demonstration of the ability to tune the variable-T nature of D via ligand selection in any complex, the first for the Mn2+ metal ion, and demonstrate higher sensitivities than the NV center of diamond (74 kHz/K). | Anthony Campanella; Amanda Gin; Siyoung Sung; Cassidy Jackson; Roxanna Martinez; Andrew Ozarowski; Indrani Bhowmick; Joseph Zadrozny | Inorganic Chemistry; Coordination Chemistry (Inorg.); Magnetism | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/654fbcfedbd7c8b54b154672/original/amplifying-the-temperature-sensitivity-of-zero-field-splitting-in-mn-ii-through-ligand-tuning.pdf |
65aee1afe9ebbb4db9bf4bc4 | 10.26434/chemrxiv-2024-2jvms | Nitrogen-to-Carbon Single Atom Point Mutation of Pyridine N-Oxides | Single-atom editing has emerged as a powerful process for altering molecular structures with precision. Within this growing class of transformations, reactions that replace one atom for another in heterocycles, while desirable, remain limited. We report the development of a transformation that achieves an N-to-C atom swap in pyridine N-oxides utilizing a sulfoxide-derived anion as a carbon source. This ‘point mutation’ exhibits good functional group tolerance and replaces the N-oxide moiety with either unsubstituted, substituted, or isotopically labeled carbon atoms in a single laboratory operation. | Nicholas Falcone; Sam He; John Hoskin; Sandeep Mangat; Erik Sorensen | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2024-01-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65aee1afe9ebbb4db9bf4bc4/original/nitrogen-to-carbon-single-atom-point-mutation-of-pyridine-n-oxides.pdf |
6581bcd09138d231610be057 | 10.26434/chemrxiv-2023-bd24m | Structural Disorder Determines Capacitance in Nanoporous Carbons | The difficulty in characterizing the complex structures of nanoporous carbon electrodes has led to a lack of clear design principles with which to improve supercapacitors. While pore size has long been considered the main lever to improve capacitance, our study of a large series of commercial nanoporous carbons finds a lack of correlation between pore size and capacitance. Instead nuclear magnetic resonance spectroscopy measurements and simulations reveal a strong correlation between structural disorder in the electrodes and capacitance. More disordered carbons with smaller graphene-like domains show higher capacitances due to the more efficient storage of ions in their nanopores. Our findings will stimulate a new wave of research to understand and exploit disorder to achieve highly energy dense supercapacitors. | Xinyu Liu; Dongxun Lyu; Céline Merlet; Matthew Leesmith; Xiao Hua; Zhen Xu; Clare Grey; Alexander Forse | Physical Chemistry; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Spectroscopy (Physical Chem.); Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2023-12-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6581bcd09138d231610be057/original/structural-disorder-determines-capacitance-in-nanoporous-carbons.pdf |
60c73fd7bb8c1a927c3d9c12 | 10.26434/chemrxiv.7496294.v1 | “Lights, Camera, Questions and Answers!”: Talking About Science on Camera | Three video packages taken from on-camera interviews, discussion a range of topics from motivations for choosing careers in science, to discussions of the societal implications of scientific research. | Buddini Karawdeniya; Y.M. Nuwan D.Y. Bandara; Julie Whelan; John Yacano; Marissa DeOliveira; Dana Neugent; Regina Bell; Jason Dwyer | Chemical Education - General | CC BY NC ND 4.0 | CHEMRXIV | 2018-12-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73fd7bb8c1a927c3d9c12/original/lights-camera-questions-and-answers-talking-about-science-on-camera.pdf |
6666a17512188379d8c1080f | 10.26434/chemrxiv-2024-tc9ms | Light-triggered simultaneous release of reactive oxygen species and thymol from mesoporous organosilica particles with potential application in deep tissue | Antibiotic resistance in bacterial pathogens is a global health problem requiring enormous research into alternative, easily accessible antibacterial substances and treatments to replace antibiotics. Components of essential oils (EOs) that possess broad-spectrum antibacterial properties are promising candidates. However, due to their high volatility and low solubility, their administration remains difficult. A promising method is to load materials with the active component and design a triggered release system to avoid rapid exhaustion of the carried material. If such a drug-release system would additionally exhibit antibacterial properties itself, it could significantly advance combatting bacterial infections. Therefore, in the present study, we combine the light-triggered and simultaneous release of the antimicrobial substance thymol with antibacterial photodynamic therapy (aPDT) within one nanoparticle. The irradiation of an immobilized photosensitizer produces reactive oxygen species (ROS) that oxidatively cleave a linker and ultimately releases thymol detected by GC-MS. Antibacterial properties towards Staphylococcus aureus biofilm formation were verified by ATP-based viability assay. To improve the application for deep tissue delivery, we also take into account the low transmittance of visible light. A highly developed trifunctional material enables 2-photon excitation via Förster resonance energy transfer (FRET) and thus shifts the wavelength into the biological window. The release of the third functionality can be monitored in situ by fluorescence microscopy. This model system lays the foundation for future antibacterial materials | Hannah Bronner; Katharina Doll-Nikutta; Sören Donath; Nina Ehlert; Yasar Krysiak; Alexander Heisterkamp; Meike Stiesch; Stefan Kalies; Sebastian Polarz | Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6666a17512188379d8c1080f/original/light-triggered-simultaneous-release-of-reactive-oxygen-species-and-thymol-from-mesoporous-organosilica-particles-with-potential-application-in-deep-tissue.pdf |
6788b23f6dde43c908c81473 | 10.26434/chemrxiv-2024-tvmn2-v3 | Ionic gradients in flow to control the transport of emissive ions | Concentration gradients of simple salts in microfluidic channels control the transport of a common photo-redox catalyst. | Lucy L. Fillbrook; Isis A. Middleton; Hamid Rashidnejad; Aditya Sapre; Ayusman Sen; Jonathon Beves; Timothy Schmidt | Physical Chemistry; Organic Chemistry; Nanoscience; Physical Organic Chemistry; Physical and Chemical Properties | CC BY NC 4.0 | CHEMRXIV | 2025-01-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6788b23f6dde43c908c81473/original/ionic-gradients-in-flow-to-control-the-transport-of-emissive-ions.pdf |
65d51d1066c13817291b16f4 | 10.26434/chemrxiv-2024-9czk6 | In vitro evaluation of the antiparasitic activity of p-coumaric acid prenylated derivatives | We have evaluated eight p-coumaric acid prenylated derivatives in vitro for their antileishmanial activity against Leishmania amazonensis promastigotes and their antischistosomal activity against Schistosoma mansoni adult worms. Compound 7 (methyl 3,5-diprenyl-4-prenyloxycinnamate) was the most active against L. amazonensis (IC50 = 45.92 µM) and S. mansoni (IC50 = 64.25 µM). None of the tested compounds killed S. mansoni adult worms. Data indicated that the number of prenyl groups, the presence of hydroxyl at C9, and a single bond between C7 and C8 are important structural features for the antileishmanial activity of p-coumaric acid prenylated derivatives. | Tatiana Vieira; Júlia Barco; Lucas Paula; Paulo Félix; Jairo Bastos; Lizandra Magalhães; Antônio Crotti | Biological and Medicinal Chemistry; Organic Chemistry; Natural Products; Organic Synthesis and Reactions; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65d51d1066c13817291b16f4/original/in-vitro-evaluation-of-the-antiparasitic-activity-of-p-coumaric-acid-prenylated-derivatives.pdf |
62447a38855ee5f366ddce04 | 10.26434/chemrxiv-2022-24cjb | An Environment-Adaptive and Climate-Responsive MOF Water Harvester with Proven Production of Clean, Drinkable Water | Harvesting water vapor from desert, arid environments by metal-organic framework (MOF) based devices to deliver clean, drinkable liquid water is critically dependent on environment and climate conditions. However, reported devices have yet been developed to adapt in real-time to such conditions during their operation, which severely limits water production efficiency and unnecessarily increases power consumption. Herein, we report and detail a new mode of water harvesting operation, termed ‘adaptive water harvesting’, from which a MOF-based device was proven capable of adapting the adsorption and desorption phases of its water harvesting cycle to climate fluctuations throughout a given day, week, month, and year such that its water production efficiency is continuously optimized. In performance evaluation experiments in a desert, arid climate (17-32% RH), the adaptive water harvesting device achieved a 169% increase in water production (3.5 LH2O kgMOF-1 d-1) when compared to the best-performing, reported active device (0.7 – 1.3 LH2O kgMOF-1 d-1 at 10 – 32% RH), a lower power consumption (1.67 – 5.25 kWh LH2O-1), and saved time by requiring nearly 1.5 cycles less than a counterpart active device. Furthermore, the produced water was demonstrated, for the first time, to meet the national drinking standards of a potential technology-adopting country facing considerable water scarcity challenges (Jordan). | Husam Almassad; Rada Abaza; Lama Siwwan; Bassem Al-Maythalony; Kyle Cordova | Materials Science; Inorganic Chemistry; Coordination Chemistry (Inorg.); Solid State Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62447a38855ee5f366ddce04/original/an-environment-adaptive-and-climate-responsive-mof-water-harvester-with-proven-production-of-clean-drinkable-water.pdf |
60c758ecbb8c1a5c503dcb11 | 10.26434/chemrxiv.14602803.v1 | Correcting Frost Diagram Misconceptions Using Interactive Frost Diagrams | <p>Frost diagrams provide
convenient illustrations of the aqueous reduction potentials and thermodynamic
tendencies of different oxidation states of an element. Undergraduate textbooks
often describe the lowest point on a Frost diagram as the most stable oxidation
state of the element, but this interpretation is incorrect because the
thermodynamic stability of each oxidation state depends on the specific redox
conditions in solution (i.e., the potential applied by the environment or an
electrode). Further confusion is caused by the widespread use of different,
contradictory conventions for labeling the y-axis of these diagrams as either n<i>E</i>°
or −n<i>E</i>°, among other possibilities. To aid in discussing and correcting
these common mistakes, we introduce a series of interactive Frost diagrams that
illustrate the conditional dependence of the relative stabilities of each
oxidation state of an element. We include instructor’s notes for using these interactive
diagrams and a written activity for students to complete using these diagrams.</p> | Kaitlyn Dutton; Mark C. Lipke | Chemical Education - General; Electrochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c758ecbb8c1a5c503dcb11/original/correcting-frost-diagram-misconceptions-using-interactive-frost-diagrams.pdf |
635486391db0bd9075357d2b | 10.26434/chemrxiv-2022-0hd6r | Direct Catalytic Enantioselective Hydrophosphonylation of N-Unsubstituted Ketimines | We report a direct catalytic enantioselective hydrophosphonylation of N-unsubstituted ketimines that affords N-unprotected α-tetrasubstituted α-aminophosphonates without protection/deprotection steps. The reaction is suitable for N-unsubstituted isatin-derived ketimines and N-unsubstituted trifluoromethyl ketimines, affording products in high yields with excellent enantioselectivity. Applications of the reaction and a proposed transition state model are also described. | Koki Yamada; Yuta Kondo; Akihiko Kitamura; Tetsuya Kadota; Hiroyuki Morimoto; Takashi Ohshima | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Homogeneous Catalysis; Organocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/635486391db0bd9075357d2b/original/direct-catalytic-enantioselective-hydrophosphonylation-of-n-unsubstituted-ketimines.pdf |
6646d0d3418a5379b07fe6e3 | 10.26434/chemrxiv-2024-c7539 | New strategies for diversifying steroidal scaffold to generate b17-heterocycle-substituted derivatives from a common readily accessible intermediate | This article presents new strategies for diversifying a steroidal skeleton to access various b17-oxygen heterocycle-substituted scaffolds. Using pregnenolone as the starting building block, a common propargyl alcohol-containing intermediate 1 was accessed in 4 steps, 60% overall yield. This intermediate (1) was subsequently explored in cyclative transformations with the objective to generate various 5- or 6-membered oxygen-containing heterocycles at the C17-position of pregnenolone. As the result of these studies, four different subsets of catalytic conditions were identified to achieve divergent single-step function-alizations of 1 to access furane-substituted scaffold 2 (51% yield), butenolide-containing scaffold 3 (28% yield), and 6-membered lactones 4 (23% yield) and 5 (22% yield). In addition, single-step conversion of 1 into allene-containing product 17 was accomplished by exposing 1 to catalytic phosphines in 34-38% yield. | Ryan Rutkoski; Andrey Firsov; Hongdi Wu; Pavel Nagorny | Organic Chemistry; Bioorganic Chemistry; Organic Compounds and Functional Groups | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6646d0d3418a5379b07fe6e3/original/new-strategies-for-diversifying-steroidal-scaffold-to-generate-b17-heterocycle-substituted-derivatives-from-a-common-readily-accessible-intermediate.pdf |
65bb3b7066c1381729b74047 | 10.26434/chemrxiv-2024-3rdv1 | Accurate Collisional Cross Section Measurement by Multi-pass Cyclic Ion Mobility Spectrometry | Ion mobility-mass spectrometry (IM-MS) is a powerful analytical tool for structural characterization. IM measurement provides collision cross section (CCS) values that facilitate analyte identification. While CCS values can be directly calculated from mobility measurements obtained using drift tube ion mobility spectrometry (DT-IMS), this method has limited mobility resolution due to the practical constraints on the length of the ion drift path. Consequently, DT-IMS cannot differentiate analytes with similar mobilities or resolve fine mobility features of individual ions. Cyclic IMS (cIMS) instruments leverage a cyclic path enabled by traveling wave ion mobility (TWIM) technology and offer increased mobility solution to address this challenge. While TWIM devices must first be calibrated to enable CCS measurements, current calibration strategies are primarily tailored for single-pass analyses. This preference is partly attributed to the challenges associated with multi-pass calibration methods, which require both calibrants and analytes to experience the same number of passes. Achieving this consistency can be complicated due to factors like peak splitting and diffusion, and may not be feasible for on-line IM-MS analyses. A recent report employed average ion velocities obtained from multiple measurements under different separation pathlengths as a pathlength-independent metric for CCS calibration. However, the ability to exploit this averaging approach is limited by observed variation in ion drift time/velocity in these measurements. In this study, we introduce a novel calibration strategy designed for multi-pass cIMS analyses, directly targeting the root cause for the pathlength- and mobility-dependent variations in ion drift time. With this method, we demonstrate that CCS values derived from multi-pass measurements closely align with those obtained from single-pass analyses, with an average deviation of 0.1%. We apply this method to characterize four isomeric trisaccharides. Our approach not only results in excellent agreement between our measured cIMSCCS values and the reported DTCCS values, with an average difference of only 0.5%, but also allows us to effectively identify subtle mobility characteristics of each compound and determine their respective CCS values. This level of detail and accuracy was previously unattainable using DT-IMS or single-pass cIMS measurements. We developed an algorithm for reconstructing arrival time distribution in cases where wrap-around has resulted in peak splitting. Collectively, the new calibration strategy and the reconstruction procedure maintain reproducibility and precision in CCS measurements while largely eliminating the need for meticulous selection of separation times. We expect that our method will empower researchers to harness the high mobility resolution offered by multi-pass cIMS analyses without compromising the accuracy of CCS measurement, making it appropriate for straightforward use across a wide range of applications. | Chaoshuang Xia; Elias Mernie; Joseph Zaia; Catherine Costello; Cheng Lin | Analytical Chemistry; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65bb3b7066c1381729b74047/original/accurate-collisional-cross-section-measurement-by-multi-pass-cyclic-ion-mobility-spectrometry.pdf |
60c7463bbdbb892db0a38ba8 | 10.26434/chemrxiv.11105576.v1 | Zn Doping Induced Band Gap Widening of Ag2O Nanoparticles | <p>The present investigation widens the
narrow bandgap of Ag<sub>2</sub>O to make it a semiconductor with more
attractive properties. A typical hydrothermal synthesis procedure was used to prepare
Zn doped Ag<sub>2</sub>O nanoparticles. The X-ray diffraction analysis of the
prepared powder samples showed that the lattice parameters of Ag<sub>2</sub>O
increase with doping, indicating the occupation
of interstitial positions by the dopant atoms. Density functional theory
calculations also demonstrated the expansion of the Ag<sub>2</sub>O crystal
lattice with the dopant at an interstitial location. The bandgap of the Ag<sub>2</sub>O
increases to 1.65 eV for 5-mole percent doping. The doped Ag<sub>2</sub>O
nanoparticles photocatalytically degrade methyl orange under aerobic visible
light conditions. It appears that the rise in the percentage of higher valence Zn
doping converts the originally p-type to an n-type semiconductor.</p> | Arup Kumar De; Sourav Majumdar; Shaili Pal; Sunil Kumar; Indrajit Sinha | Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7463bbdbb892db0a38ba8/original/zn-doping-induced-band-gap-widening-of-ag2o-nanoparticles.pdf |
64860c9be64f843f41a41398 | 10.26434/chemrxiv-2023-3qrhl | Ultra-sparse View X-ray Computed Tomography for 4-D Imaging | X-ray Computed Tomography (CT) is a non-invasive, non-destructive approach to imaging materials, material systems and engineered components in two- and three- dimensions. Acquisition of 3D images requires the collection of hundreds or thousands of through-thickness X-ray radiographic images from different angles. Such 3D data acquisition strategies commonly involve sub-optimal temporal sampling for in situ and operando studies (4D imaging). Herein, we introduce a sparse-imaging approach, Tomo-NeRF, which is capable of reconstructing high-fidelity 3D images from <10 two-dimensional radiographic images. Experimental 2D and 3D X-ray images were used to test the reconstruction capability in two-view, four-view, and six-view scenarios. Tomo-NeRF is capable of reconstructing 3D images with a structural similarity of 0.9971-0.9975 and voxel-wide accuracy of 81.83–89.59% from 2-D experimentally obtained images. The reconstruction accuracy for the experimentally obtained images is less than the synthetic structures which demonstrated a similarity of 0.9973-0.9984 and voxel-wise accuracy of 84.31-95.77% | Kelsey Hatzell; Yanjie Zheng | Materials Science | CC BY 4.0 | CHEMRXIV | 2023-06-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64860c9be64f843f41a41398/original/ultra-sparse-view-x-ray-computed-tomography-for-4-d-imaging.pdf |
65a6f6f3e9ebbb4db9510a74 | 10.26434/chemrxiv-2024-rbbnk | SHP-1 Variants Broaden the Understanding of pH-Dependent Activities in Protein Tyrosine Phosphatases | The protein tyrosine phosphatase (PTP) SHP-1 plays an important role in both immune regulation and oncogenesis. This enzyme is part of a broader family of PTPs that all play important regulatory roles in vivo. Common to these enzymes is a highly conserved aspartic acid (D421 in SHP-1) that acts as an acid/base catalysis during the PTP-catalyzed reaction. This residue is located on a mobile loop, the WPD-loop, the dynamical behavior of which is intimately connected to catalytic activity. The SHP-1 WPD-loop variants H422Q, E427A, and S418A have been kinetically characterized and compared to the WT enzyme. These variants exhibit limiting magnitudes of kcat ranging from 43% to 77% of the WT enzyme. However, their pH profiles are significantly broadened in the basic pH range. As a result, above pH 6 the E427A and S418A variants have notably higher turnover numbers than WT SHP-1. Molecular modeling results indicate that the shifted pH dependencies result primarily from changes in solvation and hydrogen-bonding networks that affect the pKa of the D421 residue, explaining the changes in pH-rate profiles for kcat on the basic side. In contrast, a previous study of a noncatalytic residue variant of the PTP YopH, which also exhibited changes in pH dependency, showed that catalytic change arose from mutation-induced changes in conformational equilibria of the WPD-loop. That finding, and the present study, show the existence of distinct strategies for nature to tune the activity of PTPs in particular environments through controlling the pH-dependency of catalysis. | Ruidan Shen; Alfie-Louise Brownless; Nikolas Alansson; Marina Corbella; Shina Caroline Lynn Kamerlin; Alvan Hengge | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Biochemistry; Biophysics; Theory - Computational | CC BY 4.0 | CHEMRXIV | 2024-01-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a6f6f3e9ebbb4db9510a74/original/shp-1-variants-broaden-the-understanding-of-p-h-dependent-activities-in-protein-tyrosine-phosphatases.pdf |
646fcc49be16ad5c57e928b3 | 10.26434/chemrxiv-2023-dghwg | Ni-Catalyzed Linearizable Cyclization/Alkylmetal Interception with Silicon-Oxygen as a Detachable Linker: Regioselective Access to 1,2-Oxasilolane Heterocycles, 3-Hydroxysilanes and 4-Arylalkanols | We disclose a Ni-catalyzed cyclization/alkylmetal interception reaction in which products are readily linearized to permit regiodefined alkene dicarbofunctionalization. This method offers a convenient route to access 1,2-oxasilolane heterocycles, 3-hydroxysilanes and 4-arylalkanols with the formation of C(sp3)-C(sp3) bonds at primary and secondary alkyl carbon centers. In this reaction, a silicon-oxygen (Si-O) bond functions as a detachable linker that can be delinked with several hydride, alkyl, aryl and vinyl nucleophiles to create profusely functionalized 3-hydroxysilanes. A silicon motif in the cyclic C(sp3)-Si-O construct in 1,2-oxasilolane heterocycles can also be selectively deleted by Pd-catalyzed hydrodesilylation affording Si-ablated linear alcohol products reminiscent of vicinal ethylene dicarbofunctionalization with C(sp3) and C(sp2) carbon sources. | Margaret G. Lakomy; Ava C. Del Rio; Ramesh Giri | Catalysis; Homogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2023-05-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/646fcc49be16ad5c57e928b3/original/ni-catalyzed-linearizable-cyclization-alkylmetal-interception-with-silicon-oxygen-as-a-detachable-linker-regioselective-access-to-1-2-oxasilolane-heterocycles-3-hydroxysilanes-and-4-arylalkanols.pdf |
63db7b2be136d9bc552935d3 | 10.26434/chemrxiv-2023-ssv30 | Precise, orthogonal remote-control of cell-free systems using photocaged nucleic acids | Cell-free expression of a gene to protein has become a vital tool in nanotechnology and synthetic biology. Remote-control of cell-free systems with multiple, orthogonal wavelengths of light would enable precise, non-invasive modulation, opening many new applications in biology and medicine. While there has been success in developing ON switches, the development of OFF switches has been lacking. Here, we have developed orthogonally light-controlled cell-free expression OFF switches by attaching nitrobenzyl and coumarin photocages to antisense oligonucleotides. These light-controlled OFF switches can be made from commercially available oligonucleotides and show a tight control of cell-free expression. Using this technology, we have demonstrated orthogonal degradation of two different mRNAs, depending on the wavelength used. By combining with our previously generated blue light-activated DNA template ON switch, we were able to start transcription with one wavelength of light and then halt the translation of the corresponding mRNA to protein with a different wavelength, at multiple timepoints. This precise, orthogonal ON and OFF remote-control of cell-free expression will be an important tool for the future of cell-free biology, especially for use with biological logic gates and synthetic cells. | Giacomo Mazzotti; Denis Hartmann; Michael Booth | Biological and Medicinal Chemistry; Organic Chemistry; Photochemistry (Org.); Bioengineering and Biotechnology; Chemical Biology | CC BY 4.0 | CHEMRXIV | 2023-02-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63db7b2be136d9bc552935d3/original/precise-orthogonal-remote-control-of-cell-free-systems-using-photocaged-nucleic-acids.pdf |
64e5827ddd1a73847f53d793 | 10.26434/chemrxiv-2023-7btwh-v2 | Functional polythioamides derived from thiocarbonyl fluoride | Polythioamide is a unique type of sulfur-containing polymers with advanced functionalities. However, current synthetic approaches based on elemental sulfur, which could easily react with unsaturated functional groups, restrict the choice of substrates. Inspired by the highly efficient sulfur-fluoride exchange (SuFEx) polymerization through discrete hubs, we here report a novel and general method for the synthesis of polythioamides from diboronic acids, secondary diamines, and thiocarbonyl fluoride as the connective hub. Well-defined structures, including previously inaccessible unsaturated substrates, were realized. The polythioamides can efficiently and selectively bind to metal ions and were applied in precious metal recovery. Further development results in PdII-crosslinked single-chain nanoparticles acting as a recyclable homogeneous catalyst, demonstrating promising applications of these unprecedented polythioamides. We anticipate that thiocarbonyl fluoride could be a powerful hub for the challenging synthesis of sulfur-containing polymers. | Haonan Xiang; Jieping Wang; Zihao Guo; Yucong Chen; Beihan Jiang; Sitao Ye; Wenbin Yi | Polymer Science; Polymerization (Polymers) | CC BY NC 4.0 | CHEMRXIV | 2023-08-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e5827ddd1a73847f53d793/original/functional-polythioamides-derived-from-thiocarbonyl-fluoride.pdf |
620e52c5c86ae296c424b3e0 | 10.26434/chemrxiv-2022-hhb6c | Inhibitory Prodrug Approach for Selective Elimination of Immunosuppressive M2 Macrophages | Tumor associated macrophages (TAMs) support tumor development and have emerged as important regulators of therapeutic response to cytostatic agents. To target TAMs, we have developed a novel drug delivery approach which induces drug release in response to inhibition of pro-tumor cysteine cathepsin activity. Such inhibitory prodrug (IPD) establishes a self-regulated delivery system where drug release stops after all cysteine cathepsins are inhibited. This could improve the therapeutic window for drugs with severe side effects. We demonstrate this self-regulation concept with a fluorogenic IPD model. We have applied our IPD strategy to two cytotoxic agents, doxorubicin and monomethyl auristatin E, which could be efficiently released from the IPD scaffold to induce concentration dependent toxicity in RAW macrophages. Lastly, by taking advantage of the increased cathepsin activity in TAM-like M2 polarized bone marrow derived macrophages, we show that IPD Dox selectively eliminates M2 over M1 macrophages. This demonstrates the potential of our IPD strategy for selective drug delivery and modulation of the tumor microenvironment. | Floris Jacco van Dalen; Martijn Verdoes | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC 4.0 | CHEMRXIV | 2022-02-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/620e52c5c86ae296c424b3e0/original/inhibitory-prodrug-approach-for-selective-elimination-of-immunosuppressive-m2-macrophages.pdf |
62904ae6e2ef7aff50ed8649 | 10.26434/chemrxiv-2022-dhhj9 | Ene-gamma-lactam synthesis via (3+2) vinyl azide-enolate cycloaddition: Enolate addition to vinyl triazolinone intermediates | Vinyl azides have undergone a recent renaissance as versatile synthetic reagents, however their reactivity as 1,3-dipoles in (3+2) cycloadditions remains underexplored. Here the synthesis of ene-gamma-lactam scaffolds via (3+2) cycloaddition of alpha-substituted vinyl azides with ester enolates is established. Mechanistic investigations, including isolation of reaction intermediates and density functional theory calculations, implicate an unprecedented conjugate-type addition to the exocyclic alkene of an N-vinyl triazolinone intermediate generated in the cycloaddition step. Determination of the reaction scope and application to synthesis of the natural product sargassumlactam is reported. | Joseph Bell-Tyrer; Paul Hume; Margaret Brimble; Daniel Furkert | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62904ae6e2ef7aff50ed8649/original/ene-gamma-lactam-synthesis-via-3-2-vinyl-azide-enolate-cycloaddition-enolate-addition-to-vinyl-triazolinone-intermediates.pdf |
60c7482eee301c6fc2c79818 | 10.26434/chemrxiv.11860881.v1 | Sequence-Modification in Copoly(ester-Imide)s: A Catalytic/supramolecular Approach to Writing/reading Copolymer Sequence-Information | Catalytic
ester-interchange reactions, analogous to mutation and recombination, allow new
sequence-information to be written, statistically, into NDI-based
poly(ester-imide) chains. Thus, insertion of the cyclic ester cyclopentadecanolide
("exaltolide") into an NDI-based homopolymer, and quantitative
sequence-exchange between two different homopoly(ester-imide)s, are catalysed
by di-<i>n</i>-butyl tin(IV) oxide. Emerging sequences are
identified at the triplet and quintet levels by <sup>1</sup>H NMR analysis,
using supramolecular complexation of pyrene-<i>d</i><sub>10</sub>
at the NDI residues to amplify the separation of resonances associated with
different sequences. In such systems, pyrene is able to act as a
"reader-molecule" by generating different levels of ring-current
shielding from the different patterns of supramolecular binding to all the NDI-centred
sequences of a given length. | Marcus Knappert; Howard Colquhoun | Organic Polymers; Polymer chains; Polymerization catalysts | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7482eee301c6fc2c79818/original/sequence-modification-in-copoly-ester-imide-s-a-catalytic-supramolecular-approach-to-writing-reading-copolymer-sequence-information.pdf |
60c7410a702a9b7aae18a1b6 | 10.26434/chemrxiv.7925489.v1 | Synthesis of Elaborate Benzofuran-2-Carboxamide Derivatives Through a Combination of 8-Aminoquinoline Directed C–H Arylations and Transamidations | Benzofurans are everywhere in nature and they have been extensively
studied by medicinal chemists over the years because of their chemotherapeutic
and physiological properties. Herein, we describe a strategy that can be used
to access elaborate benzo-2-carboxamide derivatives, which involves a synthetic
sequence of 8-aminoquinoline directed C–H arylations followed by transamidations.
For the directed C–H arylations, Pd catalysis was used to install a wide range
of aryl and heteroaryl substituents at the C3 position of the benzofuran
scaffold in high efficiency. Directing group cleavage and further
diversification of the C3-arylated benzofuran products were then achieved in a
single synthetic operation through the utilization of a two-step transamidation
protocol. By bocylating the 8-aminoquinoline amide moiety of these products, it
proved possible to activate them towards aminolysis with different amine
nucleophiles. Interestingly, this aminolysis reaction was found to proceed
efficiently without the need of any additional catalyst or additive. Given the
high efficiency and modularity of this synthetic strategy, it constitute a very
attractive approach for generating structurally-diverse collections of benzofuran
derivatives for small molecule screening. | Michael Oschmann; Linus Johansson Holm; Oscar Verho | Natural Products; Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2019-04-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7410a702a9b7aae18a1b6/original/synthesis-of-elaborate-benzofuran-2-carboxamide-derivatives-through-a-combination-of-8-aminoquinoline-directed-c-h-arylations-and-transamidations.pdf |
62835db343d1f06ea82f0adf | 10.26434/chemrxiv-2022-41t70 | DigiMOF: A Database of MOF Synthesis Information Generated via Text Mining | The vastness of materials space, particularly that which is concerned with metal-organic frameworks (MOFs), creates the critical problem of performing efficient identification of promising materials for specific applications. Although high-throughput computational approaches, including the use of machine learning, have been useful in rapid screening and rational design of MOFs, they tend to neglect descriptors related to their synthesis. One way to improve the efficiency of MOF discovery is to data mine published MOF papers to extract the materials informatics knowledge contained within the journal articles. Here, by adapting the chemistry-aware natural language processing tool, ChemDataExtractor (CDE), we generated an open-source database of MOFs focused on their synthetic properties: the DigiMOF database. Using the CDE web scraping package alongside the Cambridge Structural Database (CSD) MOF subset, we automatically downloaded 43,281 unique MOF journal articles, extracted 15,501 unique MOF materials and text mined over 52,680 associated properties including synthesis method, solvent, organic linker, metal precursor, and topology. This centralised, structured database reveals the MOF synthetic data embedded within thousands of MOF publications. The DigiMOF database and associated software are publicly available for other researchers to conduct further analysis of alternative MOF production pathways and create additional parsers to search for other desirable properties. | Kristian Gubsch; Rosalee Bence; Lawson Glasby; Peyman Z. Moghadam | Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2022-05-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62835db343d1f06ea82f0adf/original/digi-mof-a-database-of-mof-synthesis-information-generated-via-text-mining.pdf |
61d88efa636cc948ab420f0d | 10.26434/chemrxiv-2022-d1pzz | Machine Learning as a Tool for Specific Capacity Prediction of Prospective Potassium Battery Electrodes | Application of data science and machine learning (ML) techniques in the domain of materials science has been increasing by leaps and bounds recently. With the help of ML, through input features derived from available databases we can rapidly screen materials based on our desired output. Capacity is one of the important parameters for choosing suitable electrode materials for high energy storage metal ion battery. Exploration of suitable electrode materials for metal ion batteries other than Li ion batteries (LIBs) has been deficient, though there is a need to develop alternative battery technologies with higher energy storage characteristics and environmental safety. In this work, we have considered Li, Na and K-ion electrode materials and their available battery data from Materials Project database to predict specific capacity of prospective K-ion battery electrode materials. Suitable features have been considered and developed to train the various ML algorithms. Mean Absolute Percentage Error has been considered as the performance metrics for assessment of different ML algorithms and among them, kernel ridge regression has been adopted as the most useful to predict the capacity of unknown electrode materials for K-ion battery. Using the value of specific capacity, the number of intercalated K ions in the formula unit of the non-intercalated electrode material compounds have also been calculated. DFT calculations have also been performed to verify the results obtained through ML. Our result shows ML is an encouraging alternative to computationally demanding DFT process as it can screen electrode materials rapidly for battery. | Souvik Manna; Diptendu Roy; Sandeep Das; Biswarup Pathak | Theoretical and Computational Chemistry; Materials Science; Energy; Computational Chemistry and Modeling; Machine Learning; Energy Storage | CC BY 4.0 | CHEMRXIV | 2022-07-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61d88efa636cc948ab420f0d/original/machine-learning-as-a-tool-for-specific-capacity-prediction-of-prospective-potassium-battery-electrodes.pdf |
66dee92551558a15ef81c8fb | 10.26434/chemrxiv-2024-zg5f1 | High-resolution geospatial database: national criteria-air-pollutant concentrations in the contiguous U.S., 2016 – 2020 | Concentrations estimates for ambient air pollution are used widely in fields such as environmental epidemiology, health impact assessment, urban planning, environmental equity, and sustainability. This study builds on previous efforts by developing an updated high-resolution geospatial database of population-weighted annual-average concentrations for six criteria air pollutants (PM2.5, PM10, CO, NO2, SO2, O3) across the contiguous U.S. during a five-year period (2016-2020). We developed Land Use Regression (LUR) models within a partial-least-square – universal kriging framework by incorporating several land use, geospatial, and satellite – based predictor variables. The LUR models were validated using conventional and clustered cross-validation, with the former consistently showing superior performance in capturing the variability of air quality. Most models demonstrated reliable performance (e.g., mean squared error – based R2 > 0.8, standardized root mean squared error < 0.1). We used the best modeling approach to develop estimates by Census Block, which were then population-weighted averaged at Census Block Group, Census Tract, and County geographies. Our database provides valuable insights into the dynamics of air pollution, with utility for environmental risk assessment, public health, policy, and urban planning. | Tianjun Lu; Sun-Young Kim; Julian Marshall | Earth, Space, and Environmental Chemistry; Chemical Engineering and Industrial Chemistry; Atmospheric Chemistry; Environmental Science | CC BY NC 4.0 | CHEMRXIV | 2024-09-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66dee92551558a15ef81c8fb/original/high-resolution-geospatial-database-national-criteria-air-pollutant-concentrations-in-the-contiguous-u-s-2016-2020.pdf |
62c6bd428a8b396efbd17899 | 10.26434/chemrxiv-2022-8zt6r-v3 | Trade-off between redox potential and strength of electrochemical CO2 capture in quinones | Electrochemical carbon dioxide capture has recently emerged as a promising alternative approach to conventional energy-intensive carbon capture methods. A common electrochemical capture approach is to employ redox-active molecules such as quinones. Upon electrochemical reduction, quinones become activated for the capture of CO2 through a chemical reaction. A key disadvantage of this method is the possibility of side-reactions with oxygen, which is present in almost all gas mixtures of interest for carbon capture. This issue can potentially be mitigated by fine-tuning redox potentials through the introduction of electron-withdrawing groups on the quinone ring. In this article, we investigate the thermodynamics of the electron transfer and chemical steps of CO2 capture in different quinone derivatives with a range of substituents. By combining density functional theory calculations and cyclic voltammetry experiments, we support a previously described trade-off between redox potentials and the strength of CO2 capture. We show that redox potentials can readily be tuned to more positive values to impart stability to oxygen, but as a consequence, significant decreases in CO2 binding free energies are observed. Our calculations support this effect for a large series of anthraquinones and benzoquinones, with different trade-off relationships observed for the two classes of molecules. These trade-offs must be taken into consideration for the design of improved redox-active molecules for electrochemical CO2 capture. | Anna T. Bui; Niamh A. Hartley; Alex J. W. Thom; Alexander C. Forse | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Electrochemistry - Mechanisms, Theory & Study; Thermodynamics (Physical Chem.); Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2022-07-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62c6bd428a8b396efbd17899/original/trade-off-between-redox-potential-and-strength-of-electrochemical-co2-capture-in-quinones.pdf |
670d69c612ff75c3a16b5ee5 | 10.26434/chemrxiv-2024-n9tjc | Thermal properties of binary chlorides relevant to molten salt chemistry | Among proposed Generation IV nuclear reactors, the molten salt fast reactor (MSFR) has some of the most promising inherent safety features available. Among these includes the solidification of the molten salt matrix upon loss of external heating, preventing runaway. Other convenient features include online reprocessing and increased fuel variety. A major hurdle for MSFR design is the lack of fundamental data on the component salts, and the resulting fission and corrosion product speciation. While MSFRs are typically designed for use with fluoride salts, chloride salts have shown promise, and have had increased interest in recent years. A better understanding of the fundamental thermodynamic properties of chlorides would aid in the design of more efficient and more precise separations of the spent fuel salt mixture for recycling of fissile isotopes. This review has collected and analyzed existing literature data on the relevant thermochemical and thermophysical properties including: boiling / melting / sublimation points, heat capacity, vapor pressure expressions, enthalpic / entropic / free energy formation and phase change values. The elements of interest include that of fuel salts (actinides), solvent salts (alkali and alkaline earth metals), and fission and corrosion product (main group, transition metal, and rare earth element) chloride salts. | Alex Pixler; Colleen Kennedy; Aaron Unger; Vitaliy Goncharov; Jeremy Jones; Paul Andersen; Cory Windorff | Physical Chemistry; Inorganic Chemistry; Energy; Lanthanides and Actinides; Physical and Chemical Properties; Thermodynamics (Physical Chem.) | CC BY NC 4.0 | CHEMRXIV | 2024-10-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/670d69c612ff75c3a16b5ee5/original/thermal-properties-of-binary-chlorides-relevant-to-molten-salt-chemistry.pdf |
637d60546b4e814ffd7bb7c8 | 10.26434/chemrxiv-2022-bhzns | Introducing Savie: A Biodegradable Surfactant Enabling Chemo- and Bio-catalysis & Related Reactions in Recyclable Water | Savie is a biodegradable surfactant derived from vitamin E and polysarcosine (PSar) developed for organic synthesis in water. This includes homogeneous catalysis (including examples employing only ppm levels of catalyst), heterogeneous catalysis, and biocatalytic transformations, including a 3-step, 1-pot chemoenzymatic sequence. Savie frequently enables significantly higher yields than conventional surfactants, while obviating the need for environmentally egregious organic solvents. | Joseph R. A. Kincaid; Madison J. Wong; Nnamdi Akporji; Fabrice Gallou; David M. Fialho; Bruce H. Lipshutz | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Biocatalysis; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/637d60546b4e814ffd7bb7c8/original/introducing-savie-a-biodegradable-surfactant-enabling-chemo-and-bio-catalysis-related-reactions-in-recyclable-water.pdf |
64ed27a179853bbd78a1c0a2 | 10.26434/chemrxiv-2023-b8cnj | Predicting Surface Tensions and Electrical Conductivities for High Molecular Weight Ionic Liquid Propellants Using Quantitative Structure-Property Relationships (QSPR) | Quantitative Structure-Property Relationships (QSPR) take in existing experimental property data and output predicted properties using statistical analysis and linear regressions. A priori, QSPR can provide practical results for ionic liquid (IL) propellants of any physical property, such as density, viscosity, surface tension, electrical conductivity, etc., as well as of any chemical property such as ignition delay time. It saves time and costly resources used when first synthesizing the IL and measuring its various properties to see if it meets mission requirements. QSPR also provides benefits over first principles theoretical computational methods such as increased accuracy and reduced computational time, therefore reducing the cost over current approaches in molecular dynamics simulations. In this work, QSPR was used to predict surface tensions and electrical conductivities of ionic liquids with high molecular weights. These high molecular weight ionic liquids are being investigated for applications in electrospray propulsion because of their omniphobicity and high short-term thermal stability characteristics, which potentially give them a performance advantage over existing propellants. | Mark J. Wolf; Steven D. Chambreau; Debasis Sengupta; David A. Newsome; Ghanshyam L. Vaghjiani | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Machine Learning; Artificial Intelligence; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ed27a179853bbd78a1c0a2/original/predicting-surface-tensions-and-electrical-conductivities-for-high-molecular-weight-ionic-liquid-propellants-using-quantitative-structure-property-relationships-qspr.pdf |
66bc632ca4e53c4876544bfc | 10.26434/chemrxiv-2024-089vs | STOUT V2.0: SMILES to IUPAC name conversion using transformer models | Naming chemical compounds systematically is a complex task governed by a set of rules established by the International Union of Pure and Applied Chemistry (IUPAC). These rules are universal and widely accepted by chemists worldwide, but their complexity makes it challenging for individuals to consistently apply them accurately. A translation method can be employed to address this challenge. Accurate translation of chemical compounds from SMILES notation into their corresponding IUPAC names is crucial, as it can significantly streamline the laborious process of naming chemical structures. Here, we present STOUT (SMILES-TO-IUPAC-name translator) V2.0, which addresses this challenge by introducing a transformer-based model that translates string representations of chemical structures into IUPAC names. Trained on a dataset of nearly 1 billion SMILES strings and their corresponding IUPAC names, STOUT V2.0 demonstrates exceptional accuracy in generating IUPAC names, even for complex chemical structures. The model's ability to capture intricate patterns and relationships within chemical structures enables it to generate precise and standardised IUPAC names. Deterministic algorithms for systematically naming chemical structures have been available for many years. Also, this work has only been possible through an academic license for OpenEye’s Lexichem software. | Kohulan Rajan; Achim Zielesny; Christoph Steinbeck | Theoretical and Computational Chemistry; Chemical Education; Machine Learning; Artificial Intelligence; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2024-08-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66bc632ca4e53c4876544bfc/original/stout-v2-0-smiles-to-iupac-name-conversion-using-transformer-models.pdf |
6642514021291e5d1d27e435 | 10.26434/chemrxiv-2024-ghksq | Programming Fluid Motion Using Multi-Enzyme Micropump Systems | In the presence of appropriate substrates, surface-anchored enzymes can act as pumps and propel fluid through microchambers. Understanding the dynamic interplay between catalytic reactions and fluid flow is vital to enhancing the accuracy and utility of flow technology. Through a combination of experimental observations and numerical modelling, we show that coupled enzyme pumps can exhibit flow enhancement, flow suppression, and changes in the directionality (reversal) of the fluid motion. The pumps’ ability to regulate the flow path is due to the reaction selectivity of the enzymes; the resultant fluid motion is only triggered by the presence of certain reactants. Hence, the reactants and the sequence in which they are present in the solution, and the layout of the enzyme-attached patches form an “instruction set” that guides the flowing solution to specific sites in the system. Such systems can operate as sensors that indicate concentrations of reactants through measurement of the trajectory along which the flow demonstrates maximal speed. The performed simulations suggest that the solutal buoyancy mechanism causes fluid motion and is responsible for all the observed effects. More broadly, our studies provide a new route for forming self-organizing flow systems that can yield fundamental insight into non-equilibrium, dynamical systems. | Jiaqi Song; Jianhua Zhang; Jinwei Lin; Oleg Shklyaev; Shanid Shrestha; Aditya Sapre; Anna Balazs; Ayusman Sen | Materials Science; Catalysis; Biological Materials; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6642514021291e5d1d27e435/original/programming-fluid-motion-using-multi-enzyme-micropump-systems.pdf |
66ebc757cec5d6c142886d28 | 10.26434/chemrxiv-2024-vcppg | Graph Transformer Foundation Model for modeling ADMET properties | Pre-trained on vast datasets, foundation models demonstrate strong generalization across different tasks, particularly in natural language processing and computer vision. This study explores the potential of applying foundation models to the domain of ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) property prediction, a critical task in early-stage drug discovery. We present a Graph Transformer Foundation Model (GTFM) that combines the strengths of graph neural networks (GNNs) and transformer architectures to model molecular graphs. We use self-supervised learning (SSL) to extract useful representations from large unlabeled datasets by predicting masked nodes/edges and the Joint Embedding Predictive Architecture (JEPA). The latter demonstrates superior performance in most tasks by learning robust and predictive features from molecular graphs.
The GTFM is benchmarked against classical machine learning models using predefined molecular descriptors. The results demonstrate that the GTFM, especially when employing JEPA, outperforms classical approaches for ADMET property prediction in 8 out of 19 classification and 5 out of 9 regression tasks, being comparable in the rest. This shows foundation models, specifically GTFM, as a promising approach for ADMET modeling, providing a scalable and versatile solution for drug discovery applications. | Mikolaj Mizera; Arkadii Lin; Eugene Babin; Yury Kashkur; Tatiana Sitnik; Ien An Chan; Arsen Yedige; Maksim Vendin; Shamkhal Baybekov; Vladimir Aladinskiy | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Drug Discovery and Drug Delivery Systems; Artificial Intelligence; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66ebc757cec5d6c142886d28/original/graph-transformer-foundation-model-for-modeling-admet-properties.pdf |
616d28f1aa918db1872ed116 | 10.26434/chemrxiv-2021-dd56w-v3 | In silico investigation of ligand-regulated palladium-catalysed formic acid dehydrative decomposition under acidic conditions | In silico investigation of ligand-regulated palladium-catalysed formic acid dehydrative decomposition to carbon monoxide under acidic conditions was conducted. Two types of bidentate tertiary phosphine ligands were selected on the basis of previous experimental study. And the promoting effect of para-toluenesulfonic acid (PTSA) was specifically investigated. The pyridyl group implanted in pytbpx ligand is found to mainly contribute on enhancing the activity of palladium catalyst. The PTSA promoter displays specific role for regenerating active species and supressing dehydrogenation during Pd-pytbpx/Pd-dtbpx catalysed dehydration process. CO releasing process catalysed by Pd-dtbpx also facilitated by adding PTSA. According to the mechanism hereby supposed, introducing electron-withdrawing substitution at para-position of pyridyl rings may further improve the dehydrative decomposition activity of Pd-pytbpx. | Chaoren Shen; Kaiwu Dong; Zhihong Wei; Xinxin Tian | Theoretical and Computational Chemistry; Catalysis; Organometallic Chemistry; Computational Chemistry and Modeling; Homogeneous Catalysis; Catalysis | CC BY NC 4.0 | CHEMRXIV | 2021-10-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/616d28f1aa918db1872ed116/original/in-silico-investigation-of-ligand-regulated-palladium-catalysed-formic-acid-dehydrative-decomposition-under-acidic-conditions.pdf |
60c7556abdbb89835ba3a80c | 10.26434/chemrxiv.14102363.v1 | Origin and Control of Chemoselectivity in Cytochrome c-Catalyzed Carbene Transfer into Si–H and N–H bonds | <div><div><div><p>A cytochrome c heme protein was recently engineered to catalyze the formation of carbon–silicon bonds via carbene insertion into Si–H bonds, a reaction that was not previously known to be catalyzed by a protein. High chemoselectivity towards C–Si bond formation over competing C–N bond formation was achieved, although this trait was not screened for during directed evolution. Using computational and experimental tools, we now establish that activity and chemoselectivity are modulated by conformational dynamics of a protein loop that covers the substrate access to the iron-carbene active species. Mutagenesis of residues computationally predicted to control the loop conformation altered the protein’s chemoselectivity from preferred silylation to preferred amination of a substrate containing both N–H and Si–H functionalities. We demonstrate that information on protein structure and conformational dynamics, combined with knowledge of mechanism, leads to understanding of how non-natural and selective chemical transformations can be introduced into the biological world.</p></div></div></div> | Marc Garcia-Borràs; S. B. Jennifer Kan; Russell D. Lewis; Allison Tang; Gonzalo Jiménez-Osés; Frances H. Arnold; Kendall N. Houk | Computational Chemistry and Modeling; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-02-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7556abdbb89835ba3a80c/original/origin-and-control-of-chemoselectivity-in-cytochrome-c-catalyzed-carbene-transfer-into-si-h-and-n-h-bonds.pdf |
66013e229138d231613ce438 | 10.26434/chemrxiv-2024-5h5wh | Plastic Peril: Unveiling the Impact of Lightweight Poly Bags on Nigeria's Vital Sectors - A Call to Safeguard Health, Agriculture, Transport, Tourism, and Recreation | Plastics offer convenient and lightweight packaging solutions for consumer products, but their pervasive presence poses a significant environmental threat, particularly in developing nations. Their lightweight nature facilitates easy dispersal by wind, water, and animals, exacerbating pollution issues. Moreover, the limited incentives for recycling and challenges in collection compound these problems. This study highlights how plastic litter disproportionately affects rural areas, subsequently impacting urban dwellers and the broader Nigerian economy. It identifies issues such as transmission of diseases, contamination risks, airborne pollutants like phthalates and bisphenol, and their adverse effects on both the environment and human health. In agriculture, plastic pollution disrupts soil structure, reduces water retention, hampers microbial activity, and interferes with nutrient cycling. Additionally, it causes equipment damage, obstructs tilling operations, promotes fertilizer runoff, and contributes to erosion. In the transportation, tourism, and recreation sectors, plastic litter results in unsightly pollution, impairs visual aesthetics, blocks drainage systems, accelerates erosion, triggers flash floods, and harms wildlife habitats. While plastic bottles and similar items pose fewer environmental concerns due to their easier collection, recycling, and reuse compared to lightweight packaging polymers, urgent action is imperative to address the pervasive plastic pollution. A shift from polyethylene bags for small product packaging to plastic bottles is recommended to mitigate these adverse impacts on the Nigerian populace and the environment. | Mathew Gideon; Yusuf Muazu; Adamu Danladi Wasanmaza | Earth, Space, and Environmental Chemistry; Chemical Engineering and Industrial Chemistry; Environmental Science; Natural Resource Recovery | CC BY 4.0 | CHEMRXIV | 2024-04-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66013e229138d231613ce438/original/plastic-peril-unveiling-the-impact-of-lightweight-poly-bags-on-nigeria-s-vital-sectors-a-call-to-safeguard-health-agriculture-transport-tourism-and-recreation.pdf |
64e24db1694bf1540caf490f | 10.26434/chemrxiv-2023-rgvlz | Optimising excipient properties to prevent aggregation in biopharmaceutical formulations | Excipients are included within protein biotherapeutic solution formulations to improve colloidal and conformational stability, but are generally not designed for the specific purpose of preventing aggregation and improving cryoprotection in solution. In this work, we have explored the relationship between structure and anti-aggregation activity of excipients by utilising coarse-grained molecular dynamics modelling of protein excipient interaction. We have studied human serum albumin as a model protein, and report the interaction of 41 excipients (polysorbates, fatty alcohol ethoxylates, fatty acid ethoxylates, phospholipids, glucosides, amino acids, and others) in terms of the reduction of solvent accessible surface area of aggregation-prone regions, proposed as a mechanism of aggregation prevention. Polyoxyethylene sorbitan had the greatest degree of interaction with aggregation-prone regions, decreasing the solvent accessible surface area of APRs by 20.7 nm2. Physicochemical descriptors generated by Mordred are employed to probe the structure-activity relationship using partial least squares regression. A leave-one-out cross-validated model had a root mean square error of prediction of 4.1 nm2. Generally, longer molecules with a large number of alcohol-terminated PEG units tended to interact more, with qualitatively different protein interaction, wrapping around the protein, and would have a lesser protective effect on stability. Shorter or less ethoxylated compounds tend to form hemimicellar clusters at the protein surface. We propose that an improved design would feature many short chains of five to ten PEG units in many distinct branches and at least some hydrophobic content in the form of medium-length or greater aliphatic chains (i.e., six or more carbon atoms). The combination of molecular dynamics and quantitative modelling is an important first step in an all-purpose protein-independent model for the computer-aided design of stabilising excipients. | Toby King; James Humphrey; Charles Laughton; Neil Thomas; Jonathan Hirst | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY 4.0 | CHEMRXIV | 2023-08-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e24db1694bf1540caf490f/original/optimising-excipient-properties-to-prevent-aggregation-in-biopharmaceutical-formulations.pdf |
6517052d0065940912216af1 | 10.26434/chemrxiv-2023-8ct0c | Convergent Synthesis of a Hexadecavalent Heterobifunctional ABO Blood Group Glycoconjugate | Naturally occurring glycans are often found in a multivalent presentation. Cell surface receptors that recognize these displays may form clusters, which can lead to signalling or endocytosis. One of the challenges in generating synthetic displays of multivalent carbohydrates is providing high valency as well as access to heterofunctional conjugates to allow attachment of multiple antigens or payloads. We designed a strategy based on a set of bifunctional linkers to generate a heterobifunctional multivalent display of two carbohydrate antigens to bind BCR and CD22 with four and twelve antigen copies, respectively. We confirmed that the conjugates were able to engage both CD22 and BCR on cells by observing receptor clustering. The strategy is modular and would allow for alternative carbohydrate antigens to be attached bearing amine and alkyne groups and should be of interest for the development of immunomodulators and vaccines. | Gour Chand Daskhan; Hanh-Thuc Ton Tran; Christopher W Cairo | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6517052d0065940912216af1/original/convergent-synthesis-of-a-hexadecavalent-heterobifunctional-abo-blood-group-glycoconjugate.pdf |
650c5317b927619fe79083f8 | 10.26434/chemrxiv-2023-c5w1x-v2 | Reversible O–H bond activation by
tripodal tris(nitroxide) aluminum
and gallium complexes | Herein we report the preparation and characterization of the Group 13 metal complexes of a tripodal tris(nitroxide) based ligand, designated (TriNOx3−)M (M = Al (1), Ga (2), In (3)). Complexes 1 and 2 both activate the O–H bond of a range of alcohols spanning a ~13 pKa unit range via an element-ligand cooperative pathway to afford the zwitterionic complexes (HTriNOx2–)M–OR. Structures of these alcohol adduct products are discussed. We demonstrate that the thermodynamic and kinetic aspects of the reactions are both influenced by the identity of the metal, with 1 having higher reaction equilibrium constants and proceeding at a faster rate relative to 2 for any given alcohol. These parameters are also influenced by the pKa of the alcohol, with more acidic alcohols reacting both to more completion and faster than their less acidic counterparts. Possible mechanistic pathways are discussed. | Joseph S. Scott; Mika L. Maenaga; Audra J. Woodside; Vivian W. Guo; Alex R. Cheriel; Michael R. Gau; Paul R. Rablen; Christopher R. Graves | Inorganic Chemistry; Ligands (Inorg.); Main Group Chemistry (Inorg.); Small Molecule Activation (Inorg.) | CC BY NC 4.0 | CHEMRXIV | 2023-09-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/650c5317b927619fe79083f8/original/reversible-o-h-bond-activation-by-tripodal-tris-nitroxide-aluminum-and-gallium-complexes.pdf |
62ab72e7ecd7cd8224c6d231 | 10.26434/chemrxiv-2022-rf7z9 | Characterization of Lipid Bilayers Adsorbed to Functionalized Air/Water Interfaces | Lipid bilayers immobilized in planar geometries, such as solid-supported or "floating" bilayers, have enabled detailed studies of biological membranes with numerous experimental techniques, notably x-ray and neutron reflectometry. However, the presence of a solid support also has disadvantages as it complicates the use of spectroscopic techniques as well as surface rheological measurements that would require surface deformations. Here, in order to overcome these limitations, we investigate lipid bilayers adsorbed to inherently soft and experimentally well accessible air/water interfaces that are functionalized with Langmuir monolayers of amphiphiles. The bilayers are characterized with ellipsometry, X-ray scattering, and X-ray fluorescence. Grazing-incidence X-ray diffraction reveals that lipid bilayers in a chain-ordered state can have significantly different structural features than regular Langmuir monolayers of the same composition. Our results suggest that bilayers at air/water interfaces may be well suited for fundamental studies in the field of membrane biophysics. | Julio Martín Pusterla; Ernesto Scoppola ; Christian Appel; Tetiana Mukhina; Chen Shen; Gerald Brezesinski; Emanuel Schneck | Physical Chemistry; Nanoscience; Biophysical Chemistry; Interfaces; Structure | CC BY NC 4.0 | CHEMRXIV | 2022-06-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62ab72e7ecd7cd8224c6d231/original/characterization-of-lipid-bilayers-adsorbed-to-functionalized-air-water-interfaces.pdf |
64d48229dfabaf06ff07c3c4 | 10.26434/chemrxiv-2023-5h4xk | A Comprehensive Review of Current and Emerging Binder Technologies for Energy Storage Applications | Binders hold a crucial role in electrode fabrication by ensuring the cohesion and stability of active materials, conductive additives, and electrolytes within batteries. They also establish essential electron and ion pathways, crucial for effective lithiation and delithiation processes. Despite their relatively low concentration compared to active materials, binders significantly impact both the physical properties and electrochemical performance of electrodes. Given the escalating demand for Electric Vehicles and energy storage systems, there's an increasing need for batteries with higher energy densities and cost-effective production. This necessitates the development of new and more efficient battery materials. This review provides a detailed examination of various binders used in battery manufacturing, starting from traditional binders for Lithium-ion batteries to recent advancements for sodium-ion batteries, silicon anodes, Lithium-Oxygen batteries and other emerging technologies. By systematically exploring different binder types and their properties, this review contributes to the optimization and advancement of battery technologies. As the energy storage landscape continues to evolve, the insights presented here aim to inform innovative developments in binder design and application, ultimately catalyzing advancements in the field. | Sooryadas Sudhakaran; T. K Bijoy | Materials Science; Polymer Science; Energy; Inorganic Polymers; Organic Polymers; Energy Storage | CC BY NC 4.0 | CHEMRXIV | 2023-08-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64d48229dfabaf06ff07c3c4/original/a-comprehensive-review-of-current-and-emerging-binder-technologies-for-energy-storage-applications.pdf |
6453c5ef1ca6101a45c66c75 | 10.26434/chemrxiv-2023-34g9n | Femtosecond laser-induced desorption of hydrogen molecules from Ru(0001): A systematic study based on machine-learned potentials | Femtosecond laser-induced dynamics of molecules on metal surfaces can be seamlessly simulated with all nuclear degrees of freedom using ab-initio molecular dynamics with electronic friction (AIMDEF) and stochastic forces which are a function of a time-dependent electronic temperature. This has recently been demonstrated for hot-electron mediated desorption of hydrogen molecules from a Ru(0001) surface covered with H and D atoms [Juaristi et al., Phys. Rev. B 2017, 95, 125439]. Unfortunately, AIMDEF simulations come with a very large computational expense that severely limits statistics and propagation times. To keep ab-initio accuracy and allow for better statistical sampling, we have developed a neural network interatomic potential of hydrogen on the Ru(0001) surface based on data from ab-initio molecular dynamics simulations of recombinative desorption. Using this potential we simulated femtosecond laser-induced recombinative desorption using varying unit cells, coverages, laser fluences, and isotope ratios with reliable statistics. As a result, we can systematically study a wide range of these parameters and follow dynamics over longer times than hitherto possible, demonstrating that our methodology is a promising way to realistically simulate femtosecond laser-induced dynamics of molecules on metals. Moreover, we show that previously used cell sizes and propagation times were too small to obtain converged results. | Steven Lindner; Ivor Lončarić; Lovro Vrček; Maite Alducin; J. I. Juaristi; Peter Saalfrank | Theoretical and Computational Chemistry; Theory - Computational; Machine Learning | CC BY 4.0 | CHEMRXIV | 2023-05-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6453c5ef1ca6101a45c66c75/original/femtosecond-laser-induced-desorption-of-hydrogen-molecules-from-ru-0001-a-systematic-study-based-on-machine-learned-potentials.pdf |
616c50292aca53f31966c1b1 | 10.26434/chemrxiv-2021-rhtps | Protein corona formation around biocatalytic nanomotors unveiled by STORM | The interaction of nanoparticles with biological media is a topic of general interest for drug delivery systems and among those for active nanoparticles, also called nanomotors. Herein, we report the use of super resolu-tion microscopy, in particular stochastic optical reconstruction microscopy (STORM), to characterize the formation of protein corona around active enzyme-powered nanomotors. First, we characterize the distribu-tion and number of enzymes on nano-sized particles and characterized their motion capabilities. Then, we incubated the nanomotors with fluorescently labelled serum proteins. Interestingly, we observed a signifi-cant decrease of protein corona formation (20 %) and different composition, which was studied by a proteo-mic analysis. Moreover, motion was not hindered, as nanomotors displayed an enhanced diffusion regardless of protein corona. Elucidating how active particles interact with biological media and maintain their self-propulsion after protein corona formation will pave the way of the use these systems in complex biological fluids in biomedicine. | Tania Patino; Joaquin Llacer-Wintle; Silvia Pujals; Lorenzo Albertazzi; Samuel Sánchez | Biological and Medicinal Chemistry; Materials Science; Nanoscience; Nanodevices; Bioengineering and Biotechnology; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2021-10-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/616c50292aca53f31966c1b1/original/protein-corona-formation-around-biocatalytic-nanomotors-unveiled-by-storm.pdf |
6709adeccec5d6c142e4db3b | 10.26434/chemrxiv-2024-6bldc | Acoustofluidic Chromatography for Extracellular Vesicle Enrichment from µL Blood Plasma Samples | We present a novel acoustofluidic chromatography platform for high-throughput nanoparticle trapping and enrichment, focusing on extracellular vesicles (EVs) from blood plasma. The system consists of a packed bed of polystyrene beads within a rectangular glass capillary, acoustically excited by a piezoelectric element. Using fluorescent polystyrene particles (1.9 µm and 0.27 µm) as model nanoparticles, we characterized the device by evaluating its trapping efficiency across a frequency range of 0.45–4 MHz. Our results demonstrate efficient trapping of micro- and nanoscale particles, with increased efficiency at higher acoustic powers and lower flow rates. EV isolation from 4 µL of diluted blood plasma showed that abruptly increasing the flow rate during the release step significantly enhanced particle recovery, likely due to hydrodynamic effects. Nanoparticle tracking analysis confirmed the release of EVs at concentrations of ~2x10⁹ particles/mL, with low protein background suitable for downstream mass spectrometry.
This platform offers a promising approach for nanoparticle trapping and EV enrichment with minimal sample volumes, presenting potential applications in diagnostics and therapeutic development. Future work will focus on optimizing bead materials and sizes for EV subpopulation separation and scaling the system for clinical use.
| Michael Gerlt; Thomas Laurell | Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6709adeccec5d6c142e4db3b/original/acoustofluidic-chromatography-for-extracellular-vesicle-enrichment-from-l-blood-plasma-samples.pdf |
6697c8e301103d79c5423fbf | 10.26434/chemrxiv-2024-qkkg6 | Metabolic Engineering in Plants: Advancing Crop Productivity and Sustainability through Precision Pathway Manipulation | Metabolic engineering in plants has emerged as a powerful approach to address global challenges in agriculture, nutrition, and sustainability. This comprehensive review explores cutting-edge strategies for manipulating primary and secondary metabolic pathways in plants, utilizing advanced genetic modification tools to enhance crop yield, nutritional quality, stress tolerance, and the production of valuable metabolites. We examine recent successes in improving photosynthetic efficiency, nutrient use, and abiotic stress resistance through targeted metabolic interventions. The review also delves into emerging trends, such as synthetic biology approaches and multi-gene trait stacking, which are revolutionizing the field. By integrating omics technologies, including genomics, transcriptomics, proteomics, and metabolomics, with advanced computational modeling, researchers are optimizing metabolic engineering designs with unprecedented precision. We discuss the application of CRISPR/Cas9 and other gene editing techniques in refining plant metabolism, as well as the potential of plants as biofactories for pharmaceutical and industrial compounds. As the field rapidly evolves, we consider the regulatory and biosafety aspects of genetically modified crops, providing insights into the future of sustainable agriculture and crop improvement. This review highlights the transformative potential of plant metabolic engineering in addressing food security, climate change adaptation, and the sustainable production of valuable compounds, while also discussing the challenges and future perspectives of this dynamic field. | Katie Fan | Chemical Engineering and Industrial Chemistry; Agriculture and Food Chemistry; Feed; Food | CC BY 4.0 | CHEMRXIV | 2024-07-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6697c8e301103d79c5423fbf/original/metabolic-engineering-in-plants-advancing-crop-productivity-and-sustainability-through-precision-pathway-manipulation.pdf |
65beb37ae9ebbb4db99c1ee9 | 10.26434/chemrxiv-2024-pwt3p | Quantifying Heterogeneous Degradation Pathways and Deformation Fields in Solid State Batteries | Solid-state batteries are compelling candidates for next generation energy storage devices, promising both high energy density and improved safety, by utilizing metallic Li as the negative electrode. However, they suffer from poor cyclability and rate capability, which limits their wide application. Degradation in these devices occurs through complex mechanical, chemical and electrochemical pathways, all of which produce heterogeneous deformation fields. Therefore, isolating solid-state degradation mechanisms, and explicitly linking them to the associated deformation fields requires a multimodal characterization strategy. Here, we present a novel 3-D, in situ methodology for linking degradation to deformation in solid-state cells. X-ray imaging is used to measure the morphological degradation, and combined with X-ray diffraction to quantify (electro)chemical aspects. Finally, the heterogeneous stress fields from these various pathways are mapped in situ. This heterogeneity is shown globally, from the interface to the bulk electrolyte, as well as locally, around features such as cracks and voids. Through these analyses, it was possible to delineate the effects of solid electrolyte processing, cell assembly, and cycling on the end-of-life state of the cell. Moreover, the importance of stress mitigation in these cells is highlighted, with mean stresses around the interface and some cracks comfortably exceeding the elastic limit of Li. | Ji Hu; Robert Young; Bratislav Lukic; Ludovic Broche; Rhodri Jervis; Paul Shearing; Marco Michiel; Philip Withers; Alexander Rettie; Partha Paul | Energy; Chemical Engineering and Industrial Chemistry; Energy Storage; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65beb37ae9ebbb4db99c1ee9/original/quantifying-heterogeneous-degradation-pathways-and-deformation-fields-in-solid-state-batteries.pdf |
674f7ff45a82cea2fadf933c | 10.26434/chemrxiv-2024-7q5jg | Unveiling the Dance of Molecules: Ro-Vibrational Dynamics of Molecules under Intense Illumination at Complex Plasmonic Interfaces | Understanding the quantum dynamics of strongly coupled molecule-cavity systems remains a significant challenge in molecular polaritonics. This work develops a comprehensive self-consistent model simulating electromagnetic interactions of diatomic molecules with quantum ro-vibrational degrees of freedom in resonant optical cavities. The approach employs an efficient numerical methodology to solve coupled Schrodinger-Maxwell equations in real space-time, enabling three-dimensional simulations through a novel molecular mapping technique. The study investigates relaxation dynamics of an ensemble of molecules following intense resonant pump excitation in Fabry-Perot cavities and at three-dimensional plasmonic metasurfaces. The simulations reveal dramatically modified relaxation pathways inside cavities compared to free space, characterized by persistent molecular alignment arising from cavity-induced rotational pumping. They also indicate the presence of a previously unreported relaxation stabilization mechanism driven by dephasing of the collective molecular-cavity mode. Additionally, the study demonstrates that strong molecular coupling significantly modifies the circular dichroism spectra of chiral metasurfaces, suggesting new opportunities for controlling light-matter interactions in quantum optical systems. | Maxim Sukharev; Joseph Subotnik; Abraham Nitzan | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Optics; Photochemistry (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674f7ff45a82cea2fadf933c/original/unveiling-the-dance-of-molecules-ro-vibrational-dynamics-of-molecules-under-intense-illumination-at-complex-plasmonic-interfaces.pdf |
652b1e14bda59ceb9a983cf5 | 10.26434/chemrxiv-2023-bp4d8 | Water-Mediated Charge Transfer and Electron Localization in a Co3Fe2 Cyanide-Bridged Trigonal Bipyramidal Complex | The effects of temperature and chemical environment on a pentanuclear cyanide-bridged, trigonal bipyramidal molecular magnet has been investigated. Using element and oxidation state specific near-ambient pressure XPS
(NAP-XPS) to probe charge transfer and second order, non-
linear vibrational spectroscopy, which is sensitive to symmetry changes based on charge (de)localization coupled with DFT a detailed picture of environmental effects on charge-transfer induced spin transitions is presented. The molecular cluster, Co3Fe2(tmphen)6(μ-CN)6(t-CN)6, abbrev. Co3Fe2, shows changes in electronic behavior depending on chemical environment. NAP-XPS shows that temperature changes induce a metal-to-metal charge transfer (MMCT) in Co3Fe2 between a Co and Fe center, while cycling between ultrahigh vacuum and
2 mbar water at constant temperature, causes oxidation state changes not fully captured by the MMCT picture. Sum frequency generation vibrational spectroscopy (SFG-VS) probes the role of the cyanide ligand, which controls the electron (de)localization via the superexchange coupling. Spectral shifts and intensity changes indicate a change from a charge delocalized, Robin-Day Class II/III high spin state to a charge localized, Class I low spin state consistent with DFT. In the presence of a H-bonding solvent the complex adopts a localized electronic structure, while removal of the solvent delocalizes the charges and drives a MMCT. This change in Robin-Day classification of the complex as a function of chemical environment results in
reversible switching of the dipole moment, analogous to molecular multiferroics. These results illustrate the important role of chemical environment and solvation on underlying charge and spin transitions in this and related complexes. | Emily Hruska; Quansong Zhu; Somnath Biswas; Matthew Fortunato; Dustin Broderick; Christine Morales; John Herbert; Claudia Turro; L. Robert Baker | Theoretical and Computational Chemistry; Physical Chemistry; Inorganic Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652b1e14bda59ceb9a983cf5/original/water-mediated-charge-transfer-and-electron-localization-in-a-co3fe2-cyanide-bridged-trigonal-bipyramidal-complex.pdf |
66ac9d6dc9c6a5c07ad124c8 | 10.26434/chemrxiv-2024-nhr99 | Unlocking Novel P-Containing Scaffolds by Exploration of a Photocatalyzed Halogen-Bonding-Assisted EDA-SET Reaction. | The synthesis of new heterocyclic structures is a challenging endeavor in organic chemistry. It requires the development of innovative methods that can generate novel frameworks, thereby allowing exploration of uncharted chemical spaces for potential applications. In this context, Halogen-Bonding-Assisted EDA-SET strategy presents a promising and efficient approach. In our study, we propose employing this strategy to facilitate the exploration of diverse phosphorus-based scaffolds, which hold significant potential for future research endeavors. By leveraging the EDA strategy, we aim to unlock new opportunities and advance the field of phosphorus-based chemistry. | Clara Faure; Yurong Yuan; Diana Lamaa; Etienne Derat; Sonia Lajnef; Fabienne Peyrot; Philippe Belmont; Etienne Brachet | Organic Chemistry; Organic Synthesis and Reactions; Photochemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66ac9d6dc9c6a5c07ad124c8/original/unlocking-novel-p-containing-scaffolds-by-exploration-of-a-photocatalyzed-halogen-bonding-assisted-eda-set-reaction.pdf |
60c73e9ebdbb890c68a37e8f | 10.26434/chemrxiv.7074842.v1 | Kinetic and Thermodynamic Study of Methylene Blue Adsorption onto Chitosan: Insights about Metachromasy Occurrence on Wastewater Remediation | <p>Methylene Blue (MB) is
a dye frequently used in the textile industry and a potential wastewater
pollutant. MB adsorption onto the surface of solid materials is a promising
method for wastewater remediation. The biopolymer chitosan is one of the promising
candidates as an adsorbent for MB removal from wastewater. However, the contact
between MB and chitosan induces the aggregation of MB molecules. The formation
of MB aggregates can lead to an appearance of additional bands in the MB
visible absorption spectrum. This phenomenon is called metachromasy. In this
paper, chitosan was used as adsorbent to study the kinetics and thermodynamic
parameters related to the elimination of MB as single molecules (Sng-MB) and
aggregates (Agg-MB) species from simulated wastewater. It was found that, for
MB single molecules or aggregates, the adsorption process follows the pseudo
second order adsorption kinetics model. For each temperature studied, Agg-MB
always presented higher rate constant than Sng-MB, indicating a faster
adsorption of Agg-MB in comparison to Sng-MB.
Additionally, the adsorption process presented a lower activation energy
for Agg-MB, indicating Agg-MB adsorption is favored in relation to Sng-MB. The
thermodynamic studies indicated the adsorption process for both MB species is
endothermic and spontaneous from 298 to 348 K. The adsorption isotherms could
be properly fitted and interpreted according to Temkin and Dubinin-Radushkevich
models. Studies varying the initial pH of MB solution indicated that
metachromasy could be suppressed in acidic pH values, whereas alkaline pH
values led to an increase in the removal percentage of Sng-MB and Agg-MB in
relation to neutral conditions. The analysis of chitosan powder before and
after adsorption indicated the adsorption process does not cause structural
changes to the chitosan. The kinetic and thermodynamic study of the relative
adsorption of MB single molecules and aggregates onto chitosan can provide
fundamental information for MB wastewater remediation.</p> | Julian Kellner-Rogers; Jeffrey Taylor; Arvid M. Masud; Nirupam Aich; Alexandre Pinto | Environmental Science; Hydrology and Water Chemistry; Wastes; Chemical Kinetics; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2018-09-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e9ebdbb890c68a37e8f/original/kinetic-and-thermodynamic-study-of-methylene-blue-adsorption-onto-chitosan-insights-about-metachromasy-occurrence-on-wastewater-remediation.pdf |
66382f5d418a5379b08a5680 | 10.26434/chemrxiv-2024-m47b2 | Putting the Squeeze on Valence Tautomerism in Cobalt-Dioxolene Complexes | Two isostructural cobalt complexes, [Co(Mentpa)(dbdiox)]+ (Mentpa = tris(2-pyridylmethyl)amine where n = 2 or 3, corresponding to successive methylation of the 6-position of the pyridine rings, dbdiox = 3,5-di-tert-butyl-1,2-dioxolene), were studied using single-crystal X-ray diffraction, and supported by density functional theory (DFT) calculations. The less sterically hindered dimethylated complex exhibits two-step thermally-induced interconversion between the high-spin CoII-seminquinonate and low-spin CoIII-catecholate forms (valence tautometrism) at 155 and 95 K due to the presence of two symmetry-independent complexes. In contrast, the more sterically hindered trimethylated complex does not display thermal valence tautomerism. Both complexes exhibit unique behaviour under high pressure. The dimethylated species undergoes gradual, one-step valence tautomerism in both symmetry-independent complexes concurrently between 0.43 GPa and 1.30 GPa. In the trimethylated species, pressure is sufficient to overcome steric hindrance, leading to one-step valence tautomerism between 2.60 GPa and 3.10 GPa; the first record of pressure-induced valence tautomerism in a thermally inactive complex. | Stephen Moggach; Aston Summers; Zahra Zahir; Moya Hay; Gemma Turner; Alan Riboldi-Tunnicliffe; Rachel Williamson; Stephanie Boer; Lars Goerigk; Colette Boskovic | Inorganic Chemistry; Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66382f5d418a5379b08a5680/original/putting-the-squeeze-on-valence-tautomerism-in-cobalt-dioxolene-complexes.pdf |
671ae1031fb27ce1248396ac | 10.26434/chemrxiv-2024-m5wkv-v2 | Unveiling Non-Monotonic Deformation of Flexible MOFs during Gas Adsorption: From Contraction and Softening to Expansion and Hardening | Flexibility of metal-organic frameworks (MOFs) plays an important role in their applications, particularly in adsorption separations, energy and gas storage, and drug delivery. As an important practical example, we study adsorption of CH4, and CO2 on iso-reticular IRMOF-1 crystal at different temperatures using an original computational scheme of iterative grand canonical Monte Carlo (GCMC) and isothermal-isobaric ensemble molecular dynamics (NPT-MD) simulations. Our findings reveal that thermal fluctuations and flexibility of the host framework affect adsorption of guest molecules, which in turn exert a significant adsorption stress, up to 0.1 GPa, on the framework causing its deformation that occurs in a counterintuitive manner. Contrary to the expected gradual swelling during adsorption, we observe non-monotonic deformation, characterized by sharp contraction during the pore filling, followed by partial expansion. During the pore-filling process, guest molecules engender softening of the host structure to a nearly 100% increase in compressibility. However, upon the pore filling and further densification of the adsorbed phase, the structure hardens and compressibility decreases. These findings are supported by quantitative agreement with adsorption experiments on IPMOF-1 and are expected to be applicable to various degrees, to other MOFs and nanoporous materials. | Shivam Parashar; Nicholas J. Corrente; Alexander V. Neimark | Theoretical and Computational Chemistry; Physical Chemistry; Materials Science; Nanostructured Materials - Materials; Computational Chemistry and Modeling; Crystallography | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/671ae1031fb27ce1248396ac/original/unveiling-non-monotonic-deformation-of-flexible-mo-fs-during-gas-adsorption-from-contraction-and-softening-to-expansion-and-hardening.pdf |
66d334f7a4e53c4876406e89 | 10.26434/chemrxiv-2024-0gb8z | Methylammonium Lead Iodide across Physical Space -- Phase Boundaries and Structural Collapse | Hybrid perovskites exhibit complex structures and phase behavior under different thermodynamic conditions and chemical environments, the understanding of which continues to be of pivotal importance for tailoring their properties towards improved operational stability. To this end, we present for the first time a comprehensive neutron and synchrotron diffraction investigation over the pressure--temperature phase diagram of the paradigmatic hybrid organic-inorganic perovskite methylammonium lead iodide (MAPI). This ambitious experimental campaign down to cryogenic temperatures and tens of kbar was supported by extensive ab initio molecular dynamics simulations validated by the experimental data, to track the structural evolution of MAPI under external physical stimuli at the atomic and molecular levels. These combined efforts enable us to identify the mechanisms underpinning structural phase transitions, including those exhibiting negative thermal expansion across the boundary between the cation-ordered low-temperature phase and the dynamically disordered high-pressure cubic phase. Our results bring to the fore how pronounced octahedral distortions at high pressures ultimately drive the structural collapse and amorphization of this material. | Pelayo Marin-Villa; Mattia Gaboardi; Boby Joseph; Frederico Alabarse; Jeff Armstrong; Kacper Druzbicki; FELIX FERNANDEZ-ALONSO | Physical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66d334f7a4e53c4876406e89/original/methylammonium-lead-iodide-across-physical-space-phase-boundaries-and-structural-collapse.pdf |
63d2a2c41fb2a8767ee1e06f | 10.26434/chemrxiv-2023-nk8lr-v2 | Cation disorder dominates the defect chemistry of high-voltage LiMn1.5Ni0.5O4 (LMNO) spinel cathodes | High-voltage spinel LiMn1.5Ni0.5O4 (LMNO) can exist in a Mn/Ni ordered P4_332 or disordered Fd-3m arrangement with a majority of literature studies reporting improved electrochemical performance for the disordered phase. Through modifying synthesis conditions, the Mn/Ni ordering can be tuned, however oxygen and Mn3+ stoichiometries are also affected, making it difficult to decouple these responses and optimise performance. Here, we investigate all intrinsic defects in P4_332 LMNO under various growth conditions, using density functional theory (DFT) calculations. We find that the majority of defects are deep and associated with small polarons (Mn3+, Mn2+ and Ni3+) formation. The tendency for cation disorder can be explained by the low formation energy of the antisite defects and their stoichiometric complexes. The intrinsic Fermi level of LMNO varies from moderately n-type under oxygen-poor conditions to weakly p-type under oxygen-rich conditions. Our work explains experimental observations (e.g. the Mn/Ni disorder) and provides guidelines for defect-controlled synthesis. | Jiayi Cen; Bonan Zhu; Seán Kavanagh; Alexander Squires; David Scanlon | Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2023-01-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63d2a2c41fb2a8767ee1e06f/original/cation-disorder-dominates-the-defect-chemistry-of-high-voltage-li-mn1-5ni0-5o4-lmno-spinel-cathodes.pdf |
60c749e3f96a0019ca287348 | 10.26434/chemrxiv.12121227.v1 | Hydrolysis of Dimethyl Methylphosphonate (DMMP) in Hot-Compressed Water | <p>Dimethyl methylphosphonate (DMMP) is widely used as a chemical
surrogate for G- and V-type nerve agents, exhibiting similar physiochemical
properties, yet significantly lower toxicity. Continuous hydrolysis of DMMP in
hot-compressed water is performed at temperatures from 200 to 300 °C, pressures of 20 and
30 MPa, and residence times from 30 to 80 s to evaluate the effects of pressure
and temperature on reaction kinetics. DMMP hydrolysis is observed to follow
pseudo-first-order reaction behavior, producing methylphosphonic acid and
methanol as the only detectable reaction products. This is significant for the
practical implementation of a continuous hydrothermal reactor for chemical
warfare agent neutralization, as the process only yields stable, less-toxic
compounds. Pressure has no discernible effect on the hydrolysis rate in
compressed liquid water. Pseudo-first-order Arrhenius parameters are determined,
with an activation energy of<i> </i>90.17±5.68<i> </i>kJ mol<sup>-1</sup> and a
pre-exponential factor of 10<sup>7.51</sup><sup>±0.58</sup> s<sup>-1</sup>.<br /></p> | Brian Pinkard; Shreyas Shetty; John Kramlich; Per G. Reinhall; Igor V. Novosselov | Spectroscopy (Anal. Chem.); Reaction Engineering | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749e3f96a0019ca287348/original/hydrolysis-of-dimethyl-methylphosphonate-dmmp-in-hot-compressed-water.pdf |
60c743ecbb8c1a3d093da3e1 | 10.26434/chemrxiv.8341070.v3 | Catalytic, Transannular Carbonyl-Olefin Metathesis Reactions | A
new class of Lewis acid-catalyzed carbonyl-olefin metathesis reactions is
described that complements existing protocols for related ring-closing,
ring-opening, and intermolecular transformations. These transannular
carbonyl-olefin metathesis reactions rely on FeCl<sub>3</sub> as an inexpensive
Lewis acid catalyst and are mechanistically distinct from previously developed
protocols for ring closing, ring-opening and intermolecular metathesis.
Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction paths are
competing to ultimately favor metathesis as the thermodynamic product.
Importantly, we show that distinct Lewis acid catalysts are able to
differentiate between these pathways to enable the selective formation of
transannular carbonyl-ene or carbonyl-olefin metathesis products thus providing
a valuable approach to the molecular editing of naturally occurring complex
molecules. Additionally, these results are expected to enable further advances
in catalyst design for carbonyl-olefin metathesis to ultimately develop
efficient and high-yielding catalytic carbonyl olefination reactions. | Paul Riehl; Daniel Nasrallah; Corinna Schindler | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2019-07-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c743ecbb8c1a3d093da3e1/original/catalytic-transannular-carbonyl-olefin-metathesis-reactions.pdf |
60c74b2d4c8919060fad33b3 | 10.26434/chemrxiv.12290756.v1 | Expanding the Mechanochemical Toolbox: Combining X-Ray Absorption Spectroscopy and Scattering for in Situ Time-Resolved Monitoring of Gold Nanoparticle Mechanosynthesis | <div>The development of time-resolved in situ approaches for monitoring mechanochemical</div><div>transformations has revolutionized the field of mechanochemistry. Currently, the established in</div><div>situ approaches greatly limit the scope of investigations that are possible. Here we develop a new</div><div>approach to simultaneously follow the evolution of bulk atomic and electronic structure during a</div><div>mechanochemical synthesis. This is achieved by coupling two complementary synchrotron-based</div><div>X-ray methods: X-ray absorption spectroscopy and X-ray diffraction. We apply this method to</div><div>investigate the bottom-up mechanosynthesis of technologically important Au nanoparticles in the</div><div>presence of three different reducing agents. Moreover, we demonstrate how X-ray absorption</div><div>spectroscopy offers unprecedented insight into the early stage generation of growth species (e.g.</div><div>monomers and clusters), which lead to the subsequent formation of nanoparticles. These</div><div>processes are beyond the detection capabilities of diffraction methods. The approach is general,</div><div>and not limited to monitoring NP mechanosynthesis. This combined X-ray approach paves the</div><div>way to new directions in mechanochemical research of advanced electronic materials.</div> | Paulo F M de Oliveira; Adam Michalchuk; Ana de Oliveira Guilherme Buzanich; Ralf Bienert; Roberto M. Torresi; Pedro H. C. Camargo; Franziska Emmerling | Nanostructured Materials - Materials; Kinetics and Mechanism - Inorganic Reactions; Solid State Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74b2d4c8919060fad33b3/original/expanding-the-mechanochemical-toolbox-combining-x-ray-absorption-spectroscopy-and-scattering-for-in-situ-time-resolved-monitoring-of-gold-nanoparticle-mechanosynthesis.pdf |
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