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65827e0be9ebbb4db9531a08 | 10.26434/chemrxiv-2023-cm4hv | Redox-active ruthenium-organic polyhedra with tunable surface functionality and porosities | Dinuclear ruthenium paddlewheel complexes exhibit high structural stability against redox reactions. The use of these chemical motifs for the construction of Ru-based metal-organic polyhedral (RuMOPs) provides a route for redox-active porous materials. However, there are few studies on the synthesis and characterization of RuMOPs due to the difficulty of controlling the assembling process via the ligand-exchange reaction of equatorial acetates of the diruthenium tetraacetate precursors with dicarboxylic acid ligands. In this study, we synthesized three novel cuboctahedral RuMOPs based on the Ru2(II/III)-paddlewheel units with different alkyl functionalizations on the benzene-1,3-dicarboxylate moieties. We evaluated the effect of the external functionalization on the molecular packing and the porous and redox properties. The electrochemical measurements revealed the multi-electron transferred redox process where the electron donating/withdrawing nature of the functional groups allows the control of the redox behavior. | Fuerkaiti Tayier; Javier Troyano; Shun Tokuda; Zaoming Wang; Masa-aki Haga; Shuhei Furukawa | Inorganic Chemistry; Coordination Chemistry (Inorg.); Supramolecular Chemistry (Inorg.); Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2023-12-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65827e0be9ebbb4db9531a08/original/redox-active-ruthenium-organic-polyhedra-with-tunable-surface-functionality-and-porosities.pdf |
66f0c725cec5d6c142e67c06 | 10.26434/chemrxiv-2024-nhh8k | Two-Stage Growth of Solid Electrolyte Interphase on Copper: Imaging and Quantification by Operando Atomic Force Microscopy | The solid electrolyte interphase (SEI) plays a key role in the aging of lithium-ion batteries. The engineering of advanced negative electrode materials to increase battery lifetime relies on accurate models of SEI growth, but quantitative measurement of SEI growth rates remains challenging due to their nanoscale heterogeneity and environmental sensitivity. In this work, using operando electrochemical atomic force microscopy, we track the growth of SEI on copper in a carbonate electrolyte. From operando measurements of SEI thickness and irreversible electrochemical capacity, we directly visualize the dual growth regimes of the SEI, observing an early-stage primary SEI approximately 10 times more “electrochemically compact” than later-stage secondary SEI, as quantified via the incremental thickness per charge passed. While primary SEI is responsible for about half of the irreversible capacity loss (in a 24 h period), it accounts for only a tenth of thickness. We also show that nanoscale defects on the copper substrate play a key role in determining the non-uniform growth morphology of the SEI, thus providing novel, direct evidence that initial SEI growth is not purely transport-limited. Our experiments reveal SEI grows by two modes: first a reaction-limited nucleation and growth of a dense, passivating primary SEI layer, governed by ion-coupled electron transfer kinetics; and subsequently by diffusion-limited growth of a porous secondary SEI layer, once the primary SEI fully passivates the electrode surface. | Henry Thaman; Michael Li; Justin Rose; Swati Narasimhan; Xin Xu; Che-Ning Yen; Norman Jin; Andrew Akbashev; Isabel Davidoff; Martin Bazant; Will Chueh | Materials Science; Nanoscience; Energy; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f0c725cec5d6c142e67c06/original/two-stage-growth-of-solid-electrolyte-interphase-on-copper-imaging-and-quantification-by-operando-atomic-force-microscopy.pdf |
60c74e409abda2515af8d5e0 | 10.26434/chemrxiv.12730787.v1 | Simple Solvothermal Approach to Highly Nanostructured Hematite Thin Films | <div>In this work, we present a solvothermal method for the synthesis of hematite thin films on fluorine-doped tin oxide</div><div>substrates. This simple method uses a precursor solution of iron(III) 2,4-pentanedionate dissolved in ethanol with a</div><div>microliter-scale amount of water and yields hematite ~ 500-nm thick films after annealing. The synthesised films</div><div>were characterised using an array of methods, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, diffuse reflectance, and powder x-ray diffraction. Incorporating water into the precursor solution provides nucleation sites for the reaction and results show that by altering the amount of water used in the synthesis, it is possible to generate nanocrystalline films of different morphologies, nanocrystal size distributions, and surface areas. This synthetic procedure therefore provides control over the films’ physical and electrochemical characteristics. Doping of hematite thin films is also possible using this synthesis, as exemplified by doping with tin by adding tin(II) 2,4-pentanedionate to the precursor solution. To demonstrate utility, we build prototype photoelectrochemical cells using the synthesized hemtatite as the photoanode.</div> | Casey
M. Platnich; Jachym Slaby; David O'Connell; Simon Trudel | Coating Materials; Nanostructured Materials - Materials; Thin Films | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74e409abda2515af8d5e0/original/simple-solvothermal-approach-to-highly-nanostructured-hematite-thin-films.pdf |
60c7416cf96a00251528643e | 10.26434/chemrxiv.7246184.v2 | A biomimetic cerium-based biosensor for the direct visual detection of phosphate under physiological conditions | <div><div><div><p>
</p><p>An indicator displacement
assay (IDA) was used to probe phosphate ions in acqueous medium at neutral pH
using a dinuclear cerium based complex [Ce<sub>2</sub>(HXTA)]3+.
The homoleptic complex can be used to detect phosphate ions in micromolar
concentrations either spectrophotometrically or with the naked-eye. To our
knowledge, this is the biomimetic detection system with the highest affinity
known to date for selective, naked-eye based phosphate recognition under
physiological conditions.</p>
</div></div></div> | Thibaud Rossel; Marc Creus | Bioinorganic Chemistry; Lanthanides and Actinides; Sensors; Biochemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7416cf96a00251528643e/original/a-biomimetic-cerium-based-biosensor-for-the-direct-visual-detection-of-phosphate-under-physiological-conditions.pdf |
668d87db01103d79c58418ab | 10.26434/chemrxiv-2024-hb50k-v2 | Development and Validation of Neural Network Potentials for Multicomponent Oxide Glasses | A neural network potential (MLP) for molecular dynamics simulation (MD) of multicomponent oxide glasses was developed with special consideration of structural reproducibility. The MLP was constructed through pre-training using the dataset of density functional theory (DFT) data provided by the Open Catalysis project and fine-tuning for the dataset of nine-component glasses. A thorough validation based on previous experimental and DFT-MD data was performed for the glass structure derived from neural network molecular dynamics simulation ({\MLMD}) with the developed {\MLP}. The accuracy of {\MLMD} was investigated in terms of the local structure of the glass, comparing it to the glass derived from MD with conventional potentials. The composition dependence of the local structure in \ce{Na2O}--\ce{SiO2} and \ce{Na2O}--\ce{B2O3} glass systems was well reproduced for the {\MLMD}-derived glass. The ability to reproduce the glass structure was demonstrated in the population of four-coordinated boron population and formation of superstructures in alkali borate glasses, and the Al local structure in the novel Al-rich binary aluminoborosilicate glass. The importance of pre-training was revealed by comparing {\MLMD} results using {\MLP} developed with and without pre-training. Although better metric scores for {\MLP} without pre-training can be achieved, the resultant structure was not realistic. This is an important lesson that the metric score alone is inadequate to construct accurate {\MLP} for glasses. Finally, the developed {\MLMD} was applied to the modeling of the reference nuclear waste glass (60.1{\Si}--3.84{\Al}--15.97{\B}--12.65{\Na}--2.87{\Ca}--2.86{\Mg}--1.72{\Zr}), and the charge compensation mechanism of the cations was discussed. | Ryuki Kayano; Yaohiro Inagaki; Ryuta Matsubara; Keisuke Ishida; Takahiro Ohkubo | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Machine Learning; Structure; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-07-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/668d87db01103d79c58418ab/original/development-and-validation-of-neural-network-potentials-for-multicomponent-oxide-glasses.pdf |
67092a4c12ff75c3a122f90b | 10.26434/chemrxiv-2024-xmxrj-v2 | Morphology determination of luminescent carbon nanotubes by analytical super-resolution microscopy approaches | The ability to determine the precise structure of nano-objects is essential for a multitude of applications. This is particularly true of single-walled carbon nanotubes (SWCNTs), which are produced as heterogeneous samples. Current techniques used for their characterization require sophisticated instrumentation, such as atomic force microscopy (AFM), or a compromise on accuracy. In this paper, we propose to use super-resolution microscopy (SRM) to accurately determine the morphology (orientation, length and shape) of individual luminescent SWCNTs. We generate super-resolved images using three recently published SRM analytical software packages (DPR, eSRRF and MSSR) and metrologically compare their performance to determine the morphological properties of SWCNTs. For this, ground-truth information on nanotube morphologies were obtained using polarization measurements and AFM to directly correlate the results from SRM at the single particle level. We show a more than 4-fold improvement in resolution over standard photoluminescence imaging, revealing hidden morphologies as efficiently as AFM. We finally demonstrate that DPR, and eventually eSRRF, can effectively assess SWCNT length distribution in a much faster and more accessible way than AFM. We believe that this approach can be generalized to other types of luminescent nanostructures and thus become a standard for rapid and accurate characterization of samples. | Benjamin Lambert; Hadrien Kerkhof; Ben Flavel; Laurent Cognet | Physical Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Optics; Structure | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67092a4c12ff75c3a122f90b/original/morphology-determination-of-luminescent-carbon-nanotubes-by-analytical-super-resolution-microscopy-approaches.pdf |
62f67a4342ddf53f75b8d40c | 10.26434/chemrxiv-2022-7lt76 | Continuous, Non-Destructive Detection of Microorganism Growth at Buried Interfaces with Vascularized Polymers | Evaluating surface bacterial growth at buried interfaces can be problematic due to the difficulties associated with obtaining samples. In this work, we present a new method to detect signals from microorganisms at buried interfaces that is non-destructive and can be conducted continuously. Inspired by vascular systems in nature that permit chemical communication between the surface and underlying tissues of an organism, we created a system in which an inert carrier fluid could be introduced into an empty vascular network embedded in a polymer matrix. When a microorganism layer was grown on top, small molecules produced by the growth process would diffuse down into the carrier fluid, which could then be collected and analyzed. We used this system to non-destructively detect signals from a surface layer of Escherichia coli using conductivity, ultraviolet-visible (UV-vis) spectroscopy, and high-performance liquid chromatography (HPLC) for organic acids; methods that ranged in sensitivity, time-to-result, and cost. Carrier fluid from sample vascularized polymers with surface bacterial growth recorded significantly higher values in both conductivity and absorbance at 350 nm compared to controls with no bacteria after 24 h. HPLC analysis showed three clear peaks that varied between the samples with bacteria and the controls without. Test tracking the change in signals over 48 h showed clear trends that matched the growth curve and demonstrated the system’s ability to monitor changes over time. A theoretical model of the system closely matched the experimental results, confirming the predictability of the system. Finally, tests using clinically relevant Staphylococcus aureus and Pseudomonas aeruginosa yielded differences in conductivity, absorbance, and HPLC peak areas unique to each species. This work lays the foundation for the use of vascularized polymers as an adaptive system for the continuous, non-destructive detection of surface microorganisms at buried interfaces in both industry and medicine. | Brandon Dixon; Chenxi Sui; Anna Briley; Po-Chun Hsu; Caitlin Howell | Biological and Medicinal Chemistry; Materials Science; Biological Materials; Bioengineering and Biotechnology; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2022-08-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62f67a4342ddf53f75b8d40c/original/continuous-non-destructive-detection-of-microorganism-growth-at-buried-interfaces-with-vascularized-polymers.pdf |
60c74f3a4c89194e5aad3b7d | 10.26434/chemrxiv.12866672.v1 | The Dissolution Dilemma for low Pt Loading Polymer Electrolyte Membrane Fuel Cell Catalysts | Cost and lifetime currently hinder widespread commercialization of polymer electrolyte<br />membrane fuel cells (PEMFCs). Reduced electrode Pt loadings lower costs; however, the impact<br />of metal loading (on the support) and its relation to degradation (lifetime) remain unclear. The<br />limited research on these parameters stems from synthetic difficulties and lack of in situ<br />analytics. This study addresses these challenges by synthesizing 2D and 3D Pt/C model catalyst<br />systems via two precise routes and systematically varying the loading. Pt dissolution was<br />monitored using on-line inductively coupled plasma mass spectrometry (on-line-ICP-MS), while<br />X-ray spectroscopy techniques were applied to establish the oxidation states of Pt in correlation<br />with metal loading. Dissolution trends emerge which can be explained by three particle<br />proximity dependent mechanisms: (1) shifts in the Nernst dissolution potential, (2) redeposition,<br />and (3) alteration of Pt oxidation states. These results identify engineering limitations, which<br />should be considered by researchers in fuel cell development and related fields.
<br /> | Daniel John Seale Sandbeck; Niklas Mørch Secher; Masanori Inaba; Jonathan Quinson; Jakob Ejler Sørensen; Jakob Kibsgaard; Alessandro Zana; Francesco Bizzotto; Florian D. Speck; Michael T. Y. Paul; Alexandra Dworzak; Carsten Dosche; Mehtap Oezaslan; Ib Chorkendorff; Matthias Arenz; Serhiy Cherevko | Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f3a4c89194e5aad3b7d/original/the-dissolution-dilemma-for-low-pt-loading-polymer-electrolyte-membrane-fuel-cell-catalysts.pdf |
60c7543ef96a00f11f2885fb | 10.26434/chemrxiv.13622423.v1 | Ultimate Molecular Theory of Bitter Taste | More than thirty years ago, I proposed a theory about sweet and bitter molecules’ recognition by protein helical structures. Unfortunately the papers could not go to public platform until now. Inspired by the sweet taste theory<sup>1,2</sup>, this bitter taste theory conveys that bitter molecules are recognized by receptor protein helical structures. The recognition process is a dynamic action, in which the receptor protein helices have a torsion-spring-like oscillation between helical structures of 3.6 and 4 amino acids per turn. Based on the characteristics of the bitter receptor protein helix oscillation, it perfectly explains why in bitter molecules, only one unit of hydrogen donor (DH) or hydrogen acceptor (B) is enough in helping molecules to elicit bitter taste. The potential DH and B in bitter receptor are any NH or O of receptor’s peptide NHs and Os, which are the ones forming intramolecular H-bonds responsible for the formation of receptor protein helical structures. Furthermore, only one unit of DH or B is allowed for structurally simple ligands. As recognition sites are only associated with a small fraction – helix structure of whole bitter receptor, multiple binding sites or multiple receptors are well expected. As the oscillation may have different extent, it translates to bitterness intensity. According to ligand-receptor binding motion, bitter receptor could be divided into two kinds of spaces, which are similar to the situation in sweet taste receptor: main and side grooves. These have been discussed in context and especially great details in paper titled deciphering aspartyl peptide sweeteners <sup>2</sup>. | Huazhong He | Bioorganic Chemistry; Physical Organic Chemistry; Stereochemistry; Food; Biochemistry; Biophysics; Cell and Molecular Biology; Chemical Biology; Drug Discovery and Drug Delivery Systems; Biophysical Chemistry; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7543ef96a00f11f2885fb/original/ultimate-molecular-theory-of-bitter-taste.pdf |
60c73ffbee301c6240c789cf | 10.26434/chemrxiv.7580021.v1 | Single Crystal Automated Refinement (SCAR): A Data-Driven Method for Solving Inorganic Structures | <p>Single crystal diffraction is one of
the most common experimental techniques in chemistry for determining a crystal
structure. However, the process of crystal structure solution and refinement is
not always straightforward. Methods to simplify and rationalize the path to the
most optimal crystal structure model have been incorporated
into various data processing and crystal structure solution software, with the focus
generally on aiding macromolecular or protein structure solution. In this work,
we propose a new method that uses single crystal data to solve the crystal
structures of inorganic, extended solids
called “Single Crystal Automated Refinement (<i>SCAR</i>).” The approach was developed using data mining and machine-learning
methods and considers several structural features common in inorganic solids, like
atom assignment based on physically reasonable distances, atomic statistical
mixing, and crystallographic site deficiency. The output is a tree of possible
solutions for the data set with a corresponding fit score indicating the most
reasonable crystal structure. Here, the foundation for <i>SCAR</i> is presented followed by
the implementation of <i>SCAR</i> to solve two
newly synthesized and previously unreported phases, ZrAu<sub>0.5</sub>Os<sub>0.5</sub>
and Nd<sub>4</sub>Mn<sub>2</sub>AuGe<sub>4</sub>. The structure solutions are found
to be comparable with manually solving the data set, including the same refined
mixed occupancies and atomic deficiency, supporting the validity of this automatic
structure solution method. The proposed <i>SCAR</i>
program is thusly verified to be a fast
and reliable assistant in solving even complex single crystal diffraction data
for extended inorganic solids.</p> | Gayatri Viswanathan; Anton Oliynyk; Erin Antono; Julia Ling; Bryce Meredig; Jakoah Brgoch | Alloys; Chemoinformatics; Solid State Chemistry; Machine Learning; Artificial Intelligence | CC BY NC ND 4.0 | CHEMRXIV | 1970-01-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73ffbee301c6240c789cf/original/single-crystal-automated-refinement-scar-a-data-driven-method-for-solving-inorganic-structures.pdf |
61422fd5fc08e3ff4c9617ac | 10.26434/chemrxiv-2021-s1bbw | Divalent Ion-Specific Outcomes on Stern Layer Structure and Total Surface Potential at the Silica:Water Interface | The second-order nonlinear susceptibility, chi(2), in the Stern layer, and the total interfacial potential drop, Phi(0)tot, across the oxide:water interface are estimated from SHG amplitude and phase measurements for divalent cations (Mg2+, Ca2+, Sr2+, Ba2+) at the silica:water interface at pH 5.8 and various ionic strengths. We find that interfacial structure and total potential depend strongly on ion valency. We observe statistically significant differences between the experimentally determined chi(2) value for NaCl and that of the alkali earth series, but smaller differences between ions of the same valency in that series. These differences are particularly pronounced at intermediate salt concentrations, which we attribute to the influence of hydration structure in the Stern layer. Furthermore, we corroborate the differences by examining the effects of anion substitution (SO4 2- for Cl-). Finally, we identify that hysteresis in measuring the reversibility of ion adsorption and desorption at fused silica in forward and reverse titrations manifests itself both in Stern layer structure and in total interfacial potential for some of the salts, most notable CaCl2 and MgSO4, but less so for BaCl2 and NaCl. | Emily Ma; Franz Geiger | Physical Chemistry; Earth, Space, and Environmental Chemistry; Interfaces; Spectroscopy (Physical Chem.); Structure | CC BY 4.0 | CHEMRXIV | 2021-09-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61422fd5fc08e3ff4c9617ac/original/divalent-ion-specific-outcomes-on-stern-layer-structure-and-total-surface-potential-at-the-silica-water-interface.pdf |
622c943653225f36053ef530 | 10.26434/chemrxiv-2022-d7hl9 | Structural and Bioelectrochemical Elucidation of Direct Electron Transfer-type Membrane-bound Fructose Dehydrogenase | Flavin adenine dinucleotide (FAD)-dependent fructose
dehydrogenase (FDH) from Gluconobacter japonicus NBRC3260, a membrane-bound flavohemoprotein capable of direct electron transfer (DET)-type bioelectrocatalysis, was investigated from the viewpoints of structural biology and bioelectrochemistry. As FDH provides a strong DET-type catalytic signal, extensive research has been conducted. Structural analysis using cryo-electron microscopy (cryo-EM) and single-particle analysis revealed the entire FDH
structure. The electron transfer (ET) pathway during the catalytic oxidation of D-fructose was investigated using thermodynamic and kinetic approaches in bioelectrochemistry, as well as structural information. Key amino acid residues that play important roles in substrate specificity and ET acceleration have also been proposed. | Yohei Suzuki; Fumiaki Makino; Tomoko Miyata; Hideaki Tanaka; Keiichi Namba; Kenji Kano; Keisei Sowa; Yuki Kitazumi; Osamu Shirai | Physical Chemistry; Catalysis; Biocatalysis; Electrocatalysis; Electrochemistry - Mechanisms, Theory & Study | CC BY NC ND 4.0 | CHEMRXIV | 2022-03-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/622c943653225f36053ef530/original/structural-and-bioelectrochemical-elucidation-of-direct-electron-transfer-type-membrane-bound-fructose-dehydrogenase.pdf |
66f4206b12ff75c3a16db037 | 10.26434/chemrxiv-2024-21kf0 | The Findability of Microkinetic Parameters by Heterogeneous Chemical Reaction Neural Networks (hCRNNs) | Finding microkinetic parameters for heterogeneously catalyzed processes with conventional methods is a
challenging task. Recently, the use of artificial neural networks has been described as a promising and flexible
tool for kinetic parameter estimation. In this work, an extension to the methodology of chemical reaction
neural networks (CRNNs) to heterogeneously catalyzed reaction networks (hCRNNs) is proposed. The
developed network architecture encapsulates physically interpretable layers for the Arrhenius expression,
coverage dependency, and power-law terms encountered in a typical microkinetic model and accounts for
possible reversibility of all elementary step reactions in the mechanism. Thus, it is fully interpretable and
acts as a drop-in replacement for a conventional kinetic expression.
The methodology is further examined on a prototypical heterogeneously catalyzed reaction mechanism
under transient conditions and various operational and kinetic regimes. This work offers a framework for
quantifying network errors and interpreting its predictions as well as a systematic overview assessing its
ability to identify kinetic parameters. It is found that kinetic behavior is generally described very well by the
network. Additionally, kinetic discovery is possible for the fastest reaction in the mechanism, if observed. A
link between the results and the transient regime is established. With this, the design of suitable hCRNNs
training strategies becomes possible. | Hannes Stagge; Robert Güttel | Physical Chemistry; Catalysis; Chemical Engineering and Industrial Chemistry; Heterogeneous Catalysis; Chemical Kinetics; Physical and Chemical Processes | CC BY 4.0 | CHEMRXIV | 2024-09-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f4206b12ff75c3a16db037/original/the-findability-of-microkinetic-parameters-by-heterogeneous-chemical-reaction-neural-networks-h-crn-ns.pdf |
60c7522dbb8c1a90c83dbe36 | 10.26434/chemrxiv.13260233.v1 | Assessing Capacity Loss Remediation Methods for Asymmetric Redox Flow Battery Chemistries Using Levelized Cost of Storage | <p>Redox flow
batteries, a promising grid-scale energy storage solution, have an open
architecture that can facilitate a broad range of redox electrolytes. Vanadium
is the most mature chemistry, which is largely due to its symmetry, where all active species are based on
a single parent compound, that allows for inexpensive crossover remediation
via rebalancing; however, the industry has increasingly sought chemistries with
lower-cost and higher-abundance redox couples. Most chemistries cannot be
configured symmetrically, though, necessitating research into capacity-recovery
methods for asymmetric chemistries. In this work, we adapt our previously
developed levelized cost of storage model, which tracks capacity fade and
recovery and evaluates the costs across the battery’s lifetime, to analyze two
classes of asymmetric chemistries, those with active species of finite or
infinite lifetimes, and their respective remediation options. For finite-lifetime
chemistries, we explore active-species replacement to counter decay. For
infinite-lifetime chemistries, we consider two methods for addressing
crossover: imposition of pseudo-symmetry via the spectator strategy and
elimination of crossover via membranes with perfect selectivity. We anticipate
this framework will help guide the evaluation and design of new redox
chemistries, balancing the desire for low capital costs with the need to
remediate capacity repeatedly and inexpensively.</p> | Kara Rodby; Mike Perry; Fikile Brushett | Electrochemistry; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7522dbb8c1a90c83dbe36/original/assessing-capacity-loss-remediation-methods-for-asymmetric-redox-flow-battery-chemistries-using-levelized-cost-of-storage.pdf |
6204efbecbb4f4343ebbfb59 | 10.26434/chemrxiv-2022-pckj0 | Quantitative reversible one pot interconversion of three crystalline polymorphs by ball mill grinding. | We demonstrate here using a disulfide system the first example of reversible, selective and quantitative transformation between three crystalline polymorphs by ball mill grinding. This includes the discovery of a previously unknown polymorph. Each polymorph is reproducibly obtained under well-defined neat or liquid-assisted grinding conditions, revealing subtle control over the apparent thermodynamic stability. We discovered that presence of a contaminant as low as 1.5% mol mol-1 acting as a template is required to enable all these three polymorph transformations. The relative stabilities of the polymorphs are determined by the sizes of the nanocrystals produced under different conditions and by surface interactions with small amounts of added solvent. For the first time, we show evidence that each of the three polymorphs is obtained with a unique and reproducible crystalline size. This mechanochemical approach gives access to bulk quantities of metastable polymorphs that are inaccessible through recrystallisation. | Ana M. Belenguer; Giulio I. Lampronti; Adam A. L. Michalchuk; Franziska Emmerling; Jeremy K. M. Sanders | Physical Chemistry; Organic Chemistry; Materials Science; Materials Processing; Crystallography | CC BY 4.0 | CHEMRXIV | 2022-02-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6204efbecbb4f4343ebbfb59/original/quantitative-reversible-one-pot-interconversion-of-three-crystalline-polymorphs-by-ball-mill-grinding.pdf |
651eb126bda59ceb9aeb567c | 10.26434/chemrxiv-2023-kpm5r | Computational Study of the Reactions of Interstellar Molecules: CH2 Reacting with HCNO and HNCO | Association reactions among small molecules known to exist in the interstellar medium are interesting for theories on the origins of life. A screening of thousands of reactions, using machine learning estimates of energy barriers, identified the reaction of CH2 with HCNO and HNCO as particularly interesting. We report reaction mechanisms, including energies of transition states and products, computed with density functional theory and coupled cluster theory. The lowest energy pathway on the triplet ground state surface of CH2 + HNCO has a barrier of 11 kcal/mol and produces CH2(CO)NH. Singlet CH2 is 9 kcal/mol above the ground state. It can react with HCNO or HNCO without barrier giving four products: CH2NCHO, N-methyleneformamide, the thermodynamically favoured product; NHCHCHO; NHCHOCH; and (CH2OC)NH, oxiran-2-ylazanide. If triplet to singlet crossing occurs, an upper bound of roughly 10 kcal/mol is implied for the barrier to formation of these four products. | Hongchen Ji; Anita Rágyanszki; Rene A. Fournier | Theoretical and Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/651eb126bda59ceb9aeb567c/original/computational-study-of-the-reactions-of-interstellar-molecules-ch2-reacting-with-hcno-and-hnco.pdf |
60c750f9567dfe84c5ec597f | 10.26434/chemrxiv.13106900.v1 | Strain in Silica-Supported Ga (III) Sites: Neither Too Much nor Too Little for Propane Dehydrogenation Catalytic Activity | <p>Well-defined Ga(III) sites on SiO<sub>2</sub> are highly active, selective, and stable catalysts in the propane dehydrogenation reaction. In this contribution, we evaluate the catalytic activity towards propane dehydrogenation of tri-coordinated and tetra-coordinated Ga(III) sites on SiO<sub>2</sub> by means of first principles calculations using realistic amorphous periodic SiO<sub>2</sub>models. We evaluated the three reaction steps in propane dehydrogenation, namely the C-H activation of propane to form propyl, the beta-hydride elimination transfer to form propene, and a Ga-hydride, and the H-H coupling to release H<sub>2</sub>, regenerating the initial Ga-O bond and closing the catalytic cycle. Our work shows how Brønsted-Evans-Polanyi relationships are followed for these three reaction steps on Ga(III) sites on SiO<sub>2</sub> and highlights the role of the strain of the reactive Ga-O pairs on such sites of realistic amorphous SiO<sub>2</sub> models. While highly strained sites are very reactive sites for the initial C-H activation, they are more difficult to regenerate. The corresponding less strained sites are not reactive enough, pointing to the need of a right balance in strain to be an effective site for propane dehydrogenation. Overall, our work provides an understanding of the intrinsic activity of acidic Ga single sites towards the propane dehydrogenation reaction and paves the road towards the design and prediction of better single-site catalysts on SiO<sub>2 </sub>for the propane dehydrogenation reaction.</p> | C. S. Praveen; A. P. Borosy; Christophe Copéret; Aleix Comas Vives | Computational Chemistry and Modeling; Heterogeneous Catalysis; Bond Activation; Catalysis; Kinetics and Mechanism - Organometallic Reactions; Reaction (Organomet.); Theory - Organometallic | CC BY NC ND 4.0 | CHEMRXIV | 2020-10-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c750f9567dfe84c5ec597f/original/strain-in-silica-supported-ga-iii-sites-neither-too-much-nor-too-little-for-propane-dehydrogenation-catalytic-activity.pdf |
612f7de466deddefe3012016 | 10.26434/chemrxiv-2021-b4c8b | COVID-19: Invades Erythrocytes through Plasmodium Falciparum Antigen and Complement-Like System | Malaria symptoms are very similar to those of COVID-19, and infections can be symptomatic or asymptomatic. Common immunodominant epitopes are shared by the SARS-CoV-2 proteins and the Plasmodium falciparum antigen. Through bioinformatics methods such as domain search, this study discovered that the S, ORF3a proteins contained Plasmodium antigens rich in tryptophan and threonine. ORF3a, ORF8, S, and N and others also had more extended autotransporter domains. The Plasmodium antigen of S protein contained a C1q domain capable of binding to the complement receptor 1 on the red blood cell membrane. ORF3a contained the Plasmodium antigen EBA-175 domain, which was capable of binding to glycophorin A on the red blood cell membrane. S and ORF3a were bound to band 4.1 to anchor on the erythrocyte membrane skeleton, respectively. The Membrane attack complex component of the S protein formed fusion pores on the red blood cell membrane. Then it injected viral genetic material into the mature red blood cell. ORF3a used a thiol-activated cytolysin domain to create hemolytic pores in the red blood cell membrane. The coagulation factor calcium ions were involved in the red blood cell invasion process. The invasion would have no discernible hemolysis or hypoxia reactions. According to the Plasmodium antigen type for SARS-COV-2, the blood cells of people with blood types A and Knops were susceptible to attack by SARS-COV-2 virus proteins. | wenzhong liu; hualan li | Biological and Medicinal Chemistry; Biochemistry; Bioinformatics and Computational Biology; Cell and Molecular Biology | CC BY 4.0 | CHEMRXIV | 2021-09-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/612f7de466deddefe3012016/original/covid-19-invades-erythrocytes-through-plasmodium-falciparum-antigen-and-complement-like-system.pdf |
60c74955337d6ca106e276cb | 10.26434/chemrxiv.12052647.v1 | Double Ring-Closing Approach for the Synthesis of 2,3,6,7-Substituted Anthracene Derivatives | Anthracene derivatives have been used for a wide range of applications and many different synthetic methods for their preparation have been developed. However, despite continued synthetic efforts, introducing substituents in some positions has remained difficult. Here we present a method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions followed by a deprotection and intramolecular double ring-closing condensation reaction. Further modification of the precursor is expected to enable the introduction of additional substituents in other positions and may even enable the synthesis of fully substituted anthracene derivatives by the presented approach.<br /> | Birgit Meindl; Katharina Pfennigbauer; Berthold Stöger; Martin Heeney; Florian Glöcklhofer | Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74955337d6ca106e276cb/original/double-ring-closing-approach-for-the-synthesis-of-2-3-6-7-substituted-anthracene-derivatives.pdf |
61698d42a3d2c97229d79dd0 | 10.26434/chemrxiv-2021-lx8tx | Cross-conjugation controls the stabilities and photophysical properties of heteroazoarene photoswitches | Azoarene photoswitches are versatile molecules that interconvert from their E-isomer to their Z-isomer with light. Azobenzene is a prototypical photoswitch but its derivatives can be poorly suited for in vivo applications such as photopharmacology due to undesired photochemical reactions promoted by ultraviolet light and its relatively short half-life (t1/2) of the Z-isomer (2 days). Experimental and computational studies suggest that these properties (λmax of the E isomer and t1/2 of the Z-isomer) are inversely related. We identified isomeric azobisthiophenes and azobisfurans from a high-throughput screening study of 1700 azoarenes as photoswitch candidates with improved λmax and t1/2 values relative to azobenzene. We used density functional theory to predict the activation free energies, reaction free energies, and vertical excitation energies of the E- and Z-isomers of 2,2- and 3,3-substituted azobisthiophenes and azobisfurans. The half-lives depend on whether the heterocycles are 𝜋-conjugated or cross-conjugated with the diazo 𝜋-bond. The 2,2-substituted azoarenes both have t1/2 values on the scale of 1 hour, while the 3,3-analogues have computed half-lives of 40 (thiophene) and 230 (furan) years. The 2,2-substituted heteroazoarenes have significantly higher λmax absorptions than their 3,3-substituted analogs: 76 nm for azofuran and 77 nm for azothiophene. | Daniel Adrion; Steven Lopez | Theoretical and Computational Chemistry; Physical Chemistry; Organic Chemistry; Physical Organic Chemistry; Computational Chemistry and Modeling | CC BY 4.0 | CHEMRXIV | 2021-10-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61698d42a3d2c97229d79dd0/original/cross-conjugation-controls-the-stabilities-and-photophysical-properties-of-heteroazoarene-photoswitches.pdf |
651f9f0b8bab5d2055be7b8b | 10.26434/chemrxiv-2023-ggwtj | Exploring Natural Dye and Bioactive Secondary Metabolites in Lonchocarpus Cyanescens Benth (Fabaceae) Plant Using Liquid Chromatography-High-Resolution Mass Spectrometry and Compound DiscovererTM Software | Lonchocarpus cyanescens Benth is a native African plant commonly known as "African Indigo" or "Indigo Vine" because locals extract dyestuff from its leaves that gives it a brilliant indigo-like hue. Several scientists have reported this plant to contain indigo dye; however, there has been no evidence to justify their claim. Therefore, the primary dye component(s) responsible for the indigo-like hue has been scientifically unexplored. In this study, we utilized UV-Vis and HPLC-DAD-ESI-HRMS (OrbitrapTM) techniques to identify the main chemical compound(s) responsible for the color of the dyestuff. To our surprise, the presence of indigo dye was not detected in the isolated dye extract; we discovered that crystal violet dye and crystal violet-like molecules are present in the extract, which can be responsible for the blue color observed. In addition to its natural dye-producing capability, this plant is used by local traditional healers to heal ailments including ulcers, arthritis, intestinal disorders, etc. Many scientists have proved that the effect of this plant extract on many of these disease states was justified; however, the molecular identities of the compounds responsible for the plant's medicinal value have been unexplored. Therefore, we also analyzed the leaf extract of L. cyanescens and identified several chemical compounds having structural similarities to active drug compounds. The details of our findings will be the focus of our research work. | Tanvir Amit; Luis Colón | Analytical Chemistry; Agriculture and Food Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/651f9f0b8bab5d2055be7b8b/original/exploring-natural-dye-and-bioactive-secondary-metabolites-in-lonchocarpus-cyanescens-benth-fabaceae-plant-using-liquid-chromatography-high-resolution-mass-spectrometry-and-compound-discoverer-tm-software.pdf |
60c74b14f96a00d990287566 | 10.26434/chemrxiv.12280532.v1 | Computational Guided Identification of Novel Potent Inhibitors of NTD-N-Protein of SARS-CoV-2 | <p>The Coronavirus
Disease 2019 (COVID-19), caused by the SARS-CoV-2 virus has raised severe
health problems in china and across the world as well. CoVs encode the
nucleocapsid protein (N-protein), an essential RNA-binding protein that
performs different roles throughout the virus replication cycle and forms the
ribonucleoprotein complex with viral RNA using the N-terminal domain (NTD) of
N-protein. Recent studies have shown that NTD-N-protein is a legitimate target
for the development of antiviral drugs against human CoVs. Owing to the
importance of NTD, the present study focuses on targeting the NTD-N-protein
from SARS-CoV-2 to identify the potential compounds. The pharmacophore model
has been developed based on the guanosine monophosphate (GMP), a RNA substrate
and further pharmacophore-based virtual screening was performed against ZINC
database. The screened compounds were filtered by analysing the <i>in silico</i> ADMET properties and drug-like
properties. The pharmacokinetically screened compounds (ZINC000257324845,
ZINC000005169973, and ZINC000009913056) were further scrutinized through computational
approaches including molecular docking and molecular dynamics simulations and
revealed that these compounds exhibited good binding affinity as compared to
GMP and provide stability to their respective complex with the NTD. Our
findings could disrupt the binding of viral RNA to NTD, which may inhibit the
essential functions of NTD. These findings may further provide an impetus to
develop the novel and potential inhibitor against SARS-CoV-2.<br /></p> | Poonam Dhankhar; vikram dalal; Vishakha Singh; Shailly Tomar; pravindra kumar | Bioinformatics and Computational Biology | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74b14f96a00d990287566/original/computational-guided-identification-of-novel-potent-inhibitors-of-ntd-n-protein-of-sars-co-v-2.pdf |
65f9a126e9ebbb4db908b135 | 10.26434/chemrxiv-2024-gcck4 | “Nano-Skeleton” Si-SiOx@C Anodes towards Highly Stable Lithium-ion Batteries | A fragile solid-electrolyte interphase (SEI) layer due to the volume expansion of silicon cannot sufficiently prevent side reactions and electrolyte consumption and restricts the application of silicon anodes in lithium-ion batteries with high cycling stability. Herein, a carbon nanotube (CNT) supported “nano-skeleton” structure with high mechanical property and improved conductive pathways is designed by twining CNTs with in-situ grown SiOx@C and carbon-wrapped Si nanoparticles. The CNT “nano-skeleton” can improve electrical contact between particles, promoting the formation of a denser and more homogenous SEI layer. Moreover, the buffer region granted by the CNTs can tolerate the volume expansions of Si avoiding the repeated destruction of the SEI layer during continuous lithiation and delithiation processes. Combined with these advantages, the anode with optimal CNT content can deliver a high capacity (918 mAh·g-1 at 200 mA·g-1) and high capacity retention (74% after 300 cycles) with relieved volume expansion (71.4%). The capacity of the NMC111 full cell retains about 70 mAh·g-1 after 500 cycles at 100 mAh·g-1 with capacity retention of 72%. | Xiang Guan; Yang Zhang; Ian Kinloch; Mark Bissett | Materials Science; Nanoscience; Nanostructured Materials - Materials; Nanostructured Materials - Nanoscience; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-03-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65f9a126e9ebbb4db908b135/original/nano-skeleton-si-si-ox-c-anodes-towards-highly-stable-lithium-ion-batteries.pdf |
67a7744c6dde43c9081216ca | 10.26434/chemrxiv-2025-c4gmj | 1 The Electrochemistry of Sodiumdodecylsulfonate on Au(111) in sulfuric acid – Voltammetry, Adsorbate structure and Friction | This study deals with the adsorption of sodiumdodecylsulfonate (SDS*) on the single crystalline Au(111) surface in 0.1 M sulfuric acid. As demonstrated by cyclic voltammetry and atomic force microscopy (AFM), the SDS* adsorbate shows a transition from a flat adsorbed phase to a condensed phase with increasing electrode potential. These observations are similar to those on sodiumdodecylsulfate (SDS) 1-3, where a condensed, disordered bilayer was found 4. For the SDS* we found a well-ordered structure of the condensed layer and thus were able to suggest a structure for the condensed layer. Comparing the condensed and the flat phase, the condensed phase shows lower friction at low normal loads (tip follows corrugation) and higher friction at high normal loads (tip compresses/penetrates the layer). | Andreas Koellisch‐Mirbach; Inhee Park; Helmut Baltruschat | Physical Chemistry; Materials Science; Nanoscience; Electrochemistry - Mechanisms, Theory & Study; Interfaces; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67a7744c6dde43c9081216ca/original/1-the-electrochemistry-of-sodiumdodecylsulfonate-on-au-111-in-sulfuric-acid-voltammetry-adsorbate-structure-and-friction.pdf |
60c73e97bdbb894813a37e6b | 10.26434/chemrxiv.7033211.v1 | SemiEmpirical Born-Oppenheimer Molecular Dynamics (SEBOMD) Within the Amber Biomolecular Package | <div>Semiempirical quantum methods from the Neglect of Differential Diatomic Overlap (NDDO) family such as MNDO, AM1, or PM3 are fast albeit approximate quantum methods. By combining them with linear scaling methods like the Divide & Conquer (D&C) method, it is possible to quickly evaluate the energy of systems containing hundreds to thousands of atoms. We here present our implementation in the Amber biomolecular package of a SEBOMD module that provides a way to run SemiEmpirical Born-Oppenheimer Molecular Dynamics. At each step of a SEBOMD molecular dynamics, a fully converged SCF calculation is performed to obtain the semiempirical quantum potential energy of a molecular system encaged or not in periodic boundary conditions. We describe the implementation and the features of our SEBOMD implementation. We show the equirements to conserve the total energy in NVE simulations, and how to accelerate SCF convergence through density matrix extrapolation. Specific ways of handling periodic boundary conditions using mechanical embedding or electrostatic embedding through a tailored quantum Ewald summation is developed. The parallel performance of SEBOMD simulations using the D&C scheme are presented for liquid water systems of various sizes, and a comparison between the traditional full diagonalization scheme and the D&C approach for the reproduction of the structure of liquid water illustrates the potentiality of SEBOMD to simulate molecular systems containing several hundreds of atoms for hundreds of picoseconds with a quantum mechanical potential in a reasonable amount of CPU time.</div> | Antoine Marion; Hatice Gokcan; Gerald Monard | Computational Chemistry and Modeling; Quantum Mechanics | CC BY NC ND 4.0 | CHEMRXIV | 1970-01-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e97bdbb894813a37e6b/original/semi-empirical-born-oppenheimer-molecular-dynamics-sebomd-within-the-amber-biomolecular-package.pdf |
67a5f22a6dde43c908eb9ce2 | 10.26434/chemrxiv-2025-p2cbf | Aryl Thiocyanate as an Organic ‘CN’ Source: Circular Chemical Economy Approach to Access Thiocyano-Thioesters from Cyclic Thioacetals | We report a mild, transition metal-free, organophotoredox-catalyzed visible light mediated strategy for accessing thiocyano-thioesters from cyclic thioacetals, using aryl thiocyanate as an organic ‘CN’ source. Additionally, the by-product diaryl disul-fide is efficiently repurposed as a recyclable and reusable substrate for the sustainable synthesis of phenyl thiocyanates, supporting the circular chemical economy. This method exhibits broad functional group tolerance and is applicable to 5- to 8-membered cyclic thioacetals. The reaction is also scalable to gram quantity. A series of control experiments, fluorescence quenching and cyclic voltammetry analysis supported a plausible reaction mechanism. | Mousumi Behera; Shubham Shukla ; Pankaj D. Dharpure; Dr. Ramakrishna G. Bhat | Organic Chemistry; Catalysis; Homogeneous Catalysis; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67a5f22a6dde43c908eb9ce2/original/aryl-thiocyanate-as-an-organic-cn-source-circular-chemical-economy-approach-to-access-thiocyano-thioesters-from-cyclic-thioacetals.pdf |
60c73e550f50dbc272395629 | 10.26434/chemrxiv.6838478.v1 | Novel CO2-Thermic Oxidation Process with Mg-Based Intermetallic Compounds and Its Application to Energy Storage Materials | A novel strategy for the oxidation of Mg-based intermetallic compounds
using CO<sub>2</sub> as an oxidizing agent was realized via simple thermal
treatment, called ‘CO2-thermic Oxidation Process (CO-OP)’. Furthermore, as a
value-added application, electrochemical properties of one of the reaction
products (carbon-coated macroporous silicon) was evaluated. Considering the
facile tunability of the chemical/physical properties of Mg-based
intermetallics, we believe that this route can provide a simple and versatile
platform for functional energy materials synthesis as well as CO<sub>2</sub> chemical
utilization in an environment-friendly and sustainable way. | Younghwan Cha; Jung-In Lee; Panpan Dong; Xiahui Zhang; Min-Kyu Song | Alloys; Coating Materials; Nanostructured Materials - Materials; Kinetics and Mechanism - Inorganic Reactions; Reaction (Inorg.); Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2018-07-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e550f50dbc272395629/original/novel-co2-thermic-oxidation-process-with-mg-based-intermetallic-compounds-and-its-application-to-energy-storage-materials.pdf |
60c74397567dfe0711ec413a | 10.26434/chemrxiv.9273059.v1 | Unexpected Formation of Hexasubstituted Arenes Through a Twofold Palladium-Mediated Ligand Arylation | <div>
<p>A rearrangement reaction of biarylphosphine-supported
Pd(II) complexes was employed to synthesize 1,3,5-triaryl 2,4,6-triisopropylbenzene
compounds, a class of molecules that has not previously been reported. The
strain of the central hexasubstituted ring was investigated via X-ray
crystallography.</p>
</div>
<br /> | Corin Wagen; Bryan T. Ingoglia; Stephen L. Buchwald | Organic Synthesis and Reactions; Transition Metal Complexes (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74397567dfe0711ec413a/original/unexpected-formation-of-hexasubstituted-arenes-through-a-twofold-palladium-mediated-ligand-arylation.pdf |
650c5486b927619fe7909011 | 10.26434/chemrxiv-2023-h9ffx | Bottom-illuminated photothermal nanoscale chemical imaging with a flat silicon ATR in air and liquid | We demonstrate a novel approach for bottom-illuminated atomic force microscopy infrared spectroscopy (AFM-IR). This nearfield technique is suitable for AFM-IR measurements in liquids, taking advantage of an attenuated total reflection (ATR) setup where the developing evanescent wave is used for photothermal excitation of the sample of interest. Conventional bottom-illuminated measurements are conducted using high-refractive index prisms. We showcase the advancement of instrumentation through the introduction of novel, flat silicon substrates as replacements for prisms. We illustrate the feasibility of this technique for bottom illuminated AFM-IR in both, air and liquid. We also show how modern rapid prototyping technologies enable commercial AFM-IR instrumentations to accept these new substrates. This new methodic approach paves the way for a wide range of experiments since virtually any established protocol for Si surface functionalization can be applied to this sample carrier and the low unit cost enables rapid iteration of experiments. | Georg Ramer; Ufuk Yilmaz; Savda Sam; Bernhard Lendl | Analytical Chemistry; Nanoscience; Imaging; Spectroscopy (Anal. Chem.) | CC BY 4.0 | CHEMRXIV | 2023-09-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/650c5486b927619fe7909011/original/bottom-illuminated-photothermal-nanoscale-chemical-imaging-with-a-flat-silicon-atr-in-air-and-liquid.pdf |
666c08265101a2ffa8929722 | 10.26434/chemrxiv-2024-8lbsl-v2 | Assessment of Available Energy Resources in Louisiana, United States for Sustainable Energy Mix
Design | As the world’s population grows, industrial, agricultural, transportation and other energy-intensive activities increase exponentially, leading to high energy demands. However, overreliance on fossil fuels as a primary energy source has posed a significant threat to the planet and its habitats because of high GHG emissions into the atmosphere, resulting in an unstable climate change. To mitigate this challenge, there is a need to balance energy demand with sustainability and social, economic, and environmental impacts associated with energy usage. Unfortunately, Louisiana depends excessively on non-sustainable forms of energy to meet its high energy demands with only 3.5% of its utility-scale electricity generated from renewable energy resources, despite being blessed with an abundance of sustainable energy resources. This project conducted a feasibility study on the energy resources available in Louisiana for different energy-efficient indicators, aiming at designing an energy portfolio that is sustainable, reliable, affordable, versatile, and meets the State’s high-energy demand. Based on the results obtained, a sustainable energy mix comprising 63% natural gas, less than 6% coal, 14% nuclear, 2% hydroelectric, 6% solar, 4% biomass, and 5% wind was proposed for Louisiana’s net utility-scale electricity production to help the State achieve minimal net emissions by 2035 and still fulfill its power requirements.
Energy policies that can be implemented to catalyze the transition have also been suggested | Godwin Edor | Energy | CC BY NC 4.0 | CHEMRXIV | 2024-06-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/666c08265101a2ffa8929722/original/assessment-of-available-energy-resources-in-louisiana-united-states-for-sustainable-energy-mix-design.pdf |
60c7431abdbb892df9a385c2 | 10.26434/chemrxiv.8942678.v1 | Catalyst Design for Highly Efficient Base-Free Carbon Dioxide Hydrogenation to Formic Acid | We
report on new ruthenium complexes as catalysts for the efficient transformation
of CO<sub>2</sub> into formic acid as a high-value chemical and fuel. Remarkably,
these complexes catalyze the hydrogenation of CO<sub>2</sub> selectively and without
employing any base, which improves the sustainability of the process when
compared the common base-assisted technologies. The molecular catalyst design relies
on donor-flexible and synthetically versatile pyridylidene amide (PYA) ligands
which allows the ligand architecture to be varied in a controlled manner to
gain valuable insights for the improvement of catalyst performance. Modification
of the ligand properties directly influence the catalytic process by shifting
the turnover limiting step, the reaction mechanism and the stability upon the
acidification of the reaction media and provide access to high-performance
systems reaching turnover numbers of several thousands and turnover frequencies
up to 350 h<sup>–1</sup>. | Andreas Weilhard; Kevin Salzmann; Jairton Dupont; Martin Albrecht; Victor Sans | Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2019-07-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7431abdbb892df9a385c2/original/catalyst-design-for-highly-efficient-base-free-carbon-dioxide-hydrogenation-to-formic-acid.pdf |
60c74125337d6c4053e2683f | 10.26434/chemrxiv.7962848.v1 | Cell Adherence and Drug Delivery from Particle Based Mesoporous Silica Films | Spatially and temporally controlled drug delivery is important for implant and tissue engineering applications, as the efficacy and bioavailability of the drug can be enhanced, and can also allow for drugging stem cells at different stages of development. Long-term drug delivery over weeks to months is however difficult to achieve, and coating of 3D surfaces or creating patterned surfaces is a challenge using coating techniques like spin- and dip-coating. In this study, mesoporous films consisting of SBA-15 particles grown onto silicon wafers using wet processing were evaluated as a scaffold for drug delivery. Films with various particle sizes (100 – 900 nm) and hence thicknesses were grown onto OTS-functionalized silicon wafers using a direct growth method. Precise patterning of the areas for film growth could be obtained by local removal of the OTS functionalization through laser ablation. The films were incubated with the model drug DiO, and murine myoblast cells (C2C12 cells) were seeded onto films with different particle sizes. Confocal laser scanning microscopy (CLSM) was used to study the cell growth, and a vinculin-mediated adherence of C2C12 cells on all films was verified. The successful loading of DiO into the films was confirmed by UV-vis and CLSM. It was observed that the drugs did not desorb from the particles during 24 hours in cell culture. During adherent growth on the films for 4 h, small amounts of DiO and separate particles were observed inside single cells. After 24 h, a larger number of particles and a strong DiO signal were recorded in the cells, indicating a particle mediated drug uptake. A substantial amount of DiO loaded particles were however attached on the substrate after 24 making the films attractive as a long-term reservoir for drugs on e.g. medical implants.<br /> | Emma Björk; Bernhard Baumann; Florian Hausladen; Rainer Wittig; mika lindén | Biocompatible Materials; Coating Materials; Nanostructured Materials - Materials; Nanostructured Materials - Nanoscience; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2019-04-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74125337d6c4053e2683f/original/cell-adherence-and-drug-delivery-from-particle-based-mesoporous-silica-films.pdf |
6384fcbf9b5b800ef0d90a9b | 10.26434/chemrxiv-2022-r4hpx | Practical Stereocontrolled Access to Thioisosteres of Essential Signaling Molecules and Building Blocks for Life: Nucleoside Di- and Triphosphates | Nucleoside diphosphates and triphosphates impact nearly every aspect of biochemistry, however, the use of such compounds as tools or medicinal leads for nucleotide-dependent enzymes and receptors is hampered due to rapid metabolism. Meanwhile, a successful strategy to address the instability of the monophosphate moiety in oligonucleotide therapeutics has been accomplished by their isosteric replacement with phosphorothioates. On the contrary, no practical methods exist to rapidly and controllably access stereopure di- and triphosphate thioisosteres of both natural and unnatural nucleosides. Here we show how a modular, reagent-based platform can enable the stereocontrolled and scalable synthesis of a library of such molecules. Such thioisosteric replacements can have profound effects on the potency and stability of lead candidates, as evidenced by data demonstrating that ligand-receptor interactions can be dramatically influenced by P-stereochemistry. | Hai-Jun Zhang; Michał Ociepa; Molhm Nassir; Bin Zheng; Sarah Lewicki; Veronica Salmaso; Helay Babury; Jessica Nagel; Salahuddin Mirza; Beatriz Bueschbell; Haneen Al-Hroub; Olga Perzanowska; Ziqing Lin; Michael Schmidt; Martin Eastgate; Kenneth Jacobson; Christa Müller; Joanna Kowalska; Jacek Jemielity; Phil Baran | Biological and Medicinal Chemistry; Organic Chemistry; Organic Synthesis and Reactions; Stereochemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6384fcbf9b5b800ef0d90a9b/original/practical-stereocontrolled-access-to-thioisosteres-of-essential-signaling-molecules-and-building-blocks-for-life-nucleoside-di-and-triphosphates.pdf |
6464c975fb40f6b3eebba944 | 10.26434/chemrxiv-2023-90x56 | Electrochemical Asymmetric Diacetoxylation of Styrenes Mediated by Chiral Iodoarene Catalyst | Organocatalysis with chiral iodoarenes has emerged as a powerful approach for performing enantioselective transformations, however, suffering from the need to utilize stoichiometric amounts of peroxy acids or similar high energy oxidants. Electrosynthesis enables eliminating stoichiometric redox reagents by replacing them with electric stimuli. In this context, an electrochemically-promoted variant of the chiral iodoarene-catalyzed asymmetric diacetoxylation of styrenes was evaluated. The screening of reaction parameters established a set of conditions under which, for the first time, an enantioselective electrochemical oxidation mediated by a chiral iodoarene achieving a catalytic turnover has been accomplished. The reaction was applied for the synthesis of an array of products in 15-60% yields and 0-84% ee. The modest efficiency of the electrocatalysis was traced to a partial direct oxidation of styrene substrates leading to racemic products and undesired dimeric side-products. Cyclic voltammetry measurements demonstrated that such outcome originates from a somewhat difficult electrochemical oxidation of the applied iodoarene catalyst. Present work provides important insights and implications for the design of more efficient electrocatalytic systems employing chiral iodoarenes as mediators. | Natalia Wojciechowska; Krzysztof Bienkowski; Renata Solarska; Marcin Kalek | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6464c975fb40f6b3eebba944/original/electrochemical-asymmetric-diacetoxylation-of-styrenes-mediated-by-chiral-iodoarene-catalyst.pdf |
66fbd7d4cec5d6c142c75b66 | 10.26434/chemrxiv-2024-qg1d6 | Cycloparaazine, a full-azine carbon nanoring | Cycloparaphenylenes (CPPs) and related carbon nanorings represent iconic molecular entities in molecular nanocarbon science. While theoretical studies predict that the introduction of nitrogen atoms (N-doping) onto CPP frameworks would add a number of fascinating properties, only a handful of partially N-doped carbon nanorings have been synthesized. We herein report the synthesis of a long-awaited cycloparaazine (CPA), where every para-connected aromatic moiety consists of a N-heterocycle, and two other highly N-doped CPPs. The evaluation of optoelectronic and structural properties coupled with theoretical studies uncovered the impact of both the amount and positioning of N-doping onto the nanorings properties; far less ring strain, red-shifted UV-vis absorption and fluorescence, smaller HOMO‒LUMO gaps and both higher reduction and oxidation potentials than pristine CPPs. Ultimately, new potential applications of highly N-doped nanorings were examined in band-gap engineering with Lewis acids and as energy storage materials in batteries. | Till Drennhaus; Daiki Imoto; Elena Horst; Lena Lezius; Hiroki Shudo; Tomoki Kato; Klaus Bergander; Dirk Leifert; Akiko Yagi; Armido Studer; Kenichiro Itami | Physical Chemistry; Organic Chemistry; Materials Science; Physical Organic Chemistry; Supramolecular Chemistry (Org.); Carbon-based Materials | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66fbd7d4cec5d6c142c75b66/original/cycloparaazine-a-full-azine-carbon-nanoring.pdf |
6662dc0521291e5d1d469f0d | 10.26434/chemrxiv-2024-kkrjl | Chiral Triazole-substituted Iodonium Salts in
Enantioselective Halogen Bond Catalysis | Herein, we present the synthesis of chiral triazole-based diaryliodonium salts and their
application as monodentate asymmetric iodine(III) derivates in halogen bond (XB) catalyzed
reactions. These potential Lewis acids were successfully benchmarked in the vinylogous
Mannich reaction of cyanomethyl coumarin with isatin-derived ketimine to obtain the addition
product in up to 99% yield and >99:1 e.r. Furthermore, these halogen bond catalysts allowed
an efficient functionalization of ketimines with various alcohols toward N,O-acetals in up to 99%
yield and 90:10 e.r. Additionally, we studied the origin of the enantioselectivity based on Density
Functional Theory (DFT) and the catalyst crystal structure. These unveiled the first approach
of asymmetric induction facilitated by using σ-hole stabilized chiral moieties in iodine(III)-based
catalysts and exclusively predicated upon XB activation. | Mattis Damrath; Tarek Scheele; Daniel Duvinage; Tim Neudecker; Boris Johannes Nachtsheim | Organic Chemistry; Catalysis; Organic Compounds and Functional Groups; Homogeneous Catalysis; Organocatalysis | CC BY NC 4.0 | CHEMRXIV | 2024-06-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6662dc0521291e5d1d469f0d/original/chiral-triazole-substituted-iodonium-salts-in-enantioselective-halogen-bond-catalysis.pdf |
60c7467f842e6562e8db2800 | 10.26434/chemrxiv.11337287.v1 | Implementation of Geometry Dependent Charge Flux into Polarizable AMOEBA+ Potential | Molecular dynamics (MD) simulations employing classical
force fields (FFs) have been widely used to model molecular systems. The
important ingredient of the current FFs, atomic charge, remains fixed during MD
simulations despite the atomic environment or local geometry changes. This approximation
hinders the transferability of the potential being used in multiple phases.
Here we implement a geometry dependent charge flux (GDCF) model into the multipole-based
AMOEBA+ polarizable potential. The CF in the current work explicitly depends on
the local geometry (<i>bond and angle</i>)
of the molecule. To our knowledge, this is the first study that derives energy
and force expressions due to GDCF in a multipole-based polarizable FF framework.
Due to the inclusion of GDCF, the AMOEBA+ water model is noticeably improved in
terms of describing the monomer properties, cluster binding/interaction energy and
a variety of liquid properties, including the infrared spectra that previous
flexible water models were not able to capture. | Chengwen Liu; Jean-Philip Piquemal; Pengyu Ren | Computational Chemistry and Modeling; Theory - Computational; Quantum Computing | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7467f842e6562e8db2800/original/implementation-of-geometry-dependent-charge-flux-into-polarizable-amoeba-potential.pdf |
60c744220f50dba921396042 | 10.26434/chemrxiv.9747368.v1 | Make a Molecule: A Synthetic Organic and Medicinal Chemistry Workshop for High School Students | This manuscript describes an chemical outreach program developed to provide high school students the opportunity to make new organic molecules in a safe and user friendly fashion and test them for antibacterial activity. | Iain A. Stepek; Raphael Hofmann; Paula L. Nichols; Andrea Aschwanden; Christophe Eckard; Patrick Aschwanden; Jeffrey Bode | Chemical Education - General | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c744220f50dba921396042/original/make-a-molecule-a-synthetic-organic-and-medicinal-chemistry-workshop-for-high-school-students.pdf |
62e7919eadb01e1106b528dc | 10.26434/chemrxiv-2022-vt79c | Pressure and temperature dependence of the relaxation of the electrical double layer in hydrated magnesite rock (leukolite) | The introduction of water into the pore space of naturally occurring magnesite (leukolite) induces an intense relaxation mechanism, which is related to the electric double layer (EDL) formed on opposing sides of the solid – mater interface. The relaxation of the EDL is studied by using Broadband Dielectric Spectroscopy at different conditions of combined temperature and hydrostatic pressure. The temperature evolution of the characteristic relaxation frequency, reveals two successive temperature regions: in the low temperature one, protonic conductivity over the network of water molecules in on the solid surface, couples to the ionic transport of charged defects occurring in the solid. At higher temperatures, near – zero activation energies are found: the phenomenon is discussed theoretically and attributed to decoupling and an exchange of protons with lattice site magnesium cations, the formation of a proton enriched sub-surface layer of magnesite and subsequent release of cations to the liquid. The values of the activation volume and their independence on temperature, support the aforementioned interpretation. | Anthony Papathanassiou; Elias Sakellis | Physical Chemistry; Interfaces | CC BY NC ND 4.0 | CHEMRXIV | 2022-08-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62e7919eadb01e1106b528dc/original/pressure-and-temperature-dependence-of-the-relaxation-of-the-electrical-double-layer-in-hydrated-magnesite-rock-leukolite.pdf |
60c744bbf96a00b087286aab | 10.26434/chemrxiv.9901346.v1 | Mass Spectrometry Reveals the Assembly Pathway of Encapsulated Ferritins and Highlights a Dynamic Ferroxidase Interface | Encapsulated ferritins (EncFtn) are a recently characterised member of the ferritin superfamily. EncFtn proteins are sequestered within encapsulin nanocompartments and form a unique biological iron storage system. Here, we use native mass spectrometry and hydrogen-deuterium exchange mass spectrometry to elucidate the metal-mediated assembly pathway of EncFtn. | Jennifer Ross; Thomas Lambert; Cecilia Piergentili; Didi He; Kevin J. Waldron; C. Logan Mackay; Jon Marles-Wright; David Clarke | Analytical Chemistry - General; Mass Spectrometry; Biochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2019-09-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c744bbf96a00b087286aab/original/mass-spectrometry-reveals-the-assembly-pathway-of-encapsulated-ferritins-and-highlights-a-dynamic-ferroxidase-interface.pdf |
6267d27d11b1461c5c30b39b | 10.26434/chemrxiv-2021-1tn9k-v2 | Driving Aspirational Process Mass Intensity Using SMART-PMI and Innovative Chemistry | An important metric for gauging the impact a synthetic route has on chemical resources, cost, and sustainability is process mass intensity (PMI). Calculating the overall PMI or step PMI for a given synthesis from a process description is more and more common across the pharmaceutical industry, especially in process chemistry departments. Our company has established a strong track record of delivering on our Corporate Sustainability goals, being recognized with eight EPA Green Chemistry Challenge Awards in the last 15 years and we show how these routes help define aspirational PMI tar-gets. While green chemistry principles help in optimizing PMI and developing more sustainable processes, a key challenge for the field is defining what a ‘good’ PMI for a molecule looks like given its structure alone. An existing tool chemists have at their disposal to predict PMI requires the synthetic route be provided or proposed (e.g., via retrosynthetic analysis) which then enables practitioners to compare predicted PMIs between routes. We have developed SMART-PMI (in-Silico MSD Aspirational Research Tool) to fill the gap in predicting PMI from molecular structure alone. Using only a 2D chemical structure, we can generate a predicted SMART-PMI from a measure of molecular complexity. We show how these predictions correlate with historical PMI data from our company’s clinical and commercial portfolio of processes. From this SMART-PMI prediction, we have established target ranges which we termed “Successful”, “World Class”, and “Aspirational” PMI. The goal of this range is to set the floor for what is a “good” PMI for a given molecule and provide ambitious targets to drive innovative green chemistry. Using this model, chemists can develop synthetic strategies that make the biggest impact on PMI. As innovation in chemistry and processes lead to better and better PMIs , in turn, this data can drive ever more aggressive targets for the model. The potential of SMART-PMI to set industry-wide aspirational PMI tar-gets is discussed. | Edward Sherer; Ansuman Bagchi; Birgit Kosjek; Kevin Maloney; Zhengwei Peng; Sandra Robaire; Robert Sheridan; Essam Metwally; Louis-Charles Campeau | Theoretical and Computational Chemistry; Organic Chemistry; Chemical Engineering and Industrial Chemistry; Process Chemistry; Chemoinformatics - Computational Chemistry; Pharmaceutical Industry | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6267d27d11b1461c5c30b39b/original/driving-aspirational-process-mass-intensity-using-smart-pmi-and-innovative-chemistry.pdf |
60c73f5e469df43b2ff42abc | 10.26434/chemrxiv.7176125.v2 | Simultaneous CO2 Capture and Metal Purification from Waste Streams | The process of carbon capture, which is one of the most mature yet cost-intensive technology proposed to mitigate global warming has herein been explored as a potential strategy to generate dynamic ligands for metal separation and recovery. Spontaneous CO2 fixation by industrial amines such as diethylenetriamine affords dynamic arrays of interconverting species, from which tailored subsets can be selected yielding organometallic adducts of contrasted solubility. Quantitative compositional analyses of the phases produced with varying CO2 loadings allow to elucidate the underpining self-sorting scenario induced by each metal, and to identify the conditions affording optimal individual separation by precipitation. To illustrate the potentiality of this approach, which could bring substantial added value to the CO2 capture and utilization chain value, bimetallic separation was conducted directly from exhaust gas of an internal combustrion engine vehicle, and the three constituents of the alloys used to produce the cathodes of electric vehicles were separated and recovered by successive CO2-induced selective precipitations. This study provides a potential framework to integrated CO2 capture and utilization and paves the way toward the design of CO2-sourced sustainable processes.<br /> | Julien Leclaire; Jean Septavaux; Clara Tosi; patrick jame; Carlo Nervi; Roberto Gobetto | Combinatorial Chemistry; Supramolecular Chemistry (Org.); Atmospheric Chemistry; Wastes | CC BY NC ND 4.0 | CHEMRXIV | 2018-10-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f5e469df43b2ff42abc/original/simultaneous-co2-capture-and-metal-purification-from-waste-streams.pdf |
6231c8042c5010f92a7d0bd6 | 10.26434/chemrxiv-2022-vlhm0 | A Brief Review of Density Functional Theory and Solvation Model | In recent years, the applications of first-principles density functional theory (DFT) is diversified and expanded in a wide range due to the development of robust algorithms and more powerful computer systems. In general, DFT is used in condensed matter physics, chemistry, material science and biology to predict and interpret the behaviour of complex-system at atomic-scale. Specifically, DFT is widely applied to study the effect of dopants on phase transformation, magnetic and electronic behaviour, spin and charge transport properties, etc. in material science/condensed matter physics; geometrical and electronic structure, dynamics, spectral hyperfine-interaction, excited-state, etc. in chemistry; interactive behaviour, bond formation and breaking, stabilization, etc. in the biological system. Furthermore, the solvation models are used to include a solvent for the accuracy and realistic approach. To study the physical/chemical and biological system with DFT embedded tools such as Gaussian, Vienna Ab initio software package (VASP), Quantum espresso etc., require a basic theoretical understanding of DFT. Therefore, I have summarised DFT including basis set and solvation models for easy understanding in a short time. | Anoop Kumar Kushwaha | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Theory - Computational; Physical and Chemical Processes | CC BY 4.0 | CHEMRXIV | 2022-03-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6231c8042c5010f92a7d0bd6/original/a-brief-review-of-density-functional-theory-and-solvation-model.pdf |
6735ce245a82cea2fa181241 | 10.26434/chemrxiv-2024-d95l2 | Three-component synthesis of beta-ketosulfonamides via visible-light mediated generation of sulfamoyl radicals | Herein, we report photoredox-catalyzed, visible-light mediated 3-component synthesis of beta-ketosulfonamides from silyl enol ethers, N-aminopyridinium salts and the sulfur dioxide (SO2) surrogate DABSO (1,4-diazabicyclo[2.2.2]octane·bis (sulfur dioxide) adduct). This reaction is based on the photochemical generation of sulfamoyl radicals from N-aminopyridinium salts as nitrogen radical precursors and DABSO as easy-to-handle SO2 source. Trapping of the in situ generated sulfamoyl radicals with silyl enol ethers affords beta-ketosulfonamides in 63-97% yield in the presence of Eosin Y as organic photoredox catalyst. | Kamil Hofman; Marius Friedrich; Georg Manolikakes | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Photochemistry (Org.); Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6735ce245a82cea2fa181241/original/three-component-synthesis-of-beta-ketosulfonamides-via-visible-light-mediated-generation-of-sulfamoyl-radicals.pdf |
63dab15989c04b6693c92cba | 10.26434/chemrxiv-2023-62vzz-v2 | Syntheses and structural plasticity of kratom pseudoindoxyl metabolites | Pain management is one of the oldest challenges for medicine. Although opioids have been used in the treatment of moderate-to-severe acute and chronic pain for centuries, they cause various adverse effects and addiction. The intertwined societal, economic and public health issues of pain management and the risks of opioid abuse continue to receive attention and drive the development of safer analgesics. Recently, a kratom metabolite, mitragynine pseudoindoxyl has attracted increasing attention as a promising analgesic alternative for pain management with considerably fewer side effects. Here, we describe the first enantioselective and scalable total synthesis of this natural product in addition to its C-20 epimeric congener, speciogynine pseudoindoxyl. The characteristic spiro-5-5-6 tricyclic system of these alkaloids is formed via a protecting group-free cascade relay process in which oxidized tryptamine and secologanin analogs are used. Furthermore, we uncovered that mitragynine pseudoindoxyl exists and acts not as a single molecular entity but as a dynamic ensemble of stereoisomers in protic environments, thus, it exhibits structural plasticity in biological systems. Accordingly, these synthetic, structural, and biological studies provide a basis for the planned design of mitragynine pseudoindoxyl analogs, which can guide the development of next-generation analgesics. | Péter Angyal; Kristóf Hegedüs; Bence Balázs Mészáros; János Daru; Ádám Dudás; Anna Rita Galambos; Nariman Essmat; Mahmoud Al-Khrasani; Szilárd Varga; Tibor Soós | 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 | 2023-02-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63dab15989c04b6693c92cba/original/syntheses-and-structural-plasticity-of-kratom-pseudoindoxyl-metabolites.pdf |
637a40bc2079815d752e190e | 10.26434/chemrxiv-2022-h6f69 | Time-reversal equivariant neural network potential and Hamiltonian for magnetic materials | This work presents Time-reversal Equivariant Neural Network (TENN) framework. With TENN, the time-reversal symmetry is considered in the equivariant neural network (ENN), which generalizes the ENN to consider physical quantities related to time-reversal symmetry such as spin and velocity of atoms. TENN-e3, as the time-reversal-extension of E(3) equivariant neural network, is developed to keep the Time-reversal E(3) equivariant with consideration of whether to include the spin-orbit effect for both collinear and non-collinear magnetic moments situations for magnetic material. TENN-e3 can construct spin neural network potential and the Hamiltonian of magnetic material from ab-initio calculations. Time-reversal-E(3)-equivariant convolutions for interactions of spinor and geometric tensors are employed in TENN-e3. Compared to the popular ENN, TENN-e3 can describe the complex spin-lattice coupling with high accuracy and keep time-reversal symmetry which is not preserved in the existing E(3)-equivariant model. Also, the Hamiltonian of magnetic material with time-reversal symmetry can be built with TENN-e3. TENN paves a new way to spin-lattice dynamics simulations over long-time scales and electronic structure calculations of large-scale magnetic materials. | Hongyu Yu; Yang Zhong; Junyi Ji; Xingao Gong; Hongjun Xiang | Theoretical and Computational Chemistry; Physical Chemistry; Materials Science; Magnetic Materials; Computational Chemistry and Modeling; Machine Learning | CC BY 4.0 | CHEMRXIV | 2022-11-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/637a40bc2079815d752e190e/original/time-reversal-equivariant-neural-network-potential-and-hamiltonian-for-magnetic-materials.pdf |
6715bb72b91c6e9971a1dadc | 10.26434/chemrxiv-2024-mh3q5 | Single-Handed Helical Polymer-Based Polycarboxylate with Achiral Triarylphosphine Pendants as Chiral Catalysts for Asymmetric Cross-Coupling Reactions in Pure Water | Helical poly(quinoxaline-2,3-diyl)s (PQX) containing chiral carboxylic acid side chains derived from natural L-lactic acid were synthesized. The newly synthesized helical polymer-based polycarboxylic acid was soluble in basic pure water by forming poly-carboxylate and adopted the P-helical conformation (right-handed), whereas the M-helical conformation is predominant under weakly acidic aqueous conditions. The water-soluble PQX containing additional monomer units bearing a 2-(diarylphosphino)phenyl group was employed in the asymmetric Suzuki–Miyaura coupling reaction in pure water in the absence of organic cosolvents. Remarkable enantioselectivities up to 99% ee, which were found to be higher than the same coupling reac-tion in organic solvent using the corresponding lipophilic PQX, were obtained for the couplings of 2-substituted 1-halonaphthalenes. It is presumed that the hydrophobic reaction environment is provided by the hydrophobic main chain of PQX according to the Nile Red-based hydrophobicity test. Recovery of the crude product without using any trace of organic solvent has been demonstrated by the switch of solubility of PQX depending on pH. | Naoaki Kamiya; Takuma Kuroda; Yuuya Nagata; Takeshi Yamamoto; Michinori Suginome | Catalysis; Polymer Science; Polymer scaffolds; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6715bb72b91c6e9971a1dadc/original/single-handed-helical-polymer-based-polycarboxylate-with-achiral-triarylphosphine-pendants-as-chiral-catalysts-for-asymmetric-cross-coupling-reactions-in-pure-water.pdf |
60c7530eee301c201dc7acfb | 10.26434/chemrxiv.12950858.v4 | Ultra-Low Molecular Weight Photoswitchable Hydrogelators | Photoswitchable arylazopyrozoles 2 and 3 form hydrogels at a concentration of 1.2% (w/v). With a molecular weight of 258.11 g/mol, these are the lowest known molecular weight hydrogelators that respond reversibly to light. Single-crystal X-ray structures show anisotropic aggregation of 2 and 3 is driven by in-plane hydrogen bonding interactions and 𝝅 - 𝝅 stacking. Photoswitching of 2 and 3 from the E- to the Z-form by 365 nm light results in a macrocopic gel→sol transition; nearly an order of magnitude reduction in the measured elastic and loss moduli. Cryogenic transmission electron microscopy suggests that the 29±7 nm wide sheets in the E-2 gel state narrow to 13±2 nm upon photoswitching to the predominantly Z-2 solution state. In the case of 2, photoswitching is reversible through cycles of 365 nm and 520 nm excitation with little fatigue. The release of a Rhodamine B dye encapsulated in gels formed from 2 and 3 can be accelerated more than 20-fold upon photoswitching with 365 nm light, demonstrating these materials are suitable for light-controlled cargo release. | Fayaz Larik; Lucy Fillbrook; Sandra Nurttila; Adam D Martin; Rhiannon P. Kuchel; Karrar Al Taief; Mohan Bhadbhade; Jonathon Beves; Pall Thordarson | Supramolecular Chemistry (Org.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7530eee301c201dc7acfb/original/ultra-low-molecular-weight-photoswitchable-hydrogelators.pdf |
66ef136051558a15efaefe7e | 10.26434/chemrxiv-2024-rwrd1 | Accelerating Multicomponent Phase-Coexistence Calculations with Physics-informed Neural Networks | Phase separation in multicomponent mixtures is of significant interest in both fundamental research and technology. Although the thermodynamic principles governing phase equilibria are straightforward, practical determination of equilibrium phases and constituent compositions for multicomponent systems is often laborious and computationally intensive. Here, we present a machine-learning workflow that simplifies and accelerates phase-coexistence calculations. We specifically analyze capabilities of neural networks to predict the number, composition, and relative abundance of equilibrium phases of systems described by Flory-Huggins theory. We find that incorporating physics-informed material constraints into the neural network architecture enhances the prediction of equilibrium compositions compared to standard neural networks with minor errors along the boundaries of the stable region. However, introducing additional physics-informed losses does not lead to significant further improvement. These errors can be virtually eliminated by using machine-learning predictions as a warm-start for a subsequent optimization routine. This work provides a promising pathway to efficiently characterize multicomponent phase coexistence. | Satyen Dhamankar; Shengli Jiang; Michael Webb | Theoretical and Computational Chemistry; Physical Chemistry; Chemical Engineering and Industrial Chemistry; Machine Learning; Thermodynamics (Chem. Eng.); Physical and Chemical Properties | CC BY NC 4.0 | CHEMRXIV | 2024-09-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66ef136051558a15efaefe7e/original/accelerating-multicomponent-phase-coexistence-calculations-with-physics-informed-neural-networks.pdf |
60c744324c89193609ad2762 | 10.26434/chemrxiv.8141912.v2 | Strong Correlation and Charge Localization in Kohn-Sham Theories with Fractional Orbital Occupations: The Role of the Potential | We study static correlation and delocalisation errors and show that even methods with good energies can yield significant delocalization errors that affect the density, leading to large errors in predicting e.g. dipole moments. We illustrate this point by comparing existing state-of-art approaches with an accurate exchange correlation functional based on a generalised valence-bond ansatz, in which orbitals and fractional occupations are treated as variational parameters via an optimized effective potential (OEP). We show that the OEP exhibits step and peak features which, similar to the exact Kohn-Sham (KS) potential of DFT, are crucial to prevent charge delocalization. We further show that the step is missing in common approximations within reduced density matrix functional theory resulting in delocalization errors comparable to those found in DFT approximations. Finally, we explain the delocalization error as coming from an artificial mixing of the ground state with a charge-transfer excited state which is avoided if occupation numbers exhibit discontinuities.<br /><br /> | Maria Hellgren; Tim Gould | Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c744324c89193609ad2762/original/strong-correlation-and-charge-localization-in-kohn-sham-theories-with-fractional-orbital-occupations-the-role-of-the-potential.pdf |
60c7553df96a0041d12887fb | 10.26434/chemrxiv.14054807.v1 | Unlocking Iminium Catalysis in Artificial Enzymes to Create a Friedel-Crafts Alkylase | We show that the incorporation of the non-canonical amino acid para-aminophenylalanine (pAF) into the non-enzymatic protein scaffold LmrR creates a proficient and stereoselective artificial enzyme (LmrR_pAF) for the vinylogous Friedel-crafts alkylation between alpha, beta-unsaturated aldehydes and indoles. pAF acts as a catalytic residue, activating enal substrates towards conjugate addition via the formation of intermediate iminium ion species, whilst the protein scaffold provides rate acceleration and enantio-induction. Improved LmrR_pAF varants were identified by direted evolution advised by alanine-scanning to obtain a triple mutant that provided higher yields and enantioselectivities for a range of enals and indoles. Analys of Michaelis-Menten kinetics of LmrR-pAF and tevolved mutants reveals that new activities emerge via evolutionary pathways that diverge from one another and specialise catalytic reactivity.<br /> | Reuben B. Leveson-Gower; Zhi Zhou; Ivana Drienovská; Gerard Roelfes | Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-02-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7553df96a0041d12887fb/original/unlocking-iminium-catalysis-in-artificial-enzymes-to-create-a-friedel-crafts-alkylase.pdf |
66b1e25fc9c6a5c07a22a066 | 10.26434/chemrxiv-2024-666ll | Generation of Stereocenters via Single-Carbon-Atom Doping Using N-Isocyanides | Among the electronically unsaturated carbon species, atomic carbon is the most challenging to use for the synthesis of organic molecules, despite its potential to forge four distinct covalent bonds at a carbon center in a single process. Single-carbon-atom doping (SCAD) into organic molecules without loss of atoms in the reactant is highly attractive because it allows for a remarkable increase in molecular complexity in a single process. We have previously reported that N-heterocyclic carbenes can serve as an atomic carbon equivalent suitable for SCAD reactions. However, that method is limited to the formation of methylene carbons, leaving the full potential of the concept unrealized. Here, we report an SCAD reaction that results in the formation of stereocenters by unlocking the reactivity of (N-isocyanoimino)triphenylphosphorane as an atomic carbon equivalent. This reagent enables the single-step conversion of a range of acyl chlorides into homologated α-chloro cyclic ketones, which proceeds via the generation of four different bonds, i.e., one C-Cl, one C-H, and two C-C bonds at the incorporated carbon atom. | Hayato Fujimoto; Teruki Nishioka; Kazuya Imachi; Rio Nishimura; Mamoru Tobisu | Organic Chemistry | CC BY NC 4.0 | CHEMRXIV | 2024-08-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66b1e25fc9c6a5c07a22a066/original/generation-of-stereocenters-via-single-carbon-atom-doping-using-n-isocyanides.pdf |
671e1c9498c8527d9e85edab | 10.26434/chemrxiv-2024-rhrwx | Structure of a DNA-Stabilised Ag16Cl2 Nanocluster in Solution | We determine for the first time the structure of a DNA-stabilised Ag16Cl2 nanocluster in solution using X-ray total scattering and pair distribution function analysis. We find that the structure in solution exhibits both displacive and rotational distortions compared to the known crystal structure. Additionally, our measurements are sensitive towards changes in DNA conformation, revealing that the DNA scaffold in solution exhibits significantly more flexibility than when conformationally locked in the crystalline form. Our results demonstrate the capability to determine the structure of DNA-stabilised clusters beyond their crystallised form, an essential step towards understanding differences between their solution-phase and solid-state photophysical properties. | Adam Sapnik; Giacomo Romolini; Cecilia Cerretani; Tom Vosch; Kirsten Jensen | Biological and Medicinal Chemistry; Nanoscience; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/671e1c9498c8527d9e85edab/original/structure-of-a-dna-stabilised-ag16cl2-nanocluster-in-solution.pdf |
65d934059138d23161da5fab | 10.26434/chemrxiv-2024-x6spt | Machine learning in materials research: developments over the last decade and challenges for the future | The number of studies that apply machine learning (ML) to materials science has been growing at a rate of approximately 1.67 times per year over the past decade. In this review, I examine this growth in various contexts. First, I present an analysis of the most commonly used tools (software, databases, materials science methods, and ML methods) used within papers that apply ML to materials science. The analysis demonstrates that despite the growth of deep learning techniques, the use of classical machine learning is still dominant as a whole. It also demonstrates how new research can effectively build upon past research, particular in the domain of ML models trained on density functional theory calculation data. Next, I present the progression of best scores as a function of time on the matbench materials science benchmark for formation enthalpy prediction. In particular, a dramatic improvement of 7 times reduction in error is obtained when progressing from feature-based methods that use conventional ML (random forest, support vector regression, etc.) to the use of graph neural network techniques. Finally, I provide views on future challenges and opportunities, focusing on data size and complexity, extrapolation, interpretation, access, and relevance. | Anubhav Jain | Theoretical and Computational Chemistry; Materials Science; Theory - Computational; Artificial Intelligence | CC BY 4.0 | CHEMRXIV | 2024-02-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65d934059138d23161da5fab/original/machine-learning-in-materials-research-developments-over-the-last-decade-and-challenges-for-the-future.pdf |
60c757ccbb8c1a8b373dc8f0 | 10.26434/chemrxiv.14462391.v1 | A Boron-Transfer Mechanism Mediating the Thermally Induced Revival of Frustrated Carbene−Borane Pairs from their Shelf-Stable Adducts | Combined experimental and theoretical studies allowed clarifying the reaction
mechanism for the revival of frustrated carbene−borane pairs from external-stimuli-responsive
classical Lewis adducts comprised of N-phosphine oxide-substituted imidazolylidenes and
triarylboranes. A borane-transfer process from the carbene carbon atom to the N-phosphinoyl
oxygen atom was identified as the rate-determining event for the regeneration of the FLP
species, eventually enabling the heterolytic cleavage of H2.<br /> | Yoichi Hoshimoto; Mahiro Sakuraba; Takuya Kinoshita; Masaki Ohbo; Manussada Ratanasak; Jun-ya Hasegawa; Sensuke Ogoshi | Main Group Chemistry (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c757ccbb8c1a8b373dc8f0/original/a-boron-transfer-mechanism-mediating-the-thermally-induced-revival-of-frustrated-carbene-borane-pairs-from-their-shelf-stable-adducts.pdf |
64bfda82ae3d1a7b0d51532d | 10.26434/chemrxiv-2023-q2z25-v2 | Crystal Size Dependent Flexibility in ZIF-7: From Macro- to Nano-Scale | Flexible metal-organic frameworks (MOFs) are highly desirable materials for gas separation but most of them become rigid when the particle size is reduced towards nanoscale. We aim to comprehend the effect of textural properties such as crystal size, its distribution and morphology on the gate-opening behaviour stimulated by adsorption of guest molecules in ZIF-7. The synthesis conditions are varied to obtain ZIF-7 batches with crystal sizes ranging between 0.05 and 15 m with various size distributions. We report for the first time a CO2-filled open pore phase of ZIF-7 at 195 K (OP2) derived from in situ powder X-ray diffraction (PXRD) data measured in parallel to CO2 physisorption. The adsorption of CO2 on ZIF-7 indicates persisting flexibility for all particle size regimes; with the crystal size, its distribution and morphology having a significant impact on both gate-opening and gate-closing pressures and slope of CO2 adsorption isotherms. In situ PXRD measurement indicated further expansion of ZIF-7 framework in presence of methanol as guest species. The capability of ZIF-7 to accommodate molecules larger than its 0.3 nm window diameter signifies the importance of intermolecular interactions to overcome the energy barrier for linker movement/gating of the framework. | Rimita Bose; Volodymyr Bon; Nadine Bönisch; Parasuraman Selvam; Niket S. Kaisare; Stefan Kaskel | Physical Chemistry; Inorganic Chemistry; Coordination Chemistry (Inorg.); Physical and Chemical Processes; Physical and Chemical Properties; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64bfda82ae3d1a7b0d51532d/original/crystal-size-dependent-flexibility-in-zif-7-from-macro-to-nano-scale.pdf |
60c749e3ee301c3f09c79b5d | 10.26434/chemrxiv.12122949.v1 | First Principles Study of Reactions in Alucone Growth: the Role of the Organic Precursor | Organic-inorganic hybrid materials are a unique
class of materials with properties driven by the organic and inorganic
components, making them useful for flexible devices. Molecular layer deposition
(MLD) offers novel pathways for the fabrication of such hybrids by using
inorganic metal precursors and the vast range of organic molecules with tunable
properties. To investigate and understand the mechanism of growth a combination
of theoretical and experimental data is needed. In this contribution, we
present a first principles investigation of the molecular mechanism of the
growth of hybrid organic−inorganic thin films of aluminium alkoxides, known as
“alucones” grown by MLD. We explore the
interactions between precursors by analyzing the MLD reaction products of the
alumina surface terminated with Al(CH<sub>3</sub>) groups after the trimethyl
aluminium pulse; this yields monomethyl-Al<sub>2</sub>O<sub>3</sub> (Al-CH<sub>3</sub>-Al<sub>2</sub>O<sub>3</sub>)
and dimethyl- Al<sub>2</sub>O<sub>3</sub> (Al(CH<sub>3</sub>)<sub>2</sub>- Al<sub>2</sub>O<sub>3</sub>)
terminated surfaces. The organic precursors are ethylene glycol (EG),
diethylene glycol (DEG), triethylene glycol (TEG) and tetraethylene glycol
(FEG). A detailed comparison with alucones grown with ethylene glycol (EG) and
glycerol (GL) precursors is presented to assist the interpretation of experimental
findings regarding the differences in the hybrid films grown by EG and GL. The
results show that Al-O formation with release of methane is favorable for all
precursors. EG and GL can lie flat and create so-called double reactions
through the reaction of the two terminal hydroxyl groups with the surface
fragments. This phenomenon removes active hydroxyl sites for EG. However, for
GL the third hydroxyl group is available and growth can proceed. This analysis
shows the origin of differences in thickness of alucones found for EG and GL. | Arbresha Muriqi; Michael Nolan | Coating Materials; Hybrid Organic-Inorganic Materials; Materials Processing; Kinetics and Mechanism - Inorganic Reactions; Theory - Inorganic; Computational Chemistry and Modeling; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749e3ee301c3f09c79b5d/original/first-principles-study-of-reactions-in-alucone-growth-the-role-of-the-organic-precursor.pdf |
652bdb38bda59ceb9aa197aa | 10.26434/chemrxiv-2023-7hlkq | Metastability and polymorphism in dihydroxybenzenes – implications for thermal energy storage | State-of-the-art calorimetric techniques have been used to explore the effects of molecular isomerism on the phase behaviour of the three dihydroxybenzenes catechol, resorcinol, and hydroquinone. Within the broader remit of the search and rational design of phase-change materials for thermal-energy storage, these data reveal a surprisingly rich (and hitherto unappreciated) behaviour, ranging from an unavoidable propensity to crystallize (hydroquinone) to the emergence of both disordered and ordered metastable phases well below the range of stability of the normal liquid (resorcinol and catechol). Catechol exhibits the most complex thermophysical response, and ab-initio calculations evince a subtle interplay between intramolecular and intermolecular interactions, ultimately leading to the formation of new crystal phases. | Tomas Northam de la Fuente; Mattia Gaboardi; Kalith Ismail; Valerio Di Lisio; Daniele Cangialosi; Alberto Otero-de-la-Roza; Pedro Coto; Felix Fernandez-Alonso | Physical Chemistry; Energy | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652bdb38bda59ceb9aa197aa/original/metastability-and-polymorphism-in-dihydroxybenzenes-implications-for-thermal-energy-storage.pdf |
60c75423bdbb893389a3a5c8 | 10.26434/chemrxiv.13618958.v1 | Experimental Determination of Activation Energies for Covalent Bond Formation via Ion/Ion Reactions and Competing Processes | The combination of ion/ion chemistry with commercially available ion mobility/mass spectrometry systems has allowed rich structural information to be obtained for gaseous protein ions. Recently, the simple modification of such an instrument with an electrospray reagent source has allowed three-dimensional gas-phase interrogation of protein structures through covalent and non-covalent interactions coupled with collision cross section measurements. However, the energetics of these processes have not yet been studied quantitatively. In this work, previously developed Monte Carlo simulations of ion temperatures inside traveling wave ion guides are used to characterize the energetics of the transition state of activated ubiquitin cation/reagent anion long-lived complexes formed via ion/ion reactions. The ΔH<sup>‡</sup> and ΔS<sup>‡</sup> of major processes observed from collisional activation of long-lived gas phase ion/ion complexes, namely collision induced unfolding (CIU), covalent bond formation, or neutral loss of the anionic reagent via intramolecular proton transfer, were determined. Covalent bond formation via ion/ion complexes was found to be significantly lower energy compared to unfolding and bond cleavage. ΔG<sup>‡</sup> of activation of all three processes lie between 55 and 75 kJ/mol, easily accessible with moderate collisional activation. Bond formation is favored over reagent loss at lower activation energies, whereas reagent loss becomes competitive at higher collision energies. Though ΔG<sup>‡</sup> are between CIU of a precursor ion and covalent bond formation of its ion/ion product complex are comparable, our data suggest covalent bond formation does not require extensive isomerization, supporting evidence from previous structural studies that these ion/ion reactions measure compact gas phase structures. | Melanie Cheung See Kit; Samantha O. Shepherd; James Prell; Ian Webb | Mass Spectrometry; Biophysical Chemistry; Chemical Kinetics; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75423bdbb893389a3a5c8/original/experimental-determination-of-activation-energies-for-covalent-bond-formation-via-ion-ion-reactions-and-competing-processes.pdf |
65fd478766c138172989af91 | 10.26434/chemrxiv-2024-pjwm4 | MobiLipid: A Tool for Enhancing CCS Quality Control of Ion Mobility-Mass Spectrometry Lipidomics by Internal Standardization | Ion mobility-mass spectrometry (IM-MS) offers benefits for lipidomics by obtaining IM-derived collision cross sections (CCS), a conditional physicochemical parameter of an ion which can enhance lipid identification. While drift tube (DT) IM-MS retains a direct link to the primary experimental method to derive CCS values, other IM technologies rely solely on external CCS calibration, posing challenges due to dissimilar chemical properties between lipids and calibrants. To address this, we introduce MobiLipid, a novel tool facilitating CCS quality control of IM-MS lipidomics workflows by internal standardization. MobiLipid utilizes a newly established DTCCSN2 library for uniformly (U)13C labeled lipids, derived from a U13C labeled yeast extract, containing 377 DTCCSN2 values. This automated open-source R markdown tool enables internal monitoring and straightforward compensation for CCSN2 biases. It supports lipid class- and adduct-specific CCS corrections, requiring only three U13C labeled lipids per lipid class-adduct combination across 10 lipid classes, without requiring additional external measurements. The applicability of MobiLipid is demonstrated for trapped IM (TIM)-MS measurements of an unlabeled yeast extract spiked with U13C labeled lipids. Monitoring the CCSN2 biases of TIMCCSN2 values compared to DTCCSN2 library entries utilizing MobiLipid resulted in mean absolute biases of 0.78% and 0.33% in positive and negative ionization mode, respectively. By applying the CCS correction integrated into the tool for the exemplary dataset, the mean absolute CCSN2 biases of 10 lipid classes could be reduced to approximately 0%. | Felina Hildebrand; Gunda Koellensperger; Tim Causon | Analytical Chemistry; Mass Spectrometry; Separation Science | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65fd478766c138172989af91/original/mobi-lipid-a-tool-for-enhancing-ccs-quality-control-of-ion-mobility-mass-spectrometry-lipidomics-by-internal-standardization.pdf |
60c740c9702a9b867c18a144 | 10.26434/chemrxiv.7834838.v1 | Oxygen-Enhanced Upconversion of near Infrared Light from Below the Silicon Band Gap | <div>Here we demonstrate an upconversion composition using semiconductor nanocrystal sensitizers that employs molecular triplet states below the singlet oxygen energy. We show that, contrary to the usual expectation, the admission of oxygen enhances the intensity of upconverted light and significantly speeds up the photochemical processes involved. Further, we demonstrate photochemical upconversion from below the silicon band gap in the presence of oxygen.</div> | Timothy Schmidt; Elham Gholizadeh; Shyamal Prasad; Zhi Li Teh; Thilini Ishwara; Sarah Norman; Anthony J Petty; John E. Anthony; Shujuan Huang | Photovoltaics; Photochemistry (Physical Chem.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-03-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c740c9702a9b867c18a144/original/oxygen-enhanced-upconversion-of-near-infrared-light-from-below-the-silicon-band-gap.pdf |
6605e28ce9ebbb4db9d320a5 | 10.26434/chemrxiv-2024-sv55n-v2 | Molecular origin of distinct hydration dynamics in double helical DNA and RNA sequences | Water molecules are essential to determine the structure of nucleic acids and mediate their interactions with other biomolecules. Here, we characterize the hydration dynamics of analogous DNA and RNA double helices with unprecedented resolution and elucidate the molecular origin of their differences: localization of the slowest hydration water molecules---in the groove in DNA, next to phosphates in RNA--- and a markedly distinct hydration dynamics of the two phosphate oxygen atoms OR and OS in RNA. Using our Extended Jump Model for water reorientation, we assess the relative importance of previously proposed factors, including the local topography, water bridges and the presence of ions. We show that the slow hydration dynamics at RNA OR sites is not due to bridging water molecules, but is caused by both a larger excluded volume and a stronger initial H-bond next to OR, which can be linked to different phosphate orientations in A-form double helical RNA. | Elisa Frezza; Damien Laage; Elise Duboué-Dijon | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Theory - Computational; Interfaces | CC BY 4.0 | CHEMRXIV | 2024-03-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6605e28ce9ebbb4db9d320a5/original/molecular-origin-of-distinct-hydration-dynamics-in-double-helical-dna-and-rna-sequences.pdf |
669278cd01103d79c5e83c2a | 10.26434/chemrxiv-2024-zmdnw | Enzyme-assisted electrochemical point-of-care test for miRNA detection towards liquid biopsy application | Liquid biopsy enables emerging biomarkers detection, such as circulating tumor DNA (ctDNA), microRNAs (miRNAs), and exosomes, leading to real-time monitoring of cancer progression and therapy effectiveness. Important circulating miRNAs, serving as biomarkers, have been correlated to breast cancer (BC) metastasis and therapy efficiency. In particular, among the BC, the Triple negative BC (TNBC) is an aggressive and heterogeneous subtype, accounting for 40% of BC related mortality. Rapid detection of these miRNAs through non-invasive liquid biopsy can significantly enhance diagnosis and prognosis, thereby improving survival rates. Considering these emerging biomarkers within the framework of personalized medicine, affordable and portable devices could enable quicker monitoring for cancer patients, including those in remote areas. In this context, we have developed an enzyme-assisted electrochemical point-of-care (POC) test. The proposed miRNA detection system is boosted by the use of duplex-specific nuclease (DSN) as the recognition element of miRNA. The DSN enzyme exhibits high selectivity to discriminate DNA-RNA heteroduplexes triggering isothermal target recycling and signal enhancement. This capability is crucial for overcoming the limitations often associated with detecting trace amounts of miRNA in biofluids. In our study, the specific probe for the miRNA target was labelled with a redox mediator, methylene blue, to enable the detection of enzymatic products via electrochemical measurements on screen-printed electrode. Optimization studies have been performed to obtain the enzymatic reaction in terms of probe and enzyme concentration. A calibration graph was obtained for various target concentrations ranging from 0.1 pM to100 nM, and a detection limit down to the fM level was achieved. Specificity studies were performed with random miRNA targets, and finally the device was applied in spiked commercial serum samples. These promising results suggest potential for developing novel class of POC tests towards the realization of an all-in-one sustainable platform for liquid biopsy applications. | Panagiota M Kalligosfyri; Wanda Cimmino; Nicola Normanno; Stefano Cinti | Analytical Chemistry; Analytical Chemistry - General; Electrochemical Analysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669278cd01103d79c5e83c2a/original/enzyme-assisted-electrochemical-point-of-care-test-for-mi-rna-detection-towards-liquid-biopsy-application.pdf |
66c668e0f3f4b05290abcf3e | 10.26434/chemrxiv-2024-d2n98 | In silico insights: QSAR modeling of TBK1 kinase inhibitors for enhanced drug discovery | TBK1, or TANK-binding kinase 1, is an enzyme that functions as a serine/threonine protein kinase. It plays a crucial role in various cellular processes, including the innate immune response to viruses, cell proliferation, apoptosis, autophagy, and anti-tumor immunity. Dysregulation of TBK1 activity can lead to autoimmune diseases, neurodegenerative disorders, and cancer. Due to its central role in these critical pathways, TBK1 is a significant focus of research for therapeutic drug development.
In this paper, we explore data from the CAS Content Collection regarding TBK1 and its implication in a large assortment of diseases and disorders. With the demand for developing efficient TBK1 inhibitors been outlined, we focus on utilizing machine learning approach for developing predictive models for TBK1 inhibition, derived from the fragment-functional analysis descriptors. Using the extensive CAS Content Collection we assembled a training set of TBK1 inhibitors with experimentally measured IC50 values. We explored several machine learning techniques combined with various molecular descriptors to derive and select the best TBK1 inhibitor QSAR models. Certain significant structural alerts that potentially contribute to inhibition of TBK1 are outlined and discussed. The merit of the article stem from identifying the most adequate TBK1 QSAR models and subsequent successful development of advanced positive training data to facilitate and enhance drug discovery for an important therapeutic target such as TBK1 inhibitors, based on extensive, wide-ranging set of scientific information provided by the CAS Content Collection.
| Julian Ivanov; Rumiana Tenchov; Krittika Ralhan; Kavita Iyer; Shivangi Agarwal; Qiongqiong Angela Zhou | Biological and Medicinal Chemistry; Bioinformatics and Computational Biology | CC BY 4.0 | CHEMRXIV | 2024-08-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66c668e0f3f4b05290abcf3e/original/in-silico-insights-qsar-modeling-of-tbk1-kinase-inhibitors-for-enhanced-drug-discovery.pdf |
60c7521a702a9b349118c090 | 10.26434/chemrxiv.13252286.v1 | Coloring Molecules with Explainable Artificial Intelligence for Preclinical Relevance Assessment | Graph neural networks are able to solve certain drug discovery tasks such as molecular property prediction and de novo molecule generation. However, these models are considered 'black-box' and 'hard-to-debug'. This study aimed to improve modeling transparency for rational molecular design by applying the integrated gradients explainable artificial intelligence (XAI) approach for graph neural network models. Models were trained for predicting plasma protein binding, cardiac potassium channel inhibition, passive permeability, and cytochrome P450 inhibition. The proposed methodology highlighted molecular features and structural elements that are in agreement with known pharmacophore motifs, correctly identified property cliffs, and provided insights into unspecific ligand-target interactions. The developed XAI approach is fully open-sourced and can be used by practitioners to train new models on other clinically-relevant endpoints. | Jose Jimenez-Luna; Miha Skalic; Nils Weskamp; Gisbert Schneider | Machine Learning; Artificial Intelligence; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7521a702a9b349118c090/original/coloring-molecules-with-explainable-artificial-intelligence-for-preclinical-relevance-assessment.pdf |
663a1d0f418a5379b0aa286b | 10.26434/chemrxiv-2024-gx5zh | M2ara: unraveling metabolomic drug responses in whole-cell MALDI mass spectrometry bioassays | Fast computational evaluation and classification of concentration responses for hundreds of metabolites represented by their mass-to-charge (m/z) ratios is indispensable for unraveling complex metabolomic drug actions in label-free, whole-cell Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI MS) bioassays. In particular, the identification of novel pharmacodynamic biomarkers to determine target engagement, potency and potential polypharmacology of drug-like compounds in high-throughput applications requires robust data interpretation pipelines. Given the large number of mass features in cell-based MALDI MS bioassays, reliable identification of true biological response patterns and their differentiation from potentially present measurement artefacts is critical. To facilitate the exploration of metabolomic responses in complex MALDI MS datasets, we present a novel software tool, M2ara. Implemented as a user-friendly R-based shiny application, it enables rapid evaluation of Molecular High Content Screening (MHCS) assay data. Furthermore, we introduce the concept of Curve Response Score (CRS) and CRS fingerprints to enable rapid visual inspection and ranking of mass features. In addition, these CRS fingerprints allow direct comparison of cellular effects among different compounds. Beyond cellular assays, our computational framework can also be applied to MALDI MS-based (cell-free) biochemical assays in general. | Thomas Enzlein; Alexander Geisel; Carsten Hopf; Stefan Schmidt | Biological and Medicinal Chemistry; Analytical Chemistry; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/663a1d0f418a5379b0aa286b/original/m2ara-unraveling-metabolomic-drug-responses-in-whole-cell-maldi-mass-spectrometry-bioassays.pdf |
668d913bc9c6a5c07ac96fb1 | 10.26434/chemrxiv-2023-97hjq-v2 | Ni-Catalyzed Asymmetric Reductive Arylation of ⍺-Substituted Imides | α-Aryl imides are common structural motifs in bioactive molecules and proteolysis-targeting chimeras designed for targeted protein deg-radation. An asymmetric Ni-catalyzed reductive cross-coupling of imide electrophiles and (hetero)aryl halides has been developed to synthesize enantioenriched α-arylglutarimides from simple starting materials. Judicious selection of electrophile pairs allows for coupling of both electron-rich and electron-deficient (hetero)aryl halides in good yields and enantioselectivities. | Li Ming Chen; Chung Keun Shin; Travis Delano; Golsa Gheibi; Sarah Reisman | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Stereochemistry; Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/668d913bc9c6a5c07ac96fb1/original/ni-catalyzed-asymmetric-reductive-arylation-of-substituted-imides.pdf |
60c751df0f50db62a539786d | 10.26434/chemrxiv.13224296.v1 | Insights into the Lithium Substructure of the Superionic Conductors Li3YCl6 and Li3YBr6 | The recent interest in the halide-based solid electrolytes Li<sub>3</sub>MX<sub>6</sub> (M = Y, Er, In; X = Cl, Br, I) shows these materials to be promising candidates for solid-state battery application, due to high ionic conductivity and large electrochemical stability window. However, almost nothing is known about the underlying lithium sub-structure within those compounds. Here, we investigate the lithium sub-structure of Li<sub>3</sub>YCl<sub>6</sub> and Li<sub>3</sub>YBr<sub>6</sub> using temperature-dependent neutron diffraction. We compare compounds prepared by classic solid-state syntheses with a mechanochemical synthesis to shed light on the influence of the synthetic approach on the reported yttrium disorder and the resulting surrounding lithium sub-structure. This work provides a better understanding of the strong differences in ionic transport depending on the synthesis procedure of Li<sub>3</sub>MX<sub>6</sub>. | Roman Schlem; Ananya Banik; Saneyuki Ohni; Emmanuelle Suard; Wolfgang Zeier | Solid State Chemistry; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c751df0f50db62a539786d/original/insights-into-the-lithium-substructure-of-the-superionic-conductors-li3y-cl6-and-li3y-br6.pdf |
6619338921291e5d1dafcda9 | 10.26434/chemrxiv-2024-mjxf4 | Leveraging Triphenylphosphine-Containing Polymers to Explore Design Principles for Protein-Mimetic Catalysts | Complex interactions between non-coordinating residues are significant yet commonly overlooked components of macromolecular catalyst function. While these interactions have been demonstrated to impact binding affinities and catalytic rates in metalloenzymes, the roles of similar structural elements in synthetic polymeric catalysts remain underexplored. Using a model Suzuki-Miyuara cross-coupling reaction, we performed a series of systematic studies to probe the interconnected effects of metal-ligand cross-links, electrostatic interactions, and local rigidity in polymer catalysts. To achieve this, a novel bi-functional triphenylphosphine acrylamide (BisTPPAm) monomer was synthesized and evaluated alongside an analogous monofunctional triphenylphosphine acrylamide (TPPAm). In model copolymer catalysts, increased initial reaction rates were observed for copolymers untethered by Pd complexation (BisTPPAm-containing) as compared to the Pd-cross-linked catalysts (TPPAm-containing). Further, incorporating local rigidity through secondary structure-like and electrostatic interactions revealed nonmonotonic relationships between composition and reaction rate, demonstrating the potential for tunable behavior through secondary sphere interactions. Finally, through rigorous cheminformatics featurization strategies and statistical modeling, we quantitated relationships between chemical descriptors of the substrate and reaction conditions on catalytic performance. Collectively, these results provide insights into relationships between composition, structure, and function of protein-mimetic catalytic copolymers. | Matthew Sanders; Supraja Chittari; Jack Foley; William Swofford; Bridgette Elder; Abigail Knight | Polymer Science; Organic Polymers | CC BY NC ND 4.0 | CHEMRXIV | 2024-04-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6619338921291e5d1dafcda9/original/leveraging-triphenylphosphine-containing-polymers-to-explore-design-principles-for-protein-mimetic-catalysts.pdf |
651ae52700659409124cb03d | 10.26434/chemrxiv-2023-hsc1f-v2 | Computing the relative affinity of chlorophylls
𝘢 and 𝘣 to light-harvesting complex II | In plants and algae, the primary antenna protein bound to photosystem II is light harvesting complex II (LHCII), a pigment-protein complex that binds both chlorophyll (Chl) 𝘢 and Chl 𝘣 molecules. Chl 𝘢 and Chl 𝘣 have similar structures but differ in the chemical composition of their side chains. Chl 𝘢 has a methyl group (-CH₃) on one of its pyrrole rings, while Chl 𝘣 has a formyl group (-CHO) in the same position. There are 14 Chl binding sites but it is not known how the protein selectively binds the right chlorophyll type in each site. Knowing the selection criteria would allow the design of light harvesting complexes which bind different Chl types allowing an organism to utilize light of different wavelengths. The difference in the binding affinity of Chl 𝘢 and Chl 𝘣 in pea and spinach LHCII was calculated using Multiconformation Continuum Electrostatics and Free Energy Perturbation. Both methods identify some Chl sites where the Chl type (𝘢 or 𝘣) bound has significantly higher affinity, especially when the protein provides a hydrogen bond for the Chl 𝘣 formyl group. However, the Chl 𝘢 sites often have little calculated preference for one Chl type, so they are predicted to bind a mixture of Chl 𝘢 and 𝘣. Therefore, the electron density of the spinach LHCII was reanalyzed, confirming there is negligible Chl 𝘣 in the Chl 𝘢 binding sites. It is suggested that the protein chooses the correct Chl type during folding, segregating the preferred Chl to the correct binding site. | Gehan A. Ranepura; Junjun Mao; Josh V. Vermaas; Jimin Wang; Christopher J. Gisriel; Rongmei Wei; Jose Ortiz-Soto; MD Raihan Uddin; Muhamed Amin; Gary W. Brudvig; Marilyn R. Gunner | Theoretical and Computational Chemistry; Physical Chemistry; Energy; Computational Chemistry and Modeling; Artificial Intelligence; Electrochemistry - Mechanisms, Theory & Study | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/651ae52700659409124cb03d/original/computing-the-relative-affinity-of-chlorophylls-a-and-b-to-light-harvesting-complex-ii.pdf |
66ed2db312ff75c3a1e63db6 | 10.26434/chemrxiv-2024-g3wmn | An Adaptable Blueprint for Non-Metal Near-Infrared Organic Photo-catalysts by Aromatic Sulfones | We present a versatile approach for designing and utilizing high-performance near-infrared (NIR) organic photo-catalysts based on aromatic sulfones. Our sulfone-rosamine-based photo-catalyst 3 demonstrates exceptional capabilities, including high photo-oxidation ability for metal-free photo-oxidative bromination, intrinsically oxygen-independent redox reactions, and remarkable photo-stability with a turnover number (TON) exceeding 2800. We showcase the photo-catalyst's efficacy in photo-oxidative bromination of aromatic compounds under 738 nm illumination. The reaction mechanism is elucidated through a combination of electrochemical studies, time-resolved spectral measurements, and DFT calculations. Transient absorption measurements using the randomly interleaved pulse train (RIPT) method reveal the photo-excited state of 3 approximately 1 ns post-excitation, demonstrating electron transfer from the substrate to excited 3 as the initial step. 3 demonstrated its photocatalytic ability for several aromatic substances, including those that exhibit strong light absorption below 500 nm, which overlaps with the absorption of certain conventional organic photo-catalysts. This aromatic sulfone-based approach offers a robust blueprint for developing NIR organic non-metal photo-catalysts with superior photo-oxidation ability and stability, addressing key limitations of conventional organic NIR-photocatalysts. | Kazuya Yoshida; Toshiaki Suzuki; Vasudevanpillai Biju; Yuta Takano | Organic Chemistry; Catalysis; Photochemistry (Org.); Photocatalysis; Redox Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66ed2db312ff75c3a1e63db6/original/an-adaptable-blueprint-for-non-metal-near-infrared-organic-photo-catalysts-by-aromatic-sulfones.pdf |
64afdd23b605c6803b9e8fac | 10.26434/chemrxiv-2023-bxnnl | The Role of Oxygen in Automotive Grade Lithium-Ion Battery Cathodes: An Atomistic Survey of Ageing | The rising demand for high-performance lithium-ion batteries, pivotal to electric transportation, hinges on key materials like the Ni-rich layered oxide LiNixCoyAlzO2 (NCA) used in cathodes. The present study investigates the redox mechanisms, with particular focus on the role of oxygen in commercial NCA electrodes, both fresh and aged under various conditions (aged cells have performed > 900 cycles until cathode capacity retention ∼80%). Our findings reveal that oxygen participates in charge compensation during NCA delithiation, both through changes in transition metal (TM) - O bond hybridization and formation of partially reversible O2, the latter occurs already below 3.8 V vs Li/Li+. Aged NCA material undergoes more significant changes in TM - O bond hybridization when cycling above 50% SoC while reversible O2> formation is maintained. Nickel is found to be redox active throughout the entire delithiation, and shows a more classical oxidation state change during cycling with smaller changes in the Ni-O hybridization. By contrast, Co redox activity relies on a stronger change in Co-O hybridization, with only smaller Co oxidation state changes. The Ni-O bond displays an almost twice as large change in its bond length on cycling as the Co-O bond. The Ni-O6 octahedra are similar in size as the Co-O6 octahedra in the delithiated state, but are larger in the lithiated state, a size difference that increases with battery ageing. These contrasting redox activities are reflected directly in structural changes. The NCA material exhibits the formation of nanopores upon ageing, and a possible connection to oxygen redox activity is discussed. The difference in interaction of Ni and Co with oxygen provides a key understanding of the mechanism and the electrochemical instability of Ni-rich layered transition metal oxide electrodes. Our research specifically highlights the significance of the role of oxygen in the electrochemical performance of electric-vehicle-grade NCA electrodes, offering important insights for the creation of next-generation long-lived lithium-ion batteries. | Anastasiia Mikheenkova; Soham Mukherjee; Moritz Hirsbrunner; Pontus Törnblom; Cheuk-Wai Tai; Carlo U. Segre; Yujia Ding; Wenliang Zhang; Tegun Citra Asmara; Yuan Wei; Thorsten Schmitt; Håkan Rensmo; Laurent Duda; Maria Hahlin | Energy; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64afdd23b605c6803b9e8fac/original/the-role-of-oxygen-in-automotive-grade-lithium-ion-battery-cathodes-an-atomistic-survey-of-ageing.pdf |
633caed8e6150244dc31ba33 | 10.26434/chemrxiv-2022-fp6lg | Effects of Poly(3-hexylthiophene) Molecular Weight and the Aging of Spinning Solution on the Electrospun Fiber Properties | The electrospinning technique has been considered an attractive route for processing conjugated polymers in a significant quantity for large-scale applications. The processing-structure-property relationship of the electrospinning process for conjugated polymers is not well understood. Here, we report the electrospinning of poly(3-hexylthiophene) (P3HT) for three different molecular weights of P3HT: 31, 58, and 83 kDa. Chloroform was used as a solvent, and a high molecular weight poly(ethylene oxide) (PEO) was utilized to facilitate the processing of P3HT. The electrospinning was performed on the freshly prepared and 24 h aged spinning solutions. The aging of the spinning solution led to the self-assembly of P3HT chains, particularly with dominant H-aggregation for 83 kDa P3HT. The structure development and properties of the fibers were investigated, including the single-fiber electrical conductivity measured using a custom-built setup. The electrical conductivity has been found to be increasing with increasing molecular weight, and as high as a five-fold enhancement in single fiber electrical conductivity was obtained compared to the fiber from the freshly-prepared solution. Despite a 25% PEO concentration in the fibers, the maximum electrical conductivity of a single fiber was found to be ≈2.7 X 10^(-5) S/cm, similar to the pristine P3HT thin films. Our study provides an additional understanding of P3HT structure development in electrospun fibers as a function of polymer molecular weight and processing steps and relates that to fiber properties. | Humayun Ahmad; Song Zhang; Chih-Ting Liu; Guorong Ma; Jason Azoulay; Xiaodan Gu; Mahesh Gangishetty; Santanu Kundu | Materials Science; Polymer Science; Nanoscience; Materials Processing; Nanostructured Materials - Materials; Conducting polymers | CC BY NC 4.0 | CHEMRXIV | 2022-10-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/633caed8e6150244dc31ba33/original/effects-of-poly-3-hexylthiophene-molecular-weight-and-the-aging-of-spinning-solution-on-the-electrospun-fiber-properties.pdf |
60c74095702a9bef5d18a0ee | 10.26434/chemrxiv.7067687.v3 | Methylamines as Nitrogen Precursors in Chemical Vapor Deposition of Gallium Nitride | Chemical vapor deposition (CVD) is one of the most important techniques for depositing thin films of the group 13 nitrides (13-Ns), AlN, GaN, InN and their alloys, for electronic device applications. The standard CVD chemistry for 13-Ns use ammonia as the nitrogen precursor, however, this gives an inefficient CVD chemistry forcing N/13 ratios of 100/1 or more. Here we investigate the hypothesis that replacing the N-H bonds in ammonia with weaker N-C bonds in methylamines will permit better CVD chemistry, allowing lower CVD temperatures and an improved N/13 ratio. Quantum chemical computations shows that while the methylamines have a more reactive gas phase chemistry, ammonia has a more reactive surface chemistry. CVD experiments using methylamines failed to deposit a continuous film, instead micrometer sized gallium droplets were deposited. This study shows that the nitrogen surface chemistry is most likely more important to consider than the gas phase chemistry when searching for better nitrogen precursors for 13-N CVD. | Karl Rönnby; Sydney C. Buttera; Polla Rouf; Sean Barry; Lars Ojamäe; Henrik Pedersen | Materials Processing; Thin Films; Ligands (Inorg.); Main Group Chemistry (Inorg.); Reaction (Inorg.); Computational Chemistry and Modeling; Ligand Design; Interfaces; Surface | CC BY NC ND 4.0 | CHEMRXIV | 2019-01-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74095702a9bef5d18a0ee/original/methylamines-as-nitrogen-precursors-in-chemical-vapor-deposition-of-gallium-nitride.pdf |
643dee9d08c86922ff30541e | 10.26434/chemrxiv-2023-lfz9p | Molecular dynamics studies of Ho(III) aqua-tris(dibenzoylmethane) complex: Role of water dynamics | The seven-coordinate Ho(III) aqua-tris(dibenzoylmethane) complex, referred to as Ho-(DBM)3.H2O, was first reported in the late 1960s. It has a three-fold symmetric structure, with Ho at the center of three {\ligand} ligands and hydrogen bonded to a water molecule. It is considered that the hydrogen bonds between the water molecule and the ligands surrounding Ho play an important role in the formation of its symmetrical structure. In this work, we developed new force-field parameters for classical molecular dynamics (CMD) simulations to theoretically elucidate the structure and dynamics of Ho-(DBM)3.H2O. To develop the force field, structural optimization and molecular dynamics were performed on the basis of ab initio calculations using the plane-wave pseudopotential method. The force-field parameters for CMD were then optimized to reproduce the data obtained from the ab initio calculations. Validation of the developed force field showed good agreement with the experimental crystalline structure and the ab initio data. The vibrational properties of water in Ho-(DBM)3.H2O were investigated by comparison with bulk liquid water. The vibrational motion of water was found to have a characteristic mode originating from stationary rotational motion along the c axis of Ho(III) aqua-tris(dibenzoylmethane). Contrary to expectations, the hydrogen-bond dynamics of water in Ho-(DBM)3.H2O were found to be almost equivalent to those of bulk liquid water except for librational motion. This development route for force-field parameters for CMD and the establishment of water dynamics can advance the understanding of water-coordinated metal complexes with high coordination numbers such as Ho-(DBM)3.H2O. | Takahiro Ohkubo; Nao Komiyama; Hyuma Masu; Keiki Kishikawa; Michinari Kohri | Inorganic Chemistry; Coordination Chemistry (Inorg.) | CC BY 4.0 | CHEMRXIV | 2023-04-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643dee9d08c86922ff30541e/original/molecular-dynamics-studies-of-ho-iii-aqua-tris-dibenzoylmethane-complex-role-of-water-dynamics.pdf |
64edb2513fdae147fa0ebc2f | 10.26434/chemrxiv-2023-bzz0k-v2 | Unlocking the Chain-Walking Process in Gold Catalysis | The successful realization of gold-catalyzed chain-walking reactions, facilitated by ligand-enabled Au(I)/Au(III) redox catalysis, has been reported for the first time. This breakthrough has led to the development of gold-catalyzed annulation reaction of alkenes with iodoarenes by leveraging the interplay of chain-walking and π-activation reactivity mode. The reaction mechanism has been elucidated through comprehensive experimental and computational studies. | Vivek W. Bhoyare; Akash G. Tathe; Vincent Gandon; Nitin T. Patil | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Homogeneous Catalysis; Redox Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64edb2513fdae147fa0ebc2f/original/unlocking-the-chain-walking-process-in-gold-catalysis.pdf |
636bc077bef5d45b264ec688 | 10.26434/chemrxiv-2022-9gtnm-v2 | Connecting the Dots for Fundamental Understanding of Structure-Photophysics-Property Relationships of COFs, MOFs, and Perovskites using a Multiparticle Holstein Formalism | Photoactive organic and hybrid organic-inorganic materials, such as conjugated polymers, covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and layered perovskites, display intriguing photophysical signatures upon interaction with light. Elucidating structure-photophysics-property relationships across a broad range of functional materials is nontrivial and requires our fundamental understanding of the intricate interplay among excitons (electron-hole pair), polarons (charges), bipolarons, phonons (vibrations), inter-layer stacking interactions, and different forms of structural and conformational defects. In parallel with electronic structure modeling and data-driven science that are actively pursued to successfully accelerate materials discovery, an accurate, computationally inexpensive, and physically-motivated theoretical model, which consistently makes quantitative connections with conceptually complicated experimental observations, is equally important. Within this context, the first part of this Perspective highlights a unified theoretical framework in which the electronic coupling as well as the local coupling between the electronic and nuclear degrees of freedom can be efficiently described for a wide range of quasiparticles with similarly structured Holstein-style Hamiltonians. The second part of this Perspective discusses excitonic and polaronic photophysical signatures in polymers, COFs, MOFs, and perovskites, and makes a unique attempt to bridge the gap between different research fields using a common theoretical construct - the Multiparticle Holstein Formalism. We envision that the synergistic integration of state-of-the-art computational approaches with the Multiparticle Holstein Formalism will help identify and establish new, transformative design strategies that will guide the synthesis and characterization of next-generation energy materials optimized for a broad range of optoelectronic, spintronic, and photonic applications. | Raja Ghosh; Francesco Paesani | Theoretical and Computational Chemistry; Physical Chemistry; Theory - Computational; Quasiparticles and Excitations; Transport phenomena (Physical Chem.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/636bc077bef5d45b264ec688/original/connecting-the-dots-for-fundamental-understanding-of-structure-photophysics-property-relationships-of-co-fs-mo-fs-and-perovskites-using-a-multiparticle-holstein-formalism.pdf |
60c7463a0f50db60ba3963e9 | 10.26434/chemrxiv.10315901.v1 | Optoelectronic Materials Based on Gaq3@ZIF-8 Metal-Organic Framework Composites for Solid-State Lighting | <p>Light-emitting diodes (LEDs) are an efficient source of lighting, with many commercial applications like general illumination, camera flashes, phone or laptop displays, and TV screens. However, they present some limitations, including low-quality colour rendition, and the use of expensive/toxic rare-earth elements. Therefore there is an urgent need for the development of improved luminescent materials free of rare earths. Luminescent metal-organic framework (LMOF) materials have emerged as promising candidates for photonics devices. Most of the MOF-LEDs reported hitherto are of the down-converter type, where UV or blue LED are coated with LMOFs, however there is very limited progress in the development of LED using LMOFs as the electroluminescent layer. Herein, we report a novel Guest@MOF composite synthesized by encapsulating a semiconducting Gaq3 metal complex [gallium(III) tris(8-hydroxyquinolinato)], into the ZIF-8 pore [Zn (2-methylimidazolate)<sub>2</sub>], yielding a green-yellowish luminescent material exhibiting a relatively high quantum yield (15%) upon photo-excitation. Subsequently, we show a down-converter LED made from 405-nm violet LED coated with Gaq3@ZIF-8, yielding a white MOF-LED. Then we demonstrate the use of Gaq3@ZIF-8 as an electroluminescent layer in a hybrid-LED, achieving an orange-yellowish emitting device. This work reveals the potential of LMOFs for next-generation LED technology, by exploiting the Guest@MOF concept to enable electroluminescent applications.</p> | Mario Gutierrez; Cristina Martín; Mark Van der Auweraer; Johan Hofkens; Jin-Chong Tan | Hybrid Organic-Inorganic Materials; Nanostructured Materials - Materials; Optical Materials; Plasmonic and Photonic Structures and Devices; Photochemistry (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 1970-01-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7463a0f50db60ba3963e9/original/optoelectronic-materials-based-on-gaq3-zif-8-metal-organic-framework-composites-for-solid-state-lighting.pdf |
679734876dde43c9088e1623 | 10.26434/chemrxiv-2025-mf5t7 | Developments in Suzuki-Miyaura cross coupling reaction (SMR) towards green synthesis | A comprehensive overview of Suzuki-Miyaura coupling reaction promoted through greener techniques is provided, covering the literature over last two decades. This review embodies the modification Suzuki-Miyaura coupling reaction via various reaction device and various greener pathway which paves the way for a sustainable future. | Subir Panja; Biprajit Paul; Ankita Mandal | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/679734876dde43c9088e1623/original/developments-in-suzuki-miyaura-cross-coupling-reaction-smr-towards-green-synthesis.pdf |
6510d5b9ed7d0eccc32796e5 | 10.26434/chemrxiv-2023-w341f-v2 | Benchmarking Density Functional Theory Methods for Metalloenzyme Reactions: The Introduction of the MME55 Set | We present a new benchmark set of metalloenzyme model reaction energies and barrier heights, which we call MME55. The set contains ten different enzymes, representing eight transition metals, both open and closed shell systems, and system sizes of up to 116 atoms. We use four DLPNO-CCSD(T)-based approaches to calculate reference values, against which we then benchmark the performance of a range of density functional approximations with and without dispersion corrections. Dispersion corrections improve the results across the board, and triple-ζ basis sets provide the best balance of efficiency and accuracy. Jacob's ladder is reproduced for the whole set based on averaged mean absolute (percentage) deviations, with the double hybrids SOS0-PBE0-2-D3(BJ) and revDOD-PBEP86-D4 standing out as the most accurate methods for the MME55 set. The range-separated hybrids ωB97M-V and ωB97X-V also perform well here and can be recommended as a reliable compromise between accuracy and efficiency; they have already been shown to be robust across many other types of chemical problems as well. Despite the popularity of B3LYP in computational enzymology, it is not a strong performer on our benchmark set, and we discourage its use for enzyme energetics. | Dominique Wappett; Lars Goerigk | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Organometallic Chemistry; Computational Chemistry and Modeling; Bioorganometallic Chemistry; Catalysis | CC BY 4.0 | CHEMRXIV | 2023-09-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6510d5b9ed7d0eccc32796e5/original/benchmarking-density-functional-theory-methods-for-metalloenzyme-reactions-the-introduction-of-the-mme55-set.pdf |
61e0f8c9eab6ef2614e09c12 | 10.26434/chemrxiv-2021-8fq9b-v3 | Biocatalytic One-Carbon Ring Expansion of Aziridines to Azetidines via a Highly Enantioselective [1,2]-Stevens Rearrangement | We report enantioselective one-carbon ring expansion of aziridines to make azetidines as a new-to-nature activity of engineered ‘carbene transferase’ enzymes. A laboratory-evolved variant of cytochrome P450BM3, P411-AzetS, not only exerts unparalleled stereocontrol (99:1 er) over a [1,2]-Stevens rearrangement, but also overrides the inherent reactivity of aziridinium ylides, cheletropic extrusion of olefins, to perform a [1,2]-Stevens rearrangement. By controlling the fate of the highly reactive aziridinium ylide intermediates, these evolvable biocatalysts promote a transformation which cannot currently be performed using other catalyst classes. | David Miller; Ravi Lal; Luca Marchetti; Frances Arnold | Organic Chemistry; Catalysis; Biocatalysis | CC BY 4.0 | CHEMRXIV | 2022-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61e0f8c9eab6ef2614e09c12/original/biocatalytic-one-carbon-ring-expansion-of-aziridines-to-azetidines-via-a-highly-enantioselective-1-2-stevens-rearrangement.pdf |
6659c572418a5379b0bfe3b3 | 10.26434/chemrxiv-2024-kq3wd | Reverse engineering of vinyl acetate polymerizations by
genetic algorithm-based multi-objective optimization | This work proposes a multi-objective optimization
(MOO) approach for reverse engineering of vinyl acetate polymerization processes. Our method leverages machine learning (ML) models trained on data from kinetic Monte Carlo (kMC) simulations to replace expensive laboratory experiments. We employ a genetic algorithm (GA) as the MOO optimizer, considering reaction time, monomer conversion, and molar mass distribution (MMD) similarity as objectives. The trained ML models assist the optimization process and predict key polymer properties for candidate recipes generated by the GA, enabling rapid fitness function evaluation. The proposed framework involves: (1) training ML models for monomer concentration and MMD prediction using kMC simulation data; (2) performing GA-based MOO to identify optimal recipes (Pareto front) for a target MMD (3) selecting the most suitable recipe based on user priorities from the resulting Pareto front, considering user-defined weights for each objective (reaction time, conversion, MMD). Our experiments demonstrate that the GA, coupled with simulation-supported ML, efficiently identifies optimal recipes with high accuracy. Notably, the ML models achieve good performance even with limited training data. This approach offers a rapid and cost-effective solution for reverse engineering of vinyl acetate polymerization processes | Jelena Fiosina; Philipp Sievers; Marco Drache; Sabine Beuermann | Polymer Science; Polymerization (Polymers) | CC BY NC 4.0 | CHEMRXIV | 2024-06-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6659c572418a5379b0bfe3b3/original/reverse-engineering-of-vinyl-acetate-polymerizations-by-genetic-algorithm-based-multi-objective-optimization.pdf |
60c74e75842e6586ccdb3668 | 10.26434/chemrxiv.12759449.v1 | Bioinspired Thermo-Responsive Xyloglucan-Cellulose Nanocrystal Hydrogels | Thermo-responsive hydrogels present unique properties, such as tunable mechanical performance or changes in volume, which make them attractive for applications including wound healing dressings, drug delivery vehicles, and implants, among others. This work reports the implementation of bio-based thermo-responsive hydrogels comprised of xyloglucan (XG) and cellulose nanocrystals (CNCs). Thermo-responsive properties were obtained by enzymatic degalactosylation of tamarind seed XG (DG-XG), which reduced the galactose residue content by ~50%, and imparted a reversible thermal transition. XG with comparable molar mass to DG-XG was achieved by ultrasonication treatment (XGu) for direct comparison of behavior. The hydrogels were prepared by simple mixing of DG-XG or XGu with CNCs in water. Phase diagrams were established to identify the ratios of DG-XG or XGu to CNCs (from 1:300 to 20:1 by mass) that yielded a viscous liquid, a phase separated mixture, a simple gel, or a thermo-responsive gel. Gelation occurred at a DG-XG or XGu to CNC ratio higher than that needed for the full surface coverage of CNCs, and required relatively high overall concentrations of both components (tested concentrations up to 20 g/L XG and 30 g/L CNCs). This is likely a result of the increase in effective hydrodynamic volume of CNCs due to the formation of XG-CNC complexes. Investigation of the adsorption behavior indicated that DG-XG formed a more rigid layer on CNCs compared to XGu. Rheological properties of the hydrogels were characterized and a reversible thermal transition was found for DG-XG/CNC gels at 35°C, where the mechanical properties of the gel could be tuned by adjusting the CNC content | Malika Talantikite; Taylor C. Stimpson; Antoine Gourlay; Sophie Le-Gall; Céline Moreau; Emily
D. Cranston; Jose Moran-Mirabal; Bernard Cathala | Biopolymers; Cellulosic materials; Hydrogels | CC BY NC ND 4.0 | CHEMRXIV | 2020-08-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74e75842e6586ccdb3668/original/bioinspired-thermo-responsive-xyloglucan-cellulose-nanocrystal-hydrogels.pdf |
60c748c99abda249c3f8cafd | 10.26434/chemrxiv.11916615.v2 | Computational Investigation of APOBEC3H Substrate Orientation and Selectivity | There are several available crystal structures for APOBEC3H, however, none with bound substrate. Our manuscript presents a theoretical investigation of the binding orientation of the ssDNA substrate for the DNA deaminase APOBEC3H. Here, we have used classical MD simulations to explore the possible<br />binding orientation of a dsDNA substrate, as well as the possible factors leading to the observed substrate sequence selectivity. | Mark A. Hix; G. Andres Cisneros | Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2020-03-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c748c99abda249c3f8cafd/original/computational-investigation-of-apobec3h-substrate-orientation-and-selectivity.pdf |
60c7574ff96a00b41d288c3b | 10.26434/chemrxiv.14393297.v1 | Synergistic Catalysis of Tandem Michael Addition/Enantioselective Protonation Reactions by an Artificial Enzyme | Enantioselective protonation is conceptually one of the most attractive methods to generate an α-chiral center. However, enantioselective protonation presents major challenges, especially in water as a solvent. Herein, we report an artificial enzyme catalyzed tandem Michael addition and enantioselective protonation reaction of α-substituted acroleins with 2-acyl imidazole derivatives in water. The artificial enzyme uses a synergistic combination of two abiological catalytic sites: a genetically encoded non-canonical p-aminophenylalanine residue and a Lewis acid Cu(II) complex. The exquisite stereochemical control achieved in the protonation of the transient enamine intermediate generated by conjugate addition of the Michael donor is illustrated by the >20:1 dr and up to >99% ee obtained for the products. These results illustrate the potential of exploiting synergistic catalysis in artificial enzymes for challenging reactions.<br /> | Zhi Zhou; Gerard Roelfes | Biocatalysis; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-04-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7574ff96a00b41d288c3b/original/synergistic-catalysis-of-tandem-michael-addition-enantioselective-protonation-reactions-by-an-artificial-enzyme.pdf |
6745ba4a7be152b1d0e911a7 | 10.26434/chemrxiv-2024-x72vw | Red-light Active N,C,N-Pincer Bismuthinidene: Excited State Dynamics and Mechanism of Oxidative Addition into Aryl Iodides | Despite the progress made in the field of synthetic organic photocatalysis over the last decade, the use of higher wavelengths, especially those in the deep-red portion of the electromagnetic spectrum, remain comparatively rare. We have previously disclosed that a well-defined N,C,N-pincer bismuthinidene (1a) can undergo formal oxidative addition into a wide range of aryl electrophiles upon absorption of low-energy red light. In this study, we map out the photophysical dynamics of 1a and glean insights into the nature of the excited state responsible for the activation of aryl electrophiles. Transient-absorption and emission techniques reveal that, upon irradiation with red light, the complex undergoes a direct S0 → S1 metal-to-ligand charge transfer (MLCT) transition, followed by rapid intersystem crossing (ISC) to a highly reducing emissive triplet state (−2.62 V vs Fc+/0 in MeCN). The low dissipative losses incurred during ISC (~6% of the incident light energy) help rationalize the ability of the bismuthinidene to convert low-energy light into useful chemical energy. Spectroelectrochemical and computational data support a charge-separated excited-state structure with radical-anion character on the ligand and radical-cation character on bismuth. Kinetic studies and competition experiments afford insights into the mechanism of oxidative addition into aryl iodides; concerted and inner-sphere processes from the triplet excited state are ruled out, with the data strongly supporting a pathway that proceeds via outer-sphere dissociative electron transfer. | Alexios Stamoulis; Mauro Mato; Paolo Cleto Bruzzese; Markus Leutzsch; Alejandro Cadranel; Marcos Gil-Sepulcre; Frank Neese; Josep Cornella | Organic Chemistry; Catalysis; Organometallic Chemistry; Bond Activation; Kinetics and Mechanism - Organometallic Reactions; Main Group Chemistry (Organomet.) | CC BY 4.0 | CHEMRXIV | 2024-11-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6745ba4a7be152b1d0e911a7/original/red-light-active-n-c-n-pincer-bismuthinidene-excited-state-dynamics-and-mechanism-of-oxidative-addition-into-aryl-iodides.pdf |
655156806e0ec7777fd2b0fe | 10.26434/chemrxiv-2023-3n1d0 | Fluorescence of the retinal chromophore in microbial and animal rhodopsins | Fluorescence of the vast majority of natural opsin-based photoactive proteins is extremely low in accordance with their functions that depend on efficient transduction of absorbed light energy. However, recently proposed several classes of engineered rhodopsins with enhanced fluorescence along with the discovery of a new natural highly fluorescent rhodopsin, NeoR, opened a way to exploit these transmembrane proteins as fluorescent sensors and draw more attention to studies on this untypical rhodopsins property. Here we review available data on the fluorescence of the retinal chromophore in microbial and animal rhodopsins and their photocycle intermediates as well as different isomers of the protonated retinal Schiff base in different solvents and the gas phase. | Dmitrii M. Nikolaev; Andrey A. Shtyrov; Sergey Yu. Vyazmin; Andrey V. Vasin; Maxim S. Panov; Mikhail N. Ryazantsev | Biological and Medicinal Chemistry; Biophysics | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/655156806e0ec7777fd2b0fe/original/fluorescence-of-the-retinal-chromophore-in-microbial-and-animal-rhodopsins.pdf |
67b861bb81d2151a026be8b8 | 10.26434/chemrxiv-2025-2glvd | Natural Deep Eutectic Solvent Acts as an Activator of Laccase Enzyme | Laccase is a highly versatile biocatalyst with broad applications across bioremediation, biofuel production, organic synthesis and in industries such as food and paper manufacturing. However, the industrial use of laccase is often limited by its inactivation under harsh conditions, including the presence of non-aqueous solvents, extreme pH and high temperatures. To overcome these challenges, various solvent engineering strategies have been explored, including the use of natural deep eutectic solvents (NADESs) as environmentally friendly alternatives to traditional organic solvents. In this study, the effects of NADESs composed of betaine, choline chloride, L-proline, and sorbitol were evaluated. Sorbitol was consistently used as the hydrogen bond donor to assess the impact of different hydrogen bond acceptors. Laccase activity, structural stability and interactions with the NADES components were investigated using enzyme activity assays, intrinsic fluorescence, circular dichroism (CD) spectroscopy and molecular docking studies. The results revealed a significant enhancement in laccase activity when Betaine:Sorbitol NADES was used, suggesting its potential as a sustainable solvent system for industrial applications. In contrast, the NADESs containing choline chloride and L-proline as the acceptors showed an inhibitory effect on laccase activity, highlighting the importance of carefully selecting NADES components. CD and intrinsic fluorescence measurements indicated that the reduced activity of laccase in the L-proline:sorbitol system was due to a substantial structural change in the enzyme. In contrast, the enhanced activity observed in the Betaine:Sorbitol NADES could be attributed to the retention of laccase structural stability and favorable interactions between the NADES components and the enzyme's active site residues. These findings provide valuable insights into the design and selection of NADESs for various industrial applications, with the potential for improved enzyme stability and activity. | Madushmita Hatimuria; Jyoti Vishwakarma; Sudhanshu Sharma; Krishna Gavvala; ASHOK PABBATHI | Physical Chemistry; Catalysis; Chemical Engineering and Industrial Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67b861bb81d2151a026be8b8/original/natural-deep-eutectic-solvent-acts-as-an-activator-of-laccase-enzyme.pdf |
60c74693bdbb89ed3fa38c2b | 10.26434/chemrxiv.11359316.v1 | Molecular Crowding and a Minimal Footprint at a Gold Nanoparticle Support Stabilize Glucose Oxidase and Boost its Activity | Enzymes conjugated to nanomaterials are used in the design of various biotechnologies. In development of biosensors, surface modifications with the enzyme glucose oxidase (GOx) serve to aid the detection of blood glucose. In order to optimize sensor effectiveness, the enzyme tertiary structure needs to be preserved upon immobilization to retain the enzyme´s catalytic activity. Due to the nature of GOx, it suffers from tendency to denature when immobilized at a solid surface, methods to optimize enzyme stability are of great importance. Here, we introduce the study of the interaction of GOx to the highly curved surface of 20 nm gold nanoparticles (AuNP) that shows how placing a monolayer of enzyme where the enzyme spreads thin at the AuNP surface still provides stable catalytic performance up to14 days compared to enzymes free in solution. Moreover, by increasing enzyme density and creating a molecularly crowded environment at the highly curved nanoparticle surface, which limits the size of the enzyme footprint for attachment, the activity per enzyme can be enhanced up to 300%. This is of great importance for implementing stable and sensitive sensor technologies that are constructed by enzyme-based nanoparticle scaffolds. Here, we show by using the conditions that maintain GOx structure and function when limiting the enzyme coating to an ultra-thin layer, the design and construction of ultrafast responding diagnostic sensor technology for glucose can be achieved, which is crucial for monitoring rapid fluctuations of for instance, glucose in the brain. | Yuanmo Wang; Rima Jonkute; Hampus Lindmark; Jacqueline D. Keighron; Ann-Sofie Cans | Nanocatalysis - Catalysts & Materials; Nanocatalysis - Reactions & Mechanisms | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74693bdbb89ed3fa38c2b/original/molecular-crowding-and-a-minimal-footprint-at-a-gold-nanoparticle-support-stabilize-glucose-oxidase-and-boost-its-activity.pdf |
631098b4f07ee15b17f9cabe | 10.26434/chemrxiv-2022-r2szm | Electrochemical detection of dopamine using a simple redox cycling-based device | Here, a dual ITO microchip was fabricated for high sensitive detection of dopamine (DA) based on redox-cycling. The
ITO electrodes with 3×3 mm working areas were made via photolithography and dry etching processes. The microchip
was obtained by first aligning the working areas of two ITO electrodes to overlap and then fixing them in that position
using a double-sided tape, which also formed a sealed microchannel between the ITO electrodes for test solution delivery. The ITO electrodes and microchips were electrochemically characterized using EIS, cyclic voltammetry and chronoamperometry. Compared to a single ITO electrode in a microchannel, the microchip had a significantly higher signal due to redox cycling. The microchip was lastly used for the detection of DA at varying concentrations. According to the results, the microchip had an LOD of 0.15 μM in a linear detection region of 0.1 to 50 μM. The microchip requires less than 1 μl of solution to complete the analysis and has great potential to be applied for immunosensing. | Mustafa Şen | Analytical Chemistry; Electrochemical Analysis | CC BY 4.0 | CHEMRXIV | 2022-09-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/631098b4f07ee15b17f9cabe/original/electrochemical-detection-of-dopamine-using-a-simple-redox-cycling-based-device.pdf |
632ab423114b7ee6eb177c16 | 10.26434/chemrxiv-2022-s2jz1 | Efficient multi-configurational quantum chemistry approach to single-ion magnets based on density matrix embedding theory | Density matrix embedding theory (DMET) provides a systematic framework to combine low-level (e.g. Hartree-Fock approximation) and high-level correlated quantum chemistry methods to treat strongly correlated systems with remarkable accuracy and efficiency. In this work, we proposed an efficient quantum embedding approach that uses the restricted open-shell Hartree-Fock (ROHF) as the low level solver and combines DMET with the complete active space self-consistent field and subsequent state interaction treatment of spin-orbit coupling (CASSI-SO), and applied it to theoretical description of single-ion magnets (SIMs). We have developed a novel direct inversion of iterative subspace (DIIS) technique that incorporates a regularization term related to the spin polarization entropy, termed as R-DIIS, and ensures ROHF to converge to physically correct ground state, which is found to be crucial for the efficacy of subsequent CASSI-SO calculation. We found that the DMET+CASSI-SO approach can produce reliable zero-field splitting (ZFS) parameters in typical 3d-SIMs with dramatically reduced computational cost compared to its all-electron counterpart. This work therefore demonstrates the great potential of the DMET-based CASSI-SO approach for efficient \textit{ab initio} study of magneto-structural correlations in complex molecular magnetic systems. | Yuhang Ai; Qiming Sun; Hong Jiang | Theoretical and Computational Chemistry; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632ab423114b7ee6eb177c16/original/efficient-multi-configurational-quantum-chemistry-approach-to-single-ion-magnets-based-on-density-matrix-embedding-theory.pdf |
6414ad012bfb3dc251ef93f2 | 10.26434/chemrxiv-2023-mqzjb | Machine Learning Modeling and Insights into the Structural Foundations of Polymyxin-like Antimicrobials | Antimicrobial resistance (AMR) is a silent pandemic that represents an urgent threat to human health. Unfortunately, the antibiotic development pipeline is slow even though AMR has been escalating uncontrollably fast, namely amongst Gram-negative pathogens. Although out of use until recently due to their toxic side effects, polymyxins have been revived as a last-line therapeutic option since all other antibiotics are currently failing. In an attempt to ameliorate their toxicity and improve antimicrobial activity, many studies have been generating polymyxin analogues through different strategies, mostly empirical. As such, there is still a lack of faster and more reliable approaches to make analog design efficient in order to tackle AMR in a timely fashion. The solution to accelerate the discovery of new drugs probably lies in the use of in silico approaches, such as machine learning, due to their faster pace and time and cost efficiency. In this work, machine learning was applied to Quantitative Structure-Activity Relationship (QSAR) modeling with the objective of providing a working semi-quantitative model capable of predicting the activity of polymyxin-like molecules for a given species. For this, we applied four different learning algorithms and ten different families of molecular descriptors to our dataset of 408 molecule/microorganism pairs retrieved from PubChem. The AdaBoost model devised using the CKP set of descriptors was the best performer, with good accuracies and very low false negative and positive predictions. Preliminary exploration of the model's response to systematic changes in the structure of polymyxin B reveals a trend towards increased antimicrobial activity when exchanging some of its constituent amino acids for more lipophilic ones. Experimental studies are already underway based on this model's application and we believe it will become a crucial tool for drug development. | Inês Machado; João Inácio; Paula Jorge; Filipe Teixeira | Biological and Medicinal Chemistry; Bioinformatics and Computational Biology; Drug Discovery and Drug Delivery Systems; Microbiology | CC BY NC 4.0 | CHEMRXIV | 2023-03-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6414ad012bfb3dc251ef93f2/original/machine-learning-modeling-and-insights-into-the-structural-foundations-of-polymyxin-like-antimicrobials.pdf |
60c741e9bdbb89569ea383e1 | 10.26434/chemrxiv.8166767.v1 | A linear-scaling method for non-covalent interactions | A novel method for the accurate and efficient calculation of interaction energies in weakly-bound complexes comprised of a large number of molecules is presented. The new ALMO+RPAd method circumvents the prohibitive scaling of coupled cluster singles and doubles while still providing similar accuracy across a diverse range of intermolecular interactions. Tests on various dimers and the S66 benchmark set demonstrate results within 0.5 kcal/mol of coupled cluster singles and doubles results. On a large cluster of water molecules, we achieve calculations involving over 3500 orbital and 12000 auxiliary basis functions in under ten minutes on a single CPU core. | Robert Shaw; Grant Hill | Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2019-05-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c741e9bdbb89569ea383e1/original/a-linear-scaling-method-for-non-covalent-interactions.pdf |
647b9c2e4f8b1884b7c95317 | 10.26434/chemrxiv-2023-brpwt | Teaching biologics formulation using molecular modeling and simulations | Teaching chemistry and chemical engineering students about biologics formulation remains challenging despite its increasing importance in pharmaceutical development. Monoclonal antibodies, commonly called mAbs, are the most popular biologics. They have been developed into drugs to treat various diseases in the past decades. Multiple challenges exist for designing proper formulations to stabilize mAbs, such as preventing aggregation and mitigating viscosity. Molecular modeling and simulations can improve pharmaceutical products by examining the interactions between mAbs and other compounds, such as excipients. To introduce students to biopharmaceuticals, eight chemical engineering students at the Stevens Institute of Technology participated in a semester-long course to learn the challenges of pharmaceutical development and different computational skills to study biologics formulation. The students started with a limited background in this field. Throughout one semester, they were introduced to various literature and software tools for modeling antibodies and studying their interactions with excipients. Positive learning outcomes were achieved through pre- and post-course assessments. This paper aims to develop a course structure to be replicated at other universities and institutions to teach biopharmaceutical development to students. | Andrew Phillips; Anusha Srinivas; Ilina Prentoska Prentoska; Margaret O'Dea; Matthew Kustrup; Sarah Hurley; Savannah Bruno; Vy Nguyen; Pin-Kuang Lai | Chemical Education; Chemical Education - General | CC BY 4.0 | CHEMRXIV | 2023-06-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/647b9c2e4f8b1884b7c95317/original/teaching-biologics-formulation-using-molecular-modeling-and-simulations.pdf |
627357e943d1f02a2820332a | 10.26434/chemrxiv-2022-k23gz | A Review on Removal of Carbon Dioxide (CO2) using Zeolitic Imidazolate Frameworks: Adsorption and Conversion via Catalysis | Carbon dioxide (CO2) is one of the culprit causes of global climatic changes. Furthermore, the efficient separation of CO2 from other gaseous mixtures using ZIFs-based materials is vital for several processes such as flue gas separation, gas sweetening, and natural gas processing. Zeolitic imidazolate frameworks (ZIFs)-based materials are emerging adsorbents and catalysts for CO2 gas removal via adsorption and conversion into valuable chemicals. ZIFs-based adsorbents with high adsorption/conversion efficiencies and tunable properties can be achieved by judicious synthesis and fabrication methods. We reviewed ZIF-based materials for CO2 removal via adsorption and catalysis (e.g., cycloaddition, carboxylation, hydrogenation, N-formylation, electrocatalysis, and photocatalysis). In addition, recent development methods such as membrane synthesis and ways to improve the gas separation performance of ZIF membranes were highlighted. The prospective point of view to promote industrial applications and commercialization of ZIF-based materials was briefly discussed. Once challenges such as low performance and reproducibility for ZIFs-based materials are solved, scalability and cost-effectiveness should not become issues. | Hani Nasser Abdelhamid | Materials Science; Inorganic Chemistry; Catalysis; Supramolecular Chemistry (Inorg.); Electrocatalysis; Photocatalysis | CC BY 4.0 | CHEMRXIV | 2022-05-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/627357e943d1f02a2820332a/original/a-review-on-removal-of-carbon-dioxide-co2-using-zeolitic-imidazolate-frameworks-adsorption-and-conversion-via-catalysis.pdf |
669fb8465101a2ffa8b97129 | 10.26434/chemrxiv-2024-t0fgj | Teaching Softness of Polymer Microgels Employing Atomic Force Microscopy | Studying the properties of soft nanoparticles exposes students to emerging trends in materials science, fosters interdisciplinary knowledge, and prepares them for their own contributions in both academic and industrial settings. We developed a laboratory atomic force microscopy (AFM) experiment using poly-N -isopropylacrylamide (PNI- PAM) microgels and investigated single nanogels as well as monolayers by AFM and quantitative image analysis. The experiments show how soft nanogels are deformed at interfaces and the students learn to quantify the deformation by quantitative analysis of height and phase images. The deformation is related to a core-corona type of crosslinker distribution inside the microgel. Further experiments address the structure of microgel monolayers and demonstrate structural transitions from a hexagonal phase of microgels in corona-corona contact toward a different regime at higher interfacial concentrations in which microgels form a second hexagonal phase in core-core contact. A quantitative analysis of height images provides the distribution of nearest-neighbor distances. The students use dip-coating to prepare the samples and learn how to correlate AFM exper- iments in the dry state, i.e., at the solid/air interface after evaporation of the solvent, with properties of the microgel in bulk solution, and at the water/air interface. | M. Friederike Schulte; Simon Schog; Steffen Bochenek; Timon Kratzenberg; Michael Schröder; Walter Richtering | Chemical Education | CC BY NC 4.0 | CHEMRXIV | 2024-07-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669fb8465101a2ffa8b97129/original/teaching-softness-of-polymer-microgels-employing-atomic-force-microscopy.pdf |
60c74b6b702a9b7b6e18b413 | 10.26434/chemrxiv.12330923.v1 | Low Pressure Gas Electron Diffraction: an Experimental Setup and Case Studies | <div>Principles of low pressure gas electron diffraction(LPGED) are introduced. An experimental setup has</div><div>been constructed for measuring electron diffraction patterns of gaseous samples at pressures below 10−3</div><div>mbar. Test measurements have been performed for benzoic acid at T = 287 K corresponding to a vapor </div><div>pressure of the substance P = 2 × 10−4 mbar, for iodoform CHI3 at T = 288 K (P = 4 × 10−4 mbar) and for carbon tetraiodide CI4 at T = 290K (P = 1 × 10−4 mbar). Due to the low experimental temperature thermal decomposition of CI4 has been prevented, which was unavoidable in previous classical measurements at higher temperatures.</div><div>From the obtained data the molecular structures have been successfully refined. The most important</div><div>semi-empirical equilibrium molecular parameters are re(Car–Car)av = 1.387(5) Å in benzoic acid, re(C–I)</div><div>= 2.123(3) Å in iodoform and re(C–I) = 2.133(7) Å in carbon tetraiodide. The determined parameters</div><div>showed consistency with theoretically predicted values. A critical comparison with results of the earlier</div><div>investigations has also been done.</div> | Yury Vishnevskiy; Sebastian Blomeyer; Christian G. Reuter | Spectroscopy (Physical Chem.); Structure | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74b6b702a9b7b6e18b413/original/low-pressure-gas-electron-diffraction-an-experimental-setup-and-case-studies.pdf |
60c754299abda24b50f8e133 | 10.26434/chemrxiv.13614146.v1 | Efficient, Green, and Renewable N-Di-Methylation Synthesis of Amines by a Novel Nano-Catalyst of NiNiO@C | <p><a></a><a>The development
of Earth-abundant reusable and no-toxic heterogeneous catalyst applied in the
pharmaceutically, bio-active relevant compounds synthesis as well as other
organic syntheses still remains as the most important goal of the general
chemical research. N-methylated compounds, as one of the most essential
bioactive compounds,</a> have been
widely used in the fine and bulk industries for the production of high-value
chemicals including pharmaceuticals, agrochemicals, and dyes. As their reports, activated toxic methyl iodide and dimethyl
sulfoxide were usually employed in the traditional N-methylation, which easily
suffer from narrow scopes of amines, generation of by-products, and a large
amount of waste. <a>Very recently, </a>transition metal-catalyzed methylation
of amines has become an efficient, practical, and cost-effective method for the
one-pot selective synthesis of N-methylamines with C<sub>1</sub> sources. Herein, we first
developed a simple and <a>environmentally friendly</a> method
for the preparation of efficient, reusable, and low-cost graphene spheres
encapsulated Ni/NiO nanoalloy catalysts (Ni/NiO@C) for highly selective
synthesis of the N-methylated compounds by using various functional amines and
aldehydes under easily
handle-able and industrially <a></a><a>applicable </a>conditions.<b> </b>A large number of primary, secondary
amines (more than 70 examples) could be converted smoothly to the corresponding
N, N-dimethylamines with the participation of different functional aldehydes.
The gram-scale synthesis was also demonstrated in an excellent yield; not only
that, the catalyst was further proved that it could be easily recycled by its
intrinsic magnetism and reused up to ten times without losing activity and
selectivity. Both of them are the great advantages in contrast to other
catalysts reported previously. And also, for the first time, we have developed
the highly efficient, cost-effective tandem synthesis of N, N-dimethylamines products in a one-pot
process by means of aldehydes and NH<sub>3</sub>. As far as we know, this is
the first example of the synthesis of tertiary
amines with the combined reaction process of reductive
amination of aldehydes and N-methylation of primary amines only with the single
one earth-abundant metal catalyst. Overall, the
advantages of this newly developed method including operational simplicity,
high stability, easily recyclable, cost-effective of the catalyst, and good
functional group compatibility for the synthesis of N-methylation products, as well as the
highly efficient and industrial applicable tandem synthesis process.</p> | Jianguo Liu; Yanpei Song; Xiuzheng Zhuang; Mingyue Zhang; Longlong Ma | Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c754299abda24b50f8e133/original/efficient-green-and-renewable-n-di-methylation-synthesis-of-amines-by-a-novel-nano-catalyst-of-ni-ni-o-c.pdf |
60c748c84c89190143ad2fa4 | 10.26434/chemrxiv.11971938.v1 | A General Approach for Encapsulation of Biomolecules Using MOF Particles | Encapsulation of biomoleucles
in metal organic frameworks (MOFs) has recently attracted significant interest
because of the benign process including room temperature, neutral pH and
without the requirement of any other chemical reagents. Also, these biomolecule
incorporated MOFs (biomolecules@MOFs) have demonstrated their potential in
biomolecule protection and controlled release for various applications such as drug delivery, vaccines, etc. This work aims to develop a
general strategy to make biomolecules@MOFs via a biomimetic mineralization
process. | Da Zou; Lei Yu; Qi Sun; Yue Hui; Teng Jisi; Yun Liu; Guangze Yang; David Wibowo; Chun-Xia Zhao | Biocompatible Materials; Biodegradable Materials; Controlled-Release Systems; Hybrid Organic-Inorganic Materials; Nanostructured Materials - Materials | CC BY NC ND 4.0 | CHEMRXIV | 2020-03-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c748c84c89190143ad2fa4/original/a-general-approach-for-encapsulation-of-biomolecules-using-mof-particles.pdf |
6534c42c87198ede0700b8dd | 10.26434/chemrxiv-2023-qrkjs | Photocatalytic Generation of Alkyl Carbanions from Alkenes | Organometallic reagents are routinely used as fundamental building blocks in organic chemistry to rapidly diversify molecular fragments via carbanion intermediates. However the catalytic generation of carbanion equivalents particularly from sp3-hybridized alkyl scaffolds, remains an underdeveloped goal in chemical synthesis. To align with the demands of modern synthetic protocols, a general method for the catalytic generation of alkyl carbanions must operate under benign reaction conditions and access commercially available feedstock chemicals. Alkenes constitute an attractive source of latent alkyl carbanion equivalents, however methods for the conversion of carbon-carbon bonds into carbanions is challenged by the need for precious metals and aggressive stoichiometric reductants. Here we disclose an approach for the controlled generation of 2-electron carbon nucleophiles via single electron reduction of aryl alkenes, facilitated by the highly reducing environment of multiphoton photoredox catalysts. We demonstrate that alkene radical anions engage in catalytic, metal free, intermolecular C-C bond-forming reactions with carbonyl derivatives, in a manner analogous to Grignard reagents. Under this reaction manifold, the alkene can be considered a dicarbanion synthon offering new opportunities for orthogonal diversification. This concept was illustrated by the development of four distinct C-C bond forming reactions with aromatic alkenes: hydroalkoxylation, hydroamidation, aminoalkylation and carboxyaminoalkylation, to generate a range of valuable and complex scaffolds. | Milena Czyz; Tyra Horngren; Andrew Kondopoulos; Liam Franov; José Forni; Le Nhan Pham; Michelle Coote; Anastasios Polyzos | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Photochemistry (Org.); Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6534c42c87198ede0700b8dd/original/photocatalytic-generation-of-alkyl-carbanions-from-alkenes.pdf |
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