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66d2d44220ac769e5f700bba | 10.26434/chemrxiv-2024-mzzcr-v2 | Photosynthesis of NH3 from NO3– using CH4 in Homogenous Re Catalysis at Room Temperature and Normal Pressure | We present rhenium (Re) catalysis of one-pot synthesis of ammonia (NH3) from nitrate (NO3–) using methane (CH4) as a reductant under ultraviolet (UV) light irradiation at room temperature and normal pressure. Currently, a large amount of NH3 is synthesized through nitrogen fixation by artificial methods in addition to natural synthesis. The amount of NH3 from the artificial Haber-Bosch process using hydrogen (H2) and nitrogen (N2) gases increases in industrial process, which causes the increases of amount of reactive nitrogens (Nrs) containing NO3– on the earth. NO3– leads to environmental issues such as water contamination, eutrophication and biodiversity loss. In a natural system and a sewage facility, NO3– can be detoxified to N2 using hydrogen donors by microbial process. However, it is better to convert NO3– to NH3 rather than N2 since N2 must be converted back to NH3 by the energy-intensive Haber-Bosch process. To develop a desirable process of NO3– to NH3 for a sustainable society, it is required that the reducing agent is derived from a renewable resource/energy. Thus, we turned our attention to CH4, which has high affinity with renewable resource/energy since it can be produced from livestock waste. Therefore, our system reported here is to directly convert NO3– to NH3 using CH4 with light energy without going through the Haber-Bosch process. To the best of our knowledge, this is the first time of NH3 synthesis from NO3– using CH4 as a reductant. | Genta Nakamura; Masaya Sakurai; Yohei Kametani; Yudai Kawasaki; Yoshihito Shiota; Kazunari Yoshizawa; Seiji Ogo; Takahiro Matsumoto | Organometallic Chemistry; Coordination Chemistry (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66d2d44220ac769e5f700bba/original/photosynthesis-of-nh3-from-no3-using-ch4-in-homogenous-re-catalysis-at-room-temperature-and-normal-pressure.pdf |
63973ec8b103af0d3816369f | 10.26434/chemrxiv-2022-mczh4-v2 | Rapid Adsorption Enthalpy Surface Sampling (RAESS) to Characterize Nanoporous Materials | Molecular adsorption in nanoporous materials has many large-scale industrial applications ranging from separation to storage. To design the best materials, computational simulations are key in guiding the experimentation and engineering processes. Because nanoporous materials exist in a plethora of forms, we need to speed up the existing simulation tools to be able to screen databases of hundreds of thousands structures. Here, we describe a new algorithm that quickly calculates adsorption enthalpies by sampling the surface of the material instead of the whole porous space. This surface sampling has been tested on the CoRE MOF 2019 database and has been proven to be more than 2 orders of magnitude faster than the gold standard method (Widom insertion), with an acceptable level of error on the enthalpy value of 0.34 kJ/mol, and is therefore proposed as a valuable addition to the high-throughput screening toolbox. | Emmanuel Ren; François-Xavier Coudert | Theoretical and Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2022-12-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63973ec8b103af0d3816369f/original/rapid-adsorption-enthalpy-surface-sampling-raess-to-characterize-nanoporous-materials.pdf |
66994c2301103d79c55945ff | 10.26434/chemrxiv-2024-94t4d | Cyclobutane-linked Nanothreads through Thermal and Photochemically Mediated Polymerization of Cyclohexadiene | Carbon nanothreads are a rapidly growing class of 1D nanomaterials with sp3-hybridized diamond-like backbones. Most nanothreads are synthesized through the pressure-induced polymerization of aromatics, resulting in diverse structures and functionalities. Aside from precursor selection, there are currently limited means to control nanothread reaction pathway or polymerization outcome. Analogous to selection rules that govern outcomes in small molecule chemistry, we investigated both thermally and photochemically mediated polymerizations of skipped and conjugated dienes (1,3- and 1,4-cyclohexadiene) under high pressure and explored the resultant product selectivity. For 1,3-cyclohexadiene, both approaches yield largely amorphous products owing to competing reaction pathways. Thermally mediated polymerization of 1,4-cyclohexadiene yields a crystalline product; however, the identification of the backbone composition is consistent with multiple different reaction pathways being accessible. While support for cyclobutane structures is present, comparison to the simulated structures suggests multiple products are obtained from the thermal polymerization of 1,4-cyclohexadiene. In contrast, the recovered product obtained from photochemically mediated polymerization of the skipped diene has different d-spacings and is consistent with simulations that support a single reaction pathway toward cyclobutane-linked nanothreads. These results suggest that photochemical activation can enable product selectivity in nanothread synthesis. | Morgan Murphy; Bohan Xu; Katie Rank; Sikai Wu; Steven Huss; John Badding; Steven Lopez; Vincent Crespi; Elizabeth Elacqua | Organic Chemistry; Polymer Science; Photochemistry (Org.); Physical Organic Chemistry; Organic Polymers; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66994c2301103d79c55945ff/original/cyclobutane-linked-nanothreads-through-thermal-and-photochemically-mediated-polymerization-of-cyclohexadiene.pdf |
62f21c9d6948b931cdb1c5d2 | 10.26434/chemrxiv-2022-4n79q-v2 | Powerful avidity with a limited valency for virus-attachment blockers on DC SIGN: Combining chelation and statistical rebinding with structural plasticity of the receptor | The C-type lectin receptor DC-SIGN has been highlighted as co-receptor for the spike protein of
the SARS-CoV-2 virus. A multivalent glycomimetic ligand, Polyman26, has been found to inhibit DCSIGN- dependent trans-infection of SARS-CoV-2. The molecular details underlying avidity generation in such systems remain poorly characterized. In an effort to dissect the contribution of the known multivalent effects - chelation, clustering and statistical rebinding – we studied a series of dendrimer constructs related to Polyman26 with a rod core rationally designed to engage simultaneously two binding sites of the tetrameric DC-SIGN. Binding properties of these compounds have been studied with a range of biophysical techniques, including recently developed Surface Plasmon Resonance oriented-surface methodology. Using molecular modelling we addressed, for the first time, the impact of the carbohydrate recognition domains’ flexibility of the DC-SIGN tetramer on the compounds’ avidity. We were able to gain deeper insight into the role of different binding modes, which in combination produce a construct with a nM affinity despite a limited valency. This multi-faceted experimental-theoretical approach provides detailed understanding of multivalent ligand/multimeric protein interactions which can lead to future predictions. This work opens the way to the development of new virus attachment blockers adapted to different C-type lectin receptors of viruses. | Vanessa Porkolab; Martin Lepšík; Stefania Ordanini; Alexander St John; Aline Le Roy; Michel Thépaut; Emanuele Paci; Christine Ebel; Anna Bernardi; Franck FIESCHI | Biological and Medicinal Chemistry; Biochemistry; Biophysics; Chemical Biology | CC BY NC 4.0 | CHEMRXIV | 2022-08-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62f21c9d6948b931cdb1c5d2/original/powerful-avidity-with-a-limited-valency-for-virus-attachment-blockers-on-dc-sign-combining-chelation-and-statistical-rebinding-with-structural-plasticity-of-the-receptor.pdf |
60c74622702a9b28de18ab47 | 10.26434/chemrxiv.10790369.v1 | Tautomer Database: A Comprehensive Resource for Tautomerism Analyses | <p>We report a database of tautomeric
structures that contains 2,819 tautomeric tuples extracted from 171 publications.
Each tautomeric entry has been annotated with experimental conditions reported
in the respective publication, plus bibliographic details, structural
identifiers (e.g. NCI CADD identifiers
FICTS, FICuS, uuuuu, and Standard InChI), and chemical information (e.g.
SMILES, molecular weight). The majority of tautomeric tuples found were pairs,
the remaining 10% were triples, quadruples, or quintuples, amounting to a total
number of structures of 5,977. The types of tautomerism were mainly prototropic
tautomerism (79%), followed by ring-chain (13%) and valence tautomerism (8%).
The experimental conditions reported in the publications included about 50 pure
solvents and 9 solvent-mixtures with 26 unique spectroscopic or
non-spectroscopic methods. <sup>1</sup>H and <sup>13</sup>C NMR were the most
frequently used methods. A total of 77 different tautomeric transform rules
(SMIRKS) are covered by at least one example tuple in the database. This
database is available as a spreadsheet for free download from <a href="https://cactus.nci.nih.gov/download/tautomer/">https://cactus.nci.nih.gov/download/tautomer/</a>.</p> | Devendra K. Dhaked; Laura Guasch; Marc Nicklaus | Chemoinformatics - Computational Chemistry | CC BY NC 4.0 | CHEMRXIV | 2019-11-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74622702a9b28de18ab47/original/tautomer-database-a-comprehensive-resource-for-tautomerism-analyses.pdf |
60c73d0e4c8919378aad1b5f | 10.26434/chemrxiv.5419270.v1 | Oxidase Catalysis via Aerobically Generated Hypervalent Iodine Intermediates | Development of sustainable oxidation chemistry
demands strategies to harness O<sub>2</sub> as a terminal oxidant. In
particular, oxidase
catalysis, in which O<sub>2</sub> serves as a chemical oxidant without
necessitating oxygen incorporation into reaction products, would allow diverse
substrate functionalization chemistry to be coupled to O<sub>2</sub> reduction.
Direct O<sub>2</sub> utilization must overcome
the intrinsic challenges imposed by the triplet ground state of O<sub>2</sub> and
the disparate electron inventories of four-electron O<sub>2</sub> reduction and
two-electron substrate oxidation. Here, we generate hypervalent iodine
reagents, a broadly useful class of selective two-electron oxidants, from O<sub>2</sub>.
Synthesis of these oxidants is achieved by intercepting reactive intermediates
of aldehyde autoxidation. The use of aryl iodides as mediators of aerobic
oxidation underpins an oxidase catalysis platform that couples a broad array of
substrate oxidations to O<sub>2</sub> reduction, including olefin
functionalization chemistry, carbonyl a-oxidation, oxidative dearomatization, and
aerobic C–H amination chemistry. | Asim Maity; Sung-Min Hyun; David Powers | Redox Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2017-09-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73d0e4c8919378aad1b5f/original/oxidase-catalysis-via-aerobically-generated-hypervalent-iodine-intermediates.pdf |
6789279bfa469535b94970b6 | 10.26434/chemrxiv-2025-2l3xh | On the origin of stability in the Li-LiPON solid electrolyte interphase | Lithium phosphorus oxynitride (LiPON) is one of the few solid electrolytes that forms a truly passivating solid electrolyte interphase (SEI) when in contact with metallic lithium. Investigations into the origin of this stability may provide the insights needed to replicate it in the SEIs of alternative solid electrolyte materials. In this study we used in situ lithium plating X-ray photoelectron spectroscopy (XPS) to investigate the formation and evolution of the Li-LiPON SEI for the first time. We show that the SEI is chemically and structurally inhomogeneous, with the fully reduced compounds identified in previous studies (Li2O, Li3N and Li3P) concentrated near the lithium metal side and partially lithiated species, including Lix P, predominant closer to the LiPON side. Li3P and Lix P have recently been suggested as enablers of continuous SEI growth in thiophosphate solid electrolytes. We suggest that the stability of the Li-LiPON SEI is derived from a combination of the LiPON reduction potential (0.68 V vs. Li+/Li), which is below the oxidation potentials of the fully reduced SEI compounds, and the graded structure of the SEI, which ensures that the most reduced species are not in physical or electrical contact with the LiPON layer. | Stephen J Turrell; Yi Liang; Tiancheng Cai; Ben Jagger; Mauro Pasta | Materials Science; Energy; Thin Films; Energy Storage; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6789279bfa469535b94970b6/original/on-the-origin-of-stability-in-the-li-li-pon-solid-electrolyte-interphase.pdf |
664ae96391aefa6ce17cc3d4 | 10.26434/chemrxiv-2024-qcf03-v3 | Unlocking the Potential of Nanostructured DyFeO3 Pho- tocatalyst for Environmental Remediation: Authenticity and Stability | Understanding the authentic nature and stability of a photocatalyst through diverse experiments and calculations is crucial for advancing environmental remediation. In this study, we synthesized nano-sized DyFeO3 particles with a porous structure, featuring an average pore size of 40 nm, to meticulously evaluate their photocatalytic efficacy in degrading aquatic pollutants under solar irradia- tion. These nanoparticles exhibit a direct band gap of 2.1 eV, rendering them well-suited for effective solar light absorption. Additionally, the conduction band minimum suggests potential participation in reduction reactions, while the valence band maximum is conducive to oxidation reactions. To confirm the authentic catalytic efficiency of DyFeO3 photocatalysts, we assessed their ability to de- grade both colored Rhodamine B (RhB) and colorless antibiotic Levofloxacin (LFX). Notably, their photocatalytic performance in decomposing the colorless pollutant LFX, alongside the colored RhB, eliminates any potential influence of dye sensitization. Moreover, the presence of DyFeO3 in the solution medium decreased the activation energy of LFX degradation from 38.4 kJ mol-1 K-1 to 34.1 kJ mol-1 K-1 , providing further evidence of their true catalytic function. Furthermore, their apparent Quantum Yield values of 28.94% and 32.83% for RhB and LFX degradation, respectively, demon- strate superior solar energy harvesting capability compared to commercially available TiO2. The high degradation efficiency, high quantum yield, and excellent stability of single-structured DyFeO3 nanoparticles indicate their considerable potential for large-scale production in photocatalytic and related applications. | Mohasin Tarek; Ferdous Yasmeen; M. A. Basith | Materials Science; Catalysis; Nanoscience; Catalysts | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/664ae96391aefa6ce17cc3d4/original/unlocking-the-potential-of-nanostructured-dy-fe-o3-pho-tocatalyst-for-environmental-remediation-authenticity-and-stability.pdf |
60c74991bdbb895bd3a391c9 | 10.26434/chemrxiv.12083004.v1 | Discovery of New Hydroxyethylamine Analogs Against 3CLpro Protein Target of SARS-CoV-2: Molecular Docking, Molecular Dynamics Simulation and Structure-Activity Relationship Studies | <p><br /></p>
<p>A novel coronavirus, SARS-CoV-2
has caused a recent pandemic called
COVID-19 and a severe health threat around the world. In the current situation,
the virus is rapidly spreading worldwide, and the discovery of
vaccine and potential therapeutics are critically essential. The crystal structure
for main protease (M<sup>pro</sup>) of SARS-CoV-2, 3-chymotrypsin-like
cysteine protease (3CL<sup>pro</sup>) was recently made available and is
considerably similar to previously reported SARS-CoV. Due to its essentiality
in viral replication, it represents a potential drug target. Herein,
computer-aided drug design (CADD) approach was implemented for the initial
screening of 13 approved antiviral drugs. Molecular docking of 13 antivirals against 3-chymotrypsin-like cysteine protease (3CL<sup>pro</sup>)
enzyme was accomplished and indinavir was described as a lead drug with a
docking score of -8.824 and a XP Gscore of -9.466 kcal/mol. Indinavir possesses
an important pharmacophore, hydroxyethylamine (HEA), and thus a new library of HEA
compounds (>2500) was subjected to virtual screening that led to 25 hits with
a docking score more than indinavir. Exclusively, compound <b>16</b> with
docking score of -8.955 adhered to drug like parameters, and the Structure-Activity
Relationship (SAR) analysis was demonstrated to highlight the importance of
chemical scaffolds therein. Molecular Dynamics (MD) simulation studies carried
out at 100ns supported the stability of <b>16</b> within the binding pocket. Largly,
our results supported that this novel compound <b>16</b> binds to the domain I &
II, and domain II-III linker of 3CL<sup>pro</sup> protein, suggesting its
suitablity as strong candidate for therapeutic discovery against COVID-19. Lead
compound <b>16</b> could pave incredible directions for the design of novel 3CL<sup>pro</sup> inhibitors and ultimately therapeutics
against COVID-19 disease.</p>
<p><br /></p>
<p> </p> | Sumit Kumar; Prem Prakash Sharma; Uma Shankar; Dhruv Kumar; Sanjeev K Joshi; Lindomar Pena; Ravi Durvasula; Amit Kumar; Prakasha Kempaiah; Poonam .; Brijesh Rathi | Computational Chemistry and Modeling; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74991bdbb895bd3a391c9/original/discovery-of-new-hydroxyethylamine-analogs-against-3c-lpro-protein-target-of-sars-co-v-2-molecular-docking-molecular-dynamics-simulation-and-structure-activity-relationship-studies.pdf |
647dd06abe16ad5c57822750 | 10.26434/chemrxiv-2023-ncbm8 | Electric Field Susceptibility of Chlorophyll c and its Effect on the Excitation Energy Ladder in the Major Light-Harvesting Complex of Diatoms | Diatoms are one of the most abundant photosynthetic organisms on earth and contribute largely to the atmospheric oxygen production. They contain fucoxanthin and chlorophyll-a/c binding proteins (FCPs) as light-harvesting complexes with a remarkable adaptation to the fluctuating light on ocean surfaces. To understand the basis of the photosynthetic process in diatoms, the excitation energy funneling within FCPs needs to be probed. A state-of-the-art multiscale analysis within a quantum mechanics/molecular mechanics framework has been employed. To this end, the chlorophyll (Chl) excitation energies within the FCP complex from the diatom Phaeodactylum tricornutum have been determined. The Chl-c excitation energies were found to be significantly lower than those in organic solvents. This finding challenges the general belief that the excitation energy of Chl-c is higher than that of Chl-a in FCP proteins and reveals that Chl-c molecules are much more sensitive to electric fields within protein scaffolds than Chl-a pigments. A direct connection to experiment is obtained by analysis of the linear absorption spectrum of FCP. | Sayan Maity; Vangelis Daskalakis; Ulrich Kleinekathöfer | Theoretical and Computational Chemistry; Physical Chemistry; Energy; Computational Chemistry and Modeling; Theory - Computational; Photochemistry (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2023-06-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/647dd06abe16ad5c57822750/original/electric-field-susceptibility-of-chlorophyll-c-and-its-effect-on-the-excitation-energy-ladder-in-the-major-light-harvesting-complex-of-diatoms.pdf |
63c82c90aadd951ea7770587 | 10.26434/chemrxiv-2023-ljqrp | Understanding correlation between structure and entangled photon pair properties with metal-organic frameworks |
Spontaneous parametric down conversion (SPDC) is a quantum second-order non- linear optical process where the photons generated are frequently used in quantum information processing. Materials with large second-order nonlinearities (χ(2)) can be used as entangled photon sources with high brightness. The source brightness scales as the square of the effective nonlinearity (deff ) which is an intrinsic property of the mate- rial. Understanding material factors which can significantly alter this intrinsic property is useful in developing new materials which are SPDC efficient. In our work, we focus on understanding factors affecting the entangled photon pair properties such as the arrangements of ligands within the Zn(3-ptz)3 metal-organic framework (MOF) crystal and temperature. We find that the arrangement and alignment of the pyridine rings in the crystal structure significantly affect the deff and birefringence (∆n). Smaller pyri- dine ring alignments relative to the optic c-axis increases the ∆n, which in turn leads to larger photon pair correlation times (τc) in coincidence measurements. Our work has significant implication in understanding the effect of ligand arrangement on deff and τc for any MOF crystal structure, providing a tool to rationalize the optimization of MOF crystals for the development of efficient nonlinear optical devices. | Sanoj Raj; Rubén A. Fritz; Felipe Herrera; Yamil J. Colón | Theoretical and Computational Chemistry; Materials Science; Optical Materials; Computational Chemistry and Modeling; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63c82c90aadd951ea7770587/original/understanding-correlation-between-structure-and-entangled-photon-pair-properties-with-metal-organic-frameworks.pdf |
66e9e828cec5d6c1425ea019 | 10.26434/chemrxiv-2024-qhsj9 | Compatibilization of polyolefin blends through acid–base interactions | Polyolefins are ubiquitous in consumer products but are notoriously difficult to recycle due to the inherent incompatibility of their common varieties. Existing approaches to addressing this challenge either require complex syntheses or compromise the properties of the parent materials. Here, a new method to compatibilize mixed polyolefins is developed. With a single-step photocatalysis, acid or base functionality can be readily installed onto polyolefins. The combination of acid- and base-modified polyolefins functions as compatibilizers. Incorporating them into polyolefin blends results in excellent mechanical strength, with up to an 82-fold increase in ductility. Importantly, compatibilization can be readily achieved on post-consumer polyolefin mixtures. Furthermore, direct functionalization and compatibilization of polyolefin blends is achieved. This strategy promises to transform polyolefin recycling and will likely find broad applications. | Yucheng Yuan; Jiawei He; Jiangwei Liu; Ming-Chi Wang; Tuhin Ganguly; John Santoro; Junpeng Wang; Jeffery Byers; Jia Niu; Mingjiang Zhong; Dunwei Wang | Catalysis; Polymer Science; Earth, Space, and Environmental Chemistry; Polymer blends; Wastes; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-09-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66e9e828cec5d6c1425ea019/original/compatibilization-of-polyolefin-blends-through-acid-base-interactions.pdf |
60c73cc9842e657db8db16a3 | 10.26434/chemrxiv.14757975.v1 | A Self-Improving Photosensitizer Discovery System via Bayesian Optimization and Quantum Chemical Calculation | Artificial intelligence (AI) based self-learning or self-improving material discovery system is the holy grail of next-generation material discovery and materials science. Herein, we demonstrate how to combine accurate prediction of material performance via quantum chemical calculations and Bayesian optimization-based active learning to realize a self-improving discovery system for high-performance photosensitizers (PS). Through self-improving cycles, such a system can improve the model prediction accuracy (best mean average error of 0.09 eV for singlet-triplet spitting) and high-performance PS search ability, realizing the efficient discovery of PS. From a molecular space with more than 7 million molecules, 5950 potential high-performance PSs were discovered. | Shidang Xu; Jiali Li; Pengfei Cai; Xiaoli Liu; Bin Liu; Xiaonan Wang | Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-06-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73cc9842e657db8db16a3/original/a-self-improving-photosensitizer-discovery-system-via-bayesian-optimization-and-quantum-chemical-calculation.pdf |
60c74b6d4c89197fabad3453 | 10.26434/chemrxiv.12331301.v1 | A CNS-Targeting Prodrug Strategy for Nuclear Receptor Modulators | Neurodegenerative diseases lack a breadth of treatment options due, in part, to the known difficulties associated with a drug’s passage across the blood-brain barrier. In this study, we provide a blueprint for how to get drug-like structures which feature carboxylic acid motifs across the blood-brain barrier, while attenuating their peripheral exposure using a chemical prodrug strategy. This prodrug strategy utilizes endogenous fatty-acid amide hydrolase expressed in the CNS to cleave and release parent drugs for CNS drug action to commence. In particular, we demonstrate the successes and limitations of this prodrug strategy within a series of nuclear receptor modulators, which have shown promise as potential therapeutics for neurodegenerative diseases. | Skylar Ferrara; Thomas Scanlan | Chemical Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2020-05-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74b6d4c89197fabad3453/original/a-cns-targeting-prodrug-strategy-for-nuclear-receptor-modulators.pdf |
674035537be152b1d04cc4c9 | 10.26434/chemrxiv-2024-pgqr6 | Learning kinetics from non-ideal reactors by implicitly solved finite volumes and global reaction neural networks | The digitalization of chemical research and industry generates large amounts of data, offering new opportunities for developing and parameterizing kinetic models. Leveraging this data requires machine learning techniques capable of autonomously extracting kinetics from reactor datasets. Recently, neural ordinary differential equations (neural ODEs) were coupled with reactor models to learn kinetics from ideal reaction systems, such as plug-flow reactors. However, real reactor set-ups commonly feature non-idealities such as heat- and mass transfer limitations, described by partial differential equations (PDEs) or differential-algebraic equations (DAEs). Discretizing such non-ideal PDE or DAE reactor models by finite volumes yields algebraic balance equations, which are solved by numerical schemes. In this work, we propose to learn kinetics from non-ideal reactor data using these balance equations and implicit neural networks, avoiding expensive backpropagation through the numerical solution by utilizing the implicit function theorem. The approach is demonstrated for the example of a mass transfer limited flat plate reactor for the preferential catalytic oxidation of CO. We show that Global Reaction Neural Networks, embedding thermodynamic and stoichiometric prior knowledge, coupled with a discretized two-phase CSTR cascade reactor model extract intrinsic kinetics from 50 integral reactor experiments. These kinetics generalize to new reactor geometries, where kinetics obtained by neural ODEs fail. Further, the approach is robust, recovering accurate kinetics even when training data is perturbed by 10% Gaussian noise. We expect that combining neural network-based kinetics with non-ideal reactor models will broaden the scope of kinetic model discovery and improve access to accurate kinetic models. | Tim Kircher; Martin Votsmeier | Chemical Engineering and Industrial Chemistry; Reaction Engineering; Transport Phenomena (Chem. Eng.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-11-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674035537be152b1d04cc4c9/original/learning-kinetics-from-non-ideal-reactors-by-implicitly-solved-finite-volumes-and-global-reaction-neural-networks.pdf |
60cce9a026161123b48b1aaa | 10.26434/chemrxiv-2021-pctv8 | Polysaccharide - Modified MMT/ Modified MMT/ Polysaccharide – MNP, Lignin - Modified MMT Nanocomposites Verses Polyethyleneimineimine- Modified MMT-: A Comparative Analysis of Sustained Pesticide Delivery | Highlights:
• At the nanoscale, the characteristics of a material can alter dramatically. With only a reduction in size and no change to the substance itself, materials can display new qualities.
• Polysaccharide-Modified MMT/ Modified MMT/ Polysaccharide – MNP, Lignin-Modified MMT Nanocomposites vs. Polyethyleneimineimine-Modified MMT have been compared for a Sustained Pesticide Delivery in this manuscript.
• We anticipate that this description will aid researchers in selecting the best technique for developing pesticides and improving pesticide delivery.
| RITU Mahajan | Nanoscience; Agriculture and Food Chemistry; Nanostructured Materials - Nanoscience | CC BY 4.0 | CHEMRXIV | 2021-06-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60cce9a026161123b48b1aaa/original/polysaccharide-modified-mmt-modified-mmt-polysaccharide-mnp-lignin-modified-mmt-nanocomposites-verses-polyethyleneimineimine-modified-mmt-a-comparative-analysis-of-sustained-pesticide-delivery.pdf |
62ff6e3d1945ad5634dee451 | 10.26434/chemrxiv-2022-wt440-v2 | rxnutils – A Cheminformatics Python Library for Manipulating Chemical Reaction Data | We introduce the Python package rxnutils that can be used to manipulate chemical reactions, reaction templates and reaction datasets. The package is built entirely on open-source software such as RDKit and is designed with robustness, extendibility, and reproducibility in mind. Currently, it consists of three sub-packages one for working with chemical entities, one provides pipelining capabilities, and one provides an end-to-end pipeline for preparing the US patent reaction dataset for modelling. In this software research note we discuss the design of the package and provide some code examples. The project is open-source with a Apache 2.0 license and available at GitHub: https://github.com/MolecularAI/reaction_utils | Christos Kannas; Amol Thakkar; Esben Bjerrum; Samuel Genheden | Theoretical and Computational Chemistry; Machine Learning; Chemoinformatics - Computational Chemistry | CC BY NC 4.0 | CHEMRXIV | 2022-08-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62ff6e3d1945ad5634dee451/original/rxnutils-a-cheminformatics-python-library-for-manipulating-chemical-reaction-data.pdf |
64edbda53fdae147fa0fb40c | 10.26434/chemrxiv-2023-zc87c | Revisiting Ion-Pair Interactions in Phase Transfer Catalysis: From Pure Ionic Compounds to Real Catalyst Systems | Ion-pairing is a fundamental phenomenon that significantly influences phase-transfer catalysis. In this study, we conduct a comprehensive investigation of ion-pair interactions, aiming to establish a comprehensive understanding of their nature and implications. The study begins with the examination of pure ionic compounds to define the concept of an ion-pair in the context of phase-transfer catalysis. Subsequently, a diverse range of ion-pair catalyst models were explored to gain insight into the factors governing their interactions. Finally, the focus shifts towards the characterization of real phase- transfer catalysts, bridging the gap between theoretical models and practical applications. Through a combination of computational approaches and theoretical analysis, this work provides valuable insight into the nature of ion-pair interactions within phase-transfer catalysis fields. | Iñigo Iribarren; Eric Mates; Cristina Trujillo | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY 4.0 | CHEMRXIV | 2023-08-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64edbda53fdae147fa0fb40c/original/revisiting-ion-pair-interactions-in-phase-transfer-catalysis-from-pure-ionic-compounds-to-real-catalyst-systems.pdf |
640af9ac6642bf8c8f483fde | 10.26434/chemrxiv-2023-1k49m | Electrostatic Assistance of 4-Mercaptophenylacetic acid catalyzed Native Chemical Ligation | 4-mercaptophenylacetic acid (MPAA) is a popular catalyst of the native chemical ligation (NCL) but has to be used in large excess for achieving practically useful rates (up to 50-100 equivalents). We report here that the catalytic potency of MPAA can be boosted by introducing a stretch of arginines in the departing thiol from the thioester. By doing so, the electrostatically-assisted NCL reaction proceeded rapidly by using sub-stoichiometric concentrations of MPAA, an advantage that enabled useful synthetic applications. | Nathalie Ollivier; Eliott Roy; Rémi Desmet; Vangelis Agouridas; Vincent Diemer; Oleg Melnyk | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Homogeneous Catalysis; Organocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/640af9ac6642bf8c8f483fde/original/electrostatic-assistance-of-4-mercaptophenylacetic-acid-catalyzed-native-chemical-ligation.pdf |
60c73f80bb8c1a55cf3d9b81 | 10.26434/chemrxiv.7388723.v1 | Gas Phase Stability of Protein Ions in a Cyclic Ion Mobility Spectrometry Travelling Wave Device | <div>Ion mobility mass spectrometry (IM-MS) allows separation of native protein ions into “conformational families”. Increasing the IM resolving power should allow finer structural information to be obtained, and can be achieved by increasing the length of the IM separator. This, however, increases the time that protein ions spend in the gas phase and previous experiments have shown that the initial conformations of small proteins can be lost within tens of milliseconds. Here, we report on investigations of protein ion stability using a multi-pass travelling wave (TW) cyclic IM (cIM) device. Using this device, minimal structural changes were observed for Cytochrome C after hundreds of milliseconds, while no changes were observed for a larger multimeric complex (Concanavalin A). The geometry of the instrument (Q-cIM-ToF) also enables complex tandem IM experiments to be performed which were used to obtain more detailed collision induced unfolding pathways for Cytochrome C. The novel instrument geometry provide unique capabilities with the potential to expand the field of protein analysis via IM-MS.</div> | Charles Eldrid; Jakub Ujma; Symeon Kalfas; nick tomczyk; Kevin Giles; mike morris; Konstantinos Thalassinos | Mass Spectrometry; Biochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2018-11-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f80bb8c1a55cf3d9b81/original/gas-phase-stability-of-protein-ions-in-a-cyclic-ion-mobility-spectrometry-travelling-wave-device.pdf |
60c73dd3f96a007051285e24 | 10.26434/chemrxiv.5891602.v2 | Bonded Force Constant Derivation of Lysine-Arginine Cross-linked Advanced Glycation End-Products | <div>
<div>
<div>
<p>The computational study of advanced glycation end-product cross-
links remains largely unexplored given the limited availability of bonded
force constants and equilibrium values for molecular dynamics force fields.
In this article, we present the bonded force constants, atomic partial
charges and equilibrium values of the arginine-lysine cross-links DOGDIC,
GODIC and MODIC. The Hessian was derived from a series of <i>ab initio</i>
quantum mechanical electronic structure calculations and from which a
complete set of force constant and equilibrium values were generated using our publicly available software, ForceGen. Short <i>in vacuo</i> molecular
dynamics simulations were performed to validate their implementation
against quantum mechanical frequency calculations.
</p>
</div>
</div>
</div> | Anthony Nash; Nora H de Leeuw; Helen L Birch | Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2018-02-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73dd3f96a007051285e24/original/bonded-force-constant-derivation-of-lysine-arginine-cross-linked-advanced-glycation-end-products.pdf |
60c7515d4c891930c2ad3f34 | 10.26434/chemrxiv.13148234.v1 | Using Photoactive N-Heterocyclic Carbenes Monolayers to Identify the Influence of Surface Proximity on Photoswitching Activity | <p>Self-assembly of photoresponsive
molecules is a robust technology for reversibly tuning the chemical and
electronic properties of functional materials. In most systems the photoactive
group is separated from the surface by a spacer and thus the photo-responsiveness
does not benefit from interactions with the metal. Herein, the impact of metal photoactive-group
interactions on photoswitchability and surface potential were probed by self-assembly
of N-heterocyclic carbene molecules (NHCs) that were functionalized with stilbene
group directly on their imidazole ring. Stilbene-NHCs that were adsorbed on weakly
interacting Au surface accumulated a vertical orientation, as identified by FTIR measurements. This
positioning enabled structural flexibility and high photoisomerization
efficiency that induced reversible changes in surface potential. Stilbene-NHCs
that were anchored on Pt film accumulated flat-lying adsorption geometry due to
strong metal-adsorbate interactions. These interactions limited the structural
flexibility of the stilbene groups and induced deteriorated photoswitchability
that led to lower photoinduced changes in surface potential. While stronger
metal-adsorbate interactions hindered the photo-induced isomerization yield of
stilbene, these interactions prompted the <i>cis</i>-to-<i>trans</i> thermal-induced
isomerization rate, which was an order of magnitude higher on Pt than on Au. </p> | Shahar Dery; Israel Alshanski; Evgeniy Mervinetsky; Daniel Feferman; Shlomo Yitzchaik; Mattan Hurevich; Elad Gross | Photosensitizers; Interfaces; Self-Assembly; Surface | CC BY NC ND 4.0 | CHEMRXIV | 2020-10-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7515d4c891930c2ad3f34/original/using-photoactive-n-heterocyclic-carbenes-monolayers-to-identify-the-influence-of-surface-proximity-on-photoswitching-activity.pdf |
6169d47b7d3da5de5df943e5 | 10.26434/chemrxiv-2021-38h45 | Chemodivergent Organolanthanide Catalyzed C-H a-Mono-1 Borylation of Azines | C-H activation and functionalization of pyridinoid azines is a key transformation forthe synthesis of many natural products, pharmaceuticals, and materials. Reflecting the azinyl nitrogen lone-pair steric repulsion, tendency to irreversibly bind to metal ion catalysts, and the electron-deficient nature of pyridine, C-H functionalization at the important a-position remains challenging. Thus, the development of earth abundant catalysts for the a-selective mono-functionalization of azines is a crucial hurdle for modern chemical synthesis. Here, the selective organolanthanide catalyzed a-mono-borylation of a diverse series of pyridines is reported, affording a valuable precursor for cross-coupling reactions. Experimental and theoretical mechanistic evidence support the formation of a C-H activated η2-lanthanide-azine complex, followed by intermolecular a-mono-borylation via σ-bond metathesis. Notably, varying the lanthanide identity and substrate electronics promotes chemodivergence of the catalytic selectivity: smaller/more electrophilic lanthanide3+ ions and electron-rich substrates favor selective a-C-H functionalization, whereas larger/less electrophilic lanthanide3+ 1 ions and electron poor substrates favor selective B-N bond-forming 1,2-dearomatization. Such organolanthanide series catalytic chemodivergence is, to our knowledge, unprecedented. | Jacob O. Rothbaum; Alessandro Motta; Yosi Kratish; Tobin Marks | Organic Chemistry; Inorganic Chemistry; Catalysis; Kinetics and Mechanism - Inorganic Reactions; Lanthanides and Actinides; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-10-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6169d47b7d3da5de5df943e5/original/chemodivergent-organolanthanide-catalyzed-c-h-a-mono-1-borylation-of-azines.pdf |
63f70e1a897b18336ffdb4f5 | 10.26434/chemrxiv-2023-ggvn4 | Over 20% 13C Hyperpolarization for Pyruvate Using Deuteration and Rapid SLIC-SABRE in Mictrotesla Fields
| Carbon-13 hyperpolarized pyruvate is about to become
the next-generation contrast agent for molecular magnetic resonance imaging of cancer and other diseases. Here, efficient and rapid pyruvate hyperpolarization is achieved via Signal Amplification
by Reversible Exchange (SABRE) with parahydrogen through synergistic use of substrate deuteration, alternating, and static microtesla magnetic fields. Up to 22% and 6% long-lasting 13C polarization (T1=3.7±0.25min and T1=1.7±0.1min) is demonstrated for the C1 and C2 nuclear sites, respectively. The remarkable polarization levels become possible due to favorable relaxation
dynamics at the microtesla fields. The ultra-long polarization lifetimes will be conducive to yielding high polarization after purification, quality assurance, and injection of the hyperpolarized molecular imaging probes. These results pave the way to future in vivo translation of carbon-13 hyperpolarized molecular imaging probes prepared by this approach. | Andreas B. Schmidt; James Eills; Laurynas Dagys; Martin Gierse; Michael Keim; Sebastian Lucas; Michael Bock; Ilai Schwartz; Maxim Zaitsev; Eduard Y. Chekmenev; Stephan Knecht | Physical Chemistry; Biological and Medicinal Chemistry; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-02-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63f70e1a897b18336ffdb4f5/original/over-20-13c-hyperpolarization-for-pyruvate-using-deuteration-and-rapid-slic-sabre-in-mictrotesla-fields.pdf |
62711536368ab64f0d96b09f | 10.26434/chemrxiv-2022-1k4nt | Enantioselective para-C(sp2)-H Functionalization of Alkyl Benzene Derivatives via Cooperative Catalysis of Gold/Chiral Bronsted Acid | Herein, we developed an asymmetric para-C(sp2)-H bond functionalization of alkyl benzene derivatives via cooperative catalysis of gold and chiral phosphoric acid, leading to synthetically useful diaryl chiral centers. In this transformation, chiral phosphoric acid, ligand, and molecular sieves were all crucial for enantioselectivity control. The salient features of this protocol include mild conditions, high efficiency, readily avail-able starting materials, highly chemo- and site- as well as enantioselective aromatic C−H functionalization, broad substrate scope, and exten-sive applications of the chiral products. The mechanistic studies showed that one gold complex and two CPAs might be involved in the chiral induction. | Xun-Shen Liu; Zhiqiong Tang; Zhikun Zhang; Lei Zhao; Lu Liu | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Stereochemistry; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62711536368ab64f0d96b09f/original/enantioselective-para-c-sp2-h-functionalization-of-alkyl-benzene-derivatives-via-cooperative-catalysis-of-gold-chiral-bronsted-acid.pdf |
63bef7f9d19cc51cf50208b5 | 10.26434/chemrxiv-2023-0jdvk | A Model Ensemble Approach Enables Data-Driven Property Prediction for Chemically Deconstructable Thermosets in the Low Data Regime | Data science can accelerate materials discovery by learning composition-processing-performance models from pre-existing data sets, which then feed into active learning cycles in the laboratory. Thermoset polymer waste is a pressing environmental challenge that may be addressed by the accelerated discovery of new deconstructable variants; however, the combinatorial space of possible monomers, crosslinkers, additives, and manufacturing conditions is vast and Edisonian experimentation may struggle to find optimal designs. Moreover, data-driven strategies are limited for complex (co)polymers like thermosets because the training data is scarce and sourced from heterogeneous experimental approaches, resulting in overfit transferable models. Here, we introduce a novel closed-loop approach to the predictive design of chemically deconstructable thermosets that leverages experimental synthesis and characterization, machine learning, and virtual screening. Our computational model learns to map the molecular features of bifunctional silyl ether (BSE)-based cleavable comonomers to the thermal properties of the industrial thermoset polydicyclopentadiene (pDCPD). We address the challenges of limited data and overfitting by relying on both structural and information-rich domain-specific molecular features as inputs and by thoroughly quantifying model uncertainty. By training an ensemble of predictive models mixing multiple model architectures and parametrizations, our approach achieves predictions of a key thermoset parameter—the glass transition temperature—within less than 15 °C error over a wide temperature range with only 101 data points. The trained models were used to screen new possible BSE comonomer compositions and synthesis conditions, with promising combinations successfully validated experimentally. This work offers a closed-loop design process that we expect to be widely applicable to the discovery of deconstructable polymeric materials. | Yasmeen AlFaraj; Somesh Mohapatra; Peyton Shieh; Keith Husted; Douglas Ivanoff; Evan Lloyd; Julian Cooper; Yutong Dai; Avni Singhal; Jeffrey Moore; Nancy Sottos; Rafael Gomez-Bombarelli; Jeremiah Johnson | Organic Chemistry; Polymer Science; Organic Polymers; Polymerization (Polymers); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63bef7f9d19cc51cf50208b5/original/a-model-ensemble-approach-enables-data-driven-property-prediction-for-chemically-deconstructable-thermosets-in-the-low-data-regime.pdf |
618dd79f642380a607cff60a | 10.26434/chemrxiv-2021-9pztk | Enabling Tunable Hydrophilicity of PDMS via Metal-ligand Coordinated Dynamic Networks | Polydimethylsiloxane (PDMS) has been widely used in various fields due to its appealing physical and chemical properties. However, its high hydrophobicity not only yields poor adhesion to substrates but also facilitates undesired adsorption of substances such as proteins, biofoulers, etc., which limits the performance and lifetime of PDMS. Moreover, traditional surface modification techniques are often not efficient on PDMS surfaces because of the surface reconstruction. Although new methods involving chemical modification have been developed, most of them require complicated procedures and equipment. To overcome this challenge, we incorporate metal-ligand coordination, a non-covalent interaction bearing polar functionality, into PDMS, which exposes the hydrophilicity progressively upon dynamic bond breakage and reformation. We demonstrate that the hydrophilicity of coordinated PDMS can be tailored by the choice of network structure, counter anions, and metal cations, which yield distinct network dynamics. The wetting mechanism is discussed in the context of chain reconfiguration and surface reconstruction. We also show that a properly designed metal-ligand coordinated PDMS has potential as a superior marine fouling release coating by weakening diatom attachment. Through this paper, we introduce a new concept for tuning material hydrophilicity via dynamic polar functionalities, which is applicable to a wide range of polymers. | Xinyue Zhang; Ralph Crisci; John. A Finlay; Hongyi Cai; Anthony S. Clare; Zhan Chen; Meredith N. Silberstein | Materials Science; Polymer Science; Coordination polymers | CC BY NC ND 4.0 | CHEMRXIV | 2021-11-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/618dd79f642380a607cff60a/original/enabling-tunable-hydrophilicity-of-pdms-via-metal-ligand-coordinated-dynamic-networks.pdf |
667d218201103d79c5419eab | 10.26434/chemrxiv-2024-mn61n | Identification of novel triazolylquinoxaline-based metal complexes supported by experimental and virtual screenings | The formation of novel complexes from so far non-investigated ligands and different metal centers is important for the development of new functional materials such as (photo)catalysts or biologically active compounds. Still, promising strategies to quickly and systematically investigate the complexation behavior of selected ligands are rare. We developed an NMR-based screening approach to monitor changes within reaction mixtures containing metals and ligands on a small scale via a simple but reliable protocol. Based on the obtained data, we could draw conclusions on the formation of 2-(1', 2', 3'-triazol-1'yl)quinoxaline-based transition metal complexes. The NMR screening results obtained were confirmed by the repetition of selected experiments on a large scale, and wherever possible, the type of complex obtained was evaluated by crystal structure elucidation. We could show the versatile complexation of the selected ligands with copper, gold, and silver in a bridging, chelating, or monodentate manner. The calculated theoretical properties supported the experimental results and enabled initial in silico predictions of similar compounds before conducting the complexation experiments and structural analyses. | Laura Holzhauer; Vitalii Shekhovtsev; Cecilia Bruschi; Mathis Gunther; Olaf Fuhr; Patrick Hodapp; Claudia Bizzarri; Wolfgang Wenzel; Nicole Jung; Stefan Bräse | Theoretical and Computational Chemistry; Organometallic Chemistry; Spectroscopy (Organomet.); Transition Metal Complexes (Organomet.) | CC BY 4.0 | CHEMRXIV | 2024-07-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/667d218201103d79c5419eab/original/identification-of-novel-triazolylquinoxaline-based-metal-complexes-supported-by-experimental-and-virtual-screenings.pdf |
6780e3cefa469535b9701802 | 10.26434/chemrxiv-2024-4w0kc-v2 | Listening to the formation of polymorphs in a ball-mill | IIn this contribution, we apply our newly developed ball-milling operando platform, which combines Raman spectroscopy, thermal (IR) imaging, as well as acoustic and high-speed optical video recordings, to the synthesis and transformation of citric acid – isonicotinamide (1 : 2) cocrystal polymorphs in transparent PMMA jars. Particularly, we demonstrate how Raman, temperature, acoustic and video data are complementary and enable to detect and connect together chemical and physical events happening during the ball-milling in a time-resolved manner. Importantly, we show that the formation of the three cocrystal polymorphs can be detected through the acoustic analyses solely. Even more impressively, the meticulous analyses of the sound data allowed subtle polymorphic transitions to be perceived in operando mode when the Raman spectroscopy was not conclusive enough. Such changes in sound signatures are greatly linked to the beads’ motions in the milling jar. A new data analysis methodology of acoustic recordings is proposed through a combination of energetical and statistical approaches, which simplifies the data analyses for potential users. The interpretation of the detected sound signals was further validated thanks to the high-speed videos recorded in synchronization with all other operando techniques. Finally, we broaden this acoustic methodology to opaque stainless-steel jars, showing the relevance of the acoustic analysis method for following cocrystal, as well as for pure substances, polymorphic transformations in any type of milling jars. | Eloïse Marie Samantha Parlier; Kinann Al Amir; Thomas-Xavier Métro; Pierre Granjon; Danielle Laurencin; César Leroy | Analytical Chemistry; Analytical Chemistry - General; Spectroscopy (Anal. Chem.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6780e3cefa469535b9701802/original/listening-to-the-formation-of-polymorphs-in-a-ball-mill.pdf |
6396a3d192f08421f631f168 | 10.26434/chemrxiv-2022-hzdjq | Computational Study of the Effect of π-Congestion on the Singlet Biradical Character and Stacked Antiaromaticity in Acene Dimers | We demonstrated the computational study of the π-congestion effects in benzene, naphthalane, anthracene, teteracene, and pentacene dimers close with two positions at Ca···Ca’ and Cb···Cb’ to elucidate the singlet biradical characters as well as the stacked antiaromaticity. By extending the π-system from benzene to pentacene, the singlet biradical character increase whereas the stacked antiaromaticity decrease at near the transition state of [4+4]pericyclic reaction in ground state. Especially, the pentacene dimer exhibits large biradical character y0 = 61% with a weak antiaromaticity of NICSxx = +11 ppm at the distance of 2.80 Å between π-planes. These calculated results provided a unique idea to extract the similar electronic and magnetic natures as seen in transition state where the bond-order of the sp2 and sp3 carbon changes, like the graphite-to-diamond transformation. | Yuta Makihara; Tomohiko Nishiuchi; Ryohei Kishi; Takashi Kubo | Theoretical and Computational Chemistry; Organic Chemistry; Physical Organic Chemistry; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2022-12-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6396a3d192f08421f631f168/original/computational-study-of-the-effect-of-congestion-on-the-singlet-biradical-character-and-stacked-antiaromaticity-in-acene-dimers.pdf |
60c73e564c891952c5ad1d7c | 10.26434/chemrxiv.6852035.v1 | Hypoxia-Activated Small Molecule-Induced Gene Expression | <div><div><div><p>Hypoxia, conditions of reduced oxygen, occur in a wide variety of biological contexts, including solid tumours and bacterial biofilms, which are relevant to human health. Consequently, the development of chemical tools to study hypoxia is vital. Here we report a hypoxia-activated small molecule-mediated gene expression system using a bioreductive prodrug of the inducer isopropyl 1-thio-β-D-galactopyranoside (IPTG). As a proof-of-concept we have placed the production of a green fluorescent protein under the control of hypoxia. Our system has the potential to be extended to regulate the production any given protein of choice.</p></div></div></div> | Sarah L. Collins; Jaideep Saha; Laure C. Bouchez; Ester M. Hammond; Stuart Conway | Biochemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2018-07-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73e564c891952c5ad1d7c/original/hypoxia-activated-small-molecule-induced-gene-expression.pdf |
64e4b9d03fdae147fa9af644 | 10.26434/chemrxiv-2023-b0f9h | Decarboxylative Halogenation of Indoles by Vanadium Haloperoxidases | Halogenated heteroarenes are key building blocks across numerous chemical industries. Here, we report that vanadium haloperoxidases are capable of producing 3-haloindoles through decarboxylative halogenation of 3-carboxyindoles. This biocatalytic method is applicable to decarboxylative chlorination, bromination, and iodination in moderate to high yields and with excellent chemoselectivity. | Lauren J. Harstad; Clare E. Wells; Hyung Ji Lee; Lauren P.T. Ramos; Manik Sharma; Cameron A. Pascoe; Kyle F. Biegasiewicz | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e4b9d03fdae147fa9af644/original/decarboxylative-halogenation-of-indoles-by-vanadium-haloperoxidases.pdf |
653a8b8c48dad231206969b6 | 10.26434/chemrxiv-2023-97rmb | Machine Learned Potentials by Active Learning from Organic Crystal Structure Prediction Landscapes | A primary challenge in organic molecular crystal structure prediction (CSP) is accurately ranking the energies of potential structures. While high-level solid-state density functional theory (DFT) methods allow for mostly reliable discrimination of the low energy structures, their high computational cost is problematic because of the need to evaluate tens to hundreds of thousands of trial crystal structures to fully explore typical crystal energy landscapes. Consequently, lower-cost but less accurate empirical force fields are often used, sometimes as the first stage of a hierarchical scheme involving multiple stages of increasingly accurate energy calculations. Machine learned potentials (MLPs), trained to reproduce the results of ab initio methods with computational cost close to that of force fields, can improve the efficiency of CSP by reducing or eliminating the need for costly DFT calculations at the final stages of CSP. Here, we investigate active learning methods for training MLPs with CSP datasets. The combination of active learning with the well-developed sampling methods from CSP yields potentials in a highly automated workflow that are relevant over a wide range of the crystal packing space. To demonstrate these potentials, we illustrate efficiently re-ranking large, diverse crystal structure landscapes to near-DFT accuracy from force field-based CSP, improving the reliability of the final energy ranking. Furthermore, we demonstrate how these potentials can be extended to more accurately model structures far from lattice energy minima through additional on-the-fly training within Monte Carlo simulations. | Patrick W. V. Butler; Roohollah Hafizi; Graeme Day | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Machine Learning; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2023-10-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/653a8b8c48dad231206969b6/original/machine-learned-potentials-by-active-learning-from-organic-crystal-structure-prediction-landscapes.pdf |
60c7502e4c8919c394ad3d2b | 10.26434/chemrxiv.13002950.v1 | Millimeter-Sized Metal-Organic Framework Single Crystals without Inversion Symmetry: Controlled Growth and Self-Assembly Mechanism | The controllable growth of non-centrosymmetric metal organic framework (MOF) beyond the conventional micrometer crystal dimensions would represent an enabling step in the development of MOF-based devices for coherent nonlinear optics. This goal has been elusive so far, as MOF crystal typical self-assemble under metastable synthesis conditions that have several competing crystallization pathways open, and only a modest amount of external control over the crystal nucleation and growth rates is currently possible. We overcome some of these issues and achieve the controlled growth of large single crystals of the non-centrosymmetric MOF Zn(3-ptz)<sub>2</sub>, with surface areas of up to 25 mm<sup>2</sup> in 24 hours, in a single solvothermal reaction with <i>in-situ</i> ligand formation. No additional growth steps are necessary. We carry out a mechanistic study to unravel the reaction steps leading to the self-assembly of Zn(3-ptz)<sub>2</sub> crystals, by identifying and isolating several intermediate crystal structures that directly connect with the target MOF, and reversibly interconverting between them. We identify the synthesis parameters that control the size and morphology of our target MOF crystal and model its nucleation and growth kinetics using <i>ex-situ</i> image processing data. Our work is a step forward is understanding and controlling the factors that stabilize the growth of high-quality MOF crystals with sizes that are relevant for coherent optics, thus untapping possible applications of metal-organic frameworks in classical and quantum communication technology. | Juan Manuel Garcia Garfido; javier enriquez; Ignacio Chi-Duran; Ivan Jara; Leonardo Vivas; Federico
J. Hernandez; Felipe Herrera; Dinesh Pratap Singh | Aggregates and Assemblies; Hybrid Organic-Inorganic Materials; Optical Materials; Coordination Chemistry (Inorg.); Kinetics and Mechanism - Inorganic Reactions; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7502e4c8919c394ad3d2b/original/millimeter-sized-metal-organic-framework-single-crystals-without-inversion-symmetry-controlled-growth-and-self-assembly-mechanism.pdf |
657723187acf130c32fe70c1 | 10.26434/chemrxiv-2023-3btbw | Ion and Molecular Sieving with Ultrathin Polydopamine Nanomembranes | In contrast to biological cell membranes, it is still a major challenge for synthetic membranes to efficiently separate ions and small molecules, due to their similar sizes in the sub-nanometer range. Inspired by biological ion channels with their unique channel wall chemistry that facilitates ion sieving by ion-channel interactions, we report here the first free-standing, ultrathin (10-17 nm) nanomembranes composed entirely of polydopamine (PDA) for efficient ion and molecular sieving via an easily scalable electropolymerization strategy. These nanomembranes feature well-defined nanochannels, as well as abundant amine and catechol groups, which provide a favourable chemical environment for ion-channel electrostatic and hydrogen bond interactions, emulating the analogous function of biological ion channels. They exhibit remarkable selectivity for monovalent ions over multivalent ions and larger species with K+/Mg2+ of ≈4.2, K+/[Fe(CN)6]3- of ≈10.2, and K+/Rhodamine B base of ≈261.9 in a pressure-driven process, as well as cyclic reversible pH-responsive gating properties. Infrared spectra reveal hydrogen bond formation between hydrated multivalent ions and PDA, which prevents transport of multivalent ions and facilitates the high selectivity. We propose chemically rich, free-standing and pH-responsive PDA nanomembranes with specific interaction sites as customizable high-performance sieves for a wide range of challenging separation requirements. | Jiyao Yu; Tommaso Marchesi D’Alvise; Iain Harley; Adam Krysztofik; Ingo Lieberwirth; Przemyslaw Pula; Pawel W. Majewski; Bartlomiej Graczykowski; Johannes Hunger; Katharina Landfester; Christopher V. Synatschke ; Tanja Weil | Materials Science; Nanoscience; Biocompatible Materials; Nanostructured Materials - Materials; Thin Films; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2023-12-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/657723187acf130c32fe70c1/original/ion-and-molecular-sieving-with-ultrathin-polydopamine-nanomembranes.pdf |
6406f04a0e6a36fabadfcd2d | 10.26434/chemrxiv-2023-dl5c6 | Synthetic strategies and self-assembly properties of thiophene-functionalized hydrogen-bonded diketopyrrolopyrrole derivatives | The optoelectronic properties of thiophene-capped diketopyrrolopyrrole (DPP) derivatives can be tuned by adding differ-ent electroactive moieties to the main central core or by regulating their self-assembly through the interplay of noncova-lent interactions. While the alkylation of the DPP lactam rings is common, the alkylation of the thiophene rings on the DPP extremities is challenging, especially when supramolecular moieties are incorporated. Here we report an efficient synthetic method towards the thiophene functionalization with amide-containing substituents of single core thiophene-capped DPP derivatives. | Amparo Ruiz Carretero; Nelson Ricardo Avila Rovelo; Gabriel Martinez | Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Supramolecular Chemistry (Org.); Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6406f04a0e6a36fabadfcd2d/original/synthetic-strategies-and-self-assembly-properties-of-thiophene-functionalized-hydrogen-bonded-diketopyrrolopyrrole-derivatives.pdf |
63c1a9553af97332a367a26b | 10.26434/chemrxiv-2023-mfxxz-v2 | Synthesis and Structure-Activity Relationship Studies of
C(13)-Desmethylene-(−)-Zampanolide Analogs
| We have prepared a series of partially reduced or demethylated analogs of the natural microtubule stabilizer (−)-zampanolide and we have assessed their antiproliferative activity, their microtubule-binding affinity and their effects on the cellular microtubule network and on cell cycle progression. For reasons of synthetic efficiency, these analogs were derived from 13-desmethylene-(-)-zampanolide, which we had previously shown to be an equally potent cancer cell growth inhibitor as the natural product. The synthesis of all compounds was based on a unified strategy that included final formation of the macrobicyclic core by an intramolecular HWE reaction and a stereoselective aza-aldol reaction to establish the C(20) stereocenter as the key steps. For the 5-desmethyl macrocycle, ring-closure relied on macrolactonization; however, elaboration of the macrocyclic aldehyde into the corresponding zampanolide analog was unsuccessful.All structural modifications investigated led to reduced cellular activity and lower microtubule-binding affinity compared to the parent 13-desmethylene-(–)-zampanolide, which may be ascribed to increased conformational flexibility due to the formal reduction of double bonds or the removal of the C(17)-methyl group. Notwithstanding this general trend, the cellular potency of 2,3-dihydro-13-desmethylene zampanolide as the most potent analog identified remained within a 9-fold range of that of 13-desmethylene-(–)-zampanolide (for 5 out of 6 cell lines). Notably, while the formal reduction of the C=C double bond of the enone system that is required for the covalent attachment of (−)-zampanolide to beta-tubulin caused a drop in antiproliferative activity of several hundred fold, the compound does bind to microtubules and shows the typical cellular hallmarks of a microtubule-stabilizing agent. | Tobias Michael Brütsch; Etienne Cotter; Daniel Lucena-Agell; Mariano Redondo-Horcajo; Carolina Davies; Bernhard Pfeiffer; Sandro Pagani; Simone Berardozzi; J. Fernando Díaz; John H. Miller; Karl-Heinz Altmann | 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 | 2023-01-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63c1a9553af97332a367a26b/original/synthesis-and-structure-activity-relationship-studies-of-c-13-desmethylene-zampanolide-analogs.pdf |
60c74450337d6c81f9e26d8e | 10.26434/chemrxiv.9777257.v1 | Instant and Persistent Hydrogen Production Using Nano High Entropy Catalyst | <div>Renewable harvesting clean and hydrogen energy using the benefits of novel multicatalytic materials of high entropy alloy (HEA equimolar Cu-Ag-Au-Pt-Pd) from formic acid with minimum energy input has been achieved in the present investigation. The synthesis effect of pristine elements in the HEA drives the electro-oxidation reaction towards non-carbonaceous pathway . The atomistic simulation based on DFT rationalize the distinct lowering of the d-band center for the individual atoms in the HEA as compared to the pristine counterparts. This catalytic activity of the HEA has also been extended to methanol electro-oxidation to show the unique capability of the novel catalyst. The nanostructured HEA, properties using a combination of casting and cry omilling techniques can further be utilized as fuel cell anode in direct formic acid/methanol fuel cells (DFFE).<br /></div> | Nirmal Kumar; Subramanian Nellaiappan; Ritesh Kumar; Kirtiman
Deo Malviya; K. G. Pradeep; Abhishek
Kumar Singh; Sudhanshu Sharma; Chandra Sekhar Tiwary; Krishanu Biswas | Nanocatalysis - Reactions & Mechanisms | CC BY NC ND 4.0 | CHEMRXIV | 2019-09-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74450337d6c81f9e26d8e/original/instant-and-persistent-hydrogen-production-using-nano-high-entropy-catalyst.pdf |
6279e9eb3f1e7c4854b85db4 | 10.26434/chemrxiv-2022-gl832 | Towards a circular economy: sustainability assessment of biorefineries for green energy and polyphenolic production from biomass | Pomace is a waste stream that is generated during fruit processing and is regarded as highly polluting due to its high moisture content, biological instability and acidic properties. To facilitate pomace management, the current study has applied the biorefinery concept to develop systems that facilitate value extraction. In this regard, alternative scenarios for the production of polyphenolic compounds and electricity from apple pomace were investigated using ASPEN Plus for process simulations. Scenarios enabling the production of polyphenols using green solvents of subcritical water (scenario (a)) and ethanol (scenario (b)), while also co-producing electricity, were compared to scenario (c) in which the pomace was employed in only electricity production. Comparisons of profitabilities and environmental performances were achieved via a consideration of the net present values (NPVs) and potential environmental impacts (PEIs) respectively, of all scenarios. The study was able to show that scenario (a) constituted the only economically viable strategy, with an NPV of US$19.86 million, while scenarios (b) and (c) were determined to have NPVs of US$-88.12 million and US$-4.05 million respectively. Scenario (b) was also determined to have the poorest environmental performance with a PEI of 148 kPEI/h. Notably, although scenario (c) (PEI of 0.21 kPEI/h) was determined to present a better environmental performance than scenario (a) (PEI of 47 kPEI/h), its economic infeasibility indicated that it will be impractical to consider it as a viable pomace strategy in a future scaled-up system. The present study therefore proposed that scenario (a) may constitute a preferred pomace valorization strategy provided technological innovations i.e. use of renewable energy and gas filters are explored and integrated to reduce the major existing challenge of greenhouse gas emissions. This study provides information regarding the sustainability implications of executing the proposed biorefinery scenarios for pomace management in the fruit processing industry. | Oseweuba Okoro; Lei Nie; Daria Podstawczyk; Amin Shavandi | Chemical Engineering and Industrial Chemistry; Natural Resource Recovery; Process Control; Reaction Engineering | CC BY NC 4.0 | CHEMRXIV | 2022-05-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6279e9eb3f1e7c4854b85db4/original/towards-a-circular-economy-sustainability-assessment-of-biorefineries-for-green-energy-and-polyphenolic-production-from-biomass.pdf |
60c748ba469df40543f43aa6 | 10.26434/chemrxiv.11962266.v1 | N,N’-bis(2-(benzylthio)ethyl)malonamides: Synthesis, Electronic and Steric effects in Silver(I) Extraction and Silver(I) Binding Studies | Unsubstituted and
gem-diethyl substituted malonamide derivatives, bearing benzylthio arms were
prepared in moderate to high yields at room temperature. It was observed that
electronics effects at the 4-aryl position in the malonamide derivatives had a
significant effect on the selectivity, but little effect on silver(I)
extraction efficiency measured by liquid-liquid extraction experiments (with
the 4-methoxy analogue proving the most selective). Increased steric hindrance
near the sulfur donor had a small negative effect on silver(I) extraction
efficiency, while hindrance at the methylene centre reduces selectivity. One of
the malonamide derivatives prepared was found to bind to silver(I) in a 1:1
fashion suggesting a tetrahedral coordination type. | Abiodun Aderibigbe; Andrew J. Clark | Organic Synthesis and Reactions; Coordination Chemistry (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c748ba469df40543f43aa6/original/n-n-bis-2-benzylthio-ethyl-malonamides-synthesis-electronic-and-steric-effects-in-silver-i-extraction-and-silver-i-binding-studies.pdf |
65414e5848dad23120cadc40 | 10.26434/chemrxiv-2023-j4glq | Three photon absorbing photocatalyst enabled defluorinative amination of fluoroarenes | We have developed a photocatalytic system that explores the latent potential of a new photocatalyst HATCN. The architecture of this flat molecule is well poised to pose it as a great photooxidant, that can also afford multiple redox states. The excited reduction potential of HATCN is calculated as 2.83 V which corroborates well with its strong oxidizing behavior. A large number of SNAr reactions have been conducted over a wide variety of fluororenes with varying electronic nature. The catalytic efficiency of the photocatalyst has been demonstrated by successful reaction to both electron-neutral and -poor fluoroarenes. Furthermore, the great utility of this developed protocol has been established by applying this method over a large number of building blocks of drugs and pharmaceutically important moieties. An extensive studies delineate the involvement of three photons for one catalytic cycle, that is unprecedented in photocatalysis. Furthermore, the redox modularity of the photocatalyst gives access to the oxidant and reductant behavior of the same molecule at different stages of the catalytic cycle. This discovery of novel mechanistic paradigm will translate in solving challenging photochemical processes. | Argha Saha; Monojit Roy; Shyamali Maji; Gourav Rana; Anindya Datta; Debabrata Maiti; Debashis Adhikari | Physical Chemistry; Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Photochemistry (Org.); Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65414e5848dad23120cadc40/original/three-photon-absorbing-photocatalyst-enabled-defluorinative-amination-of-fluoroarenes.pdf |
60c74e24702a9bc30918b983 | 10.26434/chemrxiv.12702485.v1 | Synthesis of Anthradithiophene Containing Conjugated Polymers via a Cross-coupling Strategy | New conjugated polymers that incorporate dihexylanthradithiophene (DHADT) in the main chain were prepared by Stille and Sonogashira cross-coupling polymerization reactions. The polymerization chemistry is enabled by a soluble 5,11-dibromodihexylanthradithiophene monomer that is capable of cross-coupling reactions. Four readily soluble DHADT containing co-polymers were prepared and characterized experimentally and computationally. These polymers possess HOMO energies of -5.18 eV to -5.43 eV and LUMO energies of -3.0 eV to -2.82 eV. The notable optical features include broad absorption and band gaps ranging from 1.62 eV to 2.15 eV. | Waseem A. Hussain; Kyle Plunkett | Conducting polymers; Organic Polymers; Polymerization (Polymers) | CC BY NC ND 4.0 | CHEMRXIV | 2020-07-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74e24702a9bc30918b983/original/synthesis-of-anthradithiophene-containing-conjugated-polymers-via-a-cross-coupling-strategy.pdf |
6471af4ce64f843f41d94704 | 10.26434/chemrxiv-2023-twhqj | Ligand controlled orthogonal selectivity between distal positions of fully unbiased aliphatic amines | Aliphatic C(sp3)‒H bonds are inherently difficult to activate owing to their inertness and chemical indistinguishability. This challenge has been overcome mostly by directing group approach however the regioselectivity in distal aliphatic positions has mostly been substrate dependent, with substrate biasness being a pre-requisite for distal C(sp3)‒H activation; a direct consequence of the Thorpe-Ingold effect. Extending the methodology to fully unbiased straight chain aliphatic substrates, in which all the available positions are sterically and statistically equally probable for functionalization and in which the Thorpe-Ingold effect loses its significance, has been a long-standing problem. To this aim, we developed a ligand enabled orthogonal selectivity between the proximal γ and distal δ positions of such fully unbiased straight chain aliphatic amines in a regioselective fashion. These straight chain alkyl amines, though both δ and γ positions are equally probable for functionalization, can be orthogonally functionalized between these two positions just by changing the ligand, all other reaction parameters remaining constant; signifying the immense importance of ligand in controlling the selectivity between the aforementioned positions of such inert aliphatic C(sp3)‒H bonds. Experimental as well as DFT studies have been carried out to generalize the nature of ligand that would be promoting the orthogonal selectivity between these positons, with electron-rich pyridone ligands favoring selective distal δ functionalization while electron-deficient pyridone ligands tuning the selectivity favorably towards the γ position. This regioselective orthogonal selectivity tuned from γ to δ positions have also been mechanistically established through control reactions, kinetic studies and theoretical calculations. | Soumya Kumar Sinha; Nupur Goswami; Yingzi Li; Suman Maji; Anjana S. S.; Srimanta Guin; Robert S. Paton; Debabrata Maiti | Theoretical and Computational Chemistry; Catalysis; Organometallic Chemistry; Homogeneous Catalysis; Ligand Design; Transition Metal Complexes (Organomet.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6471af4ce64f843f41d94704/original/ligand-controlled-orthogonal-selectivity-between-distal-positions-of-fully-unbiased-aliphatic-amines.pdf |
618b23af47f47d26d89b8a4a | 10.26434/chemrxiv-2021-tjsr8 | Co@CoO: a Unique Catalyst for Hydrogenolysis of Biomass-derived 5-Hydroxymethylfurfural to 2,5-Dimethylfuran | The development of precious-metal-free catalysts to promote the sustainable production of fuels and chemicals from biomass remains an important and challenging target. Here, we report the efficient hydrogenolysis of biomass-derived 5-hydroxymethylfurfural to 2,5-dimethylfuran over a unique core-shell structured catalyst Co@CoO that affords the highest productivity among all catalysts reported to date. Surprisingly, we found that the catalytically active sites reside on the shell of CoO with oxygen vacancies rather than the metallic Co. The combination of various spectroscopic experiments and computational modelling reveals that the CoO shell incorporating oxygen vacancies drives the heterolytic and homolytic cleavage of dihydrogen to yield active Hδ- species, resulting in the exceptional catalytic activity. Co@CoO also exhibits excellent activity toward the direct hydrodeoxygenation of lignin model compounds. This study unlocks, for the first time, the potential of metal-oxide catalysts for the production of renewable biomass-derived fuels. | Shuang Xiang; Lin Dong; Zhiqiang Wang; Xue Han; Luke Daemen; Yongqiang Cheng; Yong Guo; Xiaohui Liu; Anibal J Ramirez-Cuesta; Sihai Yang; Xue-Qing Gong; Yanqin Wang | Catalysis; Heterogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-11-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/618b23af47f47d26d89b8a4a/original/co-co-o-a-unique-catalyst-for-hydrogenolysis-of-biomass-derived-5-hydroxymethylfurfural-to-2-5-dimethylfuran.pdf |
616944c2cada1f0b8ed6dc3f | 10.26434/chemrxiv-2021-v9q4z | Microscopic picture of molecular double doping | Double doping, in which a single dopant molecule induces two charge carriers in an organic
semiconductor (OSC), was recently experimentally observed and promises to enhance the efficiency
of molecular doping. Here we present a theoretical investigation of p-type molecular double doping
in a CN6-CP:bithiophene–thienothiophene OSC system. Our analysis is based on density functional
theory (DFT) calculations for the electronic ground state. In a molecular complex with two OSC
oligomers and one CN6-CP dopant molecule we explicitly demonstrate double integer charge transfer
and find formation of two individual polarons on the OSC molecules and a di-anion dopant molecule.
We show that the vibrational modes and related infrared absorption spectrum of this complex can
be traced back to those of the charged dopant and OSC molecules in their isolated forms. The
near-infrared optical absorption spectrum calculated by time-dependent DFT shows both features
of typical intra-molecular polaron excitations and weak inter-molecular charge transfer excitations
associated with the doping-induced polaron states. | Thomas Bathe; Chuan-Ding Dong; Stefan Schumacher | Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2021-10-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/616944c2cada1f0b8ed6dc3f/original/microscopic-picture-of-molecular-double-doping.pdf |
65c6236a9138d23161c0ffea | 10.26434/chemrxiv-2024-tknr6 | Structure-Reactivity relationship of olefins as Electrophiles and Nucleophiles: Factors Influencing | This article depicts the reactivity study of olefins towards nucleophilic and electrophilic reactions. The real-time NMR kinetic experiments showcased how the reactivity of the olefins varies with varying electron density over the olefinic bond. Additionally, the SC-XRD study reveals not only the electron density over olefin makes the difference in reactivity but the planar arrangement also has an impact and could nullify these substitution effects. | Jeetendra Panda; Jigyansa Sahoo; Gokarneswar Sahoo | Organic Chemistry; Organic Synthesis and Reactions; Physical Organic Chemistry; Crystallography – Organic | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c6236a9138d23161c0ffea/original/structure-reactivity-relationship-of-olefins-as-electrophiles-and-nucleophiles-factors-influencing.pdf |
60c74f99842e651900db387b | 10.26434/chemrxiv.12923942.v1 | Predicted 3D Models of the SARS-CoV-2 Spike Protein Membrane Proximal External Region and Transmembrane Domain | The transmembrane helix domain (TMD), membrane proximal external region (MPER) and part of heptad repeat 2 (HR2) domain in SARS-CoV-2 spike protein were modelled using a constrained fold-and-dock strategy. The resulting structures were clustered and their large scale pose variability and energy landscape is described; several representative models are discussed. The results suggest considerable flexibility in the conformation of those regions, which may have an important role in the ability of spike protein to fuse the cell and viral membranes. | Alexander Izvorski | Bioinformatics and Computational Biology | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f99842e651900db387b/original/predicted-3d-models-of-the-sars-co-v-2-spike-protein-membrane-proximal-external-region-and-transmembrane-domain.pdf |
60c7422bf96a00671528656f | 10.26434/chemrxiv.8229833.v1 | Unraveling Fullerene-Perovskite Interactions Introduces Advanced Blend Films for Performance-Improved Solar Cells | <div>Through the identification of specific perovskite fullerene interactions, the relevance of derivatizing a fullerene for perovskite: fullerene blend films is linked to the final device performance. With advanced understanding of perovskite-fullerene complexes, a structurally-optimized fullerene is synthesized and used for improving the performance and proving its universality for several device configurations.</div><div><br /></div> | Jorge Pascual; Silvia Vollavini; Sebastian
F. Völker; Nga Phung; Elisa Palacios-Lidon; Lourdes Ibáñez; hans jurgen-grande; Antonio Abate; juan luis delgado cruz; Ramón Tena-Zaera | Thin Films; Photovoltaics; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2019-06-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7422bf96a00671528656f/original/unraveling-fullerene-perovskite-interactions-introduces-advanced-blend-films-for-performance-improved-solar-cells.pdf |
62ccd5d614201f06e5315eb7 | 10.26434/chemrxiv-2022-xzqk0 | Aza-BODIPY Based Carbonic Anhydrase IX: Strategy to Overcome Hypoxia Limitation in Photodynamic Therapy | Hypoxia caused by photodynamic therapy (PDT) is a major hurdle to cancer treatment since it can promote recurrence and progression by activating angiogenic factors, lowering therapeutic efficacy dramatically. In this work, AZB-I-CAIX2 was developed as a carbonic anhydrase IX (CAIX)-targeting NIR photosensitizer that can overcome the challenge by utilizing a combination of CAIX knockdown and PDT. AZB-I-CAIX2 showed a specific affinity to CAIX-expressed cancer cells and enhanced photocytotoxicity compared to AZB-I-control (the molecule without acetazolamide). Moreover, selective detection and effective cell cytotoxicity of AZB-I-CAIX2 by PDT in hypoxic CAIX-expressed murine cancer cells were achieved. Essentially, AZB-I-CAIX2 could minimize tumor size in the tumor-bearing mice compared to that in the control groups. The results suggested that AZB-I-CAIX2 can improve therapeutic efficiency by preventing PDT-induced hypoxia through CAIX inhibition. | Thitima Pewklang; Kantapat Chansaenpak; Rung-Yi Lai; Siti Nursyahirah Bakar; Chin Siang Kue; Anyanee Kamkaew | Biological and Medicinal Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-07-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62ccd5d614201f06e5315eb7/original/aza-bodipy-based-carbonic-anhydrase-ix-strategy-to-overcome-hypoxia-limitation-in-photodynamic-therapy.pdf |
6430aee60784a63aeeb99b35 | 10.26434/chemrxiv-2022-cr5ws-v2 | Quantitative image analysis of microplastics in bottled water using Artificial Intelligence | The ubiquitous occurrence of microplastics (MPs) in the environment and the use of plastics in packaging materials result in the presence of MPs in the food chain and the exposure of consumers. Yet, no fully validated analytical method is available for microplastic (MP) quantification, thereby preventing the reliable estimation of the level of exposure and, ultimately, the assessment of the food safety risks associated with MP contamination. In this study, a novel approach is presented that exploits interactive artificial intelligence tools to enable the automation of MP analysis. An integrated method for the analysis of MPs in bottled water based on Nile Red staining and fluorescent microscopy was developed and validated, featuring a partial interrogation of the filter and a fully automated image processing workflow based on a Random Forest classifier, thereby boosting the analysis speed. The image analysis provided particle count, size and size distribution of the MPs. From these data, a rough estimation of the mass of the individual MPs, and consequently of the MP mass concentration in the sample, could be obtained as well. Critical materials, method performance characteristics, and final applicability were studied in detail. The method showed to be highly sensitive in sizing MPs down to 10 µm, with a particle count limit of detection and quantification of 28 and 85 items/500 mL, respectively. Linearity of mass concentration determined between 10 ppb and 1.5 ppm showed a regression coefficient of (R2) of 0.99. Method precision was demonstrated by repeatability of 9 - 16% RSD (n = 7) and within-laboratory reproducibility of 15 - 27 % RSD (n = 21). Accuracy based on recovery was 92 ± 15 % and 98 ± 23 % at a level of 0.1 and 1.0 ppm, respectively. The quantitative performance characteristics thus obtained complied with regulatory requirements. Finally, the method was successfully applied to the analysis of twenty commercial samples of bottled water, with and without gas and flavor additives, yielding results ranging from values below the limit of detection to 7237 (95% CI [6456, 8088]) items/500 mL. | Clementina Vitali; Ruud J. B. Peters; Hans-Gerd Janssen; Anna K. Undas; Sandra Munniks; Francesco Simone Ruggeri; Michel W. F. Nielen | Analytical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-04-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6430aee60784a63aeeb99b35/original/quantitative-image-analysis-of-microplastics-in-bottled-water-using-artificial-intelligence.pdf |
669d4567c9c6a5c07a31f985 | 10.26434/chemrxiv-2024-t9qbd | Filling the gap in LogP and pK_a evaluation for saturated fluorine-containing derivatives with machine learning | Lipophilicity and acidity/basicity are fundamental physical properties that profoundly affect the compound's pharmacological activity, bioavailability, metabolism, and toxicity. Predicting lipophilicity, measured by LogP (1-octanol-water distribution coefficient logarithm), and acidity/basicity, measured by pKa (negative of acid ionization constant logarithm), is essential for early drug discovery success. However, the limited availability of experimental data and poor accuracy of standard LogP and pKa assessment methods for saturated fluorine-containing derivatives pose a significant challenge to achieving satisfactory results for this compound class. We compiled a unique dataset of saturated fluorinated and corresponding non-fluorinated derivatives with LogP and pKa experimental values to overcome this challenge. Aiming to create an optimal approach to acidity/basicity and lipophilicity prediction, we evaluated, trained from scratch, or fine-tuned more than 40 machine learning models, including linear, tree-based, and neural networks. The study was supplemented with a substructure mask explanation (SME), which confirmed the critical role of the fluorinated substituents on both physicochemical properties studied and testified to the consistency of the developed models. The results were open-sourced as a GitHub repository, pip, conda packages, and a KNIME node, allowing the public to perform the targeted molecular design of the proposed class of compounds. | Oleksandr Gurbych; Petro Pavliuk; Dmytro Krasnienkov; Oleksandr Liashuk; Kostiantyn Melnykov; Oleksandr Grygorenko | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Drug Discovery and Drug Delivery Systems; Machine Learning; Artificial Intelligence | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669d4567c9c6a5c07a31f985/original/filling-the-gap-in-log-p-and-p-k-a-evaluation-for-saturated-fluorine-containing-derivatives-with-machine-learning.pdf |
60c753fcf96a00c8d2288584 | 10.26434/chemrxiv.13591427.v1 | Theoretical Calculation of Self-Propagating High-Temperature Synthesis (SHS) Preparation of AlB12 | Although experimental results of preparing AlB12 by self-propagating high-temperature synthesis using Mg-B2O3-Al2O3 as raw material has been studied, the theoretical calculations for the preparation of AlB12 have not been examined as thoroughly. In this article, for the first time, we report on the study of theoretical calculation and the adiabatic temperature, calculated, and compared with the actual reaction temperature. The Gibbs free energy for each level of reaction is also calculated. The calculation results show that the adiabatic temperature is 2789.5 K, the standard Gibbs free energy of each reaction is less than 0, and the reaction can proceed spontaneously, which is consistent with the results of the experiment.
<br /> | Chao Wang; Xiaoming Cao; Mengge Dong; Lu Zhang; Jianxing Liu; Xiaozhou Cao; Xiangxin Xue | Ceramics | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c753fcf96a00c8d2288584/original/theoretical-calculation-of-self-propagating-high-temperature-synthesis-shs-preparation-of-al-b12.pdf |
627013b988636cfc9627eff4 | 10.26434/chemrxiv-2022-p5l50 | Interactive Software for Visualization of Non-Targeted Mass Spectrometry Data – FluoroMatch Visualizer | There are thousands of different per- and polyfluoroalkyl substances (PFAS) in everyday products and in the environment. Discerning the abundance and diversity of PFAS is essential for understanding sources, fate, exposure routes, and the associated health impacts of PFAS. While comprehensive detection of PFAS requires use of non-targeted mass spectrometry, data-processing is time intensive and prone to error. While automated approaches can compile all mass spectrometric evidence (e.g., retention time, isotopic pattern, fragmentation, and accurate mass) and provide ranking or scoring metrics for annotations, confident assignment of structure often still requires extensive manual review of the data. To aid this process, we present FluoroMatch Visualizer which was developed to provide interactive visualizations which include normalized mass defect plots, retention time versus accurate mass plots, MS/MS fragmentation spectra, and tables of annotations and meta-data. All graphs and tables are interactive and have cross-filtering such that when a user selects a feature, all other visuals highlight the feature of interest. Several filtering options have been integrated into this novel data visualization tool, specifically with the capability to filter by PFAS chemical series, fragment(s), assignment confidence, and MS/MS file(s). FluoroMatch Visualizer is part of FluoroMatch Suite, which consists of FluoroMatch Modular, FluoroMatch Flow, and FluoroMatch Generator. FluoroMatch Visualizer enables annotations to be extensively validated, increasing annotation confidence. The resulting visualizations and datasets can be shared online in an interactive format for community based PFAS discovery. FluoroMatch visualizer holds potential to promote harmonization of non-targeted data-processing and interpretation throughout the PFAS scientific community. | Jeremy Koelmel; Paul Stelben; David Godri; Jiarong Qi; Carrie McDonough; David Dukes; Juan Aristizabal-Henao; John Bowden; Sandi Sternberg; Emma Rennie; Krystal Godri Pollitt | Analytical Chemistry; Earth, Space, and Environmental Chemistry; Environmental Science | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/627013b988636cfc9627eff4/original/interactive-software-for-visualization-of-non-targeted-mass-spectrometry-data-fluoro-match-visualizer.pdf |
61e59857eab6ef814ce45ec3 | 10.26434/chemrxiv-2022-038b3 | The Ir–OOOO–Ir Transition State and the Mechanism of the Oxygen Evolution Reaction on IrO2(110) | Carefully assessing the energetics along the pathway of the oxygen evolution reaction (OER), our computational study reveals that the “classical” OER mechanism on the (110) surface of iridium dioxide (IrO2) must be reconsidered. We find that the OER follows a bi-nuclear mechanism with adjacent top surface oxygen atoms as fixed adsorption sites, whereas the iridium atoms underneath play an indirect role and maintain their saturated 6-fold oxygen coordination at all stages of the reaction. The oxygen molecule is formed, via an Ir–OOOO–Ir transition state, by association of the outer oxygen atoms of two adjacent Ir–OO surface entities, leaving two intact Ir–O entities at the surface behind. This is drastically different from the commonly considered mono-nuclear mechanism where the O2 molecule evolves by splitting of the Ir–O bond in an Ir–OO entity. We regard the rather weak reducibility of crystalline IrO2 as the reason for favoring the novel pathway, which allows the Ir–O bonds to remain stable and explains the outstanding stability of IrO2 under OER conditions. The establishment of surface oxygen atoms as fixed electrocatalytically active sites on a transition-metal oxide represents a paradigm shift for the understanding of water oxidation electrocatalysis, and it reconciles the theoretical understanding of the OER mechanism on iridium oxide with recently reported experimental results from operando X-ray spectroscopy. The novel mechanism provides an efficient OER pathway on a weakly reducible oxide, defining a new strategy towards the design of advanced OER catalysts with combined activity and stability. | Tobias Binninger; Marie-Liesse Doublet | Theoretical and Computational Chemistry; Catalysis; Energy; Computational Chemistry and Modeling; Theory - Computational; Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-01-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61e59857eab6ef814ce45ec3/original/the-ir-oooo-ir-transition-state-and-the-mechanism-of-the-oxygen-evolution-reaction-on-ir-o2-110.pdf |
60c74870f96a00f2b628707d | 10.26434/chemrxiv.11907918.v1 | Geminal Dimethyl Substitution Enabled Controlled Ring-Opening Polymerization and Selective Depolymerization of Penicillamine-Derived β-Thiolactones | To access infinitely
recyclable plastics, one key is to design thermodynamically neutral systems
based on dynamic bonds for easy manipulation of the polymerization and the
reverse depolymerization under low energy cost. Here, we present the controlled
ring-opening polymerization of various penicillamine-derived β-thiolactones and
the highly specific depolymerization of the resultant polythioesters (PN<sup>R</sup>-PenTE)
for complete monomer recycling. The <i>gem</i>-dimethyl
group confers better ROP control by reducing the activity of the chain-end
thiolate groups and stabilizing the thioester linkages in the polymer backbone.
High molar mass and narrow dispersity PN<sup>R</sup>-PenTE are conveniently
accessible at room temperature bearing well-defined end groups and tunable side
chains. PN<sup>R</sup>-PenTE can be tailored with water solubility, and/or be
easily fabricated into persistent films or fibers with interesting thermal and
mechanical properties. Most importantly, PN<sup>R</sup>-PenTE can be recycled
to pristine enantiopure β-thiolactones at >95% conversion in a
well-controlled unzipping fashion within min to hours at room temperature.
Overall, this work may streamline the rapid development of a wide range of polythioesters
with immense application potential as self-immolative building blocks, high
value biomaterials, and sacrificial domain for nanolithography. | wei xiong; Wenying Chang; Dong Shi; Lijiang Yang; Ziyou Tian; Hao Wang; Zhengchu Zhang; Xuhao Zhou; Erqiang Chen; HUA LU | Biopolymers; Polymerization (Polymers) | CC BY NC ND 4.0 | CHEMRXIV | 2020-02-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74870f96a00f2b628707d/original/geminal-dimethyl-substitution-enabled-controlled-ring-opening-polymerization-and-selective-depolymerization-of-penicillamine-derived-thiolactones.pdf |
64e02cbd694bf1540c9921b9 | 10.26434/chemrxiv-2023-wc3mx-v2 | Representing structures of the multiple conformational states of proteins | Biomolecules exhibit dynamic behavior that single-state models of their structures cannot fully capture. We review some recent advances for investigating multiple conformations of biomolecules, including experimental methods, molecular dynamics simulations, and machine learning. We also address the challenges associated with representing single- and multiple-state models in data archives, with a particular focus on NMR structures. Establishing standardized representations and annotations will facilitate effective communication and understanding of these complex models to the broader scientific community. | Theresa Ramelot; Roberto Tejero; Gaetano Montelione | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Biochemistry; Bioinformatics and Computational Biology; Cell and Molecular Biology | CC BY 4.0 | CHEMRXIV | 2023-08-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e02cbd694bf1540c9921b9/original/representing-structures-of-the-multiple-conformational-states-of-proteins.pdf |
65e1a4999138d2316168b30d | 10.26434/chemrxiv-2024-7zv3t | Dilithium phthalocyanine - A Single Ion Transport Interfacial layer for Solid-State Lithium Batteries | All-solid-state batteries possess several advantages including high safety, flexibility to use high-capacity metal anodes and are projected to be the next generation energy storage devices. Garnet-type cubic Li7La3Zr2O12 (LLZO) solid electrolyte is of particular interest due to its high ionic conductivity under ambient conditions and compatibility with Li metal. However, large electrode/electrolyte interfacial resistance constraints their development. Herein, the use of a highly lithium ion conducting dilithium phthalocyanine (Li2Pc) as an interlayer is proposed to effectively suppress the high impedance at the interface thus improving the electrode-electrolyte contact. Fast Li+ mobility and high dielectric constant of dilithium phthalocyanine enhance the kinetics of Li+ transport across the interface. A significant reduction in overpotential and very stable stripping/plating cycling are observed in lithium symmetric cells upon introducing Li2Pc interlayer as compared to the use of bare tantalum doped lithium lanthanum zirconium oxide (LLZTO) electrolyte. Cells comprising interlayer-modified Li|LLZTO|LiFePO4 show high capacity with excellent cycling and rate capability. The performance of full cells using lithiated graphite and lithium titanate anodes has also been evaluated. This study presents a promising application of garnet electrolytes towards the advancement of solid-state lithium batteries. | Chesta Chesta; Bindu Kalleshappa; Sampath Srinivasan | Physical Chemistry; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Interfaces; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65e1a4999138d2316168b30d/original/dilithium-phthalocyanine-a-single-ion-transport-interfacial-layer-for-solid-state-lithium-batteries.pdf |
63f52323fcfb27a31f2f0686 | 10.26434/chemrxiv-2023-4h3x8 | TaOx electron transport layers for CO2 reduction Si photocathodes | Electron transport layers (ETLs) used as components of photocathodes for light-driven CO2 reduction (CO2R) in aqueous media should have good electronic transport, be stable under CO2R conditions, and, ideally, be catalytically inert for the competing hydrogen evolution reaction (HER). Here, using planar p-Si (100) as the absorbing material, we show that TaOx satisfies all three of the above criteria. TaOx films were synthesized by both pulsed laser deposition (PLD) and radio-frequency (RF) sputtering. In both cases, careful control of the oxygen partial pressure during growth was required to produce ETLs with acceptable electron conductivity. p-Si/TaOx photocathodes were interfaced with ca. 10 nm of a CO2R catalyst: Cu or Au. Under front illumination with simulated AM 1.5G in CO2-saturated bicarbonate buffer, we observed, for both metals, faradaic efficiencies for CO2R products of ~50% and ~30% for PLD TaOx and RF sputtered TaOx, respectively, at photocurrent densities up to 8 mA cm-2. p-Si/TiO2/Cu photocathodes were also evaluated but produced mostly H2 (>97%) due to reduction of the TiO2 to Ti metal under CO2R conditions. In contrast, a dual ETL photocathode (p-Si/TiO2/TaOx/Cu) was selective for CO2R, which suggests a strategy for separately optimizing selective charge collection and the stability of the ETL/water interface. The maximum photovoltage obtained with p-Si/TaOx/Cu devices was 300 mV which was increased to 430-460 mV by employing ion implantation to make pn+-SiTaOx/Cu structures. Photocathodes with RF sputtered TaOx ETLs are stable for CO2R for at least 300 min. Techno-economic analysis shows that the reported system, if scaled, could allow for an economically viable production of feedstocks for chemical synthesis under the adoption of specific CO2 credit schemes, thus becoming a significant component to carbon-neutral manufacturing. | Rajiv Prabhakar; Raphaël Lemerle; Magda Barecka; Minki Kim; Sehun Seo; Elif Nur Dayi; Irene Dei Tos; Joel Ager | Materials Science; Energy; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-02-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63f52323fcfb27a31f2f0686/original/ta-ox-electron-transport-layers-for-co2-reduction-si-photocathodes.pdf |
64379e3d08c86922ffe2f5ac | 10.26434/chemrxiv-2023-d9f4c | Oxidative decarboxylation of fatty acids to terminal alkenes by a membrane-bound metalloenzyme, UndB | Biosynthetically produced alkenes are high-value molecules that can serve as ‘drop-in’ replacements for fossil fuels. Alkenes are also heavily used in the polymer, lubricant, and detergent industries. UndB is the only known membrane-bound fatty acid decarboxylase that catalyzes the conversion of fatty acids to terminal alkenes at the highest reported in vivo titers. However, the enzyme remains poorly understood and enigmatic. Here, we demonstrate the first-time purification of UndB and establish that it is an oxygen-dependent, non-heme diiron enzyme that engages conserved histidine residues at the active site. We also identify redox partners that support the activity of UndB and determine the enzyme's substrate specificity and kinetic properties. We detect CO2 as the co-product of the UndB-catalyzed reaction and provide the first evidence in favor of the hydrogen atom transfer (HAT) mechanism of the enzyme. Our findings decipher the biochemistry of an enigmatic metalloenzyme that catalyzes 1-alkene biosynthesis at the membrane interface with the highest known efficiency. | Tabish Iqbal; Subhashini Murugan; Kalpana Rajendran; Jagpreet Singh Sidhu; Debasis Das | Biological and Medicinal Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-04-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64379e3d08c86922ffe2f5ac/original/oxidative-decarboxylation-of-fatty-acids-to-terminal-alkenes-by-a-membrane-bound-metalloenzyme-und-b.pdf |
634af02e4b0af38092c695c8 | 10.26434/chemrxiv-2022-jktk8 | Spin–orbit couplings within spin-conserving and spin-flipping time-dependent density functional theory: Implementation and benchmark calculations | We present a new implementation for computing spin-orbit couplings (SOCs) within time-dependent density-functional theory (TD-DFT) framework in the stan- dard spin-conserving formulation as well in the spin-flip variant (SF-TD-DFT). This approach employs the Breit-Pauli Hamiltonian and Wigner-Eckart’s theorem ap- plied to the reduced one-particle transition density matrices, together with the spin–orbit mean-field (SOMF) treatment of the two-electron contributions. We use state-interaction procedure and compute the SOC matrix elements using zero-order non-relativistic states. Benchmark calculations using several closed-shell organic molecules, diradicals, and a single-molecule magnet (SMM) illustrate the efficiency of the SOC protocol. The results for organic molecules (described by standard TD- DFT) show that SOCs are insensitive to the choice of the functional or basis sets, as long as the states of the same characters are compared. In contrast, the SF-TD- DFT results for small diradicals (CH2, NH+2 , SiH2, and PH+2 ) show strong functional dependence. The spin-reversal energy barrier in a Fe(III) SMM computed using non- collinear SF-TD-DFT (PBE0, ωPBEh/cc-pVDZ) agrees well with the experimental estimate. | Saikiran Kotaru; Pavel Pokhilko; Anna Krylov | Theoretical and Computational Chemistry; Theory - Computational | CC BY NC ND 4.0 | CHEMRXIV | 2022-10-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/634af02e4b0af38092c695c8/original/spin-orbit-couplings-within-spin-conserving-and-spin-flipping-time-dependent-density-functional-theory-implementation-and-benchmark-calculations.pdf |
654e5832dbd7c8b54b05e4f2 | 10.26434/chemrxiv-2023-37dnc | Morphological Properties and Electrochemical Performance for Compressed Carbon-fiber Electrodes in Redox Flow Batteries | Recognizing the urgent need for further cost reduction to drive deep penetration of redox flow batteries as grid-scale stationary energy storage systems in the global energy mix, it is critical to improve reactor performance to bring down the high capital cost. As one of the main contributors to the overall internal resistance, porous electrodes with properly designed microstructure and optimized physiochemical properties are preferable for boosting electrochemical and fluid dynamic performance. The present study aims to unveil the relationship between electrode morphology and electrochemical performance under varying electrode compression. Three representative, commercially available, carbon-fiber electrodes (i.e., paper, felt, and cloth) with distinct microstructures were selected here, and a comprehensive study was conducted to compare morphology, hydraulic permeability, mechanical behavior, electrochemical properties including decoupled kinetic and mass transfer resistances, and overall battery performance in a lab-scale vanadium redox flow battery at 0-50% compression ratios. The 3D electrode morphology was characterized through X-ray computed tomography and the extracted key microstructure parameters (e.g., surface area and tortuosity) were compared with corresponding electrochemically determined parameters. It was found that the cloth possessed a bimodal pore size distribution due to its distinct woven microstructure and that it was sensitive to the applied compression. The large pores formed at the intersections between fiber bundles collapsed under excessive compression, which greatly reduced the advantageous high permeability and low mass transfer resistances characteristic of the uncompressed cloth. The paper electrodes exhibited a strongly growing compression force accompanied by increased in-plane tortuosity and mass transfer resistance even at low compression (<20%). During battery operation, the cloth maintains a good balance between performance and pressure drop at moderate compression. The optimal trade-off between fluid dynamics and electrochemical performance occurred at the compression ratios of 30%, 20%, and 20% for the felt, paper, and cloth, respectively. | Baichen Liu; Søren Bredmose Simonsen; Johan Hjelm | Physical Chemistry; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/654e5832dbd7c8b54b05e4f2/original/morphological-properties-and-electrochemical-performance-for-compressed-carbon-fiber-electrodes-in-redox-flow-batteries.pdf |
62a305c3ae34b583949830bf | 10.26434/chemrxiv-2022-4rcdc | Radical Activation of Ammonia and Water at Bismuth(II) | The development of unconventional strategies for the activation of ammonia (NH3) and water (H2O) is of capital importance for the advancement of sustainable chemical strategies. Herein we provide the synthesis and characterization of a Radical Equilibrium Com-plex based on bismuth featuring an extremely weak Bi‒O bond, that permits the in situ generation of reactive Bi(II) species. The en-suing organobismuth(II) engages with various ammines and alcohols and exerts an unprecedented effect onto the X‒H, leading to low BDFEX-H. As a result, radical activation of various N‒H and O‒H bonds—including ammonia and water—occurs in seconds at room temperature, delivering well-defined Bi(III)-amido and -alkoxy complexes. Moreover, we demonstrate that the resulting Bi(III)‒N complexes engage in a unique reactivity pattern with the triad of H+, H‒ and H· sources, thus providing alternative pathways for main group chemistry. | Xiuxiu Yang; Edward Reijerse; Kalishankar Bhattacharyya; Markus Leutzsch; Markus Kochius; Nils Nöthling; Julia Busch; Alexander Schnegg; Alexander Auer; Josep Cornella | Inorganic Chemistry; Catalysis; Organometallic Chemistry; Coordination Chemistry (Organomet.); Main Group Chemistry (Organomet.); Small Molecule Activation (Organomet.) | CC BY 4.0 | CHEMRXIV | 2022-06-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62a305c3ae34b583949830bf/original/radical-activation-of-ammonia-and-water-at-bismuth-ii.pdf |
60c74dc19abda2a8d1f8d506 | 10.26434/chemrxiv.12661310.v1 | A Mesoporous Zirconium-Isophthalate Multifunctional Platform | <p>Mesoporous materials suffer from
limitations including poor crystallinity and hydrolytic stability, lack of
chemical diversity, insufficient pore accessibility, complex synthesis and
toxicity issues. Here the association of non-toxic Zr-oxo clusters and
feedstock isophthalic acid (IPA) via a Homometallic-Multicluster-Dot strategy results
in a robust crystalline mesoporous MOF, denoted as MIP-206, that overcomes the
aforementioned limitations. MIP-206, built up from an unprecedented combination
of Zr<sub>6</sub> and Zr<sub>12</sub> oxo-cluster inorganic building units into
a single structure, exhibits accessible meso-channels of ca. 2.6 nm and displays
excellent chemical stability under different hydrolytic and harsh conditions. Owing
to the abundant variety of functionalized IPA linkers, the chemical environment
of MIP-206 can be easily tuned without hampering pore accessibility due to its
large pore windows. As a result, MIP-206 loaded with palladium nanoparticles acts
as an efficient and durable catalyst for the dehydrogenation of formic acid
under mild conditions, outperforming benchmark mesoporous materials. This paves
the way towards the utilization of MIP-206 as a robust mesoporous platform for
a wide range of potential applications.</p> | Sujing Wang; Liyu Chen; Mohammad Wahiduzzaman; Antoine Tissot; Lin Zhou; Ilich A. Ibarra; Aída Gutiérrez-Alejandre; Ji Sun Lee; Jong-San Chang; Zheng Liu; Jérôme Marrot; William Shepard; Guillaume Maurin; Qiang Xu; Christian Serre | Hybrid Organic-Inorganic Materials | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74dc19abda2a8d1f8d506/original/a-mesoporous-zirconium-isophthalate-multifunctional-platform.pdf |
670c54b612ff75c3a153d46b | 10.26434/chemrxiv-2024-llc9d | Exciton Transfer Simulations in LH2 Accelerated by Machine-Learned Hamiltonians Reveal Transient Delocalization Mechanism | The astonishing efficiency of exciton transfer in light-harvesting (LH) complexes has prompted a multitude of experimental and theoretical studies over the past two decades. However, the revision of the long-held role of electronic coherences calls for alternative explanations. In this study, we investigate the exciton motion through the LH2 complex of Rhodospirillum molischianum using a mixed quantum-classical approach, leading to a fully ’classical’ explanation of the transport efficiency. Our multi-scale approach comprises a coupled quantum mechanical molecular mechanics (QM/MM) embedding, a fragmentation of the electronic structure in the QM region via a Frenkel Hamiltonian, neural networks to accelerate the quantum calculations, and non-adiabatic molecular dynamics (NAMD) to treat the combined electronic-nuclear dynamics. This enables us to sample hundreds of trajectories of this large quantum system, each lasting several picoseconds. Our simulations describe the transitions within the B800 and B850 rings in agreement with experimental findings, suggesting an incoherent hopping process in the B800, and a more delocalized transfer in the B850 subsystem. The reorganization energies and excitonic couplings are comparable in the B850 ring, promoting the transport model “transient delocalization”. This theory is characterized by a dynamic interdependence of moderately delocalized excitons that exhibit large delocalization events. To demonstrate the efficiency of this transport, we compare the exciton dynamics in LH2 with the most efficient electron and exciton transfer processes in organic semiconductors. We find that the Bacteriochlorophyll’s unusual electronic properties, leading to tiny inner and outer-sphere reorganization energies, are the reason for the astonishing efficiency. | David Sebastian Hoffmann; Philipp Dohmen; Monja Sokolov ; Ulrich Kleinekathöfer; Marcus Elstner | Physical Chemistry; Physical and Chemical Processes | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/670c54b612ff75c3a153d46b/original/exciton-transfer-simulations-in-lh2-accelerated-by-machine-learned-hamiltonians-reveal-transient-delocalization-mechanism.pdf |
6698d11a01103d79c550fc06 | 10.26434/chemrxiv-2024-r9tgw | Picking and sorting single-transition NMR lines at two fields:
unveiling the pure-shift information | A procedure to construct numerically a pure-shift NMR spectrum is described. The method correlates frequencies of single-transition lines picked from two conventional 1D NMR spectra acquired at two different fields. The resulting 2-field 2D plot synthetically refocuses J-coupling multiplicities along straight lines of slope 1 and intercepts related to the sole chemical shifts. In the general case of overlapping multiplicities, if the order of single transitions is different at the two considered fields, an algorithm to sort the frequencies and establish correct correlations is introduced. In general, given n single-transition frequencies at one field, there exists one of the n! permutations of such frequencies that identifies the ‘decoupled’ correlation with n frequencies at a second field. This synthetic decoupling method is in principle as sensitive and as quantitative as the 1D spectra used for its execution. The resolution is decreased by a factor which depends on the strength of the two fields. The procedure is tested by numerical simulations for weakly- and strongly-coupled 1H spin systems and on experimental data for a sample of cyclosporine A in C6D6. Possible applications on NMR spectra of quadrupolar nuclei in the solid state are briefly discussed. | Diego Carnevale | Physical Chemistry; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6698d11a01103d79c550fc06/original/picking-and-sorting-single-transition-nmr-lines-at-two-fields-unveiling-the-pure-shift-information.pdf |
6470799fbe16ad5c57f2877f | 10.26434/chemrxiv-2023-3pv3c | Preorganized Internal Electric Field Promotes a Double-displacement Mechanism for the Adenine Excision Reaction by Adenine DNA Glycosylase | Adenine DNA glycosylase (MutY) is a monofunctional glycosylase, removing adenines (A) misinserted opposite 8-oxo-7,8-dihydroguanine (OG), a common product of oxidative damage to DNA. Through multiscale calculations, we decipher a de-tailed adenine excision mechanism of MutY that is consistent with all available experimental data, involving an initial proto-nation step and two nucleophilic displacement steps. During the first displacement step, N-glycosidic bond cleavage is ac-companied by the attack of residue Asp144 at the anomeric carbon (C1′), forming a covalent glycosyl-enzyme intermediate to stabilize the fleeting oxocarbenium ion. After departure of the excised base, water nucleophiles can be recruited to displace Asp144, completing the catalytic cycle with retention of stereochemistry at the C1′ position. Unsurprisingly, in the absence of the protein environment, the first displacement reaction, where Asp144 acts as the nucleophile, is highly exothermic with a negative barrier, yet the second, where an un-activated water molecule acts as the nucleophile, is prohibitive both kinetically and thermodynamically. Intriguingly, we find that the enzyme modulates these two reactions by coupling them together through an internal electric field at its active site, which reduces the barrier of the difficult one at the expense of raising that of the easy one, thereby allowing both reactions to occur. These findings not only increase our understanding of the strate-gies used by DNA glycosylases to repair DNA lesions, but also have important implications for how internal/external electric field can be applied to modulate multi-step reactions. | Wenwen Diao; James D. Farrell; Binju Wang; Fangfu Ye; Zhanfeng Wang | Theoretical and Computational Chemistry; Catalysis; Computational Chemistry and Modeling; Acid Catalysis; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6470799fbe16ad5c57f2877f/original/preorganized-internal-electric-field-promotes-a-double-displacement-mechanism-for-the-adenine-excision-reaction-by-adenine-dna-glycosylase.pdf |
61c0a9855b23d40c3403c804 | 10.26434/chemrxiv-2021-qfjw9 | Thionolactone as Resin Additive to Prepare (bio)degradable 3D Objects via VAT Photopolymerization | 3D printing and especially VAT photopolymerization leads
to cross-linked materials with high thermal, chemical and mechanical properties. Nevertheless, such stability is incompatible with degradability and re/upcyclability. We showed here that thionolactone and especially dibenzo[c,e]-oxepane-5-thione (DOT) could be used as an additive (2 wt%) to acrylate-based resins to introduce weak
bonds into the network via a radical ring-opening polymerization process. The low amount of additive allows to only slightly modify the printability of the resin, keep intact its resolution and maintain the mechanical properties of the 3D object. The resin with additive was used in UV microfabrication and 2-photon stereolithography setup and
commercial 3D printers. The fabricated objects were shown to degrade in basic solvent as well in a home-made compost. The rate of degradation is nonetheless dependent of the size of the object. This feature was used to prepare 3D objects with support structures that could be easily solubilized. | Noemie Gil; Constance Thomas; Rana Mhanna; Jessica Mauriello; Romain Maury; Benjamin Leuschel; Jean-Pierre Malval; Jean-Louis Clément; Didier Gigmes; Catherine Lefay; Olivier Soppera; Yohann Guillaneuf | Materials Science; Polymer Science; Biodegradable Materials; Polymerization (Polymers); Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2021-12-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61c0a9855b23d40c3403c804/original/thionolactone-as-resin-additive-to-prepare-bio-degradable-3d-objects-via-vat-photopolymerization.pdf |
60c746c8bdbb8913dda38ca1 | 10.26434/chemrxiv.11400495.v1 | Electrochemically Triggered Dynamics Within a Hybrid Metal-Organic Electrocatalyst | <p> A wide
array of systems, ranging from enzymes to synthetic catalysts, exert adaptive
motifs to maximize their functionality. In a related manner, select
metal-organic frameworks (MOFs) and related systems exhibit structural
modulations under stimuli such as the infiltration of guest species. Probing
their responsive behavior <i>in-situ</i> is
a challenging but important step towards understanding their function and
subsequently building from there. In this report, we investigate the dynamic
behavior of an electrocatalytic Mn-porphyrin containing MOF system (Mn-MOF). We
discover, using a combination of electrochemistry and <i>in-situ</i> probes of UV-Vis absorption, resonance Raman and infrared
spectroscopy, a restructuration of this system via a reversible cleavage of the
porphyrin carboxylate ligands under an applied voltage. We further show, by
combining experimental data and DFT calculations, as a proof of concept, the
capacity to utilize the Mn-MOF for electrochemical CO<sub>2</sub> fixation and
to spectroscopically capture the reaction intermediates in its catalytic cycle.
The findings of this work and methodology developed opens opportunities in the
application of MOFs as dynamic, enzyme-inspired electrocatalytic systems.</p> | Nina Heidary; Mathieu Morency; Daniel Chartrand; Khoa Ly; Radu Iftimie; Nikolay Kornienko | Nanocatalysis - Catalysts & Materials; Nanostructured Materials - Nanoscience; Electrochemistry; Electrocatalysis; Nanocatalysis - Reactions & Mechanisms; Redox Catalysis; Electrochemistry - Mechanisms, Theory & Study; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c746c8bdbb8913dda38ca1/original/electrochemically-triggered-dynamics-within-a-hybrid-metal-organic-electrocatalyst.pdf |
6659557521291e5d1db68b01 | 10.26434/chemrxiv-2024-x9t38 | Self-adaptive photochromism | Camouflage is critically important because it improves the survival ability of animals when facing predators1. Some organisms (e.g., chameleon, octopus) with an active camouflage ability exhibit a changeable appearance with switching of environments2-4. However, manmade active camouflage systems heavily rely on the integration of electronic devices, which encounters problems such as a complex structure, poor usability, and high cost5-7. In the current work, we report active camouflage as an intrinsic function of materials by proposing self-adaptive photochromism (SAP). The SAP materials were fabricated using donor-acceptor Stenhouse adducts (DASAs) as the negative photochromic phases and organic dyes as the fixed phases. Incident light with a specific wavelength induces linear-to-cyclic isomerization of DASAs, which generates an absorption gap at the wavelength and accordingly switches the color. The SAP materials are in the primary black state in the dark and spontaneously switch to another color upon triggering by transmitted and reflected light in the background. SAP films and coatings were fabricated by incorporating polycaprolactone and are applicable to a wide variety of surfaces. Our work reports SAP as a distinct intrinsic property of materials, guiding the development of source-free active camouflage and anticounterfeiting technology. | Fanxi Sun; Ang Gao; Boyun Yan; Jing Zhang; Xiangru Wang; Hanjun Zhang; Dacheng Dai; Yonghao Zheng; Xu Deng; Chen Wei; Dongsheng Wang | Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-05-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6659557521291e5d1db68b01/original/self-adaptive-photochromism.pdf |
62140b5d7a054a0d7f15bd9e | 10.26434/chemrxiv-2022-kppd6 | Conical intersection and coherent vibrational dynamics in alkyl iodides captured by attosecond transient absorption spectroscopy | The photodissociation dynamics of alkyl iodides along the C-I bond are captured by attosecond extreme-ultraviolet (XUV) transient absorption spectroscopy employing resonant ~20 fs UV pump pulses. The methodology of previous experiments on CH3I [Chang, et al., J. Chem. Phys. 154, 234301 (2021)] is extended to the investigation of a C-I bond-breaking reaction in the dissociative A-band of C2H5I, i-C3H7I, and t-C4H9I. Probing iodine 4d core-to-valence transitions in the XUV enables one to map wave packet bifurcation at a conical intersection in the A-band as well as coherent vibrations in the ground state of the parent molecules. Analysis of spectroscopic bifurcation signatures yields conical intersection crossing times, found to be 15 ± 4 fs for CH3I, 14 ± 5 fs for C2H5I, and 24 ± 4 fs for i-C3H7I and t-C4H9I. Observations of coherent vibrations, resulting from a projection of A-band structural dynamics onto the ground state by resonant impulsive stimulated Raman scattering (RISRS), indirectly reveal multimode C-I stretch and CCI bend vibrations in the A-band of C2H5I, i-C3H7I, and t-C4H9I. | Kristina Chang; Han Wang; Sonia Marggi Poullain; Jesus Gonzalez-Vazquez; Luis Banares; David Prendergast; Daniel Neumark; Stephen Leone | Physical Chemistry; Photochemistry (Physical Chem.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-02-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62140b5d7a054a0d7f15bd9e/original/conical-intersection-and-coherent-vibrational-dynamics-in-alkyl-iodides-captured-by-attosecond-transient-absorption-spectroscopy.pdf |
674f38d75a82cea2fadae5b3 | 10.26434/chemrxiv-2024-8bkp0 | Pushing Carbon Nanohoops to Dark Green | Molecules that absorb red or near-infrared (NIR) light have been widely utilized in various fields, with most reported NIR-absorbing materials focusing on planar conjugated molecules and polymers. However, the potential of curved carbon nanohoops as NIR absorbers has yet to be investigated. In this present study, for the first time, we synthesize a series of novel carbon nanohoops [n]CPP-BODIPY (n = 6, 7, and 9) by embedding boron dipyrromethene (BODIPY) dye into cycloparaphenylene scaffolds. These compounds exhibit an exclusive dark green color in the solid state. Notably, the absorption maxima of [n]CPP-BODIPY (n = 6, 7, and 9) exhibited a redshift over 140-170 nm compared to the BODIPY monomer and even > 300 nm compared to their corresponding CPP nanohoops, extending absorption feature into the first near-infrared window. This establishes them as a novel class of carbon nanohoops with the most significant redshifted absorption to date. The successful application of this approach introduces a novel concept for synthesizing NIR absorbers based on CPP structures. | Bing Yuan; Jinyi Wang; Xinyu Zhang; Jingwen Xu; Kang Wei; Jianlong Xia; Jun Liu; Pingwu Du | Physical Chemistry; Organic Chemistry; Organic Compounds and Functional Groups; Photochemistry (Org.); Physical and Chemical Properties; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/674f38d75a82cea2fadae5b3/original/pushing-carbon-nanohoops-to-dark-green.pdf |
66cf27c0a4e53c4876e466e7 | 10.26434/chemrxiv-2024-cr9sz | Visible light-mediated photocatalytic coupling between tetrazoles and carboxylic acids for protein and cell labelling | We present a photocatalytic reaction of tetrazoles to form nitrile imines, which can be coupled with carboxylic acids in aqueous environments. This reaction is applied for photocatalyst-dependent labelling of proteins and cells. | Takuro Matsuoka; Ryosuke Takasaki; Hiroki Akiba; Kosuke Ogata; Akira Hattori; Norihito Arichi; Hideaki Kakeya; Sho Yamasaki; Yasushi Ishihama; Hiroaki Ohno; Shinsuke Inuki | Biological and Medicinal Chemistry; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66cf27c0a4e53c4876e466e7/original/visible-light-mediated-photocatalytic-coupling-between-tetrazoles-and-carboxylic-acids-for-protein-and-cell-labelling.pdf |
631f7e70173b5d5d09fa9fa1 | 10.26434/chemrxiv-2022-htz7b-v2 | A synergistic Pt-Ru-nitrogen-doped-carbon hydrogen oxidation catalyst | Hydroxide exchange membrane fuel cell (HEMFC) is a potentially cost-effective energy conversion technology. However, current state of the art HEMFCs require a high loading of platinum-group-metal (PGM) catalysts, especially for the hydrogen oxidation reaction (HOR). Here we develop a porous nitrogen-doped carbon-supported PtRu HOR catalyst (PtRu/pN-C) that has the highest reported intrinsic and mass activity in alkaline condition. Spectroscopic and microscopic data indicate the presence of Pt single atoms (SAs) in addition to PtRu nanoparticles on pN-C. Mechanistic study suggests Ru modulates the electronic structure of Pt for an optimized hydrogen binding energy, while Pt-SAs on pN-C optimize the interfacial water structure. These synergetic interactions are responsible for the high catalytic activity of this catalyst. An HEMFC with a low loading of this catalyst and a commercial Fe-N-C oxygen reduction reaction (ORR) catalyst achieves the highest reported PGM utilization rate. The current density at 0.65 V of this HEMFC reaches 1.5 A/cm2, exceeding the US DOE 2022 target (1 A/cm2) by 50 %. | Weiyan Ni; Hassan Noor Ul ; Josephine Meibom; You-Chiuan Chu; Miyeon Chang; Anna Krammer; Songlan Sun; Lichen Bai; Wenchao Ma; Seunghwa Lee; Seongmin Jin; Jeremy Luterbatcher; Andreas Schueler; Hao Ming Chen; William Mustain; Xile Hu | Catalysis; Energy; Electrocatalysis; Fuel Cells | CC BY 4.0 | CHEMRXIV | 2022-09-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/631f7e70173b5d5d09fa9fa1/original/a-synergistic-pt-ru-nitrogen-doped-carbon-hydrogen-oxidation-catalyst.pdf |
6290750beac79acba99bd194 | 10.26434/chemrxiv-2022-nfl1j | Ab Initio Molecular Dynamics Study of Heterogeneity at Amorphous Silica/Water Interface | We study the surface heterogeneity of the amorphous silica/water interface by ab initio molecular dynamics simulations. The structure of bulk amorphous silica produced by thermal annealing and the silanol (Si-OH) density at the silica surface reproduce the experiment. The angular probability distribution of silanol OH groups along the surface normal direction is quite broad, and the computed pKa strongly depends on the silanol species. All computed properties show large heterogeneity of the interface. | Tatsuya Joutsuka | Theoretical and Computational Chemistry; Physical Chemistry; Theory - Computational; Interfaces; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6290750beac79acba99bd194/original/ab-initio-molecular-dynamics-study-of-heterogeneity-at-amorphous-silica-water-interface.pdf |
60c74be5bdbb8913a2a396b4 | 10.26434/chemrxiv.12398552.v1 | Structures of Self-Assembled n-Alkanethiols on Gold by Reflection High-Energy Electron Diffraction | <div>TThe structures of long-chain alkanethiols (C<sub>18</sub>H<sub>37</sub>SH) chemisorbed on an Au(111) single crystal were investigated using reflection high-energy electron diffraction (RHEED). The primary (√3x√3)R30° structure observed as a major species in the as-deposited films contains gold adatoms below the sulfur headgroups. Between the small ordered domains with the alkyl chains tilting toward six directions are azimuthally disorderly packed regions, with a similar average tilt of 30.2°. In contrast, a significant reduction in the coverage of gold adatoms is found in the thermally-induced (2√3x3)<sub>rect</sub> phase. This superlattice is shown to contain a mixture of two sulfur arrangements, both of which exhibit a small S‒S distance, and the pairing of the aliphatic chains. A microscopic picture is then given for the structural transition. These findings demonstrate how the RHEED technique may be used to resolve structures of nanometer-thick thin films with multiple orders at the interfaces.</div> | Mithun Ghosh; Ding-Shyue Yang | Interfaces; Self-Assembly; Structure; Surface; Crystallography | CC BY NC ND 4.0 | CHEMRXIV | 2020-06-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74be5bdbb8913a2a396b4/original/structures-of-self-assembled-n-alkanethiols-on-gold-by-reflection-high-energy-electron-diffraction.pdf |
6679297dc9c6a5c07a410a37 | 10.26434/chemrxiv-2024-qlj57-v2 | Comprehensive cell biological investigation of cytochalasin B derivatives with distinct activities on the actin network | In search of a more comprehensive structure activity relationship (SAR) regarding the inhibitory effect of cytochalasin B (CB) on actin polymerization, a virtual docking of CB onto monomeric actin was conducted. This led to the identification of potentially important functional groups of CB (i.e. the NH group of the isoindolone core (N-2), and the hydroxyl groups at C-7 and C-20) involved in interactions with the residual amino acids of the binding pocket of actin. Chemical modifications of CB at positions C-7, N-2, and C-20 led to derivatives CB1-CB4, which were analyzed for their bioactivities. CB1-CB4 exhibited reduced or no cytotoxicity in murine L929 fibroblasts compared to CB. Moreover, short- and long-term treatments of human osteosarcoma cells (U-2OS) affected the actin network to variable extent, partially accompanied by the induction of multinucleation. Derivatives displaying acetylation at C-20 and N-2 were subject to slow intracellular conversion to highly cytotoxic CB. Together, this study highlights the importance of the hydroxy group at C-7 and the NH function at N-2 for CB potency on the inhibition of actin polymerization. | Mervic D. Kagho; Katharina Schmidt; Christopher Lambert; Thomas Kaufmann; Lili Jia; Jan Faix; Klemens Rottner; Marc Stadler; Theresia Stradal; Philipp Klahn | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Natural Products; Cell and Molecular Biology; Chemical Biology | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6679297dc9c6a5c07a410a37/original/comprehensive-cell-biological-investigation-of-cytochalasin-b-derivatives-with-distinct-activities-on-the-actin-network.pdf |
66715478c9c6a5c07abc2337 | 10.26434/chemrxiv-2024-9h3q9 | A deamination-driven biocatalytic cascade for the synthesis of ribose-1-phosphate | Ribose-1-phosphate (Rib1P) is a key substrate for the synthesis of difficult-to-access nucleoside analogues by nucleoside phosphorylases. However, its use in preparative synthesis is hampered by low yields and low selectivity during its preparation by conventional methods. Although biocatalysis permits straightforward access to Rib1P directly from natural nucleosides, these transformations are tightly thermodynamically controlled and suffer from low yields and non-trivial work-up procedures. To address these challenges, we developed a biocatalytic cascade that allows near-total conversions of natural guanosine into α-anomerically pure Rib1P. The key to this route is a guanine deaminase, which removes the accumulated guanine byproduct. Under optimised conditions, this cascade proved readily scalable to the gram scale, delivering isolated yields of up to 79% and a purity of 94% without any chromatography. Our cascade approach reduced the need for toxic reagents and purification steps inherent to previous methods, reducing the environmental burden of the route, as confirmed by CHEM21 Zero Pass and E-factor calculations. Thus, our work will broadly strengthen the applicability of nucleoside phosphorylase-mediated chemistry. | Jonas Motter; Sarah Westarp; Jonas Barsig; Christina Betz; Amin Dagane; Felix Kaspar; Lena Neumair; Sebastian Kemper; Peter Neubauer; Anke Kurreck | Catalysis; Biocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66715478c9c6a5c07abc2337/original/a-deamination-driven-biocatalytic-cascade-for-the-synthesis-of-ribose-1-phosphate.pdf |
60f3c58830f1affe67824df4 | 10.26434/chemrxiv-2021-pg6gc | CH-π interaction boosts photocatalytic CO2 reduction activity in a noble-metal-free system with a molecular cobalt catalyst anchored on carbon nitride | The construction of efficient noble-metal-free systems for visible-light-driven CO2 reduction still remains a key challenge. Here we report an efficient molecular hybrid system composed of a Co-PYN5 catalyst that contains a pyrene functionality that anchors on g-C3N4 dye surface via CH-π interactions. This hybrid material achieves high TONs and TOFs for visible light reduction of CO2 to CO of 533 and 95 h-1, that are within the best reported up to now. The exceptional performance is rationalized in terms of the electronic coupling that takes place with the π-system of the pyrene group with both the g-C3N4 surface and the Co-pyridyl moiety of the catalysts. | Jia-Wei Wang; Macros Gil Sepulcre; Hai-Hua Huang; Eduardo Solano; Yan-Fei Mu; Antoni Llobet; Gangfeng Ouyang | Catalysis; Energy; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2021-07-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60f3c58830f1affe67824df4/original/ch-interaction-boosts-photocatalytic-co2-reduction-activity-in-a-noble-metal-free-system-with-a-molecular-cobalt-catalyst-anchored-on-carbon-nitride.pdf |
60c73f18bb8c1afa863d9a36 | 10.26434/chemrxiv.7210409.v1 | Detection of Adsorbates on Emissive MOF Surfaces with X-Ray Photoelectron Spectroscopy | A metal organic framework containing an azobenzene chromophore exhibits luminescence that is quenched by nitro-phenol derivatives. The model system was used to develop an new analytical approach to differentiating between encapsulated guest molecules and those adsorbed on the outside of the MOF | Shawn Burdette; Jingjing Yan; Ron Grimm; Peter Mueller; Alexander Carl; John MacDonald | Hybrid Organic-Inorganic Materials; Ligands (Organomet.); Structure | CC BY NC ND 4.0 | CHEMRXIV | 2018-10-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f18bb8c1afa863d9a36/original/detection-of-adsorbates-on-emissive-mof-surfaces-with-x-ray-photoelectron-spectroscopy.pdf |
66f33ee051558a15ef02f8b4 | 10.26434/chemrxiv-2024-2tbm9 | The effects of device degradation on perovskite solar cell
impedance spectra: insights from a drift-diffusion model | Adrift-diffusion model is used to investigate the effect of device degradation on the
impedance response of a perovskite solar cell (PSC). Modifications are made to the
open-source drift-diffusion software IonMonger to replicate the effects of a realistic lab
protocol on an unstable PSC. These are modelled using a time-dependent degradation
factor that simulates increases in the bulk SRH recombination rate. It is shown that
degradation occurring during measurement can induce loops in the Nyquist plot and
that there are subtle, but clear, distinctions between these loops and those that occur
in non-degrading cells. Furthermore, impedance spectroscopy is demonstrated to be
remarkably sensitive to changes in device power conversion efficiency. A PCE decrease
of 0.18% during the experiment is sufficient to induce a visible loop in the Nyquist plot
and a drop of 0.06% between successive measurements causes noticeable changes to the
spectrum. | Will Clarke; Petra Cameron; Giles Richardson | Energy; Photovoltaics | CC BY NC 4.0 | CHEMRXIV | 2024-09-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f33ee051558a15ef02f8b4/original/the-effects-of-device-degradation-on-perovskite-solar-cell-impedance-spectra-insights-from-a-drift-diffusion-model.pdf |
6389149792f0840c2d2319c3 | 10.26434/chemrxiv-2022-lcfbq | Accelerated Entropic Path Sampling Elucidates Entropic Effects in Mediating the Ambimodal Selectivity of NgnD-Catalyzed Diels–Alder Reaction | Reaction dynamics trajectory simulations have been conducted to predict the product ratio of reactions with post-transition state bifurcation. However, it remains unknown how the entropy of reactive species along the reaction path mediates ambimodal selectivity. Here, by leveraging deep generative model, we developed an accelerated entropic path sampling approach that evaluates the change of entropy along the post-transition-state reaction path for each product using merely a few hundred reaction dynamic trajectories. The new method, called bidirectional generative adversarial network - entropic path sampling (BGAN-EPS), can enhance the estimation of probability density functions of molecular configurations by generating pseudo-molecular configurations that are statistically indistinguishable from the true data. The method was tested using cyclopentadiene dimerization as a model reaction, in which we reproduced the reference entropic profiles (derived from 2,480 trajectories) using merely 124 trajectories. We further applied BGAN-EPS method to NgnD-catalyzed Diels–Alder reaction to investigate the entropic origin behind its ambimodal selectivity. The results show that the ambimodal preference towards the formation of the [6+4]-adduct over the [4+2]-adduct is contributed by both energetic and entropic forces. | Wook Shin; Xinchun Ran; Xin Wang; Zhongyue Yang | Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Theory - Computational; Artificial Intelligence | CC BY 4.0 | CHEMRXIV | 2022-12-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6389149792f0840c2d2319c3/original/accelerated-entropic-path-sampling-elucidates-entropic-effects-in-mediating-the-ambimodal-selectivity-of-ngn-d-catalyzed-diels-alder-reaction.pdf |
661fa46521291e5d1d046a6b | 10.26434/chemrxiv-2024-1s397 | Assimilating an Enantiopure Supramolecular Nanocage from Achi-ral Building Blocks: The Impact of Chiral Recognition and Spin-crossover | Chiral recognition and discrimination are not only of significance in nature’s intricate biochemical processes but also, at the supramolecular level, have proved to aid the understanding and exploration of chirality and their effects in sensing, molecular separation, and so on. Herein, we discuss the coordination-driven self-assembly to fabricate an enantioselective tetra-hedral nanocage with a general formula MII4L4 (MOC-1, M = Zn, Fe) starting from achiral building blocks. Systematic employment of tris-(4-aminophenyl)triazine (TzTa) with hydrogen bonding acceptor sites as triazine core and 2-butyl-5-chloro-imidazole-4-carboxaldehyde results in a racemic mixture of two enantiomeric cages (Td1), while the absence of such chirality directing groups (Td0), or hydrogen bonding acceptor sites (Td2) assimilates as a dynamic mixture of multiple stereoisomers. Interestingly, the compelling interplay of hydrogen bonding presented by R- or S-Binol as a chiral bias during the subcomponent self-assembly of Td1 induced the selective formation of a single enan-tiopure cage MOC-1Zn(R/S) via “reverse chiral recognition”, where the ultimate stereochemistry of the cage is deter-mined by the guest (Binol). Furthermore, subsequent replacement of the ZnII vertices of MOC-1Zn(R/S) by FeII ions al-lows the straightforward imprinting of a given stereochemistry in MOC-1Fe(R/S), unlike the racemization occurred by the subcomponent self-assembly (Fe4AS). The effective stereochemical coupling between the Binol and enantiopure MOC-1Fe(R/S) dictates the effective spin-state stabilization of the host and, thus, their magnetic responses. This exciting feature opens a new paradigm to associate the spin-crossover phenomenon with supramolecular chirality. | ABHIK PAUL; Misthi Singh; Sanjit Konar | Organic Chemistry; Inorganic Chemistry; Coordination Chemistry (Inorg.); Magnetism; Supramolecular Chemistry (Inorg.) | CC BY NC 4.0 | CHEMRXIV | 2024-04-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/661fa46521291e5d1d046a6b/original/assimilating-an-enantiopure-supramolecular-nanocage-from-achi-ral-building-blocks-the-impact-of-chiral-recognition-and-spin-crossover.pdf |
63aff09ca53ea6442b5d6c41 | 10.26434/chemrxiv-2023-57g3f | Diagnosis of Viral Infections: A Review of the Current Assays and the Prediction of the Future | Different types of diagnostics methods were introduced to the public due to the recent global pandemic. From the real-time reverse transcript polymerase chain reaction (RT-qPCR) to antigen lateral flow assay (LFA), these tests allow relatively accurate and rapid diagnosis of the infection with SARS-CoV-2 virus. Because each assay has separate principles, benefits, and limitations, many of which have complementary advantages and disadvantages, the diagnostic methods in the future, with the rapid development of new techniques, could provide quick, accurate, and accessible point-of-care testing (POCT). New technologies could be used to identify the virus for future epidemics or other infections that occur in every-day lives, potentially stopping another global pandemic from affecting the community, the economy, and the government. | Sanghyuk Ko | Biological and Medicinal Chemistry; Chemical Engineering and Industrial Chemistry; Biochemistry; Bioengineering and Biotechnology; Cell and Molecular Biology | CC BY 4.0 | CHEMRXIV | 2023-01-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63aff09ca53ea6442b5d6c41/original/diagnosis-of-viral-infections-a-review-of-the-current-assays-and-the-prediction-of-the-future.pdf |
66ad6d7c5101a2ffa8f6d2e0 | 10.26434/chemrxiv-2024-nqsh2-v2 | Cold Sintering of Halide-in-Oxide Composite Solid-State Electrolytes | All-solid-state batteries (ASSBs) have attracted increasing attention for next-generation electrochemical energy storage owing to their high energy density and enhanced safety, achieved through the use of non-flammable solid-state electrolytes (SSEs). Oxide-based SSEs, such as Li1.3Al0.3Ti1.7(PO4)3 (LATP), are notable for their high ionic conductivity and excellent chemical and electrochemical oxidation stability. Nevertheless, their brittle mechanical properties and poor interface contact with electrode materials necessitate high-temperature and long-duration sintering or post calcination processes, limiting their processability for real-world applications. Additionally, the formation of secondary phases can detrimentally affect the ionic conductivity of LATP electrolytes. Emerging halide-based SSEs offer reliable deformation for practical processing while maintaining high ionic conductivity. In this work, we report a transient liquid-assisted cold sintering process to integrate oxide-based LATP as the matrix and halide-based Li3InCl6 as the conductive boundary phase into a halide-in-oxide ceramic composite electrolyte at a low processing temperature of 150 ℃. This composite structure significantly reduces interface resistance, effectively addressing ion transport depletion across the boundaries between LATP particles. Consequently, the co-sintered LATP-Li3InCl6 composite SSE exhibits high ionic conductivity of 1.4x10-4 S cm-1 at ambient temperature. Furthermore, the symmetric Li|LATP-Li3InCl6∙nDMF|Li cell demonstrates stable stripping and plating processes for 1600 hours at 55 ℃ (0.1 mA cm-2) and 1200 hours at 100 ℃ (1 mA cm-2). This work represents the first demonstration of ceramic-in-ceramic SSEs that combine the advantages of oxides and halides for high-performance SSBs. | Bo Nie; Ta-Wei Wang; Hongtao Sun | Materials Science; Energy; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66ad6d7c5101a2ffa8f6d2e0/original/cold-sintering-of-halide-in-oxide-composite-solid-state-electrolytes.pdf |
61f90d9f71868d372ac5c34c | 10.26434/chemrxiv-2021-sqvv9-v3 | On the value of using 3D-shape and electrostatic similarities in deep generative methods | Multi-parameter optimization, the heart of drug design, is still an open challenge. Thus, improved methods for automated compounds design with multiple controlled properties are desired. Here, we present a significant extension to our previously described fragment-based reinforcement learning method (DeepFMPO) for the generation of novel molecules with optimal properties. As before, the generative process outputs optimized molecules similar to the input structures, now with the improved feature of replacing parts of these molecules with fragments of similar 3D-shape and electrostatics. By performing comparisons of 3D-fragments, we can simulate 3D properties while overcoming the notoriously difficult step of accurately describing bioactive conformations. We developed a new python package, ESP-Sim, for the comparison of electrostatic potential and molecular shape, allowing the calculation of state-of-the-art partial charges (e.g., RESP with B3LYP/6-31G**) obtained using the quantum chemistry program Psi4. The new improved generative (DeepFMPO v3D) method is demonstrated with a scaffold-hopping exercise identifying CDK2 bioisosteres. All code is open-source and freely available. | Giovanni Bolcato; Esther Heid; Jonas Boström | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems; Artificial Intelligence; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2022-02-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61f90d9f71868d372ac5c34c/original/on-the-value-of-using-3d-shape-and-electrostatic-similarities-in-deep-generative-methods.pdf |
628d0b5259f0d6486d9bfe9a | 10.26434/chemrxiv-2022-p1lf5 | Synthesis and styrene copolymerization of novel halogen, methyl, methoxy and nitro ring-substituted octyl phenylcyanoacrylates | Novel ring-substituted octyl phenylcyanoacrylates, RPhCH=C(CN)CO2CH2(CH2)6CH3 (where R is 2-chloro-6-fluoro, 3-chloro-4-fluoro, 2-chloro-5-nitro, 4-chloro-3-nitro, 5-chloro-2-nitro, 5-iodo-2-methoxy, 2,4,5-trimethyl, 2,4,6-trimethyl, pentamethyl, 2,3-dimethyl-4-methoxy, 2,5-dimethyl-4-methoxy, 2,4-dimethoxy-3-methyl) were prepared and copolymerized with styrene. The acrylates were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and octyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C NMR. All the acrylates were copolymerized with styrene in solution with radical initiation at 70C. The compositions of the copolymers were calculated from nitrogen analysis. | Christian D. Etnyre; Carlos S. Font; Azxiel Frutos; Emily L. Fung; Cassandra E. Gomez; Ashley G. Gil Cardenas; Alexander P. Lopez; Leticia Martinez; Ruanum H. Razak; Sara M. Rocus; William S. Schjerven; Gregory B Kharas | Organic Chemistry; Polymer Science; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Organic Polymers | CC BY 4.0 | CHEMRXIV | 2022-05-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/628d0b5259f0d6486d9bfe9a/original/synthesis-and-styrene-copolymerization-of-novel-halogen-methyl-methoxy-and-nitro-ring-substituted-octyl-phenylcyanoacrylates.pdf |
60c74f76bb8c1a6e323db931 | 10.26434/chemrxiv.12906533.v1 | Inhibitors of Thiol-Mediated Uptake | Viral entry into cells can involve thiol-disulfide exchange with exofacial thiols on cell surfaces. The importance of thiol-mediated uptake for viral entry and beyond is poorly understood because efficient inhibitors do not exist. Here we use fluorescent cyclic oligochalcogenides that enter cells by thiol-mediated uptake to systematically screen for inhibitors, including epidithiodiketopiperazines, benzopolysulfanes, disulfide-bridged g-turned peptides, heteroaromatic sulfones and cyclic thiosulfonates, thiosulfinates and disulfides. Different activities found with different reporters reveal thiol-mediated uptake as a complex multitarget process. Initial tests with pseudo-lentivectors expressing SARS-CoV-2 spike protein do not exclude potential for the development of new antivirals | Yangyang Cheng; Anh-Tuan Pham; Takehiro Kato; Bumhee Lim; Dimitri Moreau; Javier López-Andarias; Lili Zong; Naomi Sakai; Stefan Matile | Organic Compounds and Functional Groups; Chemical Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f76bb8c1a6e323db931/original/inhibitors-of-thiol-mediated-uptake.pdf |
666a45ec12188379d8f999b2 | 10.26434/chemrxiv-2024-p3vhn | Atomistic Phase Transition Mechanism of Zero-Strain Electrode Material: Transmission Electron Microscopy Investigation of Li4Ti5O12 Spinel Lattice Upon Lithiation | The lithiation mechanism of electrode materials is important for understanding the basic reactions in Li-ion batteries. In particular, zero-strain materials have garnered interest owing to their stable charge–discharge performances. In this study, we investigated the atomistic phase transition mechanism of spinel Li4Ti5O12, a well-known zero-strain material, using high-resolution transmission electron microscopy. A single-crystalline Li4Ti5O12 (100) specimen was prepared and observed in situ at a lattice resolution under electron beam-assisted lithiation. The lattice fringes originating from the Li plane of the spinel crystal were anisotropically altered during phase transition, suggesting the asymmetrical site shifting of Li atoms during lithiation. This spontaneous symmetry-breaking mechanism for the phase transition is considered essential for the lithiation of the spinel lattice. | Mitsunori Kitta; Noboru Taguchi; Hiroyuki Ozaki; Tetsu Kiyobayashi | Materials Science; Energy; Energy Storage | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/666a45ec12188379d8f999b2/original/atomistic-phase-transition-mechanism-of-zero-strain-electrode-material-transmission-electron-microscopy-investigation-of-li4ti5o12-spinel-lattice-upon-lithiation.pdf |
6770509d81d2151a02378e34 | 10.26434/chemrxiv-2024-fwnsl | Crystal-phase engineering of nanowires and platelets of KxIrO2 for efficient water oxidation | Nanostructuring electrocatalysts based on precious metals can be an effective tool to increase the dispersion and hence increase the mass activity. Here, we demonstrate the crystal phase engineering of two different potassium iridates polymorphs. We develop a selective solid-state synthesis of either a 1-dimensional K0.25IrO2 nanowires with a hollandite crystal structure, or 2-dimensional KIrO2 hexagonal platelets. Both structures present increased specific and mass electrocatalytic activity for water oxidation reaction in acidic media compared to commercial rutile IrO2 of up to 40%, with the 1D nanowires outperforming the 2D platelets. XANES, EXAFS and XRD investigations prove the structural stability of these two different allotropes of K-IrO2 compounds upon electrocatalytic testing. These low dimensional nanostructured 1D and 2D KxIrO2 compounds with superior mass activity to commercial IrO2 can pave the way towards the design of new electrocatalysts architectures with reduced Ir loading content for Proton Exchange Membrane water electrolyser anodes | Rachael Quintin-Baxendale; Maria Sokolikova; Tao Yemin; Evan Fisher; Goli Nagaraju; Haoyu Bai; James Murawski; Yang Guangmeimei; Veronica Celorrio; Caiwu Liang; Reshama R Rao; Ifan Stephens; Cecilia Mattevi | Catalysis; Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6770509d81d2151a02378e34/original/crystal-phase-engineering-of-nanowires-and-platelets-of-kx-ir-o2-for-efficient-water-oxidation.pdf |
65936154e9ebbb4db9378fba | 10.26434/chemrxiv-2023-j935v-v2 | Comprehensive analysis of nitrile probe IR shifts and intensities in proteins: experiment and critical evaluation of simulations | Molecular dynamics (MD) simulations are frequently carried out for proteins to investigate the role of electrostatics in their biological function. The choice of force field (FF) can significantly alter the MD results as the simulated local electrostatic interactions lack benchmarking in the absence of appropriate experimental methods. We recently reported that the transition dipole moment (TDM) of the popular nitrile vibrational probe varies linearly with the environmental electric field, overcoming well-known hydrogen bonding (H-bonding) issues for the nitrile frequency and, thus, enabling the unambiguous measurement of electric fields in proteins (J. Am. Chem. Soc. 2022, 144 (17), 7562-7567). Herein, we utilize this new strategy to enable comparisons of experimental and simulated electric fields in protein environments. Specifically, previously determined TDM electric fields exerted onto nitrile-containing o-cyanophenylalanine residues in photoactive yellow protein are compared with MD electric fields from the fixed-charge AMBER FF and the polarizable AMOEBA FF. We observe that the electric field distributions for H-bonding nitriles are substantially affected by the choice of FF. As such, AMBER underestimates electric fields for nitriles experiencing moderate field strengths; in contrast, AMOEBA robustly recapitulates the TDM electric fields. The FF dependence of the electric fields can be partly explained by the presence of additional negative charge density along the nitrile bond axis in AMOEBA, which is due to the inclusion of higher-order multipole parameters; this in turn begets more head-on nitrile H-bonds. We conclude by discussing the implications of the FF dependence for the simulation of nitriles and proteins in general. | Jacob M. Kirsh; Jared Bryce Weaver; Steven G. Boxer; Jacek Kozuch | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Biophysical Chemistry | CC BY 4.0 | CHEMRXIV | 2024-01-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65936154e9ebbb4db9378fba/original/comprehensive-analysis-of-nitrile-probe-ir-shifts-and-intensities-in-proteins-experiment-and-critical-evaluation-of-simulations.pdf |
60c74682ee301c2226c7953b | 10.26434/chemrxiv.11340752.v1 | Tracing Dynamic Nuclear Polarization Pathways Using Transition Metal - Nuclear Spin Rulers | <p><a></a>The ubiquitous technique of nuclear magnetic resonance (NMR) spectroscopy suffers from relatively low sensitivity due to the low polarization of nuclei. For decades, the technique of dynamic nuclear polarization (DNP) has been harnessed to increase the sensitivity of NMR, enabling detection of low abundance nuclei such as <sup>17</sup>O and elucidation of protein structures. Yet, the catalogue of DNP agents today is limited to organic radical species, accompanied by a handful of metal ions (Cr<sup>3+</sup>, Mn<sup>2+</sup>, and Gd<sup>3+</sup>). This study significantly expands the scope and catalogue of DNP with the first demonstration of amplification of nuclear spin polarization at a set distance from a transition metal center (V<sup>4+</sup>) that has g-values significantly varied from 2 and anisotropic EPR line that is more than 3GHz broad.We showed that <sup>1</sup>H NMR signal enhancements of up to 33 can be achieved at 6.9T field and 4K temperature using a home-built DNP instrumentation that allows microwave irradiation over a frequency range of more than 10 GHz with pulse shaping capabilities by arbitrary waveform generator. A series of systematically designed vanadyl complexes, with V<sup>4+</sup>-<sup>1</sup>H distances in range 4.0 Å to 13.6 Å, was used to trace the polarization pathway of DNP and determine the size of the spin-diffusion barrier.<br /></p> | Sheetal Kumar Jain; Chung-Jui Yu; Blake Wilson; Tarnuma Tabassum; Danna E. Freedman; Songi Han | Spectroscopy (Anal. Chem.); Transition Metal Complexes (Inorg.); Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74682ee301c2226c7953b/original/tracing-dynamic-nuclear-polarization-pathways-using-transition-metal-nuclear-spin-rulers.pdf |
6269c5e211b146300b32d927 | 10.26434/chemrxiv-2022-8zl4x | Therapeutic Potency of Mono and Diprenylated Acetophenone: A Case Study of in-vivo Antimalarial Evaluation | Malaria remains a febrile infection of public health concern in many countries especially tropical countries in Africa, and certain countries in Southern and North America such as Brazil, Costa Rica, Mexico, Dominican Republic, Colombia, and Ecuador. Hence this has made research into this area paramount. Acetophenones are active fragments in many compounds with promising antimalarial activity, such as chalcones. In this study, 3,5-diprenyl acetophenone (I) and 5-diprenyl (II) acetophenone were synthesized using an aromatic substitution reaction and tested for in-vivo antimalarial activity. The in-vivo antimalarial potential of the synthesized compounds was carried out using a curative model with plasmodium berghei infected mice. At all the three doses tested; 25 mgkg-1, 50 mgkg-1 and 100 mgkg-1 3,5-diprenyl acetophenone (I) showed promising activity with percentage inhibition of 68.03%, 65.16% and 69.75% respectively demonstrating dose-dependent activity. However, 5-prenyl acetophenone (II) only displayed significant activity (72.12% inhibition) at a dose of 100 mgkg-1. The two compounds passed Lipinski’s rule of five and thus drug-like candidates. | Sodeeq Babalola; Hayatudeen Muhammad; Abdullah Idris; Asmau Hamza; Nosa Igie; Isaiah Odeyemi; Aliyu Musa; Amina Olorukooba | Biological and Medicinal Chemistry; Organic Chemistry; Bioorganic Chemistry; Drug Discovery and Drug Delivery Systems | CC BY 4.0 | CHEMRXIV | 2022-06-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6269c5e211b146300b32d927/original/therapeutic-potency-of-mono-and-diprenylated-acetophenone-a-case-study-of-in-vivo-antimalarial-evaluation.pdf |
652ef1e38bab5d20558f91f8 | 10.26434/chemrxiv-2023-2wl84 | Self-Decorating Cells Via Surface-Initiated Enzymatic Controlled Radical Polymerizations | Innovatively utilizing surface-displayed horseradish peroxidase, this paper explores the enzymatic catalysis of both bioRAFT polymerization and bioATRP to prompt polymer synthesis on the surface of Saccharomyces cerevisiae cells, with bioATRP outperforming bioRAFT polymerization. The resulting surface modification of living yeast cells with synthetic polymers allows for a significant alternation of yeast phenotype, including growth profile, aggregation characteristics, and conjugation of non-native enzymes to the clickable polymers on the cell surface, opening new avenues in bioorthogonal cell-surface engineering. | Andrea Belluati; Dominic Happel; Malte Erbe; Nicole Kirchner; Anna Szwelwicka; Adrian Bloch; Valeria Berner; Andreas Christmann; Brigitte Hertel; Raheleh Pardehkhorram; Amin Reyhani; Harald Kolmar; Nico Bruns | Biological and Medicinal Chemistry; Polymer Science; Biopolymers; Bioengineering and Biotechnology; Microbiology | CC BY 4.0 | CHEMRXIV | 2023-10-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652ef1e38bab5d20558f91f8/original/self-decorating-cells-via-surface-initiated-enzymatic-controlled-radical-polymerizations.pdf |
60c7510d842e652a8edb3b08 | 10.26434/chemrxiv.13114583.v1 | Design of a Well-Defined Poly(Dimethylsiloxane)-Based Microbial Nanoculture System | <p>Organosilanes contain hydrocarbon-like backbones, allowing them to react with silicone-based agents in the presence of a catalyst and polymerize into membranes with tunable transport and mechanical properties. Owing to their high hydrophobicity, Poly(dimethylsiloxane) (PDMS) membranes, and more particularly, Sylgard® 184, have been used for applications including drug delivery, gas separation, and microfluidics fabrication. However, the undefined composition of the material and its ability to leach out uncured oligomers make its functionalization and usage challenging for many biological applications. This article presents the design of a novel culture system generated using PDMS-based membranes to study microbial dynamics. The microbial culture system that is referred to as “nanoculture” serves to encapsulate and grow microbes in semipermeable membranes. The mechanical properties of the membranes are reinforced through osmotic annealing, which enable the nanocultures to withstand high shear stress similar to environmental conditions while maintaining transport properties essential to microbial communication and growth. The present study lays the foundation for a novel microbial culture system that would enable the cultivation of microorganisms in environments other than laboratory conditions.</p> | Huda Usman; Shanna-Leigh Davidson; Nithil H. Manimaran; Jenna T. Nguyen; Aïssatou Bah; Rishabh Seth; Eric Beckman; Tagbo Niepa | Biological Materials; Bioengineering and Biotechnology; Drug Discovery and Drug Delivery Systems; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2020-10-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7510d842e652a8edb3b08/original/design-of-a-well-defined-poly-dimethylsiloxane-based-microbial-nanoculture-system.pdf |
646fe0e7be16ad5c57ea334d | 10.26434/chemrxiv-2023-jtc42 | Stereocontrolled Radical Thiophosphorylation | The first practical, fully stereoselective P(V)-radical hydrophosphorylation is presented herein using simple, limonene-derived reagent systems. A set of reagents has been developed that upon radical initiation react smoothly with olefins and other radical acceptors to generate P-chiral products which can be further diversified (with conventional 2e- chemistry) to a range of underexplored bioisosteric building blocks. The reactions have a wide scope with excellent chemoselectivity and the unexpected stereochemical outcome has been supported computationally and experimentally. Initial ADME studies are suggestive of the promising properties of this rarely explored chemical space. | Molhm Nassir; Michał Ociepa; Hai-Jun Zhang; Lauren Grant; Bryan Simmons; Martins Oderinde; Yu Kawamata; Anthony Cauley; Michael Schmidt; Martin Eastgate; Phil Baran | Biological and Medicinal Chemistry; Organic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/646fe0e7be16ad5c57ea334d/original/stereocontrolled-radical-thiophosphorylation.pdf |
655b60ae6e0ec7777f53343e | 10.26434/chemrxiv-2023-rl160 | Quantifying Atomic Volume, Partial Charge and Electronegativity in Condensed Phases | The predictive and explanatory roles of atomic properties like size, charge, and electronegativity are closely linked to their definitions. However, establishing suitable definitions becomes increasingly challenging when examining atoms within materials. This study presents a quantum-mechanical framework for the quantitatively assessment of these atomic properties in crystalline structures. Our approach utilizes Kohn-Sham density functional theory to approximate the electron energy density. We then employ a quantum chemical topological analysis of this density to derive atomic properties. The average electron energy density is conceptually powerful because it can be interpreted as a product of the electron density and the average energy of occupied molecular orbitals. Our method therefore bridges descriptive and predictive theories of electronic structure, including the quantum theory of atoms in molecules and molecular orbital theory. The applicability of our methodology is demonstrated across various materials, encompassing metals, ionic salts, semiconductors, and a hydrogen-bonded molecular crystal. This work provides insights into electronegativity inversion during bond formation. It also highlights the complementary roles of partial charge and electronegativity in electronic structure analysis, with one indicating spatial electron accumulation or depletion and the other reflecting average electron binding. | Stefano Racioppi; Per Hyldgaard; Martin Rahm | Theoretical and Computational Chemistry; Materials Science; Computational Chemistry and Modeling; Theory - Computational | CC BY 4.0 | CHEMRXIV | 2023-11-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/655b60ae6e0ec7777f53343e/original/quantifying-atomic-volume-partial-charge-and-electronegativity-in-condensed-phases.pdf |
6777e903fa469535b9a33089 | 10.26434/chemrxiv-2025-8v846 | Deciphering the Cu(I):O2 to Cu(II):O2- Transition along the Binding Pathway through Computational Transient X-ray Absorption Spectra | Oxidation state (OS) is a fundamental concept for understanding chemical compounds, especially coordination complexes. Determining the OS of a central metal can be challenging in the presence of non-innocent ligands like O2/O2-/O2 2-, as multiple OSs may arise from metal-ligand distance changes. Here, we demonstrate that transient X-ray absorption spectroscopy (TXAS) can precisely distinguish OS changes in a copper cation along its dioxygen binding pathway, by computing spectra of the CuO2+ cation at decreasing Cu-O distances, from gas- to crystal-phase geometries. The Cu(I):O2 to Cu(II):O2- transition was deciphered by comparing spectra of complexes with clearly characterized OSs, consistently on both the O K-edge and the Cu L2,3-edge. Our multiconfigurational calculations agree well with experiments, allowing reliable peak-by-peak assignments across all snapshots. This enables us to track the evolution of electronic excitations and metal-to-ligand charge transfer during the ultrafast structural dynamics. This work showcases TXAS as a powerful tool for determining OS changes, highlighting the power of precise computational TXAS spectroscopy against reaction coordinate snapshots. Our findings clarify the intrinsic electronic structure change along the Cu-O2 binding pathway, illuminating more complex biological and catalytic processes involving Cu:O2 or analogous interactions. | Sheng-Yu Wang; Jun-Rong Zhang; Guoyan Ge; Weijie Hua | Theoretical and Computational Chemistry; Physical Chemistry; Inorganic Chemistry; Coordination Chemistry (Inorg.); Reaction (Inorg.); Spectroscopy (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6777e903fa469535b9a33089/original/deciphering-the-cu-i-o2-to-cu-ii-o2-transition-along-the-binding-pathway-through-computational-transient-x-ray-absorption-spectra.pdf |
647d8cb94f8b1884b7de07f2 | 10.26434/chemrxiv-2022-4hgtc-v3 | Triticale Starch-Based pH-Responsive Hydrogel: Synthesis, Characterization, Diffusion & New Perspective of Triticale Crop as Sustainable Source for Stimuli-Response Hydrogels | Considering the FAO perspectives for agriculture towards 2030, many natural sources will be no longer profitable for the synthesis of many biomaterials. Triticale (X Triticosecale Wittmack) is a cereal crop synthesized to withstand those marginal conditions; however, it is primarily used as fodder worldwide. We reported for the first time the synthesis of a natural anionic hydrogel with gastrointestinal pH stimulus-response as new alternative of smart material, based on Eronga triticale starch as sustainable biomass, using citrate (pKa~3.1, 4.7 and 6.4) as cross-linking agent. By scanning electron microscopy and X-ray diffraction, starch granules exhibited size and semi-crystallinity A-type. The presence of the anionic sensing group (COOH) was verified by infrared spectroscopy, and through thermal analysis hydrogels exhibited four endothermic curves (115-393°C, ~1.4-38 kJ/mol Ea). The rheological analyzes showed viscoelastic tendency (G’>G’’) with high stability (Tan δ<1) in frequency, time, and strain sweeps. Gastrointestinal pH sensitivity (~2-7.8) was verified (α≤0.01) following Fick’s diffusive parameters, which resulted in a tendency to gradually release BSA with increasing pH~3-7 by anomalous and case-II diffusion, showing greater release at pH~7.8/3.5h (80-96%). We aim to expand the biomaterials area focusing on triticale starch due its limited reported investigations, low-cost, green modification, and its rheological performance as plastic. | Karen Samantha Cruz-Amaya; Carmen L. Del-Toro-Sánchez; Elizabeth Carvajal-Millan; Yubia D. Anda-Flores; Diego Hernandez-Martínez; Karla G. Martinez-Robinson; Yaeel I. Cornejo-Ramirez | Materials Science; Polymer Science; Agriculture and Food Chemistry; Thin Films; Biopolymers; Drug delivery systems | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/647d8cb94f8b1884b7de07f2/original/triticale-starch-based-p-h-responsive-hydrogel-synthesis-characterization-diffusion-new-perspective-of-triticale-crop-as-sustainable-source-for-stimuli-response-hydrogels.pdf |
655d9d6e29a13c4d47b2f48b | 10.26434/chemrxiv-2023-pq6zg-v2 | Homo- and Hetero-Recyclable Polyesters with High Refractive Index from CO2, 1,3-Butadiene and Thiols | α-Ethylidene-δ-vinyl-δ-valerolactone (EVL) is the only intermediate to synthesize copolymers of CO2 with 1,3-butadiene whose ring-opening polymerization (ROP), however, is obstructed by the tiglate group. The saturation of the conjugated double bond is essential to the living ROP of EVL, while previous reports involve irreversible hydrogenation. In the contribution, EVL derivatives are synthesized through Michael addition reaction to saturate the conjugated double bond as well as introduce various groups to synthesize polyesters with tunable glass-transition temperatures (Tg) from -45 °C to 3 °C and excellent refractive index between 1.64 and 1.85. Living and controlled polymerizations lead to polyesters with designable number average molecular weights (Mn = 6.9-12.8 kg∙mol-1) and narrow dispersities (Đ = 1.08-1.19). The obtained polyesters are able to be recycled to the corresponding monomers which can prepare comparable polymers with identical side groups, realizing the homo-recycling. The monomers are capable of being recycled to EVL and thiols through retro-Michael addition reaction, and then the recycled EVL can be re-functionalized to generate a new monomer which produces a polyester with another side group, fulfilling the hetero-recycling. We propose an “addition-elimination-re-addition” strategy for EVL derivatives and the corresponding polyesters. | Zhuorui Zhang; Ting Shen; Kaihao Chen; Junjie Zeng; Jun Ling; Xufeng Ni | Polymer Science | CC BY NC ND 4.0 | CHEMRXIV | 2023-11-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/655d9d6e29a13c4d47b2f48b/original/homo-and-hetero-recyclable-polyesters-with-high-refractive-index-from-co2-1-3-butadiene-and-thiols.pdf |
6453e66527fccdb3ea7f5bb0 | 10.26434/chemrxiv-2023-rpqv6 | Identifying Underexplored and Untapped Regions in the Chemical Space of Transition Metal Complexes | We survey over 230,000 crystallized mononuclear transition metal complexes (TMCs) to identify trends in preferred geometric structure and metal coordination. While we observe d-filling to influence coordination preference, with late TMCs preferring lower coordination number, we also note exceptions. We also observe that 4d and 5d transition metals and 3p-coordinating ligands are systematically undersampled. For the roughly one third of the set of mononuclear TMCs that are octahedral, analysis of the 67 symmetry classes of their ligand environments reveals that complexes most commonly contain monodentate ligands that may likely be removable to leave an open site amenable to catalysis. Due to their frequent use in transition metal catalysts, we analyze trends in coordination by tetradentate ligands in terms of the capacity to support multiple metals and the variability of coordination geometry. We identify promising tetradentate ligands that co-occur in crystallized complexes with labile monodentate ligands, indicating their ability to generate reactive sites. Literature mining suggests that many of these tetradentate ligands are untapped as ligands in catalytic complexes, motivating proposal of a promising octa-functionalized porphyrin in this set as a candidate ligand for catalysis. | Aditya Nandy; Michael Taylor; Heather Kulik | Theoretical and Computational Chemistry; Physical Chemistry; Inorganic Chemistry; Coordination Chemistry (Inorg.); Theory - Inorganic; Physical and Chemical Properties | CC BY 4.0 | CHEMRXIV | 2023-05-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6453e66527fccdb3ea7f5bb0/original/identifying-underexplored-and-untapped-regions-in-the-chemical-space-of-transition-metal-complexes.pdf |
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