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62c34d217b3b3063660cedcd | 10.26434/chemrxiv-2022-mbqs6 | Nickel-Catalyzed Electro-Reductive Cross-Coupling of Aliphatic Amides with Alkyl Halides as a Strategy for Dialkyl Ketone Synthesis: Scope and Mechanistic Investigations | The development and in-depth study of a novel catalytic method relying on the combination of nickel catalysis and electrochemistry for the cross-electrophile coupling of alkyl amides with alkyl halides is described. This methodology takes advantages of the stability and simple access of N-acyl imides as coupling partners for the selective synthesis of dissymmetric dialkyl ketones. Noteworthy, the developed electrochemical protocol affords selective access to linear alkyl ketones when using primary alkyl bromides featuring different chain length. Mechanistic studies including cyclic voltammetry, stoichiometric reactions, and isolation of catalytic intermediates provide a set of fundamental insights into monovalent (bpy)nickel-mediated activation of alkyl halides and alkyl amides. Alkyl bromides react with electrogenerated (bpy)Ni(I) species via single-electron oxidation to give alkyl radicals. N-acyl imides are shown to undergo spontaneous C-N bond oxidative addition at both (bpy)Ni(0) and (bpy)Ni(I) species leading to Ni(II) acyl intermediates. A stable nickel(II) acyl complex has also been isolated and fully characterized, and its catalytic competency is demonstrated. Finally, electrogenerated (bpy)Ni(I)-acyl species are shown to react with both alkyl bromide and alkyl amides. Overall, these investigations allowed for a comprehensive mechanistic picture of this selective cross-electrophile coupling to be assembled. | Taline Kerackian; Didier Bouyssi; Guillaume Pilet; Maurice Médebielle; Nuno Monteiro; Julien Vantourout; Abderrahmane Amgoune | Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Electrocatalysis; Homogeneous Catalysis | CC BY NC 4.0 | CHEMRXIV | 2022-07-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62c34d217b3b3063660cedcd/original/nickel-catalyzed-electro-reductive-cross-coupling-of-aliphatic-amides-with-alkyl-halides-as-a-strategy-for-dialkyl-ketone-synthesis-scope-and-mechanistic-investigations.pdf |
67624f34fa469535b9f25aea | 10.26434/chemrxiv-2024-x8fx0-v2 | Machine Learning in X-ray Scattering for Materials Discovery and Characterization | X-ray diffraction (XRD) is an immediate and powerful characterization technique that provides detailed information on the lattice structure and long-range order in crystalline materials. In recent decades, the quality and quantity of available crystal structure data has exploded, in large part due to the advent of online crystal structure databases, increased use of in-situ and operando methodologies, and user-accessible beamlines. The new wealth of data has also spawned an increasing use of machine learning (ML) to either construct high-throughput surrogates of established analysis or extract patterns from large datasets. However, XRD spectroscopy has been for many years solved via Rietveld refinement, while most ML techniques are simply complex statistical evaluation methods that are physics-agnostic. The discrepancy between data analysis and the underlying physics can lead to incorrect conclusions and/or limit the wide-spread adoption of ML techniques. In this review, we bridge the gap between ML and XRD spectroscopy with an introduction designed both for new data scientists and experimentalists interested in problems related to ML-guided spectroscopy analysis. We cover how supervised ML methods are used to predict likely symmetries and phases in pure and mixed samples, including challenges related to experimental artifacts and model interpretation. We also review recent uses of unsupervised methods in the extraction of patterns hidden in high-dimensional data, such as in in-situ and microscopic studies. Finally, we discuss the importance of problem formulation, data transferability, and reporting with recent case studies and give various resources throughout to expedite the learning curve for readers new to XRD or ML. We advocate for greater scrutiny of ML methods, how they are presented in the literature, and how to conduct data-driven research responsibly. | Connor Davel; Nazanin Bassiri-Gharb; Juan-Pablo Correa-Baena | Materials Science | CC BY 4.0 | CHEMRXIV | 2024-12-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67624f34fa469535b9f25aea/original/machine-learning-in-x-ray-scattering-for-materials-discovery-and-characterization.pdf |
6600dc1a9138d23161376453 | 10.26434/chemrxiv-2024-x7gf1 | Biodegradable Temperature Sensor enabled using Printed Electronics | Printed electronics are considered the future of manufacturing electronic devices due to their cost-effectiveness, speed, and customizability compared to traditional methods using silicon. As medical electronics usage increases, there's a growing concern about safely disposing of electronic waste without harming the environment, especially since many of these devices are single-use. Researchers are focusing on developing conductive materials that are non-toxic and biodegradable. In this study we demonstrate the effectiveness of a fully-biodegradable temperature sensor patch. The patch was made using a biodegradable, water-soluble substrate consisting of 3% PVA films. Ink deposition is achieved using the inkjet method. The resulting sensor is flexible, bendable, and suitable for use as an e-skin patch. Here, two different conductive materials such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and silver have been used as an active layer. The resultant sensor performance and their corresponding biodegradability studies have been studied and compared thoroughly. The fully-biodegradable PEDOT:PSS sensor exhibited good linearity in resistance measurements between 30-110 °C, with a temperature coefficient of resistance | Julia Paulina Bartnik; Devabharathi Nehru; Mahboubeh Motadayen; SHWETA AGARWALA | Materials Science; Nanoscience; Biodegradable Materials; Materials Processing | CC BY NC 4.0 | CHEMRXIV | 2024-03-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6600dc1a9138d23161376453/original/biodegradable-temperature-sensor-enabled-using-printed-electronics.pdf |
60c7583b702a9b2cb718ccb0 | 10.26434/chemrxiv.14525430.v1 | Synthesis of the Trans-Syn-Trans Perhydrobenzo[f]chromene Ring System | <p>A stereoselective synthesis of the <i>trans</i>-<i>syn</i>-<i>trans
</i>perhydrobenzo[<i>f</i>]chromene skeleton is presented. The target compound <b>3
</b>was achieved in six steps starting from the (<i>S</i>)-(+)-Wieland-Miescher
ketone. Key steps include the sp<sup>2</sup> alkylation at the a-carbon of an unsaturated ketone, Birch-type reductive alkylation, and an acid-catalyzed
cyclization. </p> | Amjad Ayad Qatran AlKhdhairawi; Syahrul Imran; Nurhuda Manshoor; Geoffrey A. Cordell; Narendra Babu Shivanagere Nagojappa; Jean-Frédéric Weber; Amjad Ayad Qatran Al-Khdhairawi | Natural Products; Organic Synthesis and Reactions; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7583b702a9b2cb718ccb0/original/synthesis-of-the-trans-syn-trans-perhydrobenzo-f-chromene-ring-system.pdf |
625fb40f11b1468e21297d57 | 10.26434/chemrxiv-2022-ww7pj-v2 | Silyl formates as hydrosilane surrogates for the transfer hydrosilylation of ketones | A transfer hydrosilylation of ketones employing silyl formates as hydrosilanes surrogates under mild conditions is presented. A total of 24 examples of ketones have been successfully converted to their corresponding silyl ethers with 61-99% yield in the presence of a PNHP-based ruthenium catalyst and silyl formate reagent. The crucial role of the ligand for the transformation is demonstrated. | R. Martin Romero; Neethu Thyagarajan; Nora Hellou; Clément Chauvier; Timothé Godou; Lucile Anthore-Dalion; Thibault Cantat | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/625fb40f11b1468e21297d57/original/silyl-formates-as-hydrosilane-surrogates-for-the-transfer-hydrosilylation-of-ketones.pdf |
6268d58dd048edc46652b16d | 10.26434/chemrxiv-2022-q8ppf | Homoepitaxial Diamond Grown in a Liquid Metal Solvent | A single-crystal diamond substrate (SCDS) with a (100) surface orientation was submerged in liquid gallium containing a small amount of dissolved silicon, and exposed to a mixture of methane and hydrogen at 1 atm and 900 ºC. New growth diamonds were found that are single crystal square pyramids with (111) facets and that are homoepitaxial to the substrate, as proven by scanning and transmission electron microscopy, and small angle X-ray scattering and diffraction. Raman spectroscopy with 13C-labeling prove that the methane as well as the SCDS are the carbon source for the newly grown diamond. This approach opens up new ways for growing diamond in liquid metal systems. | Yan Gong; Da Luo; Myeonggi Choe; Chohee Hyun; Chunhui Wang; Meihui Wang; Kyung Seong Won; Tae Joo Shin; Zonghoon Lee; Da Zhan; Rodney Ruoff | Materials Science; Catalysis; Nanoscience; Carbon-based Materials; Catalysts; Nanostructured Materials - Materials | CC BY NC ND 4.0 | CHEMRXIV | 2022-04-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6268d58dd048edc46652b16d/original/homoepitaxial-diamond-grown-in-a-liquid-metal-solvent.pdf |
63613a40ac45c7785aa0f74f | 10.26434/chemrxiv-2022-vzr8f | 13C and 15N NMR Detection of Metabolites via Relayed Hyperpolarization at 1 T and 1.4 T | Nuclear-spin hyperpolarization allows various magnetic-resonance applications in chemistry and medicine that are unattainable by standard methods. For such applications,
parahydrogen-based hyperpolarization approaches are particularly attractive because of their technical simplicity, low cost, and ability to quickly (in seconds) produce
large volumes of hyperpolarized material. Although many parahydrogen-based techniques have emerged, some of them remain unexplored due to the lack of careful
optimization studies. In this work, we investigate and optimize a novel parahydrogen-induced polarization (PHIP) technique that relies on proton exchange referred to below
as PHIP-relay. An INEPT (insensitive nuclei enhanced by polarization transfer) sequence is employed to transfer polarization from hyperpolarized protons to heteronuclei
(15N and 13C) and nuclear signals are detected using benchtop NMR spectrometers (1 T and 1.4 T, respectively). We demonstrate the applicability of the PHIP-relay technique for hyperpolarization of a wide range of biochemicals by examining such key metabolites as urea, ammonium, glucose, amino acid glycine, and a drug precursor benzamide. By optimizing chemical and NMR parameters of the PHIP-relay, we achieve a 17,100-fold enhancement of 15N signal of [13C, 15N2]-urea compared to the thermal signal measured at 1 T. We also show that repeated measurements with shorter exposure to parahydrogen provide a higher effective signal-to-noise ratio compared to longer parahydrogen bubbling. | Seyma Alcicek; Erik Van Dyke; Jingyan Xu; Szymon Pustelny; Danila Barskiy | Physical Chemistry; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-11-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63613a40ac45c7785aa0f74f/original/13c-and-15n-nmr-detection-of-metabolites-via-relayed-hyperpolarization-at-1-t-and-1-4-t.pdf |
60c750ddbdbb8964f1a39fa4 | 10.26434/chemrxiv.13090244.v1 | Kinetic Analysis of the Hydrolysis of Pentose-1-Phosphates Through Apparent Nucleoside Phosphorolysis Equilibrium Shifts | <div>Ask what an equilibrium can do for you:</div><div>Hydrolysis of pentose-1-phosphates leads to an apparent increase of the equilibrium conversion in nucleoside phosphorolysis reactions. This information can be leveraged via equilibrium thermodynamics to determine the hydrolysis kinetics of in situ generated sugar phosphates, which are known to be elusive and difficult to quantify.<br /></div> | Felix Kaspar; Peter Neubauer; Anke Kurreck | Analytical Chemistry - General; Biochemical Analysis; Spectroscopy (Anal. Chem.); Biochemistry; Biophysics; Biocatalysis; Biophysical Chemistry; Chemical Kinetics; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-10-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c750ddbdbb8964f1a39fa4/original/kinetic-analysis-of-the-hydrolysis-of-pentose-1-phosphates-through-apparent-nucleoside-phosphorolysis-equilibrium-shifts.pdf |
6282b3aa3f1e7c62e2c065d5 | 10.26434/chemrxiv-2022-1lmh5 | Supply chain readiness for widespread deployment of carbon capture and storage | There is uncertainty around whether current supply chains are able to cater for the increase in demand which will arise from carbon capture and storage (CCS) deployment. In order to meet the IPCC 2 °C target, 2800 - 4500 CCS plants of 1.7 Mtpa capacity need to be commissioned between 2030 and 2060. This study identifies the bottlenecks in the deployment of different CCS technologies by evaluating technology readiness level (TRL), commercial readiness index (CRI) and the supply chain readiness index (SCRI). Given the time required to establish supply chains, an under-developed supply chain will cause us to fall short of our climate change mitigation targets. Of the issues identified, we believe most process equipment related issues do not disqualify the deployment of a specific technology. Technologies with inefficiencies or low capacity can be addressed with multiple unit operations. However, reliance on specialised materials will limit deployment. Large-scale deployment of CCS is possible with currently available technology. We wish to highlight that increasing supply chain capacity should be a high priority, and advanced planning is required. | Mai Bui; David Danaci | Energy; Chemical Engineering and Industrial Chemistry | CC BY 4.0 | CHEMRXIV | 2022-05-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6282b3aa3f1e7c62e2c065d5/original/supply-chain-readiness-for-widespread-deployment-of-carbon-capture-and-storage.pdf |
6127c187fc08e33108831182 | 10.26434/chemrxiv-2021-rmsq8 | B,N-Embedded Double Hetero[7]helicenes with Strong Chiroptical Responses in the Visible Light Region | The development of helicene molecules with significant chiroptical responses covering a broad range of the visible spectrum is highly desirable for chiral optoelectronic applications; however, their absorption dissymmetry factors (gabs) have been mostly lower than 0.01. In this work, we report unprecedented B,N-embedded double hetero[7]helicenes with nonbonded B and N atoms, which exhibit excellent chiroptical properties, such as strong chiroptical activities from 300 to 700 nm, record high gabs up to 0.033 in the visible spectral range, and tunable circularly polarized luminescence (CPL) from red to near-infrared regions (600 ~ 800 nm) with high photoluminescence quantum yields (PLQYs) up to 100%. As revealed by theoretical analyses, the high gabs values are related to the separate molecular orbital distributions owing to the incorporation of nonbonded B and N atoms. The new type of B,N-embedded double heterohelicenes opens up an appealing avenue to the future exploitation of high-performance chiroptical materials. | Ji-Kun Li; Xing-Yu Chen; Yun-Long Guo; Xin-Chang Wang; Andrew C.-H. Sue; Xiao-Yu Cao; Xiao-Ye Wang | Organic Chemistry; Materials Science; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6127c187fc08e33108831182/original/b-n-embedded-double-hetero-7-helicenes-with-strong-chiroptical-responses-in-the-visible-light-region.pdf |
6648be2021291e5d1da1723a | 10.26434/chemrxiv-2024-vrn3h | Air-stable Membrane-free Magnesium Redox Flow Batteries | Membrane-free biphasic self-stratified batteries (MBSBs), utilizing aqueous/nonaqueous electrolyte systems, have garnered significant attention for their flexible manufacturing and cost-effectiveness. In this study, we present an ultrastable high-voltage Mg MBSB based on an aqueous/nonaqueous electrolyte system. The engineered aqueous electrolyte has a wide electrochemical stability window of 3.24 V. The Mg metal anode features an Mg2+-conductive protective coating. Two metal-free redox compounds, 2,2,6,6-tetramethyl piperidinyl oxy (TEMPO) and N-propyl phenothiazine (C3-PTZ), in dichloromethane serve as the catholyte. The Mg||TEMPO and Mg||C3-PTZ MBSBs exhibited high cell voltages of 2.07 and 2.12 V, respectively, and were studied under static, stirred, and flow conditions. The Mg MBSB was initially evaluated at different cathode concentrations (0.1, 0.3, and 0.5 M) under static conditions. Notably, Mg||TEMPO (0.5 M) and Mg||C3-PTZ (0.5 M) static batteries maintained exceptional performance over 500 cycles at 8 mA/cm2, with capacity retention rates of 97.84% and 98.87%, Coulombic efficiencies of 99.17% and 99.12%, and capacity utilization of 70.2% and 71.3%, respectively. Under stirred and flow conditions, the Mg||TEMPO (0.5 M) and Mg||C3-PTZ (0.5 M) batteries cycled 500 times at 12 mA/cm2, showing capacity retention rates of 99.82% and 99.88% (stirred), 93.58% and 92.16% (flow), respectively. The Mg||TEMPO (0.5 M) and Mg||C3-PTZ (0.5 M) batteries under flow conditions demonstrated power densities of 195 and 191 mW/cm2, respectively, surpassing those of 139 and 144 mW/cm2 under static conditions. These cost-effective Mg MBSBs offer remarkable performance, advancing Mg chemistry applications in organic flow batteries. | Rajeev Gautam; Jack McGrath; Xiao Wang; Jianbing Jiang | Energy | CC BY NC 4.0 | CHEMRXIV | 2024-05-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6648be2021291e5d1da1723a/original/air-stable-membrane-free-magnesium-redox-flow-batteries.pdf |
6135ca76fc08e3486b8baff9 | 10.26434/chemrxiv-2021-drd4l | Continuous Flow Bioconjugations of NIR-AZA Fluorophores via Strained Alkyne Cycloadditions with Intra-chip Fluorogenic Monitoring | The importance of bioconjugation reactions continues to grow as the need for cell specific targeting and dual therapeutic plus diagnostic medical applications increase. This necessitates new bioconjugation chemistries, synthetic and analytical methods. With this goal, continuous flow bioconjugations were readily achieved with short residence times for strained alkyne substituted carbohydrate and peptide biomolecules in reaction with azide and tetrazine substituted fluorophores. The catalyst and reagent-free inverse electron demand tetrazine cycloadditions proved more favourable than the azide 1,3-dipolar cycloadditions. The use of a fluorogenic tetrazine fluorophore in a glass channelled reactor chip allowed for intra-chip reaction monitoring by recording fluorescence intensities at various positions throughout the chip. As the Diels-Alder reactions proceeded through the chip, the fluorescence intensity increased accordingly in real-time. This novel approach to continuous flow bioconjugation reaction with monitoring may offer advantages over post-chip analysis. | Donal O'Shea; Sheila Fitzgerald | Organic Chemistry; Analytical Chemistry; Bioorganic Chemistry; Organic Synthesis and Reactions; Process Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2021-09-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6135ca76fc08e3486b8baff9/original/continuous-flow-bioconjugations-of-nir-aza-fluorophores-via-strained-alkyne-cycloadditions-with-intra-chip-fluorogenic-monitoring.pdf |
6532eb5cc3693ca993c1ce40 | 10.26434/chemrxiv-2023-f50w6 | Predicting Success in Cu-Catalyzed C–N Coupling Reactions using Data Science | Data science is assuming a pivotal role in guiding reaction optimization and streamlining experimental workloads in
the evolving landscape of synthetic chemistry. A discipline-wide goal is the development of workflows that integrate
computational chemistry and data science tools with high-throughput experimentation as it provides experimentalists
the ability to maximize success in expensive synthetic campaigns. Herein, we report an end-to-end data driven process
to effectively predict how structural features of coupling partners and ligands impact Cu-catalyzed C–N coupling
reactions. The established workflow underscores the limitations posed by substrates and ligands, while also providing
a systematic ligand prediction tool that uses probability to assess when a ligand will be successful. This platform is
strategically designed to confront the intrinsic unpredictability frequently encountered in synthetic reaction
deployment. | Mohammad Samha; Lucas Karas; David Vogt; Emmanuel Odogwu; Jennifer Elward; Jennifer Crawford; Janelle Steves; Matthew Sigman | Theoretical and Computational Chemistry; Organic Chemistry; Catalysis; Organic Synthesis and Reactions; Machine Learning; Chemoinformatics - Computational Chemistry | CC BY 4.0 | CHEMRXIV | 2023-10-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6532eb5cc3693ca993c1ce40/original/predicting-success-in-cu-catalyzed-c-n-coupling-reactions-using-data-science.pdf |
646f32f3be16ad5c57e3626f | 10.26434/chemrxiv-2023-kvfpw | Structure and flexibility of copper-modified DNA G-quadruplexes investigated by 19F ENDOR at 34 GHz | DNA G-quadruplexes (GQs) are of great interest due to their involvement in crucial biological processes such as telomerase maintenance and gene expression. Furthermore, they are reported as catalytically active DNAzymes and building blocks in bio-nanotechnology. GQs exhibit remarkable structural diversity and conformational heterogeneity, necessitating precise and reliable tools to unravel their structure-function relationships. Here, we present insights into the structure and conformational flexibility of unimolecular GQs with high spatial resolution via electron-nuclear double resonance (ENDOR) experiments combined with Cu(II) and fluorine labeling. These findings showcase the successful application of the 19F-ENDOR methodology at 34 GHz, overcoming the limitations posed by the complexity and scarcity of higher-frequency spectrometers. Importantly, our approach retains both sensitivity and orientational resolution. This integrated study not only enhances our understanding of GQs but also expands the methodological toolbox for studying other macromolecules. | Simon Lennard Schumann; Simon Kotnig; Yury Kutin; Maria Drosou; Lukas Stratmann; Yana Streltsova; Alexander Schnegg; Dimitrios Pantazis; Guido Clever; Müge Kasanmascheff | Physical Chemistry; Biological and Medicinal Chemistry; Biophysical Chemistry; Spectroscopy (Physical Chem.); Structure | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/646f32f3be16ad5c57e3626f/original/structure-and-flexibility-of-copper-modified-dna-g-quadruplexes-investigated-by-19f-endor-at-34-g-hz.pdf |
641b57dfdab08ad68f89e695 | 10.26434/chemrxiv-2023-q21sx | Discovery of Potential GSK-3β Allosteric Modulators for Alzheimer’s Disease | Glycogen Synthase Kinase-3 beta (GSK-3β) is a validated target-enzyme associated with Alzheimer’s Disease (AD). Usage of allosteric inhibitors of this enzyme represents a valid and promising therapeutic strategy due to their selective and subtle modulation, with a low probability of producing side effects. Nonetheless, only a few GSK-3β allosteric modulators with limited binding affinity have been uncovered so far and published in the public domain. Previous Virtual Screening (VS) studies have not considered such mechanism of action and did not achieve chemical diversity. Therefore, we applied two orthogonal VS workflows by means of shape-based similarity, QSAR, docking, and ADMET filters to select new and diverse GSK-3β allosteric inhibitors. Obtained hits have shown enhanced structural diversity and preliminary results as GSK-3β allosteric inhibitors according to in vitro assays. Furthermore, their GSK-3β allosteric inhibition were analyzed by blind docking and pocket coverage studies. These hits can be employed as template molecules for the discovery of more potent inhibitors, with the aim to expand the chemical space of GSK-3β allosteric modulators as promising agents in AD. | Guilherme Martins Silva; Vinicius Medeiros Alves; Suzane Quintana Gomes; Joshua Earl Hochuli; Eugene Muratov; Alexander Tropsha; Carlos Henrique Tomich Paula Silva | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Biochemistry; Computational Chemistry and Modeling; Machine Learning | CC BY NC ND 4.0 | CHEMRXIV | 2023-03-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/641b57dfdab08ad68f89e695/original/discovery-of-potential-gsk-3-allosteric-modulators-for-alzheimer-s-disease.pdf |
60c755a0ee301c95b6c7b1e3 | 10.26434/chemrxiv.14132108.v1 | Isoreticular Crystallization of Highly Porous Cubic Covalent Organic Cage Compounds | <p>Modular frameworks featuring well-defined pore structures in microscale domains establish tailor-made porous materials. For open molecular solids however, maintaining long-range order after desolvation is inherently challenging, since packing is usually governed by only a few supramolecular interactions. Here we report on two series of nanocubes obtained by co-condensation of two different hexahydroxy tribenzotriquinacenes (TBTQs) and benzene-1,4-diboronic acids (BDBAs) with varying linear alkyl chains in 2,5-position. <sup>n</sup>Butyl groups at the apical position of the TBTQ vertices yielded soluble model compounds, which were analyzed by mass spectrometry and NMR spectroscopy. In contrast, methyl-substituted cages spontaneously crystallized as isostructural and highly porous solids with BET surface areas and pore volumes of up to 3426 m<sup>2</sup> g<sup>−1</sup> and 1.82 cm<sup>3</sup> g<sup>−1</sup>. Single crystal X-ray diffraction and sorption measurements revealed an intricate cubic arrangement of alternating micro- and mesopores in the range of 0.97–2.2 nm that are fine-tuned by the alkyl substituents at the BDBA linker.</p> | Svetlana Ivanova; Eva Köster; Julian J. Holstein; Niklas Keller; Guido H. Clever; Thomas Bein; Florian Beuerle | Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Crystallography – Organic | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-03 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c755a0ee301c95b6c7b1e3/original/isoreticular-crystallization-of-highly-porous-cubic-covalent-organic-cage-compounds.pdf |
64bd5f97ae3d1a7b0d37d250 | 10.26434/chemrxiv-2023-09jh3-v2 | MBX: A many-body energy and force calculator for data-driven many-body simulations | MBX is a C++ library that implements many-body potential energy functions (PEFs) within the “many-body energy” (MB-nrg) formalism. MB-nrg PEFs integrate an underlying polarizable model with explicit machine-learned representations of many-body interactions to achieve chemical accuracy from the gas to the condensed phases. MBX can be employed either as a stand-alone package or as an energy/force engine that can be integrated with generic software for molecular dynamics and Monte Carlo simulations. MBX is parallelized internally using OpenMP, and can utilize MPI when available in interfaced molecular simulation software. MBX enables classical and quantum molecular simulations with MB-nrg PEFs, as well as hybrid simulations that combine conventional force fields and MB-nrg PEFs, for diverse systems ranging from small gas-phase clusters to aqueous solutions and molecular fluids to biomolecular systems and metal- organic frameworks. | Marc Riera; Christopher Knight; Ethan F. Bull-Vulpe; Xuanyu Zhu; Henry Agnew; Daniel G.A. Smith; Andrew C. Simmonett; Francesco Paesani | Theoretical and Computational Chemistry; Physical Chemistry; Materials Science; Computational Chemistry and Modeling; Machine Learning; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2023-07-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64bd5f97ae3d1a7b0d37d250/original/mbx-a-many-body-energy-and-force-calculator-for-data-driven-many-body-simulations.pdf |
667439fa01103d79c5b3306e | 10.26434/chemrxiv-2024-x2hfz-v2 | Catalytic Resonance Theory: The Catalytic Mechanics of Programmable Ratchets | Catalytic reaction networks of multiple elementary steps operating under dynamic conditions via a programmed input oscillation are difficult to interpret and optimize due to reaction system complexity. To understand these dynamic systems, individual elementary catalytic reactions were evaluated to identify their three fundamental characteristics that define their ability to promote reactions away from equilibrium. First, elementary catalytic reactions exhibit directionality to promote reactions forward or backward from equilibrium as determined by a ratchet directionality metric comprised of the input oscillation duty cycle and the reaction rate constants. Second, catalytic ratchets are defined by the catalyst state of strong or weak binding that permit reactants to proceed through the transition state. Third, elementary catalytic ratchets exhibit a cutoff frequency which defines the transition in applied frequency for which the catalytic ratchet functions to promote chemistry away from equilibrium. All three ratchet characteristics are calculated from chemical reaction parameters including rate constants derived from linear scaling parameters, reaction conditions, and catalyst conditions. The characteristics of the reaction network’s constituent elementary catalytic reactions provided an interpretation of complex reaction networks and a method of predicting the behavior of dynamic surface chemistry on oscillating catalysts. | Madeline Murphy; Sallye Gathmann; Rachel Getman; Lars Grabow; Omar Abdelrahman; Paul Dauenhauer | Catalysis; Heterogeneous Catalysis; Nanocatalysis - Reactions & Mechanisms | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/667439fa01103d79c5b3306e/original/catalytic-resonance-theory-the-catalytic-mechanics-of-programmable-ratchets.pdf |
638c44f5b103af5f7b0a3f56 | 10.26434/chemrxiv-2022-vbqkb-v2 | Self-Adapting Graphitic C6N6-Based Copper Single-Atom Catalyst for Smart Biosensors | Self-adaptability is highly envisioned for artificial devices such as robots with chemical noses. For this goal, seeking catalysts with multiple and modulable reaction pathways is promising but generally hampered by inconsistent reaction conditions. Herein, we report a self-adaptive CuSAC6N6 single-atom catalyst having two reactive oxygen-oriented pathways under the same reaction conditions. CuSAC6N6 consisted of coordinated peroxidase-like Cu-N coordination centers and photo-responsive donor-π-acceptor (D-π-A) units with promoted intramolecular charge separation and migration. Interestingly, it drove the basic oxidation of peroxidase substrates by the bound copper-oxo pathway, and undertook a second gain reaction triggered by light via the free hydroxyl radical pathway under the same conditions. A remarkable basic activity and a superb gain of up to 3.6 times under household lights were observed, significantly higher than that of its control systems, including solo carbon nitride-based nanozymes or photocatalysts, their mixtures, and even that under thermal stimuli to the maximum endured temperature for most lives. As an application, the self-adapting CuSAC6N6 was used to construct a glucose biosensor, which can intelligently switch the linear detection range and sensitivity to a diverse range of concentrations in vitro. | Qing Hong; Hong Yang; Yanfeng Fang; Wang Li; Caixia Zhu; Zhuang Wang; Sicheng Liang; Xuwen Cao; Zhixin Zhou; Yanfei Shen; Songqin Liu; Yuanjian Zhang | Catalysis; Analytical Chemistry; Analytical Chemistry - General; Biocatalysis; Redox Catalysis; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-12-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/638c44f5b103af5f7b0a3f56/original/self-adapting-graphitic-c6n6-based-copper-single-atom-catalyst-for-smart-biosensors.pdf |
6787d76081d2151a0245d9e5 | 10.26434/chemrxiv-2025-vhjcz | Simple, scalable production of ricinoleic acid-functionalized superparamagnetic nanoparticles, size- and shape-tunable, hydrophobic and hydrophilic | Materials properties at reduced dimensions are heavily influenced by both size and shape and, consequently, the synthetic approach. The synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) has been extensively explored in the literature; however, preparative routes that allow for precise particle size and shape tunability with the scope for surface functionalization and industrial scalability remain challenging. Secondly, taking into account the importance of green chemistry in nanomaterial synthesis, a synthetic protocol that limits the use of harmful chemicals is highly solicited. In this work, we outline a simple one-pot decomposition route that avoids the complexities involved in the preparation, separation, and purification of precursor complexes required of traditional preparative routes and, consequently, is easily scalable. Ricinoleic acid was employed as a greener alternative to oleic acid as both the metal complexing and the capping agent. The modified thermal decomposition route effectively bypasses the demanding precursor synthesis steps of the traditional thermal decomposition route while retaining its advantages. Minor modifications in the preparation scheme allow for the control of particle size and shape. Additionally, a simple and general NTA-mediated ligand-exchange protocol was outlined that can directly transfer the hydrophobic nanoparticles from the non-aqueous reaction mixture to an aqueous phase without the need for product separation from the crude reaction mixture. The general approach reported was extended to prepare monodispersed binary and ternary ferrite nanoparticles. Hydroxylation of the surface-attached ricinolate ligands was explored as a ligand modification strategy to render the nanoparticles hydrophilic and, thus, water-dispersible. X-ray diffraction indicated the presence of magnetite and maghemite phases. TEM images showed monodispersed nanoparticles with a narrow size distribution. EDS mapping showed the uniformity in cation distribution over the nanoparticles. XPS spectra were recorded for elemental analysis. The nanoparticles were superparamagnetic with a saturation magnetization of 41 emu/g.
| Sohel Reja; Sukumaran Vasudevan | Materials Science; Nanoscience; Magnetic Materials; Nanostructured Materials - Materials; Nanostructured Materials - Nanoscience; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6787d76081d2151a0245d9e5/original/simple-scalable-production-of-ricinoleic-acid-functionalized-superparamagnetic-nanoparticles-size-and-shape-tunable-hydrophobic-and-hydrophilic.pdf |
635fd43acf6de91bac29a203 | 10.26434/chemrxiv-2022-f8720 | Hydrolysis-resistant ester-based linkers enable ABS probe development for NIR bioluminescent imaging of hypoxia | Activity-based sensing (ABS) probes equipped with a NIR bioluminescence (BL) readout are promising chemical tools to study cancer biomarkers owing to their high sensitivity and deep tissue compatibility. However, the standard approach of installing a responsive trigger at the aniline site through a self-immolative linker is not suitable for NIR substrates because they require N,N-dialkylation at this position to achieve NIR emission. Capping the carboxylate is also unfavorable due to the instability of the resulting ester moiety which would result in high background signals. In this study, we rationally designed a hydrolysis-resistant ester featuring an isopropyl shielding arm. Compared to a benzyl ester analog (proxy for self-immolative linker), the new design is 140.5-fold and 67.8-fold more resistant toward spontaneous and esterase-mediated hydrolysis, respectively. After further in cellulo evaluation of stability, this ester moiety was transformed into a general self-immolative linker for ABS probe development via carboxylate masking. We showcased the utility of this technology by developing the first NIR BL probe for hypoxia sensing (BL660-NTR) and applied it in lung cancer cells and in a murine model of non-small cell lung cancer. | Anuj Yadav; Zhenxiang Zhao; Yourong Weng; Sarah Gardner; Catharine Brady; Oliver Pichardo Peguero; Jefferson Chan | Biological and Medicinal Chemistry; Chemical Biology | CC BY 4.0 | CHEMRXIV | 2022-11-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/635fd43acf6de91bac29a203/original/hydrolysis-resistant-ester-based-linkers-enable-abs-probe-development-for-nir-bioluminescent-imaging-of-hypoxia.pdf |
65c9ef18e9ebbb4db9297afe | 10.26434/chemrxiv-2024-v93zf | Desymmetrization of Diboron (4) by a Trifluorination B-Masking Strategy: Practical Synthesis of Unsymmetrical Diboron Species | Herein, we report a straightforward practical and simple method for efficiently synthesizing a BF3- containing unsymmetrical diboron salts. This method involves the direct desymmetrization of commercially available diboron (4). This desymmetrization is based on a selective B-masking strategy via nucleophilic trifluorination, providing the elusive diborons bearing a trifluoroborate group. The synthetic utility of these salts is demonstrated through various examples of (sequen-tial) B-ligand interconversions, enabling the synthesis of unsymmetrical diboron derivatives. These products, which serve as valuable building blocks, are obtained in high yields. | Nadim Eghbarieh ; Ahmad Masarwa | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c9ef18e9ebbb4db9297afe/original/desymmetrization-of-diboron-4-by-a-trifluorination-b-masking-strategy-practical-synthesis-of-unsymmetrical-diboron-species.pdf |
6135f40e65db1e51a6ada8ee | 10.26434/chemrxiv-2021-l3g6h | Chelator-based parameterization of the 12-6-4LJ molecular mechanics potential for more realistic metal ion-protein interactions | Metal ions are associated with a variety of proteins and play critical roles in a wide range of biochemical processes. There are multiple ways to study and quantify protein-metal ion interactions, including by molecular dynamics simulations. Recently, the Amber molecular mechanics forcefield was modified to include a 12-6-4LJ potential, which allows better description of non-bonded terms through the additional pairwise Cij coefficients. Here, we demonstrate a method of generating Cij parameters that allows parametrization of specific metal ion-ligating groups in order to tune binding energies computed by thermodynamic integration. The new Cij coefficients were tested on a series of chelators: EDTA, NTA, EGTA and the EF1 loop peptides from the proteins lanmodulin and calmodulin. The new parameters show significant improvements in computed binding energies relative to existing force fields and produce coordination numbers and ion-oxygen distances that are in good agreement with experimental values. This parametrization method should be extensible to a range of other systems and could be readily adapted to tune properties other than binding energies. | Paulius Kantakevičius; Calvin Mathiah; Linus Johannissen; Sam Hay | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2021-09-07 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6135f40e65db1e51a6ada8ee/original/chelator-based-parameterization-of-the-12-6-4lj-molecular-mechanics-potential-for-more-realistic-metal-ion-protein-interactions.pdf |
62a25ed4fe677dc52d4a4ea8 | 10.26434/chemrxiv-2022-4wrm1 | The Temperature Dependence
of the Linear-in-Density Thermal Conductivity Coefficient
Arising from the Lennard-Jones (12-6) Potential | Results of the modified Rainwater-Friend theory for the initial density dependence of the thermal conductivity arising from the Lennard-Jones (12-6) potential in the range of reduced temperature 0.5 ≤ T*≤ 100 have been correlated. Informed by theory, a collection of 41 functional temperature terms was narrowed to the eight most significant terms by structural optimization. The new formulation is the first that extrapolates correctly beyond the data range to reduced temperatures of 0.01 and 150. It contributes significantly to an improved understanding of thermal conductivities of gases at low densities and low temperatures where measurements are rare. | Arno Laesecke | Physical Chemistry; Physical and Chemical Properties; Transport phenomena (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-06-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62a25ed4fe677dc52d4a4ea8/original/the-temperature-dependence-of-the-linear-in-density-thermal-conductivity-coefficient-arising-from-the-lennard-jones-12-6-potential.pdf |
60c749a34c89198b34ad30f4 | 10.26434/chemrxiv.12093900.v1 | Potential COVID-19 Protease Inhibitors: Repurposing FDAapproved Drugs | Using as a template the crystal structure of COVID-19 protease, we developed a pharmacophore of functional centers of the protease inhibitor-binding pocket. Then we conducted data mining of the conformational database of FDA-approved drugs. This search brought 64 compounds that can be potential inhibitors of COVID-19 protease. The conformations of these compounds undergone 3D fingerprint similarity clusterization. Then we conducted docking of possible conformers of these drugs to the binding pocket of protease. We also conducted the same docking of random compounds. Free energies of the docking interaction for the selected compounds were clearly lower than random compounds. Three of the selected compounds were carfilzomib, cyclosporine A, and azithromycin—the drugs that already are tested for COVID-19 treatment. Among the selected compounds are two HIV protease inhibitors and two hepatitis C protease inhibitors. We recommend testing of the selected compounds for treatment of COVID-19.<br /><br /> | Valentina Kouznetsova; David Huang; Igor F. Tsigelny | Bioinformatics and Computational Biology | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749a34c89198b34ad30f4/original/potential-covid-19-protease-inhibitors-repurposing-fd-aapproved-drugs.pdf |
6568b5285bc9fcb5c9bdc362 | 10.26434/chemrxiv-2023-1cz5j | Strain-Released Hydrogenation of Donor-Acceptor Cyclopropane and Cyclobutane via Electrochemical Site Selective Carbonyl Reduction | An external oxidant or reductant, acid-free electrochemical protocol is established towards the hydrogenation of strained rings at room temperature and atmospheric pressure. After control experiments, it is revealed that the reaction is initiated via the reduction of the carbonyl group. The methodology is highly specific towards the strained rings and has a broad functional group tolerance. | Nakshatra Banerjee; Rakesh Kumar; Biswadeep Manna; Prabal Banerjee | Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Electrocatalysis; Redox Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2023-12-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6568b5285bc9fcb5c9bdc362/original/strain-released-hydrogenation-of-donor-acceptor-cyclopropane-and-cyclobutane-via-electrochemical-site-selective-carbonyl-reduction.pdf |
60c753714c89194104ad4329 | 10.26434/chemrxiv.13491312.v1 | High-Throughput Quality Control Assay for the Solid-Phase Syn-thesis of DNA-Encoded Libraries of Macrocycles | There is considerable interest in the development of libraries of scaffold-diverse macrocycles as a source of ligands for difficult targets, such as protein-protein interaction surfaces. A classic problem in the synthesis of high-quality macrocyclic libraries is that some linear precursors will cyclize efficiently while some will not, depending on their conformational preferences. We report here a powerful quality control method that can be employed to readily distinguish between scaffolds that do and do not cyclize efficiently during solid-phase synthesis of thioether macrocycles without the need for tedious liquid chromatography/mass spectrometry analysis. We demonstrate that this assay can be employed to identify largely linear “impurities” in a DNA-encoded library of macrocycles. We also use the method to establish a useful quality control protocol for re-synthesis of putative macrocyclic screening hits. | Animesh Roy; Thomas Kodadek | Bioorganic Chemistry; Combinatorial Chemistry; Organic Synthesis and Reactions; Chemical Biology; Drug Discovery and Drug Delivery Systems | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c753714c89194104ad4329/original/high-throughput-quality-control-assay-for-the-solid-phase-syn-thesis-of-dna-encoded-libraries-of-macrocycles.pdf |
65c57bba9138d23161b79388 | 10.26434/chemrxiv-2024-s5n5v | Double Hydrogen Atom Transfer Strategy for Catalytic Acceptorless Dehydrogenation of Cycloalkanes | The advancement of an effective hydrogen liberation tech-nology from liquid organic hydrogen carriers (LOHCs), such as cyclohexane and methylcyclohexane (MCH), holds significance in realizing a hydrogen-centric society. However, the attainment of homogeneous catalytic acceptorless dehydrogenation (CAD) characterized by elevated selectivity for thorough aromatization under mild conditions remains unrealized. In this study, a catalyst system, facilitated by a double hydrogen atom transfer (HAT) processes, has been devised for the CAD of inert cycloalkanes at ambient temperature under visible light irradiation. Through the synergistic utilization of tetrabutylammonium chloride (TBACl) and thiophosphoric acid (TPA) HAT catalysts, successful CAD with comprehensive aromatization has been accomplished with high functional group tolerance. | Rahul Jagtap; Yuki Nishioka; Stephen Geddis; Yu Irie; Fuki Masaaki; Yasuhiro Kobori; Rintaro Adachi; Akira Yamakata; Harunobu Mitsunuma; Motomu Kanai | Organic Chemistry; Catalysis; Energy; Organic Synthesis and Reactions; Homogeneous Catalysis; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-02-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c57bba9138d23161b79388/original/double-hydrogen-atom-transfer-strategy-for-catalytic-acceptorless-dehydrogenation-of-cycloalkanes.pdf |
62f1d2d1e78f708f613494cf | 10.26434/chemrxiv-2022-cw7ng | Photo-Chlorination of Linear Alkanes with 2-Position Selectivity Using a Metal-Organic Layer Catalyst | Controlling regioselectivity in activating C−H bonds in linear alkanes is challenging, as their multiple secondary C−H bonds have quite similar dissociation energies with no functional groups to differentiate between the bonds. Amidyl radicals generated from N‒halogen amides were reported to activate C−H bonds with an interesting 2-position selectivity. Here, with a possibility to access the amidyl radical photocatalytically, we coupled ligand-to-metal charge transfer (LMCT)-based radical generation and amide functional group on a tailor-designed metal-organic layer (MOL) material. We achieved efficient photo-chlorination of linear alkanes with 2-position selectivity. For example, with n-hexane as the substrate, 2-chloro-n-hexane was obtained with 85% selectivity and a turnover number of 2200 in 8 hours, together with a high apparent quantum yield of ~7% at room temperature. Transient absorption spectroscopy reveals that a FeIV species is involved in the initial photo-driven process that possibly oxidizes the amide center to an amidyl radical. | Huihui Hu; Yuming Su; Xiaoqi Cui; Boxuan Zhao; Jiawei Chen; Suyang Chen; Manting Chen; Haohua Huo; Cheng Wang | Catalysis; Heterogeneous Catalysis; Photocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2022-08-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62f1d2d1e78f708f613494cf/original/photo-chlorination-of-linear-alkanes-with-2-position-selectivity-using-a-metal-organic-layer-catalyst.pdf |
668d75efc9c6a5c07ac7d10f | 10.26434/chemrxiv-2024-06bv8 | Visualizing Plasmonic Hot Carrier-Mediated Metal Deposition and Nanoparticle Reshaping with Liquid Phase Transmission Electron Microscopy | Hot carriers generated by localized surface plasmon resonance (LSPR) in plasmonic nanoparticles can drive chemical reactions such as secondary metal deposition and organic catalysis. Rationally designing plasmonic nanostructures to target reactions requires understanding how local geometry impacts hot carrier reaction dynamics. Here we use liquid phase transmission electron microscopy (LP-TEM) and a radiolysis resistant solvent to visualize hot carrier-mediated silver deposition and gold nanorod (AuNR) reshaping. AuNRs grew primarily in the transverse direction and demonstrated tip sharpening and accelerated growth at predicted LSPR hotspots. Ex situ white- light illumination produced similar morphological and compositional changes, whereas radiolysis products did not. Nanorod growth dynamics relative to electron beam flux and AuNR orientation were supported by numerical simulations of electron beam induced LSPR. Isolating hot carrier- induced redox processes on AuNRs during LP-TEM enabled quantifying nanoscale metal deposition dynamics and spatially varying hot electron generation rates. This approach is expected to enable quantifying and visualizing a broad range of plasmonic carrier-mediated reactions. | Amy Chen; Asher Leff; Zhenpu Li; Carlos Rios Ocampo; Jonathan Boltersdorf; Taylor Woehl | Physical Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Plasmonic and Photonic Structures and Devices; Physical and Chemical Processes; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2024-07-10 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/668d75efc9c6a5c07ac7d10f/original/visualizing-plasmonic-hot-carrier-mediated-metal-deposition-and-nanoparticle-reshaping-with-liquid-phase-transmission-electron-microscopy.pdf |
6520b6ec45aaa5fdbb74f829 | 10.26434/chemrxiv-2023-gm7fh | Progress Towards the Total Synthesis of Jogyamycin Using a Tandem Ichikawa/Winstein Rearrangement | Jogyamycin is a densely functionalized aminocyclopentitol that displays potent antiprotozoal activity. Herein, we report a route to this natural product that utilizes an unprecedented transformation involving a tandem Ichikawa/Winstein rearrangement to install the C-1/C-2 diamine core. Attempts to further functionalize the C-3/C-4 alkene en route to jogyamycin are also discussed. | Kate Nicastri; Nels Gerstner; JENNIFER Schomaker | Organic Chemistry; Natural Products; Organic Synthesis and Reactions; Stereochemistry | CC BY 4.0 | CHEMRXIV | 2023-10-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6520b6ec45aaa5fdbb74f829/original/progress-towards-the-total-synthesis-of-jogyamycin-using-a-tandem-ichikawa-winstein-rearrangement.pdf |
622bfe97bbeaf3672605d57f | 10.26434/chemrxiv-2022-zg88d | Sequence and structure conservation analysis of the key coronavirus proteins supports the feasibility of discovering broad-spectrum antiviral medications. | Coronaviruses are a class of single-stranded, positive-sense RNA viruses that have caused three notable outbreaks over the past two decades: Middle East respiratory syndrome–related coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). All outbreaks have been associated with significant morbidity and mortality. In this study, we hypothesized that conserved binding sites in the key coronavirus proteins can be explored for the development of broad-spectrum direct acting anti-coronaviral compounds, identified such conserved binding site residues across coronaviruses, and validated our hypotheses with existing experimental data. We have identified four coronaviral proteins with highly conserved binding site sequence and 3D structure similarity: PLpro, Mpro, nsp10-nsp16 complex(methyltransferase), and nsp15 endoribonuclease. We have compiled all available experimental data for known antiviral medications inhibiting these targets and identified compounds active against multiple coronaviruses. The identified compounds representing potential broad-spectrum antivirals include: GC376, which is active against six viral Mpro (out of six tested, as described in research literature); mycophenolic acid, which is active against four viral PLpro (out of four); and emetine, which is active against four viral RdRp (out of four). The approach described in this study for coronaviruses, which combines the assessment of sequence and structure conservation across a viral family with the analysis of accessible chemical structure – antiviral activity data, can be explored for the development of broad-spectrum drugs for multiple viral families. | Cleber Melo-Filho; Tesia Bobrowski; Holli-Joi Martin; Zoe Sessions; Konstantin Popov; Nathaniel Moorman; Ralph Baric; Eugene Muratov; Alexander Tropsha | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Bioinformatics and Computational Biology; Chemical Biology; Chemoinformatics - Computational Chemistry | CC BY NC 4.0 | CHEMRXIV | 2022-03-14 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/622bfe97bbeaf3672605d57f/original/sequence-and-structure-conservation-analysis-of-the-key-coronavirus-proteins-supports-the-feasibility-of-discovering-broad-spectrum-antiviral-medications.pdf |
61ddcb4ddb4d9f663f9542a9 | 10.26434/chemrxiv-2022-23ck4 | Designing multifunctional CoOx layers for efficient and stable electrochemical energy conversion | Disordered and porous metal oxides are promising as earth-abundant and cost-effective alternatives to noble-metal electrocatalysts. Herein, we leverage non-saturated oxidation in plasma-enhanced atomic layer deposition to tune structural, mechanical, and optical properties of biphasic CoOx thin films, thereby tailoring their catalytic activities and chemical stabilities. To optimize the resulting film properties, we systematically vary the oxygen plasma power and exposure time in the deposition process. We find that short exposure times and low plasma powers incompletely oxidize the cobaltocene precursor to Co(OH)2 and result in the incorporation of carbon impurities. These Co(OH)2 films are highly porous and catalytically active, but their electrochemical stability is impacted by poor adhesion to the substrate. In contrast, long exposure times and high plasma powers completely oxidize the precursor to form Co3O4, reduce the carbon impurity incorporation, and improve the film crystallinity. While the resulting Co3O4 films are highly stable under electrochemical conditions, they are characterized by low oxygen evolution reaction activities. To overcome these competing properties, we applied the established relation between deposition parameters and functional film properties to design bilayer films exhibiting simultaneously improved electrochemical performance and chemical stability. The resulting biphasic films combine a highly active Co(OH)2 surface with a stable Co3O4 interface layer. In addition, these coatings exhibit minimal light absorption, thus rendering them well suited as protective catalytic layers on semiconductor light absorbers for application in photoelectrochemical devices. | Matthias Kuhl; Alex Henning; Lukas Haller; Laura Wagner; Chang-Ming Jiang; Verena Streibel; Ian Sharp; Johanna Eichhorn | Physical Chemistry; Physical and Chemical Properties | CC BY NC ND 4.0 | CHEMRXIV | 2022-01-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61ddcb4ddb4d9f663f9542a9/original/designing-multifunctional-co-ox-layers-for-efficient-and-stable-electrochemical-energy-conversion.pdf |
666f167a01103d79c559c774 | 10.26434/chemrxiv-2024-3s0kh-v2 | Enabling ionic transport in Li3AlP2 the roles of defects and disorder | Lithium phosphides are an emerging class of Li+ ion conductors for solid state battery applications. Despite potentially favorable characteristics as a solid electrolyte, stoichiometric crystalline Li3AlP2 has been reported to be an ionic insulator. Using a combined computational and experimental approach, we investigate the underlying reasons for this and show that ion transport can be induced via defects and structural disorder in this material. Lithium vacancies are shown to promote diffusion, and a low barrier to Li+ hopping of 0.2-0.3 eV is revealed by both simulations and experiment. However, polycrystalline pellets exhibit low ionic conductivity (≈10−8 S cm−1) at room temperature, attributed to crystalline anisotropy and the presence of resistive grain boundaries. These aspects can be overcome in nanocrystalline Li3AlP2, where ionic conductivity values approaching 10−6 S cm−1 and low electronic conductivities are achieved. This approach, leveraging both defects and structural disorder, should have relevance to the discovery of new, or previously overlooked, ion conducting materials. | Ji Hu; Alexander G. Squires; Jedrzej Kondek; Michael J. Johnson; Arthur B. Youd; Pooja Vadhva; Partha Paul; Philip J. Withers; Marco Di Michiel; Dean S. Keeble; Michael Ryan Hansen; David O. Scanlon; Alexander J.E. Rettie | Materials Science; Chemical Engineering and Industrial Chemistry; Materials Processing | CC BY NC ND 4.0 | CHEMRXIV | 2024-06-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/666f167a01103d79c559c774/original/enabling-ionic-transport-in-li3al-p2-the-roles-of-defects-and-disorder.pdf |
630c70d890802de4666e30a5 | 10.26434/chemrxiv-2022-btd57 | Azaboracyclooctatetraenes Reveal that the Different Aspects of Triplet State Baird-Aromaticity are Nothing but Different | The Baird-aromaticity of BN/CC cyclooctatetraene isosteres (azaboracyclooctatetraenes) in their lowest triplet states (T1) has been explored through computations of various aromaticity indices describing the different aspects of aromaticity (magnetic, electronic, energetic and geometric). While cyclooctatetraene (COT) is aromatic in its T1 state following Baird’s 4n rule, we now reveal that the degree of Baird-aromaticity of the BN isosteres varies extensively with aromaticity aspect considered. According to energetic and electronic indices, the thermodynamically most stable octagonal B4N4H8 isomer, having alternating B and N pattern (borazocine, B4N4COT-A), is only weakly aromatic or nonaromatic in T1, while the magnetic descriptors suggest it to have about two thirds the Baird-aromaticity of T1 state COT (3COT). The extent of Baird-aromaticity of intermediate BN/CC isosteres also varies markedly with aspect investigated. On the other hand, magnetic indices indicate that borazine (B3N3H6) in its singlet ground state (S0) is weakly aromatic. This opposite features in the magnetic aromaticity descriptors of, respectively, S0 state borazine (1borazine) and 3B4N4COT-A can be linked to differences in the symmetries of the orbitals involved in the virtual transitions from occupied to unoccupied orbitals which describe the response of a molecule in an external magnetic field. For azaboraCOTs, the magnetic aspect of T1 state Baird-aromaticity (response aromaticity) is not related to the electronic and energetic aspects (intrinsic aromaticity), findings that underline earlier observations on differences between the various aspects of the aromaticity phenomenon (or phenomena). | Preethanuj Preethalayam; Nathalie Proos Vedin; Slavko Radenković; Henrik Ottosson | Theoretical and Computational Chemistry; Organic Chemistry; Inorganic Chemistry; Physical Organic Chemistry; Bonding; Main Group Chemistry (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-08-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/630c70d890802de4666e30a5/original/azaboracyclooctatetraenes-reveal-that-the-different-aspects-of-triplet-state-baird-aromaticity-are-nothing-but-different.pdf |
60c749a14c89199f28ad30f3 | 10.26434/chemrxiv.12091356.v1 | Computational Search for Potential COVID-19 Drugs from FDA-Approved Drugs and Small Molecules of Natural Origin Identifies Several Anti-Virals and Plant Products | <div>The world is facing COVID-19 pandemic at the present time, for which mild symptoms include fever and dry cough. In severe cases it could lead to pneumonia and ultimately death in some instances. The pathogen, SARS-CoV-2, is one of the human coronaviruses which was identified to infect humans first in December 2019. We have interrogated the capacity to repurpose around 2300 FDA-approved drugs and more than 300,000 small molecules of natural origin towards drug identification through virtual screening and molecular dynamics. Interestingly, we observed simple molecules like lactose, previously known anti-virals and few secondary metabolites of plants as promising hits.</div><div><br /></div><div></div> | Abhishek Sharma; Vikas Tiwari; Ramanathan Sowdhamini | Computational Chemistry and Modeling; Theory - Computational; Chemoinformatics - Computational Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c749a14c89199f28ad30f3/original/computational-search-for-potential-covid-19-drugs-from-fda-approved-drugs-and-small-molecules-of-natural-origin-identifies-several-anti-virals-and-plant-products.pdf |
60c743fb4c8919f9c1ad2734 | 10.26434/chemrxiv.9734000.v1 | Intermolecular sp3-C–H Amination for the Synthesis of Saturated Azacycles | The preparation of substituted azetidines and larger-ring,
nitrogen-containing saturated heterocycles is enabled through efficient and
selective intermolecular sp<sup>3</sup>-C–H amination of alkyl bromide
derivatives. A range of substrates is demonstrated to undergo C–H amination and
subsequent sulfamate alkylation in good to excellent yield. <i>N</i>-Phenoxysulfonyl-protected products can
be unmasked under neutral or mild basic conditions to yield the corresponding cyclic
2° amines. The preparative convenience of this protocol is demonstrated through
gram-scale and telescoped multi-step procedures. Application of this technology
is highlighted in a nine step total synthesis of an unusual azetidine-containing
natural product, penaresidin B. | Kerry Betz; Nicholas Chiappini; Justin Du Bois | Natural Products; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c743fb4c8919f9c1ad2734/original/intermolecular-sp3-c-h-amination-for-the-synthesis-of-saturated-azacycles.pdf |
60c752940f50db46af3979ed | 10.26434/chemrxiv.13325228.v1 | Engineering Donor-Acceptor Conjugated Polymers for High-Performance and Fast-Response Organic Electrochemical Transistors | To
date, high-performance organic electrochemical transistors (OECTs) are all
based on polythiophene systems. Donor-acceptor (D-A) conjugated polymers are
expected to be promising materials for OECTs owing to their high mobility and
comparatively low crystallinity (good for ion diffusion). However, the OECT
performance of D-A polymers lags far behind that of the polythiophenes. Here we
synergistically engineered the backbone, side chain of a series of
diketopyrrolopyrrole (DPP)-based D-A polymers and found that redox potential,
molecular weight, solution processability, and film microstructures are
essential to their performance. Among the polymers, P(bgDPP-MeOT2) exhibited a
figure-of-merit (μC*) of 225 F cm<sup>–1</sup> V<sup>–1</sup> s<sup>–1</sup>, <a>over one order of magnitude higher than previously reported
D-A polymers. Besides, the DPP polymers exhibited high hole mobility over 2 cm<sup>2</sup>
V</a><sup>−1</sup> s<sup>−1</sup>,
significantly higher than all D-A polymers employed in OECTs, leading to fast
response OECTs with a record low turn-off response time of 30 μs. <a>The polymer also exhibited
better stability than polythiophene systems with current retention of 98.8% over
700 electrochemical switching cycles.</a> This work provides a systematic
solution to unleash the high-performance and fast-response nature of D-A
polymers in OECTs. | Hanyu Jia; Zhen Huang; Peiyun Li; song zhang; yunfei wang; jie-yu wang; Xiaodan Gu; Ting Lei | Conducting polymers; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c752940f50db46af3979ed/original/engineering-donor-acceptor-conjugated-polymers-for-high-performance-and-fast-response-organic-electrochemical-transistors.pdf |
65e1589f9138d23161633009 | 10.26434/chemrxiv-2024-4p2n8 | CO2-empowered Spin Transition in an Interdigitated Hofmann Co-ordination Polymer | The increased level of the anthropogenic emission of CO2 urges the development of CO2-responsive materials that can sense and memorize the system’s information and use it as an electronic output. Herein, we report the first case of a CO2-gated reversible spin-state switching in an interdigitated Hofmann-type coordination polymer [FeIIPd(CN)4L2] (1, L = methyl isonicotinate), showing a wide range of temperature (Teq) shift from ~150 K at PCO2 = 0 kPa to ~250 K at PCO2 = 100 kPa. Interestingly, the emergence of a stepped behavior below PCO2 = 10 kPa and overlapping magnetic susceptibility values with no change in the transition temperature (TH) above PCO2 = 10 kPa elucidate the selective stabilization of the LS state under the influence of the CO2 atmosphere. Based on the magnetic response and the phase transition diagram obtained under the respective PCO2, a plausible scenario of the spin-state switching can be inter-preted as 1LS (1LS + 1’LS) (1HS + 1’LS) 1’HS 1HS, where the CO2-free and CO2-encapsulated states are represent-ed as 1, and 1’, respectively. The highly selective CO2 sorption and the magnetic sensitivity based on the varied exter-nal CO2 pressure corroborate a novel and intriguing case for the development of CO2-responsive magnets henceforth. | ABHIK PAUL; Wataru Kosaka; Dibya Jyoti Mondal; Bhart Kumar; Hitoshi Miyasaka; Sanjit Konar | Inorganic Chemistry; Coordination Chemistry (Inorg.); Magnetism; Solid State Chemistry; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65e1589f9138d23161633009/original/co2-empowered-spin-transition-in-an-interdigitated-hofmann-co-ordination-polymer.pdf |
65e8a7b066c13817295dcf66 | 10.26434/chemrxiv-2024-h7n1z | Tc(VII)/Tc(V) direct coordination with secondary building unit of uranyl hybrid materials and their isolation as molecular cluster | Tc-99 oxoanion pertechnetate (TcO4-), reduced Tc species and actinides co-exist in spent nuclear fuel/legacy waste and co-extract together during reprocessing. Herein, we reported five new molecular cluster/extended structures with pentameric/tetrameric uranyl building units directly coordinated to oxoanion TcO4-/ReO4- (surrogate) and reduced technetium cation Tc(V). The isolation and characterization of these new compounds will be useful in furthuring the understanding of coordination between Tc species and actinides, which is critical for their efficient seperation/recovery. | Mohammad Shohel; May Nyman | Inorganic Chemistry; Energy; Earth, Space, and Environmental Chemistry; Lanthanides and Actinides; Nuclear Chemistry; Crystallography – Inorganic | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65e8a7b066c13817295dcf66/original/tc-vii-tc-v-direct-coordination-with-secondary-building-unit-of-uranyl-hybrid-materials-and-their-isolation-as-molecular-cluster.pdf |
60c7504b702a9bc48918bd42 | 10.26434/chemrxiv.13013516.v1 | Nucleotide Interaction with Chitosan Layer Deposited on Fumed Silica Surface: Practice and Theory towards Establishing the Mechanism at the Molecular Level | The growing interest in
gene therapy is coupled to the strong need for the development of safe and
efficient gene transfection vectors. A composite based on chitosan and fumed
silica has been found to be a prospective gene delivery carrier. This study
presents an investigation of the nature of the bonds between a series of mono-,
di- and triphosphate nucleotides with a chitosan layer deposited on a fumed silica
surface. It was observed that the adsorption of most of the studied nucleotides
is determined by the formation of one surface complex. Experimentally measured
surface complex formation constants (logK) of the nucleotides were found to be in
range 2.69–4.02 which is higher than that for the orthophosphate (2.39). Theoretically
calculated nucleotide complexation energies for chitosan deposited on the
surface range from 11.5 to 23.0 kcal·mol<sup>–1</sup>
in agreement with experimental data. The adsorption
of nucleotides was interpreted using their calculated speciation in aqueous
solution. Based on the structures
of all optimized complexes determined from quantum-chemical PM6 calculations, electrostatic
interactions between the surface-located NH<sub>3</sub><sup>+</sup> groups and
–PO<sub>3</sub>H<sup>–</sup>–/–PO<sub>3</sub><sup>2-</sup> fragments of the nucleotides was identified to
play the decisive role in the adsorption mechanism. The saccharide fragment of monophosphates
also plays an important role in the binding of the nucleotides to chitosan through the creation of hydrogen bonds; in the case of di- and
triphosphates the role of the saccharide fragment decreases significantly. | Tetyana Budnyak; Nataliya Vlasova; Lyudmila P. Golovkova; Olga Markitan; Glib V. Baryshnikov; Hans Ågren; Adam Slabon | Interfaces; Physical and Chemical Properties; Surface | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7504b702a9bc48918bd42/original/nucleotide-interaction-with-chitosan-layer-deposited-on-fumed-silica-surface-practice-and-theory-towards-establishing-the-mechanism-at-the-molecular-level.pdf |
6784b8356dde43c908499dfe | 10.26434/chemrxiv-2025-q53n2 | Vision intelligence assists microstructural optimization of Ag-Bi-I perovskite-inspired materials | The slow progress in microstructural design for thin-film semiconductors remains a significant bottleneck in transitioning emerging materials into practical applications. While machine learning (ML) shows great promise in accelerating data analysis, effectively linking microstructural insights to actionable synthetic plans remains a complex challenge that surpasses the capabilities of a single model. We present the Daisy Visual Intelligence Framework, a computational platform using compound ML models for semiconductor microstructure optimization. Daisy integrates goal-oriented computer vision with an optimization agent to create a feedback loop between microstructural characterization and synthesis planning. Trained on historical synthesis and scanning electron microscopy (SEM) data for Ag-Bi-I compounds, an emerging family of perovskite-inspired materials with promise for indoor photovoltaics, the framework demonstrates the ability to learn effectively from imbalanced and heterogeneous experimental datasets. The artificial intelligence agent within Daisy identified new processing windows, which were experimentally validated to produce thin films with larger grain sizes and reduced defect densities. Our work highlights the transformative potential of agentic learning using visual information in advancing microstructural design, bridging the gap between materials discovery and application readiness. | Kshithij Mysore Nandishwara; Shuan Cheng; Pengjun Liu; Huimin Zhu; Xiaoyu Guo; Fabien C.-P. Massabuau; Robert L.Z. Hoye; Shijing Sun | Materials Science; Thin Films | CC BY NC 4.0 | CHEMRXIV | 2025-01-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6784b8356dde43c908499dfe/original/vision-intelligence-assists-microstructural-optimization-of-ag-bi-i-perovskite-inspired-materials.pdf |
62bdd48abe884b50f7f654ef | 10.26434/chemrxiv-2022-mpb1w | A combined XPS and computational study of the chemical reduction of BMP-TFSI by lithium | Employing density functional theory (DFT) calculations and x-ray photoelectron spectroscopy (XPS), we identify products of the reaction of the ionic liquid N,N - butylmethylpyrrolidinum bis(trifluoromethylsulfonyl)imide (BMP-TFSI) with lithium in order to model the initial chemical processes contributing to the formation of the solid electrolyte interphase in batteries. Besides lithium oxide, sulfide, carbide and fluoride, we find lithium cyanide or cyanamide as possible, thermodynamically stable products in the Li-poor regime, whilst Li3N is the stable product in the Li-rich regime. The thermodynamically controlled reaction products as well as larger fragments of TFSI persisting due to kinetic barriers could be identified by a comparison of experimentally and computationally determined core level binding energies. | Katrin Forster-Tonigold; Florian Buchner; Joachim Bansmann; R. Jürgen Behm; Axel Gross | Theoretical and Computational Chemistry; Physical Chemistry; Energy; Computational Chemistry and Modeling; Energy Storage | CC BY NC 4.0 | CHEMRXIV | 2022-07-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62bdd48abe884b50f7f654ef/original/a-combined-xps-and-computational-study-of-the-chemical-reduction-of-bmp-tfsi-by-lithium.pdf |
6712624151558a15ef710c45 | 10.26434/chemrxiv-2023-918dp-v4 | Temperature-Dependent Diastereodivergent [4+3] Annulation: Synthesis of Ferrocene Fused Azepines via Rh(III)-Catalysis | Herein, we disclose the first temperature-dependent diastereodivergent [4+3] annulation of ferrocene-p-tosylamides via C-H activation with allenes by Rh-catalyst. At room temperature, Rh-catalyzed [4+3] annulation selectively offered one diastere-omer (>20:1 dr), whereas at 60 ᵒC, another diastereomer was obtained exclusively with >20:1 dr. The control experiments, isotopic labeling study, and DFT calculations suggested that the reaction proceeds via a σ-bonded rhodacycle avoiding steric repulsion between the phenyl ring of allene and Cp* of Rh-catalyst. Consequently, reductive elimination offered a kinetically con-trolled diastereomer at room temperature. Under heating (60 ᵒC) conditions, kinetically controlled diastereomer undergoes C-N bond ring opening to afford completely thermodynamically controlled diastereomer. | Raviraj Ananda Thorat; Devendra Parganiha; Saket Jain; Vishal Choudhary; Batul Shakir; Komal Rohilla; Raushan Kumar Jha; SANGIT KUMAR | Organic Chemistry; Catalysis; Organometallic Chemistry; Homogeneous Catalysis; Bond Activation; Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-10-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6712624151558a15ef710c45/original/temperature-dependent-diastereodivergent-4-3-annulation-synthesis-of-ferrocene-fused-azepines-via-rh-iii-catalysis.pdf |
6616cc9621291e5d1d8cd094 | 10.26434/chemrxiv-2024-c8ttb | CONDUCTOR, a fast, efficient and robust tool for continuum solvation computations for macromolecules | This introduces CONDUCTOR, an algorithm for computing solvation effects for large molecules using the continuum approximation. While we represent electrostatic polarization by the mechanism of induced surface charge, we avoid the explicit computation of a Green function as found with the Boundary Element Method (BEM). Instead, we assume as a starting point the conducting approximation for aqueous solvent, and adjust the induced polarization charge defined on the molecular surface, so as to force the electric potential to zero at field points positioned on the solvent side of the surface. The charge density for finite external dielectric constant can then be approximated using a simple perturbation approach. The reaction field arising from the induced charge distribution is used to compute the contribution of solvent to the electrostatic potential and forces for the molecular fixed charges. The method is robust, being relatively insensitive to small defects or singularities in the molecular surface, and can be extended to periodic structures such as membranes. Computations for proteins with nearly 300 residues can be carried out in about ten minutes on inexpensive server hardware. We compare the results of our new approach to the conventional Boundary Element Method, and find them equivalent, and by some measures superior, to the BEM, and achieved with much less computational expense. | Randy Zauhar; Andre Juffer | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Biophysical Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-04-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6616cc9621291e5d1d8cd094/original/conductor-a-fast-efficient-and-robust-tool-for-continuum-solvation-computations-for-macromolecules.pdf |
65c3c7a69138d23161a22ad3 | 10.26434/chemrxiv-2024-fb9zp | Biomarkers for early cancer detection: A landscape view of recent advancements, spotlighting pancreatic and liver cancers | Cancer is one of the leading causes of death worldwide. Early cancer detection is critical because it can significantly improve treatment outcome thus saving lives, reducing suffering, and lessening psychological and economic burdens. Cancer biomarkers provide varied information about cancer, from early detection of malignancy to decisions on treatment and subsequent monitoring. A large variety of molecular, histologic, radiographic, or physiological entities or features are amongst the common types of cancer biomarkers. Sizeable recent methodological progress and insights have promoted significant development in the field of early cancer detection biomarkers. Here we provide an overview of recent advancement in the knowledge related to biomolecules and cellular entities used for early cancer detection. We examine data from the CAS Content Collection, the largest human-curated collection of published scientific information, as well as from the biomarker datasets at Excelra, and analyze the publication landscape of recent research. We also discuss the evolution of key concepts, cancer biomarkers development pipelines, with a particular focus on pancreatic and liver cancers, known as remarkably difficult to detect early, with particularly high morbidity and mortality. The objective of the paper is to provide a broad overview of the evolving landscape of current knowledge on cancer biomarkers, to outline challenges and evaluate growth opportunities, in order to further efforts in solving the problems that remain. The merit of the article stems from the extensive, wide-ranging coverage of the most up-to-date scientific information, allowing unique, unmatched breadth of landscape analysis and in-depth insights. | Rumiana Tenchov; Aparna Sapra; Janet Sasso; Krittika Ralhan; Anusha Tummala; Norman Azoulay; Qiongqiong Zhou | Biological and Medicinal Chemistry; Cell and Molecular Biology | CC BY 4.0 | CHEMRXIV | 2024-02-08 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65c3c7a69138d23161a22ad3/original/biomarkers-for-early-cancer-detection-a-landscape-view-of-recent-advancements-spotlighting-pancreatic-and-liver-cancers.pdf |
60c752be0f50db69fc397a1b | 10.26434/chemrxiv.12959972.v2 | Air-Carbon Ablation Model for Hypersonic Flight from Molecular Beam Data | Recent molecular beam experiments of high velocity O, N, and O<sub>2</sub> impacting carbon material at high temperature produced detailed surface chemistry data relevant for carbon ablation processes. New data on O and N reactions with carbon has been published using a continuous molecular beam with lower velocity (2000 m/s) and approximately 500 times higher beam flux than previous pulsed-beam experiments. This data is interpreted to construct a new air-carbon ablation model for use in modeling carbon heat shield ablation. The new model comprises 20 reaction mechanisms describing reactions between impinging O, N, and O<sub>2</sub> species with carbon and producing scattered products including desorbed O and N, O<sub>2</sub> and N<sub>2</sub> formed by surface-catalyzed recombination, as well as CO, CO<sub>2</sub>, and CN. The new model includes surface-coverage dependent reactions and exhibits non-Arrhenius reaction probability in agreement with experimental observations. All reaction mechanisms and rate coefficients are described in detail and each is supported by experimental evidence or theory. The model predicts pressure effects and is tested for a wide range of temperatures and pressures relevant to hypersonic flight. Model results are shown to agree well with available data and are shown to have significant differences compared to other models from the literature. <br /> | Krishna Sandeep Prata; Timothy Minton; Thomas
E. Schwartzentruber | Space Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2020-12-01 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c752be0f50db69fc397a1b/original/air-carbon-ablation-model-for-hypersonic-flight-from-molecular-beam-data.pdf |
66dab545cec5d6c1424bc290 | 10.26434/chemrxiv-2024-jrz0h | Quasi-liquid grain boundary conductivity in solid electrolyte candidate lithium imide | All-solid-state batteries utilising a Li-metal anode have long promised to be the next-generation of high-performance energy storage device, with a step-change in energy density, cycling stability and cell safety touted as potential advantages compared to conventional Li-ion battery cells. A key to enabling this technology is the development of solid-state electrolytes with the elusive combination of high ionic conductivity, wide electrochemical stability and the ability to form a conductive and stable interface with Li metal. Presently, oxide and sulfide-based materials, particularly garnet and argyrodite-type structures, have proved most promising for this application. However, these still suffer from a number of challenges, including resistive lithium metal interfaces, poor lithium dendrite suppression (at high current density) and low voltage stability. Here we report the first application of lithium imide, an antifluorite-structured material, as a solid electrolyte in a Li-metal battery. Low-temperature synthesis of lithium imide produces promising Li-ion conductivity, reaching > 1 mS cm-1 at 30 ˚C using a modest post-synthetic mechanochemical treatment, as well as displaying at least 5 V stability vs Li+/Li. In situ electrochemical operation of lithium imide with Li-metal electrodes reveals a 1000-fold increase in its measured ionic conductivity, whilst appearing to remain an electronic insulator. It is postulated that stoichiometry variation at the grain boundary leads to a highly disordered quasi-liquid state, facilitating this conductivity improvement. Furthermore, the material is shown to possess impressive stability under high current density conditions (70 mA cm-2) as well as the ability to operate in Li-metal battery cells. These results not only highlight the promising performance of lithium imide, but also its potential to be the basis for a new family of antifluorite based solid electrolytes. | Jeremy Lowen; Teresa Insinna; Tharigopala Beatriceveena; Mark Stockham; Bo Dong; Sarah Day; Clare Grey; Emma Kendrick; Peter Slater; Paul Anderson; Joshua Makepeace | Inorganic Chemistry; Energy; Solid State Chemistry; Energy Storage; Materials Chemistry; Crystallography – Inorganic | CC BY NC 4.0 | CHEMRXIV | 2024-09-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66dab545cec5d6c1424bc290/original/quasi-liquid-grain-boundary-conductivity-in-solid-electrolyte-candidate-lithium-imide.pdf |
6495ee8e4821a835f34b54ab | 10.26434/chemrxiv-2021-qvhgs-v5 | Second-harmonic generation provides insight into the screening response of the liquid water interface | We use second harmonic generation (SHG), molecular dynamics simulation, and theoretical modeling to study the response of the neat liquid water-air interface to changes in the potential of an external electrode positioned near the liquid, but out of direct contact. We observe a parabolic dependence of second harmonic intensity on applied potential. Based on standard theory, we associate this dependence with the response of the diffuse layer water molecules to changes in interfacial potential profile. Taking the literature value for this response leads to the unexpected conclusion that the electric fields within the diffuse layer are opposite in sign from those originating from the electrodes. This conclusion implies that the traditional continuum-based models of interfacial screening lack the complexity necessary to properly describe the potential profile of the liquid water-vapor interface. Effects such as overscreening in the topmost interfacial layer and extended correlations in the interfacial hydrogen bonding network may play a role in governing the response of the water interface to external fields. | Kamal Ray; Aditya Limaye; Ka Chon Ng; Ankur Saha; Sucheol Shin; Biswajit Biswas; Marie-Pierre Gaigeot; Simone Pezzotti; Adam Willard; Heather Allen | Theoretical and Computational Chemistry; Physical Chemistry; Interfaces; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2023-06-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6495ee8e4821a835f34b54ab/original/second-harmonic-generation-provides-insight-into-the-screening-response-of-the-liquid-water-interface.pdf |
60c7592d0f50dbe83b3985aa | 10.26434/chemrxiv.14526642.v2 | Diffusion of CH4 and N2 in Barium-Exchanged Reduced Pore Zorite (Ba-RPZ) and Zeolite 4A | <pre><p>Barium-exchanged reduced pore zorite (Ba-RPZ) is a titanosilicate molecular sieve that is able to separate CH4 from N2 based on their relative molecular sizes. A detailed study of N2 and CH4 adsorption equilibrium and diffusion on Ba-RPZ was completed using low and high-pressure volumetry. Adsorption equilibrium data for Ba-RPZ from limiting vacuum to 1.2 bar were measured at 30, 40, and 50° C for CH4 and at 30, 50, and 70° C for N2. Constant volume uptake experiments were conducted to estimate the diffusivities of CH4 at 30, 40, and 50° C and N2 -20, -10, and 0° C. Similar experiments were carried out with zeolite 4A to validate the methods used in this study. On the one hand, the transport of N2 in Ba-RPZ was found to be controlled by diffusion in the micropores. On the other hand, the transport of CH4 in Ba-RPZ was described by a dual-resistance model, including a barrier resistance and micropore diffusional resistance. Both the barrier and micropore diffusion coefficients demonstrated concentration dependence. While the micropore diffusion constant followed Darken's relationship, the barrier resistance did not. A concentration-dependent dual-resistance diffusion model for methane was constructed and validated using experimental data across a range of pressures and temperatures. The concentration-dependent dual-resistance model was able to describe the complex diffusion behaviour methane displays as it progressed from the dual-resistance controlled region to the micropore-controlled region of the isotherm. The calculated CH4/N2 kinetic selectivity of Ba-RPZ was shown to be significantly larger than the current benchmark material for CH4/N2 separation.</p></pre> | Nicholas S. Wilkins; James A. Sawada; Arvind Rajendran | Separation Science | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7592d0f50dbe83b3985aa/original/diffusion-of-ch4-and-n2-in-barium-exchanged-reduced-pore-zorite-ba-rpz-and-zeolite-4a.pdf |
619f26d9f93ad36bf6b346f3 | 10.26434/chemrxiv-2021-hczsl | Intelligent Molecular Identification for High Performance Organosulfide Capture Using Active Machine Learning Algorithm | Machine learning and computer-aided approaches significantly accelerate molecular design and discovery in scientific and industrial fields increasingly relying on data science for efficiency. The typical method used is supervised learning which needs huge datasets. Semi-supervised machine learning approaches are effective to train unlabeled data with improved modeling performance, whereas they are limited by the accumulation of prediction errors. Here, to screen solvents for removal of methyl mercaptan, a type of organosulfur impurities in natural gas, we constructed a computational framework by integrating molecular similarity search and active learning methods, namely, molecular active selection machine learning (MASML). This new model framework identifies the optimal molecules set by molecular similarity search and iterative addition to the training dataset. Among all 126,068 compounds in the initial dataset, 3 molecules were identified to be promising for methyl mercaptan (MeSH) capture, including benzylamine (BZA), p-methoxybenzylamine (PZM), and N,N-diethyltrimethylenediamine (DEAPA). Further experiments confirmed the effectiveness of our modeling framework in efficient molecular design and identification for capturing methyl mercaptan, in which DEAPA presents a Henry's law constant 89.4% lower than that of methyl diethanolamine (MDEA). | Yuxiang Chen; Chuanlei Liu; Yang An; Yue Lou; Yang Zhao; Cheng Qian; Hao Jiang; Kongguo Wu; Xianghui Zhang; Hui Sun; Di Wu; Benxian Shen; Fahai Cao | Theoretical and Computational Chemistry; Chemical Engineering and Industrial Chemistry; Machine Learning; Petrochemicals; Thermodynamics (Chem. Eng.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-11-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/619f26d9f93ad36bf6b346f3/original/intelligent-molecular-identification-for-high-performance-organosulfide-capture-using-active-machine-learning-algorithm.pdf |
637bb92f7d5220968b6bb7c0 | 10.26434/chemrxiv-2022-qcjpw | Computational elucidation of the reaction mechanisms of elemental sulfur and polysulfides with cyanide and phosphines | The reactions of elemental sulfur (S8) and polysulfides with nucleophiles are relevant to organic synthesis, materials science and biochemistry, but the mechanisms by which they operate are still unknown. Depending on the nature of the nucleophile, a broad variety of products can be obtained, but reaction pathways are difficult to probe experimentally due to the inherent thermodynamic and kinetic instability of polysulfide intermediates. Using Density Functional Theory (DFT) calculations at the ωB97X-D/aug-cc-pV(T+d)Z/SMD(MeCN) // ωB97X-D/ aug-cc-pVDZ/SMD(MeCN) level of theory, this study provides the first comprehensive picture of the mechanisms behind the reaction of elemental sulfur and polysulfides with cyanide and phosphines, which quantitatively generate the monosulfide products thiocyanate and phosphine sulfides, respectively. These reactions are prototypical of the reactions of sulfur with other strong nucleophiles including carbon-based systems, and are important for the titration and detection of elemental sulfur in complex media. We first demonstrate that from the two mechanisms proposed more than 60 years ago, the Foss-Bartlett hypothesis is the most likely nucleophilic decomposition pathway for polysulfide intermediates containing good leaving groups. Importantly, we find that unimolecular decomposition pathways, either cyclizative or not, have the lowest activation barriers for most polysulfide intermediates. This indicates that such intermediates are fleeting in solution as they rapidly decompose even without an external nucleophile. Other bimolecular decomposition pathways were also located, including scrambling reactions and attack on thiosulfoxides, which are less likely to intervene as they require larger concentrations of highly-reactive intermediates. Overall, our results indicate that for long polysulfides intramolecular cyclization is the most favorable decomposition pathway. For short polysulfides, a mixture of unimolecular decomposition and nucleophilic attack can be expected, in addition to scrambling pathways if the concentration of nucleophile is low. Overall, this work highlighted the various pathways available for polysulfide decomposition, allowing the study of polysulfide reactivity in more complex settings such as organic transformations or biochemical pathways. | Jyoti Sharma; Pier Alexandre Champagne | Theoretical and Computational Chemistry; Organic Chemistry; Organic Synthesis and Reactions; Physical Organic Chemistry; Computational Chemistry and Modeling | CC BY NC 4.0 | CHEMRXIV | 2022-11-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/637bb92f7d5220968b6bb7c0/original/computational-elucidation-of-the-reaction-mechanisms-of-elemental-sulfur-and-polysulfides-with-cyanide-and-phosphines.pdf |
60c754094c89192737ad4408 | 10.26434/chemrxiv.13604420.v1 | Pyridylphosphonium Salts as Alternatives to Cyanopyridines in Radical-Radical Coupling Reactions | Radical couplings of cyanopyridine radical anions represent a valuable technology for functionalizing pyridines, which are prevalent throughout pharmaceuticals, agrochemicals, and materials. Installing the cyano group, necessary for radical anion stabilization, is challenging and limits the use of this chemistry to simple cyanopyridines. We discovered that pyridyl phosphonium salts, installed regioselectively from C-H precursors, are useful alternatives to cyanopyridines in radical-radical coupling reactions, expanding the scope of this reaction manifold to complex pyridines. Methods for both alkylation and amination of pyridines mediated by photoredox catalysis are described. Additionally, we demonstrate late-stage functionalization of pharmaceuticals, highlighting an advantage of pyridyl phosphonium salts over cyanopyridines. | Jacob W. Greenwood; Andrew McNally | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c754094c89192737ad4408/original/pyridylphosphonium-salts-as-alternatives-to-cyanopyridines-in-radical-radical-coupling-reactions.pdf |
65efbb9166c1381729ca9d8c | 10.26434/chemrxiv-2024-qwgg6 | Laser Post-Ionization Combined with Matrix-Free Laser Desorption/Ionization Enhances the Mass Spectrometry Imaging of Plant Metabolites | While the benefits of mass spectrometry imaging (MSI) coupled with recently described laser post-ionization (LPI) techniques (e.g., MALDI-2) have been well explored for the study of mammalian systems, their benefits for spatial metabolomics of plants have not. Here, we demonstrate that matrix-free laser desorption/ionization (LDI) coupled with LPI can significantly increase the number of plant metabolites detectable in an MSI experiment, compared to LDI alone, including for many flavonoids. Moreover, while many aromatic compounds are detected as their radical cations, a result of the photoionization processes accessible using LPI, many compounds (e.g., non-UV active compounds) also experience a significant increase in the abundance of their protonated ions. This suggests that endogenous UV active compounds, such as flavonoids can act as a MALDI-like matrix in promoting charge transfer upon excitation by the laser pulse used for LPI. MSI datasets using LDI-LPI acquired from Azolla filiculoides reveal rich spectra, containing several thousand peaks, with very few background-related signals, including many poly glycosylated flavonoids. This work provides an avenue to significantly enhance the capabilities for studying region-specific flavonoid metabolism within plants. | Benjamin Bartels; Erbil Güngör; Donald Smith; Henriette Schluepmann; Ron Heeren; Shane Ellis | Analytical Chemistry; Agriculture and Food Chemistry; Imaging; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65efbb9166c1381729ca9d8c/original/laser-post-ionization-combined-with-matrix-free-laser-desorption-ionization-enhances-the-mass-spectrometry-imaging-of-plant-metabolites.pdf |
679e5a91fa469535b9b82f35 | 10.26434/chemrxiv-2025-s2s0r | Understanding the pyrolysis-assisted conversion of metal salt-impregnated biomass into biogas and nanocatalyst-coated porous biochar | Slow pyrolysis is the most employed technique to design biochar at high yield. It is particularly suitable for converting impregnated biomass into biochar-immobilized nanocatalysts. The latter exhibits a porous structure compared to pristine biochar. However, this distinct behavior is yet to be understood. To this end, the coupled technique of Thermogravimetric Analysis/Fourier Transform Infrared Spectroscopy (TGA/FTIR) was used to simulate pyrolysis in a tube furnace for biochar production and to analyze syngas. Sugarcane bagasse (SCPB) powder, treated with copper and/or nickel nitrates, was pyrolyzed in a TGA under nitrogen at heating rates from RT to 500 °C for 1 hour. TGA/DTG permitted monitoring the thermal events of SCPB which was found to be exacerbated by the introduction of metals. The syngases, including COx, NOx, HNO3, and H2O, were effectively detected and analyzed by FTIR during the pyrolysis process at varying heating rates of 10, 20, and 30 °C/min. Notably, Ni(NO3)2.6H2O yielded N2O, probably associated with the formation of a biochar porous structure. The pyrolysis activation energies (Ea) of SCPB and SCPB/CuNi were determined using FWO and DAEM models. The maximum weight loss was found to occur at a thermochemical conversion of ~60% into char; and Ea = 234 kJ.mol-1 for SCPB, much higher than 90 kJ.mol-1 obtained for the wet impregnated sample SCPB/nitrates; hence the dramatic effect of the nanometal precursors on the pyrolysis process. XPS analysis demonstrated that TG-biochar and “tubular furnace” biochar exhibit identical surface chemical compositions. Raman spectroscopy brought evidence for graphitic carbon structure as judged from D and G bands in SCPB/CuNi. Microscopic observations confirmed a well-defined porous morphology.
From the above, this TG-FTIR study permitted to highlight the central role of copper and particularly nickel in the pyrolysis process. These metals:
-significantly lower the pyrolysis activation energy
- induce porous structure of the underlying biochar
-could be added to the repertoire of activators, dominated by ZnCl2 and FeCl3.
-serve as activators | Mengqi TANG; Alexandre Chevillot-Biraud; Stéphanie Lau-Truong; Ahmed Mohamed Khalil; Mohamed Mehdi Chehimi | Materials Science; Energy; Earth, Space, and Environmental Chemistry; Carbon-based Materials; Fuels - Materials; Environmental Science | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/679e5a91fa469535b9b82f35/original/understanding-the-pyrolysis-assisted-conversion-of-metal-salt-impregnated-biomass-into-biogas-and-nanocatalyst-coated-porous-biochar.pdf |
63475a86cfc0368f28d4043a | 10.26434/chemrxiv-2022-wtlpl | Promoter-poison partnership protects platinum performance in coked cluster catalysts | Deactivation via coking due to a lack of selectivity is a persistent problem for the longevity of Pt-based dehydrogenation catalysts. Ge as a promoter improves the exper- imental selectivity and stability of subnano Pt clusters. The origin of this improvement is self-limiting coking, to form a Pt4GeC2 cluster which is more stable and selective than the bare Pt4Ge cluster. In this paper we compare the dehydrogenation abilities of Pt4 and Pt4C2 with and Pt4Ge and Pt4GeC2 with DFT calculations in order to explore the origin of self-limiting coking in the presence of Ge. The unique stability of Pt4GeC2 is attributed to electron donation from Ge to the C2 atoms. This prevents the coke from drawing electrons from the Pt, which is the origin of deactivation via coking. Thus, we identify an electronic mechanism for coke deactivation and then use an electronically driven doping strategy to improve catalyst longevity. This differs from the common perception of coke deactivating via steric blocking of active sites.Furthermore, Pt4C2 and Pt4GeC2 show differences in kinetic accessibility of different isomers, which brings us into a new paradigm of sub-ensembles of isomers, where the dominant active sites are determined by kinetic stability under reaction conditions, rather than Boltzmann populations. | Patricia Poths; Harry W. T. Morgan; Guangjing Li; Autumn Fuchs; Scott L. Anderson; Anastassia N. Alexandrova | Theoretical and Computational Chemistry; Physical Chemistry; Catalysis; Computational Chemistry and Modeling; Heterogeneous Catalysis; Clusters | CC BY 4.0 | CHEMRXIV | 2022-10-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63475a86cfc0368f28d4043a/original/promoter-poison-partnership-protects-platinum-performance-in-coked-cluster-catalysts.pdf |
6751a8095a82cea2fa159733 | 10.26434/chemrxiv-2024-4vt27 | Electrochemical Dissolution: Paths in High-Entropy Alloy Composition Space | The stability of a nanoparticle catalyst during electrochemical reaction is crucial for its application. Despite increasing interest in multi-metallic alloy nanoparticles, such as high-entropy alloys (HEAs), for electrocatalysis and emerging models for their catalytic activity, there is limited work on frameworks that can predict the metastability of these alloys under reaction conditions, including stability against electrochemical surface dissolution. Incorporating electrochemical stability in multi-objective optimization would advance HEAs as a catalyst discovery platform. To address the knowledge gap on electrochemical stability, we propose a methodology for simulating the dissolution of n-element alloy nanoparticles comprised of density functional theory and machine learning regression to calculate the dissolution potentials of the surface atoms. We demonstrate the methodology for the Ag-Au-Cu-Ir-Pd-Pt-Rh-Ru HEA system with the conditions of the oxygen reduction reaction. We investigated trends in stability against dissolution through a compositional grid search for the octo-metallic composition space, uncovering two alloying strategies to increase stability against electrochemical surface dissolution: Alloying with a noble metal or a metal with high relative surface energy. In the simulations, stabilization ensues from forming a protective surface layer, and consequently, the dissolution of persistent alloyed nanoparticles results in core-shell structures. The model enables tracing the evolution of the surface and dissolved composition during electrochemical dissolution, forming paths of dissolution and revealing unretainable surface compositions. | Mads K. Plenge; Jack K. Pedersen; Luis A. Cipriano; Jan Rossmeisl | Materials Science; Catalysis; Nanoscience; Alloys; Nanocatalysis - Catalysts & Materials; Electrocatalysis | CC BY NC ND 4.0 | CHEMRXIV | 2024-12-11 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6751a8095a82cea2fa159733/original/electrochemical-dissolution-paths-in-high-entropy-alloy-composition-space.pdf |
64ee406479853bbd78b1c695 | 10.26434/chemrxiv-2023-9mxkc | Cryptic isomerization in diterpene biosynthesis and the restoration of an evolutionarily defunct P450 | Biosynthetic modifications of the 6/10-bicyclic hydrocarbon skeletons of the eunicellane family of diterpenoids are un-known. We explored the biosynthesis of a bacterial trans-eunicellane natural product, albireticulone A (3), and identified a novel isomerase that catalyzes a cryptic isomerization in the biosynthetic pathway. We also assigned functions of two cyto-chromes P450 that oxidize the eunicellane skeleton, one of which was a naturally evolved non-functional P450 that when genetically repaired, catalyzes allylic oxidation. Finally, we describe the chemical susceptibility of the trans-eunicellane skeleton to undergo Cope rearrangement to yield inseparable atropisomers. | Zining Li; Baofu Xu; Tyler Alsup; Xiuting Wei; Wenbo Ning; Daniel Icenhour; Michelle Ehrenberger; Ion Ghiviriga; Bao-Doan Giang; Jeffrey Rudolf | Biological and Medicinal Chemistry; Organic Chemistry; Catalysis; Bioorganic Chemistry; Natural Products; Biochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ee406479853bbd78b1c695/original/cryptic-isomerization-in-diterpene-biosynthesis-and-the-restoration-of-an-evolutionarily-defunct-p450.pdf |
62bb206791954930a2d78906 | 10.26434/chemrxiv-2022-mv6cl-v2 | SCORE-metabolite-ID: Semi-automatic and reliable identification of metabolites from complex mixtures by correlation of 1H NMR, MS and LC data | Due to the large number of metabolites of various compound classes present in natural products, which in addition occur in high concentration differences, the identification of individual metabolites from either 1H NMR spectra or MS spectra is hardly possible due to signal overlap and the lack of information from interrelated signals of the same compound. This paper presents a method for the three-dimensional correlation of NMR and MS data over the third dimension of the time course of a chromatographic fractionation. Compounds do not need to be isolated individually, but the NMR and MS signals of the individual compounds can be correlated mathematically. The app SCORE-metabolite-ID (Semi-automatic COrrelation analysis for REliable metabolite IDentification) was implemented in MATLAB and provides semi-automatic detection of correlated NMR and MS data. Thereby, the app enables fast and reliable dereplication of known metabolites and facilitates the dynamic analysis for the identification of unknown compounds in any complex mixture. The strategy was validated using an artificial mixture and tested further on a polar extract of a pine nut sample. Straightforward identification of 40 metabolites could be shown, including the identification of β-D-glucopyranosyl-1-N-indole-3-acetyl-N-L-aspartic acid (1) and Nα-(2-hydroxy-2-carboxymethylsuccinyl)-L-arginine (2), the latter being identified in a food sample for the first time. | Stephanie Watermann; Marie-Christin Bode; Thomas Hackl | Analytical Chemistry; Mass Spectrometry; Spectroscopy (Anal. Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2022-06-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62bb206791954930a2d78906/original/score-metabolite-id-semi-automatic-and-reliable-identification-of-metabolites-from-complex-mixtures-by-correlation-of-1h-nmr-ms-and-lc-data.pdf |
65a42dbe9138d23161e85cb4 | 10.26434/chemrxiv-2024-lml8j | In vitro and in silico studies of prenylated phenylpropanoids of green propolis and their derivatives against cariogenic bacteria | Artepillin C, drupanin, and plicatin B are prenylated phenylpanoids naturally occurring in Brazilian green propolis. In this study, these compounds and eleven derivatives were synthesized and evaluated for their in vitro antimicrobial activity against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Plicatin B (2) and its hydrogenated derivative 8 (2’,3’,7,8-tetrahydro-plicatin B) were the most active compounds. Plicatin B (2) displayed strong activity against all bacteria tested (MIC = 31.2 μg/mL). On the other hand, compound 8 (2’,3’,7,8-tetrahydro-plicatin A) displayed strong activity against Streptococcus mutans, S. salivarius, S. sobrinus, Lactobacillus paracasei (MIC = 62.5 μg/mL) and S. mitis (MIC = 31.2 μg/mL) as well as a moderate activity against Enterococcus faecalis and S. sanguinis (MIC = 125 μg/mL). In silico studies showed that the complexes formed compound 2 and 8 has energy score values close to those of the native ligands of S. mitis, S. sanguinis, and S. mutans due to the formation of strong hydrogen bonds with the active sites of those bacteria. Moreover, all the estimated physicochemical parameters satisfy the drug-likeness criteria without violating the Lipinski, Veber, and Egan rules, so these compounds are not expected to cause problems with oral bioavailability and pharmacokinetic parameters. Compounds 2 and 8 also have suitable ADME-T parameters, as the online server pkCSM calculates. These results make compounds 2 and 8 good candidates as anticariogenic compounds. | Tatiana Vieira; Anna Santos; Sara Souza; Ismail Daoud; Seyfeddine Rahalie; Noureddine Amdouni; Júlia Barco; Lucas Paula; Jairo Bastos; Carlos Martins; Ridha Ben Said; Antônio Crotti | Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Bioinformatics and Computational Biology; Drug Discovery and Drug Delivery Systems; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2024-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a42dbe9138d23161e85cb4/original/in-vitro-and-in-silico-studies-of-prenylated-phenylpropanoids-of-green-propolis-and-their-derivatives-against-cariogenic-bacteria.pdf |
60c73eb1337d6c59a5e263c2 | 10.26434/chemrxiv.6615509.v2 | Faraday-Cage Screening Reveals Intrinsic Aspects of the van der Waals Attraction | General properties of the recently observed screening of the van der Waals (vdW) attraction between a silica substrate and silica tip by insertion of graphene are predicted using basic theory and first-principles calculations. Results are then focused on possible practical applications, as well as an understanding of the nature of vdW attraction, considering recent discoveries showing it competing against covalent and ionic bonding. The traditional view of the vdW attraction as arising from pairwise-additive London dispersion forces is considered using Grimme’s “D3” method, comparing results to those from Tkatchenko’s more general many-body dispersion (MBD) approach, all interpreted in terms of Dobson’s general dispersion framework. Encompassing the experimental results, MBD screening of the vdW force between two silica bilayers is shown to scale up to medium separations as 1.25 de/d, where d is the bilayer separation and de its equilibrium value, depicting antiscreening approaching and inside de. Means of unifying this correlation effect with those included in modern density functionals are urgently required. <br /> | Musen Li; Jeffrey R. Reimers; John F. Dobson; Tim Gould | Carbon-based Materials; Theory - Computational; Structure | CC BY NC ND 4.0 | CHEMRXIV | 2018-08-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73eb1337d6c59a5e263c2/original/faraday-cage-screening-reveals-intrinsic-aspects-of-the-van-der-waals-attraction.pdf |
669be67d5101a2ffa80d55f9 | 10.26434/chemrxiv-2024-svz4w | Controlling grain boundary segregation to tune the conductivity of ceramic proton conductors | Acceptor-doped barium zirconates are of major interest as proton-conducting ceramics for electrochemical applications at intermediate operating temperatures. The proton transport through polycrystalline microstructures of yttrium doped barium zirconates is hindered by the presence of a positive space charge potential at grain boundaries. During high temperature sintering, the positive charge acts as a driving force for acceptor dopant segregation to the grain boundary. Acceptor segregation to grain boundaries has been observed in sintered ceramics, but the fundamental relationship between the segregation kinetics and the protonic conductivity is poorly understood. Here, we present a comprehensive study of the influence of acceptor dopant segregation on the electrochemical properties of grain boundaries in barium zirconate based protonic ceramics. To facilitate this study, we designed an out-of-equilibrium model material that is not in a state of thermodynamic equilibrium and displays no detectable Y segregation at its grain boundaries. This model material served as a starting point to measure the kinetics of segregation and the induced changes in grain boundary conductivity upon varying thermal histories. Furthermore, we correlated the electrochemical results from impedance spectroscopy to atomic resolution transmission electron microscopy and atom probe tomography. We discovered that acceptor dopant segregation drastically increases the proton conductivity in both our model system and several other application-relevant compositions. In all cases, high-temperature thermal treatments were necessary to equilibrate the space charge zones, allowing the segregation of cationic point defects to grain boundaries, compensating the core charge and resulting in high performance protonic ceramics. | Moritz Kindelmann; Ivan Povsturgar; Severin Kuffer; Dylan Jennings; Julian N. Ebert; Moritz L. Weber; M. Pascal Zahler; Sonia Escolantico; Laura Almar; Jose M. Serra; Payam Kaghazchi; Martin Bram; Wolfgang Rheinheimer; Joachim Mayer; Olivier Guillon | Materials Science; Ceramics | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669be67d5101a2ffa80d55f9/original/controlling-grain-boundary-segregation-to-tune-the-conductivity-of-ceramic-proton-conductors.pdf |
67d04afefa469535b9de56e7 | 10.26434/chemrxiv-2025-n67n5 | Excited-State Palladium-Catalyzed Radical Allylic Alkylation: Rap-id Access to C2-Allyl Carbohydrates | Glycomimetics has emerged as a promising strategy to mimic the biological activities of carbohydrates while enhancing drug-like properties. Yet, their efficient synthesis and modifications remain a major challenge. Herein, we report an excited-state Pd-catalyzed, rapid synthesis of C2-allylated carbohydrates, useful synthons for preparing glycomimetics, from readily available α-bromosugars. The transformation features a high level of atom economy, broad functional group tolerance, and suitability for late-stage modification of complex molecules. Preliminary experimental and computational studies suggest a radical mechanism involving excited Pd species, 1,2-radical migration (RaM), and kinetic-controlled β-H elimination processes. We anticipate that our findings will broaden the reaction profile of excited-state Pd catalysis and enable rapid access to valuable glycomimetics. | Wang Yao; Jaclyn Mauro; Yue Fu; Hang Chen; Peng Liu; Ming-Yu Ngai | Organic Chemistry; Catalysis; Photocatalysis | CC BY 4.0 | CHEMRXIV | 2025-03-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67d04afefa469535b9de56e7/original/excited-state-palladium-catalyzed-radical-allylic-alkylation-rap-id-access-to-c2-allyl-carbohydrates.pdf |
667d408a01103d79c543901e | 10.26434/chemrxiv-2024-qvfqj | Computational screening for clathrates among predicted crystal structures | We present a computational study of gas adsorption in a large set of predicted porous organic molecular crystal structures. A large number of computer-generated porous crystal structures of o- and m-fluorophenol, resorcinol and triptycene trisbenzimidazolone were screened for their ability to adsorb xenon, carbon dioxide and methane, and thereby form clathrates. The thermo- dynamic driving force for gas adsorption was calculated with rigid-body lattice dynamics and grand canonical Monte Carlo simulations, using an accurate anisotropic force field with elec- trostatic multipoles. The results suggest that the studied com- pounds may form several clathrate structures at mild temper- atures and pressures, which may facilitate carbon capture or separation of gases by molecular sieving. | Jonas Nyman; Graeme M. Day; Peter Ahlström | Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Thermodynamics (Physical Chem.); Materials Chemistry; Crystallography | CC BY 4.0 | CHEMRXIV | 2024-06-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/667d408a01103d79c543901e/original/computational-screening-for-clathrates-among-predicted-crystal-structures.pdf |
60c743ae702a9b929518a660 | 10.26434/chemrxiv.9456158.v1 | Investigation of Amorphous Mixed-Metal (Oxy)Fluorides as a New Class of Water Oxidation Electrocatalysts | <p>The development
of electrocatalysts for the oxygen evolution reaction (OER) is one of the principal
challenges in the area of renewable energy research. Within this context,
mixed-metal oxides have recently emerged as the highest performing OER
catalysts. Their structural and compositional modification to further boost
their activity is crucial to the wide-spread use of electrolysis technologies.
In this work, we investigated a series of mixed-metal F-containing materials as
OER catalysts to probe possible benefits of the high electronegativity of
fluoride ions. We found that crystalline
hydrated fluorides, CoFe<sub>2</sub>F<sub>8</sub>(H<sub>2</sub>O)<sub>2</sub>,
NiFe<sub>2</sub>F<sub>8</sub>(H<sub>2</sub>O)<sub>2, </sub>and amorphous
oxyfluorides, NiFe<sub>2</sub>F<sub>4.4</sub>O<sub>1.8 </sub>and CoFe<sub>2</sub>F<sub>6.6</sub>O<sub>0.7,
</sub>feature excellent activity and stability for the OER in alkaline
electrolyte. Subsequent electroanalytical and spectroscopic characterization
hinted that the electronic structure modulation conferred by the fluoride
ions aided their
reactivity. Finally, the best catalyst of the set, NiFe<sub>2</sub>F<sub>4.4</sub>O<sub>1.8</sub>,
was applied as anode in an electrolyzer comprised solely of earth-abundant
materials.</p> | Kévin Lemoine; Jérôme Lhoste; Annie Hémon-Ribaud; Nina Heidary; Vincent Maisonneuve; Amandine Guiet; Nikolay Kornienko | Electrochemistry; Solid State Chemistry; Spectroscopy (Inorg.); Heterogeneous Catalysis; Nanocatalysis - Reactions & Mechanisms; Redox Catalysis; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2019-08-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c743ae702a9b929518a660/original/investigation-of-amorphous-mixed-metal-oxy-fluorides-as-a-new-class-of-water-oxidation-electrocatalysts.pdf |
6274c17a809e324b80851984 | 10.26434/chemrxiv-2022-3hspc | Ortho-substituted aryldiazonium design for defect configuration-controlled photoluminescent functionalization of chiral single-walled carbon nanotubes | Defect functionalization using chemical modification of single-walled carbon nanotubes (SWCNTs) is promising, especially for near-infrared photoluminescence (NIR PL) over 1000 nm in advanced telecom and bio/medical applications. The covalent attachment of modifier molecules is utilized to create sp3 carbon defects in the sp2 carbon lattice for bright, red-shifted PL generation. The positional difference in proximal sp3 carbons, known as the defect binding configuration, can dominate NIR PL properties; however, the defect arrangement chemistry remains unelucidated. We developed aryldiazonium modifiers with -conjugated ortho-substituents (phenyl and acetylene groups) to introduce molecular interactions with nanotube sidewalls into the chemical reaction process for defect formation. Single defect emissions of ~1230–1270 nm selectively appeared in the functionalized chiral SWCNTs, showing a different binding configuration from those observed for typical aryl- or alkyl- functionalized chiral tubes emitting approximately 1150-nm PL. Moreover, the acetylene-based substituent design allows PL brightening and subsequent molecular modification using click chemistry. | Boda Yu; Sadahito Naka; Haruka Aoki; Koichiro Kato; Tsuyohiko Fujigaya; Tomohiro Shiraki | Nanoscience; Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6274c17a809e324b80851984/original/ortho-substituted-aryldiazonium-design-for-defect-configuration-controlled-photoluminescent-functionalization-of-chiral-single-walled-carbon-nanotubes.pdf |
669ce9ee5101a2ffa8388287 | 10.26434/chemrxiv-2024-6qxsx | A Twisted Chromophore that Powers a Fluorescent Protein Chloride Sensor | Chromophore nonplanarity and flexibility have long been argued to govern the fluorescence efficiency of fluorescent proteins (FPs), yet their relative importance has been elusive. Herein, we tackle this question by investigating two FP-based chloride (Cl–) sensors, ChlorON1 and 3, using ultrafast spectroscopy and theoretical calculations. We find that fluorescence enhancement of the chloride-bound ChlorON3 stems from a more twisted chromophore than ChlorON1. This counterintuitive finding indicates that chromophore planarity is not, but conformational rigidity is, the decisive factor for high fluorescence efficiency. | Cheng Chen; Vishaka Pathiranage; Whitney Ong; Sheel Dodani; Alice Walker; Chong Fang | Theoretical and Computational Chemistry; Physical Chemistry; Biological and Medicinal Chemistry; Biophysics; Chemical Biology; Photochemistry (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-07-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669ce9ee5101a2ffa8388287/original/a-twisted-chromophore-that-powers-a-fluorescent-protein-chloride-sensor.pdf |
60c7516c567dfed643ec5a63 | 10.26434/chemrxiv.13166807.v1 | Pillar[5]arene-Modified Gold Nanorods as Nanocarriers for Multi-Modal Imaging-Guided Synergistic Photodynamic-Photothermal Therapy | Supramolecular approaches have opened up vast possibilities in the construction of versatile functional materials, especially those with stimuli-responsiveness and integrated functionalities of multi-modal diagnosis and synergistic therapeutics. In this study, a hybrid theranostic nanosystem named TTPY-PyÌCP5@AuNR is constructed via facile host-guest interactions, where TTPY-Py is a photosensitizer with aggregation-induced emission and CP5@AuNR represents the carboxylatopillar[5]arene (CP5)-modified Au nanorods. TTPY-PyÌCP5@AuNR integrates the respective advantages of TTPY-Py and CP5@AuNR such as the high performance of reactive oxygen species (ROS) generation and photothermal conversion, and meanwhile shows fluorescence responses to both temperature and pH stimuli due to the non-covalent interactions. The successful modification of CP5 macrocycles on AuNRs surfaces can eliminate the cytotoxicity of AuNRs and enable them to serve as the nanocarrier of TTPY-Py for further theranostic application. Significantly, both in vitro and in vivo evaluations demonstrate that this supramolecular nanotheranostic system possesses multiple phototheranostic modalities including intensive fluorescence imaging (FLI), photoacoustic imaging (PAI), efficient photodynamic therapy (PDT), and photothermal therapy (PTT), indicating its great potentials for FLI-PAI imaging-guided synergistic PDT-PTT therapy. Besides, TTPY-Py can be released from the nanocarriers upon activating by the acidic environment of lysosomes and then specifically light up mitochondria. This study brings up a new strategy into the design of versatile nanotheranostics for accurate tumor imaging and cancer therapies. | Nan Song; Zhijun Zhang; Peiying Liu; Dihua Dai; Chao Chen; Youmei Li; Lei Wang; Ting Han; Ying-Wei Yang; Dong Wang; Ben Zhong Tang | Nanostructured Materials - Nanoscience | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-02 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7516c567dfed643ec5a63/original/pillar-5-arene-modified-gold-nanorods-as-nanocarriers-for-multi-modal-imaging-guided-synergistic-photodynamic-photothermal-therapy.pdf |
60c7596e842e6531e6db49fb | 10.26434/chemrxiv.14696463.v1 | Nafion-Induced Reduction of Manganese and Its Impact on the Electrocatalytic Properties of a Highly Active MnFeNi Oxide for Bifunctional Oxygen Conversion | Electrocatalysts for bifunctional oxygen reduction
(ORR) and oxygen evolution reaction (OER) are commonly studied under
hydrodynamic conditions, rendering the use of binders necessary to ensure the mechanical
stability of the electrode films. The presence of a binder, however, may
influence the properties of the materials under examination to an unknown
extent. Herein, we investigate the impact of Nafion on a highly active ORR/OER
catalyst consisting of MnFeNi oxide
nanoparticles supported on multi-walled carbon nanotubes. Electrochemical
studies revealed that, in addition to enhancing the mechanical stability and particle
connectivity, Nafion poses a major impact on the ORR selectivity, which
correlates with a decrease in the valence state of Mn according to X-ray
absorption spectroscopy. These findings call for awareness regarding the use of
electrode additives, since in some cases the extent of their impact on the properties
of electrode films cannot be regarded as negligible. | Dulce M. Morales; Javier Villalobos; Mariya A. Kazakova; Jie Xiao; Marcel Risch; Dulce Maria Morales Hernandez | Electrochemistry; Electrocatalysis; Fuels - Energy Science; Fuel Cells; Spectroscopy (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-05-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7596e842e6531e6db49fb/original/nafion-induced-reduction-of-manganese-and-its-impact-on-the-electrocatalytic-properties-of-a-highly-active-mn-fe-ni-oxide-for-bifunctional-oxygen-conversion.pdf |
610bf2eae540bb57db71f79d | 10.26434/chemrxiv-2021-gvm5c-v2 | Racemization-free synthesis of dipeptide, amide and ester by oxalyl chloride and catalytic triphenylphosphine oxide | An efficient triphenylphosphine oxide (Ph3PO) catalyzed amidation and esterification reaction for rapid synthesis of a series of dipeptides, amides and esters under mild condition is described. This reaction is applicable to challenging couplings of hindered carboxylic acid with low nucleophilic amine or alcohol, giving products in good yields (67-90%) without any racemization. This system employs highly reactive intermediate Ph3PCl2 as activator of carboxylate, in a catalytic manner, and drive the reac-tion to complete in short reaction time (less than 10 min). It has the advantages of good functional group tolerance, broad sub-strate scope and good atom-economy. A 100 mmol scale reaction with good yield shed light on its potential for industrial ap-plication. A plausible mechanism is proposed based on 31P NMR monitor of reaction process. | Feng Ni; Ji-Wei Ren; Meng-Nan Tong; Yu-Fen Zhao | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2021-08-06 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/610bf2eae540bb57db71f79d/original/racemization-free-synthesis-of-dipeptide-amide-and-ester-by-oxalyl-chloride-and-catalytic-triphenylphosphine-oxide.pdf |
60c746fd567dfe7c8aec4719 | 10.26434/chemrxiv.11462085.v1 | Copper(I)-Catalyzed Dearomative (3+2) Cycloaddition of 3-Nitroindoles with Propargylic Nucleophiles: a Straightforward Entry for The Preparation of Cyclopenta[b]indolines | The copper(I)-catalyzed dearomatization of
3-nitroindoles with propargylic nucleophiles is described. In mild reaction
conditions, this original dearomative (3+2) cycloaddition process gives access to
a wide variety of cyclopenta[<i>b</i>]indolines
in good to excellent yields, with high functional group tolerance. Furthermore,
an enantioselective version of this reaction is reachable by employing chiral
phosphorous ligands. A mechanism proposal is given, based on kinetic studies. | Johanne Ling; David Mara; Baptiste Roure; Maxime Laugeois; MAxime Vitale | Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2019-12-27 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c746fd567dfe7c8aec4719/original/copper-i-catalyzed-dearomative-3-2-cycloaddition-of-3-nitroindoles-with-propargylic-nucleophiles-a-straightforward-entry-for-the-preparation-of-cyclopenta-b-indolines.pdf |
60c755c3ee301c9d97c7b223 | 10.26434/chemrxiv.14159492.v1 | N-Glycosylation with Sulfoxide Donors for the Synthesis of Peptidonucleosides | <p>We report here the synthesis of peptidonucleosides obtained after
glycosylation of different pyrimidine bases with glucopyranosyl donors carrying
an azide group at the C4 position. A methodological study involving different
anomeric leaving groups (acetate, phenylsulfoxide and <i>ortho</i>-hexynylbenzoate) showed that a sulfoxide donor in combination
with trimethylsilyl triflate as the promoter led to the best yields.</p> | Margaux Beretta; Emilie Rouchaud; Lionel Nicolas; Jean-Pierre Vors; Thomas Dröge; Mazen Es-Sayed; Jean-Marie Beau; Stephanie Norsikian | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2021-03-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c755c3ee301c9d97c7b223/original/n-glycosylation-with-sulfoxide-donors-for-the-synthesis-of-peptidonucleosides.pdf |
634593072e6e7cdc5d575cba | 10.26434/chemrxiv-2022-4g4zf | Conformational preference analysis in C2H6 using Orbital Forces and Non-Covalent Interactions; comparison with related systems | Dynamic Orbital Forces (DOF) and Non-Covalent Interactions (NCIs) allow an analysis of the attractive/repulsive interactions whose variations lead to the staggered preference of ethane and some related compounds. In ethane, it is found that CH3···CH3 attractive interactions are predominant in the staggered preference with respect to adiabatic eclipsed conformation, with an important contribution. On the contrary, vertical eclipsed ethane is destabilized almost only by repulsive interactions. Weak long-range H···H repulsions favor the staggered conformation. From the sum of DOFs, the energy barrier can be decomposed into C-H and C-C bond energies. It is found due to the weakening of the C-C bond (ca. 7 kcal/mol), moderated by a strengthening of C-H ones (ca. 4 kcal/mol) arising from the decrease of hyperconjugation with respect to the staggered conformation.
In the compounds CH3-SiH3, SiH3-SiH3, CH3-CF3 and CF3-CF3, the conformational preference is predominantly or exclusively due to repulsive interactions, with respect as well to adiabatic as to vertical eclipsed structures.
| Trinidad Novoa; Julia Contreras-Garcia; Patrick Chaquin | Theoretical and Computational Chemistry; Physical Chemistry; Organic Chemistry; Physical Organic Chemistry; Stereochemistry | CC BY NC ND 4.0 | CHEMRXIV | 2022-10-12 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/634593072e6e7cdc5d575cba/original/conformational-preference-analysis-in-c2h6-using-orbital-forces-and-non-covalent-interactions-comparison-with-related-systems.pdf |
65f45cc266c13817290e8938 | 10.26434/chemrxiv-2024-tqglj | Non-bonded force field parameters from MBIS partitioning of the molecular electron density improve thermophysical properties prediction of organic liquids | The accuracy of predicting thermophysical properties through molecular dynamics simulations is constrained by the precision of models used to describe molecular interactions. The Open Force Field initiative has established a computational structure to develop new models and introduced two non-polarizable force fields, Parsley and Sage. Sage version 2.0.0 focused on refining Lennard-Jones parameters to reflect thermophysical properties accurately. In this context, we evaluate the ability of our introduced D-MBIS non-bonded force field parameters to replicate liquid densities and enthalpies of evaporation of 49 neutral compounds from the ThermoML database using the openff-evaluator package. Our findings confirm that our ab-initio derived non-bonded force field parameters accurately mirror both thermophysical properties with a high degree of precision. | Jorge Pulido; Luis Macaya; Esteban Vöhringer-Martinez | Theoretical and Computational Chemistry; Chemical Engineering and Industrial Chemistry; Computational Chemistry and Modeling; Thermodynamics (Chem. Eng.) | CC BY NC ND 4.0 | CHEMRXIV | 2024-03-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65f45cc266c13817290e8938/original/non-bonded-force-field-parameters-from-mbis-partitioning-of-the-molecular-electron-density-improve-thermophysical-properties-prediction-of-organic-liquids.pdf |
64eb3d9679853bbd788c25f0 | 10.26434/chemrxiv-2023-ph4qt | The Ambimodal Addition-Coupled Electron Transfer (ACET) Mechanism in a Pb(IV)-Promoted Oxidative Dearomatization Reaction | The mechanism of Pb(IV) promoted phenol oxidative dearomatization reaction has been traditionally attributed to a carbocation mechanism. In 2011, Pettus reported an oxidative dearomatization reaction leading to a mixture of a formal [5+2] and a C–O bond formation product. By employing density functional theory (DFT) and quasi-molecular dynamics calculations, it was demonstrated that the reaction does not occur through a carbocation intermediate, but instead proceeds through an addition-coupled electron transfer (ACET) mechanism. Moreover, the ACET exhibits ambimodality, wherein a transition state results in 4 ~ 6 distinct outcomes through post-TS bifurcation. The reported selectivity can be effectively rationalized by the newly proposed mechanism. | Yumiao Ma | Theoretical and Computational Chemistry; Organic Chemistry; Physical Organic Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2023-08-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64eb3d9679853bbd788c25f0/original/the-ambimodal-addition-coupled-electron-transfer-acet-mechanism-in-a-pb-iv-promoted-oxidative-dearomatization-reaction.pdf |
67bc86716dde43c90845d77f | 10.26434/chemrxiv-2025-hnn6b-v2 | Intermolecular Toroidal Conjugation: Circularly Stacked 16 π-Planes Formed by Supramolecular Assembly Enabling Cyclic Charge and Energy Delocalization | Toroidal conjugation is a unique way of charge and exciton delocalization via through-space overlap among circularly stacked π-orbitals, but the examples have been limited to intramolecular phenomena where π-planes are arranged around a hub molecule. In this study, we extend this concept to intermolecular phenomena and demonstrate the first example of intermolecular toroidal conjugation in designed systems, in which a circular π-stacked array is formed by molecular self-assembly. X-ray single-crystal analysis unequivocally revealed a toroidal array of 16 π-planes formed by the supramolecular dimerization of phthalocyanines substituted with eight pillar-like diazapentacenes interdigitating their π-pillars. The experimentally determined interplanar distances in the toroidal π-stacking array were close enough to realize through-space conjugation. We investigated the existence of charge and exciton delocalization in the toroidal π-stacking array using various steady-state and time-resolved spectroscopies and found that the positive charge migrated in the toroidal π-stacking array in the cationic and photoexcited states. | Daisuke Sakamaki; Koki Tsubono; Minami Nakamura; Daiki Shimizu; Yasunori Matsui; Hiroshi Ikeda; Ko Furukawa; Hideki Fujiwara | Physical Chemistry; Organic Chemistry; Physical Organic Chemistry; Supramolecular Chemistry (Org.); Self-Assembly | CC BY NC ND 4.0 | CHEMRXIV | 2025-02-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67bc86716dde43c90845d77f/original/intermolecular-toroidal-conjugation-circularly-stacked-16-planes-formed-by-supramolecular-assembly-enabling-cyclic-charge-and-energy-delocalization.pdf |
60c73fe0ee301cc40ec789ba | 10.26434/chemrxiv.7545623.v1 | Catalytic Synthesis of Trifluoromethyl Cyclopropenes and Oligo Cyclopropenes | The synthesis of trifluoromethylated cyclopropenes is very important for applications in drug discovery and functional materials. In this report, we describe the application of readily available, chiral rhodium(II) catalysts in a highly efficient asymmetric cyclopropenation reaction of fluorinated donor-acceptor diazoalkanes using a broad variety of aliphatic and aromatic alkynes. Further studies highlight the unique reactivity of fluorinated donor-acceptor diazoalkanes in the synthesis of oligo-cyclopropenes. Subsequent C-H functionalization of trifluoromethyl cyclopropenes furnishes densely substituted cyclopropene frameworks and also allows the synthesis of bis-cyclopropenes.<br /> | Uyen P. N. Tran; Renè Hommelsheim; Zhen Yang; Claire Empel; Katharina J. Hock; Thanh Vinh Nguyen; Rene Koenigs | Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Stereochemistry; Carbon-based Materials; Oligomers; Homogeneous Catalysis | CC BY NC ND 4.0 | CHEMRXIV | 2019-01-04 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73fe0ee301cc40ec789ba/original/catalytic-synthesis-of-trifluoromethyl-cyclopropenes-and-oligo-cyclopropenes.pdf |
626d38ad5b90096b10222ebb | 10.26434/chemrxiv-2022-mggxf | Photochemical Synthesis of (2E,4Z)-5-(anthracen-9-yl)-2-cyanopenta-2,4-dienamide | In this short note we describe the photochemical synthesis of (2E,4Z)-5-(anthracen-9-yl)-2-cyanopenta-2,4-dienamide (4) from the corresponding (2E,4E)-5-(anthracen-9-yl)-2-cyanopenta-2,4-dienamide (3) and subsequent purification by precipitation from aqueous surfactant. Compound like 4 belongs to a family of anthracene derivatives capable of forming crystals that can photo-mechanically deform with light. Synthesis of 3 was achieved with high yields and in less than one minute via secondary amine-catalyzed Knoevenagel condensation between commercially available (E)-3-(anthracen-9-yl)acrylaldehyde (1) and 2-cyanoacetamide (2). Photochemical conversion of a solution of the 3 in acetonitrile using light > 475 nm from a commercial blue LED leads to a mixture of 4 (87%) and unconverted 3 (13%) due to the presence of a photostationary state from overlapping absorption spectral regions. Pure 4 ( >99%) was later obtained by precipitating an organic sol1ution of the photoproduct from aqueous surfactant Sodium Dodecyl Sulfate (SDS). Pure 4 was collected in the form of acicular micro crystals that are photomechanically responsive to UV light. The products were analyzed using 1H NMR, 13C NMR, IR, UV-Vis, and HPLC. | RABIH O. AL-KAYSI; Raghad Almuzarie; Imadul Islam; Christopher J. Bardeen | Organic Chemistry; Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2022-05-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/626d38ad5b90096b10222ebb/original/photochemical-synthesis-of-2e-4z-5-anthracen-9-yl-2-cyanopenta-2-4-dienamide.pdf |
6193820e2bf8a90552de4f1a | 10.26434/chemrxiv-2021-s79hz | Ring Mechanism of Fast Na+Ion Transport in Na2LiFeTeO6: Insight from MolecularDynamics Simulation | Honeycomb layered oxides have attracted recent attention because of their rich crystal chemistry. However, the atomistic mechanisms of cationic transport in these structures remain vastly unexplored. Herein, we perform an extensive, systematic molecular dynamics study on Na2LiFeTeO6 using combined force-field and first-principles-based molecular dynamics simulations. We use are fined set of inter-atomic potential parameters of a previously reported potential model that represents various structural and transport properties of this recently reported promising material for all-solid-state battery applications. The present simulation study elucidates the roles of octahedral ordering and entropic contributions in Na+-ion distribution in the ab-plane. Our theoretical simulation also develops a ring-like atomistic diffusion mechanism and relevant atomistic energy barriers that help to understand the origin of fast ion conduction in honeycomb layered oxides. | Kartik Sau; Tamio Ikeshoji | Materials Science; Energy; Energy Storage; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2021-11-16 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6193820e2bf8a90552de4f1a/original/ring-mechanism-of-fast-na-ion-transport-in-na2li-fe-te-o6-insight-from-molecular-dynamics-simulation.pdf |
639a7c2a04902aca020363ca | 10.26434/chemrxiv-2022-jjgl5 | Computational study of H2O adsorption and
hydrolysis on (ZnO)3 nanoclusters deposited
on graphene and graphene oxides | Graphene and graphene oxide (GO) based metal oxides could play an important role
in photocatalysis using metal oxide catalysts. ZnO is a metal oxide with a 3.37 eV band
gap and is a commercially cheaper photocatalyst than titanium oxide in the production
of hydrogen (H2)by splitting water. The π conjugation structure of GO shows greater
electron mobility and could enhance the photocatalytic performance of the ZnO catalyst
by increasing the electron-hole separation. In this work, we use density functional theory
at the B3LYP/DGDZVP2 level to study the impact of adsorbing (ZnO)3 on graphene
and GO on the hydration and hydrolysis of water that precedes water splitting to
produce H2 and O2 in the gas phase. We used 5 different GO models anchoring carboxyl,
hydroxyl, and epoxy functional groups on separate layers of graphene. This study also
compares the reaction pathway of H2 and O2 production from the hydrolyzed (ZnO)3
and GO1-(ZnO)3 in the gas phase using the same level of theory.
1
| Duwage Perera; Jayendran Rasaiah | Catalysis; Nanoscience; Nanocatalysis - Catalysts & Materials; Heterogeneous Catalysis; Photocatalysis; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2022-12-15 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/639a7c2a04902aca020363ca/original/computational-study-of-h2o-adsorption-and-hydrolysis-on-zn-o-3-nanoclusters-deposited-on-graphene-and-graphene-oxides.pdf |
60c75250337d6c800ce286ea | 10.26434/chemrxiv.13285484.v1 | Highly Chemoselective Synthesis of Hindered Amides via Cobalt-Catalyzed Intermolecular Oxidative Hydroamidation | α-Tertiary amides are of great importance for medicinal chemistry. However, they are often challenging to access through conventional methods due to reactivity and chemoselectivity issues. Here we report a single-step approach towards such amides via cobalt-catalyzed intermolecular oxidative hydroamidation of unactivated alkenes, using nitriles of either solvent- or reagent-quantities. This protocol is orthogonal to groups that rapidly react under known carbocation amidation conditions such as tertiary alcohols, electron-rich alkenes, ketals, weak C−H bonds, and carboxylic acids. Straightforward access to a diverse array of hindered amides is demonstrated, including a rapid synthesis of an aminoadamantane-derived pharmaceutical intermediate. | Yun-Nian Yin; Rui-Qi Ding; Dong-Chen Ouyang; Qing Zhang; Rong Zhu | Organic Synthesis and Reactions | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-25 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75250337d6c800ce286ea/original/highly-chemoselective-synthesis-of-hindered-amides-via-cobalt-catalyzed-intermolecular-oxidative-hydroamidation.pdf |
6622a151418a5379b034981c | 10.26434/chemrxiv-2023-18w5m-v3 | Ultrafast dynamics of fluorene initiated by highly intense laser fields | We present an investigation of the ultrafast dynamics of the polycyclic aromatic hydrocarbon fluorene initiated by an intense femtosecond near- infrared laser pulse (810 nm) and probed by a weak visible pulse (405 nm). Using a multichannel detection scheme (mass spectra, electron and ion velocity-map imaging), we provide a full disentanglement of the complex dynamics of the vibronically excited parent molecule, its excited ionic states, and fragments. We observed various channels resulting from the strong-field ionization regime. In particular, we observed the formation of the unstable tetracation of fluorene, above-threshold ionization features in the photoelectron spectra, and evidence of ubiquitous secondary fragmentation. We produced a global fit of all observed time-dependent photoelectron and photoion channels. This global fit includes four parent ions extracted from the mass spectra, 15 kinetic-energy-resolved ionic fragments extracted from ion velocity map imaging, and five photoelectron channels obtained from electron velocity map imaging. The fit allowed for the extraction of 60 lifetimes of various metastable photoinduced intermediates. | Diksha Garg; Pragya Chopra; Jason W. L. Lee; Denis Tikhonov; Sonu Kumar; Oender Akcaalan; Felix Allum; Rebecca Boll; Alexander A. Butler; Benjamin Erk; Eva Gougoula; Sébastien P. Gruet; Lanhai He; David Heathcote; Ellen Jones; Mehdi M. Kazemi; Jan Lahl; Alexander K. Lemmens; Zhihao Liu; Donatella Loru; Sylvain Maclot; Robert Mason; James Merrick; Erland Müller; Terry Mullins; Christina C. Papadopoulou; Christopher Passow; Jasper Peschel; Marius Plach; Daniel Ramm; Patrick Robertson; Dimitrios Rompotis; Alcides Simao; Amanda L. Steber; Ayhan Tajalli; Atia Tul-Noor; Nidin Vadassery; Ivo S. Vinklarek; Simone Techert; Jochen Küpper; Anouk M. Rijs; Daniel Rolles; Mark Brouard; Sadia Bari; Per Eng-Johnsson; Claire Vallance; Michael Burt; Bastian Manschwetus; Melanie Schnell | Physical Chemistry; Photochemistry (Physical Chem.) | CC BY 4.0 | CHEMRXIV | 2024-04-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6622a151418a5379b034981c/original/ultrafast-dynamics-of-fluorene-initiated-by-highly-intense-laser-fields.pdf |
646cfa42b3dd6a65309be88e | 10.26434/chemrxiv-2023-vw29k-v2 | Influence of colloidal surface-additivation with surfactant-free laser-generated metal nanoparticles on Nd-Fe-B permanent magnets produced by suction casting | The development of new powder feedstocks using nanoparticles (NPs) has the potential to
enhance the functionality of as-built parts and overcome the limitations of current additive
manufacturing (AM) techniques. This study investigated the impact of magnet microparticle
feedstock modification by NPs on the microstructure and functionality of Nd-Fe-B-based
permanent magnets made by suction casting. This casting method is known to at least
partially mimic the melting and fast solidification steps inherent to metal powder-based AM
techniques such as Laser Powder Bed Fusion. Two types of NPs, Ag, and ZrB2, were used, and
their effects on grain size distribution and dendritic structure were evaluated. Ag NPs resulted
in smaller, more uniform grain sizes and increased functionality, but only for loadings > 0.5
monolayers. ZrB2 resulted in uniformly distributed grain sizes at much lower mass loadings,
with even more compact dendritic arms. The results show that feedstock powder surface
modification with low melting point metal NPs can improve the microstructure and magnetic
properties of permanent magnets produced by AM and highlight the potential of using NPs
to develop new powder feedstocks for AM. With this, it provides insights for future research
on optimizing materials for AM processes. | Jianing Liu; Ying Yang; Franziska Staab; Carlos Doñate-Buendia; René Streubel; Bilal Gökce; Fernando Macarri; Philipp Gabriel; Benjamin Zingsem; Detlef Spoddig; Konstantin Skokov; Oliver Gutfleisch; Michael Farle; Stephan Barcikowski; Anna Rosa Ziefuss | Materials Science; Nanoscience; Magnetic Materials; Materials Processing | CC BY NC ND 4.0 | CHEMRXIV | 2023-05-24 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/646cfa42b3dd6a65309be88e/original/influence-of-colloidal-surface-additivation-with-surfactant-free-laser-generated-metal-nanoparticles-on-nd-fe-b-permanent-magnets-produced-by-suction-casting.pdf |
638619e40146ef5fcb0a293b | 10.26434/chemrxiv-2022-716b5 | Mastering the synergy between Na3V2(PO4)2F3 electrode and electrolyte: A must for Na-ion cells | Sodium-ion batteries are emerging as suitable energy storage devices for special applications such as high-power devices with the advantages of being cheaper and more sustainable than the Li-ion equivalents. The sodium ion cells consisting of polyanionic Na3V2(PO4)2F3 - hard carbon electrodes exhibit high power rate capabilities but limited cycle life, especially at high temperatures. To circumvent this drawback we herein conducted in-depth analyses of the origins of structural degradations occurring in Na3V2(PO4)2F3 electrodes upon long cycling. Vanadium dissolution with associated parasitic reactions is identified as one of the major reasons for cell failure. Its amount varies depending on the electrolyte, with NaTFSI-based electrolyte showing the least vanadium dissolution as the TFSI- anion decomposes without producing acidic impurities, in contrast to the Na-PF6-based electrolyte. The dissolved vanadium species undergoes oxidation and reduction processes at the Na3V2(PO4)2F3 and HC electrodes, respectively, with the electrochemical signature of these processes being used as a fingerprint to identify state of health of the 18650 cells. Having found that surface reactivity is the primary cause of vanadium dissolution we provide methods to mitigate it by combining surface coating and optimized electrolyte formulation. | Sathiya Mariyappan; Parth Desai; Juan Forero-Saboya; Valentin Meunier; Gwenaëlle Rousse; Michael Deschamps; Artem Abakumov; Jean-Marie Tarascon | Materials Science; Energy; Energy Storage; Materials Chemistry | CC BY NC 4.0 | CHEMRXIV | 2022-11-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/638619e40146ef5fcb0a293b/original/mastering-the-synergy-between-na3v2-po4-2f3-electrode-and-electrolyte-a-must-for-na-ion-cells.pdf |
65157965a69febde9ed7dcc7 | 10.26434/chemrxiv-2023-5bp52-v2 | Chemical Biology Reveals Involvement of N-acetylglucosaminidase LytG In Cell Elongation and Division. | The growth and division of the Gram-positive cell requires the coordinated action of enzymes involved in the synthesis and degradation of the heteropolymer peptidoglycan. Herein, we present the use of the diamide Masarimycin, an inhibitor of the exo-N-acetylglucosaminidase (GlcNAcase) LytG, as a chemical biology probe to elucidate biological role of this cell wall degrading enzyme. Using a combination of chemical biology and genetic approaches we provide the first evidence that LytG activity influences the elongation and division complexes in Bacillus subtilis. Chemical inhibition of LytG results in dysregulated cell elongation and localization of division plane and the induction of the cell wall stress response. In the presence of masarimycin, cells are elongated 3-fold compared to wild-type cells and formation of daughter cells along the sidewall was observed. The use of genetic and synergy/antagonism screens established connections to late-stage peptidoglycan synthesis, particularly related to cross-linking function. These results stand in stark contrast to those observed for the lytG knockout, which does not exhibit these phenotypes. The results presented here emphasize the difficulty in assigning mode-of-action using solely genetic screens. This is the first report of assigning physiological role of LytG beyond being the major GlcNAcase during vegetative growth. | Jazmeen Hernandez; Jett Duval; Taryn Rauff; Ethan Hall; Mika Gallati; Brad Haubrich; Monica Thoma; Elimelec Aponte; Amit Basu; Joseph A. DeGiorgis; Christopher Reid | Biological and Medicinal Chemistry; Chemical Biology; Microbiology | CC BY NC ND 4.0 | CHEMRXIV | 2023-09-29 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65157965a69febde9ed7dcc7/original/chemical-biology-reveals-involvement-of-n-acetylglucosaminidase-lyt-g-in-cell-elongation-and-division.pdf |
60c74ff34c891916b2ad3cbb | 10.26434/chemrxiv.12554117.v2 | Degradation of Pharmaceuticals Through Sequential Photon Absorption and Photoionization – the Case of Amiloride Derivatives | Photodegradation of pharmaceutical and agrochemical compounds is an important concern for health and the environment. Amiloride derivatives undergo clean photosubstitution in protic solvents. We have studied this apparent photo-SNAr reaction with a range of experimental and computational techniques. Available evidence points to a mechanism starting with photoexcitation followed by absorption of a second photon to eject an electron to give a radical cation intermediate. Subsequent substitution reaction with the protic solvent is assisted by a general base, possibly strengthened by the proximal solvated electron. Final recombination with the solvated electron generates the observed product. Quantum chemical computations reveal that excited state antiaromaticity is relieved when an electron is ejected from the photoexcited molecule by the second photon, leading to a weakly aromatic radical cation. The mechanism indicated here could have wide applicability to photoinduced degradation of similar heteroaromatic compounds in the environment as well as in protic solvents. There are also strong similarities to a class of increasingly popular synthetic photoredox methods. | Kjell Jorner; Wangchuk Rabten; Tomas Slanina; Nathalie Proos Vedin; Sara Sillén; Jufang Wu Ludvigsson; Henrik Ottosson; Per-Ola Norrby | Computational Chemistry and Modeling; Photochemistry (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2020-09-09 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ff34c891916b2ad3cbb/original/degradation-of-pharmaceuticals-through-sequential-photon-absorption-and-photoionization-the-case-of-amiloride-derivatives.pdf |
60c7526a469df4dc4af44b5f | 10.26434/chemrxiv.13296359.v1 | A Rapid and Efficient Autoclave Pre-Treatment to Extract Iodine-129 from Urine Samples for AMS Analysis | <p>A new method was developed to extract <sup>129</sup>I from urine
samples and then measure it by AMS. The samples were pre-treated in an
autoclave with hydrogen peroxide to remove unwanted compounds from the urine
samples and were acidified with nitric acid, followed by precipitation of
iodine as silver iodide (AgI) for measurement by AMS. This new procedure is
substantially faster than previous methods for the extraction of iodine from
urine and results in less chemical waste. The efficiency and reproducibility of
this method were evaluated by using <sup>125</sup>I as a yield tracer,
eventually giving a recovery above 99%. To achieve this, several iterations of
the method were required. The method was then successfully applied to measure <sup>129</sup>I/<sup>127</sup>I
isotopic ratios and <sup>129</sup>I concentrations in 25 human urine samples.
The AMS results for <sup>129</sup>I in urine ranged 3.3 x 10<sup>6</sup> atoms/L
to 884 x 10<sup>6</sup> atoms/L and the isotope ratio (<sup>129</sup>I/<sup>127</sup>I)
in human urine ranged from 7.38 x 10<sup>-12 </sup>to 3.97 x 10<sup>-10 </sup>with
a median of 1.29 x 10<sup>-10</sup>. This new method will be useful for
investigations into the sources of iodine in the human diet and their relative
importance for iodine sufficiency. </p>
<p> </p> | Fahad Alotaibi; Matthew N. Herod; R. Jack Cornett | Environmental Science; Biochemical Analysis; Environmental Analysis; Mass Spectrometry | CC BY NC ND 4.0 | CHEMRXIV | 2020-11-30 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7526a469df4dc4af44b5f/original/a-rapid-and-efficient-autoclave-pre-treatment-to-extract-iodine-129-from-urine-samples-for-ams-analysis.pdf |
628937d387d01f7f81ed76f1 | 10.26434/chemrxiv-2022-q8xkr-v2 | Y2Te3: A New n-type Thermoelectric Material | Rare-earth chalcogenides Re3-xCh4 (Re = La, Pr, Nd, Ch = S, Se, Te) have been extensively studied as high-temperature thermoelectric (TE) materials owing to their low lattice thermal conductivity (kL) and tunable electron carrier concentration via cation vacancies. In this work, we introduce Y2Te3, a rare-earth chalcogenide with a rocksalt-like vacancy-ordered structure, as a promising n-type TE material. We computationally evaluate the intrinsic transport properties, optimized TE performance, and doping characteristics of Y2Te3. Combined with a low kL, multiple low-lying conduction band valleys yield a high n-type TE quality factor. We find that a maximum figure-of-merit zT > 1.0 can be achieved when Y2Te3 is optimally doped with electron concentrations 1-2 x 10^20 cm-3. We use defect calculations to show that Y2Te3 is n-type dopable under Y-rich growth conditions, which suppresses the formation of acceptor-like cation vacancies. Furthermore, we propose that optimal n-type doping can be achieved with halogens (Cl, Br, I), with I being the most effective dopant. Our computational results as well as experimental results reported elsewhere motivate further optimization of Y2Te3 as an n-type TE material. | Michael Y. Toriyama; Dean Cheikh; Sabah K. Bux; G. Jeffrey Snyder; Prashun Gorai | Theoretical and Computational Chemistry; Energy; Theory - Computational; Piezoelectricity and Thermoelectricity; Materials Chemistry | CC BY 4.0 | CHEMRXIV | 2022-05-23 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/628937d387d01f7f81ed76f1/original/y2te3-a-new-n-type-thermoelectric-material.pdf |
631c3ec403e27d38d4cfa025 | 10.26434/chemrxiv-2021-9z37h-v2 | Correlating topography and viscoelastic properties of Elastin-Like Polypeptide scaffolds probed at the nanoscale: Intermodulation Atomic Force Microscopy | The synthesis and property characterization of soft biomaterials has taken precedence in recent years. Although bulk physical-chemical properties are well known for these bio-materials, nanoscale properties still need to be probed and evaluated to fine tune the bio-compatibility (structural as well as functional) with natural tissues for regenerative medicine, prosthetics and other biological applications. In this study, we focus on a popular soft biomaterial, ELastin-like polypeptide (ELP) which has been prepared under different pH conditions. We explore the topographical features of the ELP at the nanoscale using Atomic Force Microscopy (AFM). Additionally, we employ a non linear mode of AFM called Intermodulation-AFM (ImAFM) to correlate the elastic properties (Young's modulus) of ELP probed at the nanoscale with the topographical features which gives us a deep insight into the mechanical properties offered by ELP when the structural features are altered by change in the ELP synthesis conditions. The noteworthy point is that we measure theses properties at a spatial resolution of 0.9 nm. Finally, we explain the change in the structural features of ELP with varying pH through atomistic Molecular Dynamics Simulations. We follow the interaction mechanisms of the amino acid sequences and crosslinkers with proteins as they form the backbone and sidechain of the ELP at different pH. | Sebastiano Trusso; Samantha Firman; Janani Balasubramanian; Mohammad Hassan Khatami; Hendrick deHaan; Nisha Rani Agarwal | Theoretical and Computational Chemistry; Materials Science; Nanoscience; Biological Materials; Elastic Materials; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2022-09-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/631c3ec403e27d38d4cfa025/original/correlating-topography-and-viscoelastic-properties-of-elastin-like-polypeptide-scaffolds-probed-at-the-nanoscale-intermodulation-atomic-force-microscopy.pdf |
679a4658fa469535b9502fb8 | 10.26434/chemrxiv-2025-02wrf | On the Thermodynamics of Water Displacement from Binding Sites and its Contributions to Supramolecular and Biomolecular Affinity | The role of water displacement in noncovalent binding has been debated in the fields of supramolecular chemistry and drug design. We use molecular dynamics simulations of idealized host-guest systems to address the long-standing controversy of whether water is merely a bystander or an actual driver of noncovalent binding in aqueous solution. To isolate hydration effects, we consider a pseudo-hard-sphere guest binding to a series of cucurbit[8]uril-based host models whose energetic interactions with water vary widely. The computed free energy cost of displacing water from binding sites ranges from 0 to +37 kcal/mol, strongly influencing binding affinities. However, neither water density nor excess chemical potential reliably indicates the thermodynamic favorability of cavity water. These results support the concept that "unfavorable" binding site water contributes to high-affinity binding and resolve the paradox of stable but thermodynamically unfavorable cavity water. This work provides insights into the nature of the hydrophobic effect in molecular recognition and offers a framework for understanding water's role in binding across various host-guest and protein-ligand systems. | Jeffry Setiadi; Frank Biedermann; Werner Nau; Michael K. Gilson | Theoretical and Computational Chemistry; Physical Chemistry; Biophysical Chemistry; Statistical Mechanics; Thermodynamics (Physical Chem.) | CC BY NC ND 4.0 | CHEMRXIV | 2025-01-31 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/679a4658fa469535b9502fb8/original/on-the-thermodynamics-of-water-displacement-from-binding-sites-and-its-contributions-to-supramolecular-and-biomolecular-affinity.pdf |
61310da7fc08e3e0548929f2 | 10.26434/chemrxiv-2021-dnhxj | High-pressure reaction profiles and activation volumes of 1,3-cyclohexadiene dimerizations computed by the extreme pressure-polarizable continuum model (XP-PCM) | Quantum chemical calculations are reported for the thermal dimerizations of 1,3-cyclohexadiene at 1 atm and high pressures up to 6 GPa. Previous experiments [Klärner et al. Angew. Chem. Int. Ed. 1986, 25, 108], based on measured activation energies and activation volumes, suggested concerted mechanisms for the formation of the endo [4+2] cycloadduct and a [6+4]-ene adduct, and stepwise mechanisms for the formation of the exo [4+2] cycloadduct and two [2+2] cycloadducts. Computed activation enthalpies (ωB97XD, CCSD(T) and SC-NEVPT2) of plausible dimerization pathways at 1 atm agree well with the experiment activation energies and the values from previous calculations [Ess et al. J. Org. Chem. 2008, 73, 7586]. High-pressure reaction profiles, computed by the recently-developed extreme pressure-polarizable continuum model (XP-PCM), show that the reduction of reaction barrier is more profound in concerted reactions than in stepwise reactions, which is rationalized on the basis of the volume profiles of different mechanisms. A clear shift of the transition state towards the reactant by high pressure is revealed for the [6+4]-ene reaction by the calculations. The computed activation volumes by XP-PCM agree excellently with the experimental values, confirming the existence of competing mechanisms in the thermal dimerizations of 1,3-cyclohexadiene. | Bo Chen; K. N. Houk; Roberto Cammi | Theoretical and Computational Chemistry; Organic Chemistry; Physical Organic Chemistry; Computational Chemistry and Modeling; Theory - Computational | CC BY 4.0 | CHEMRXIV | 2021-09-28 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61310da7fc08e3e0548929f2/original/high-pressure-reaction-profiles-and-activation-volumes-of-1-3-cyclohexadiene-dimerizations-computed-by-the-extreme-pressure-polarizable-continuum-model-xp-pcm.pdf |
62dfa330dc4c7844523fe0ee | 10.26434/chemrxiv-2022-nnfrh | Complexes++: Efficient and versatile coarse-grained simulations of protein complexes and their dense solutions |
The interiors of living cells are densely filled with proteins and their complexes, which perform multitudes of biological functions. We use coarse-grained simulations to reach the system sizes and time scales needed to study protein complexes and their dense solutions, and to interpret experiments. To take full advantage of coarse-graining, the models have to be implemented efficiently in simulation engines that are easy to use, modify, and extend. Here, we introduce the Complexes++ simulation software to simulate a residue-level coarse-grained model for proteins and their complexes [Kim and Hummer, J. Mol. Biol. (2008)], applying a Markov chain Monte Carlo engine to sample configurations. We designed a parallelization scheme for the energy evaluation capable of simulating both dilute and dense systems efficiently. Additionally, we designed the software toolbox pycomplexes to easily set up complex topologies of multi-protein complexes and their solutions, different thermodynamic ensembles, and replica-exchange simulations, to grow flexible polypep- tide structures connecting ordered protein domains, and to automatically visualize structural ensembles. Complexes++ simulations can be easily modified and they can be used for efficient explorations of differ- ent simulation systems and settings. Thus, the Complexes++ software is well suited for the integration of experimental data and for method development. | Max Linke; Patrick Quoika; Berenger Bramas; Jürgen Köfinger; Gerhard Hummer | Theoretical and Computational Chemistry; Computational Chemistry and Modeling | CC BY NC ND 4.0 | CHEMRXIV | 2022-07-26 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62dfa330dc4c7844523fe0ee/original/complexes-efficient-and-versatile-coarse-grained-simulations-of-protein-complexes-and-their-dense-solutions.pdf |
60c75103337d6c143ce2846d | 10.26434/chemrxiv.13012589.v2 | Dynamic Stereoselection of Peptide Helicates and Their Selective Labeling of DNA Replication Foci in Cells | <a></a><a>Peptide engineering has been extremely successful in creating new structures with defined properties and functions. Although generally overlooked in this context, coordination chemistry offers an additional set of interactions that opens unexplored design opportunities for developing complex molecular structures. With this in mind, we report the development of new artificial peptide ligands that fold into chiral and discrete supramolecular helicates in the presence of labile metal ions such as Fe(II) and Co(II). By selecting appropriate heterochiral β‑turn promoting sequences, we can encode the stereoselective folding of the peptide ligand, and define the physicochemical properties of their corresponding metal complexes. The study of these metallopeptides by CD and NMR spectroscopy, combined with computational methods allowed us to identify and determine the structure of two isochiral ΛΛ-helicates, folded as topological isomers. </a>We also show that these new peptide helicates, dynamically selected in the presence of labile Co(II) ions, can be locked as kinetically-inert species by <i>in situ</i> oxidation to Co(III). Finally, in addition to the <i>in vitro</i> characterization of their selective binding to three-way DNA, cell microscopy experiments demonstrated that a rhodamine-labeled Fe(II) helicate was internalized and selectively stains DNA replication factories in functional cells. | Jacobo Gómez-González; Yolanda Pérez; Giuseppe Sciortino; Lorena Roldán-Martín; José Martínez-Costas; Jean-Didier Maréchal; Ignacio Alfonso; Miguel Vázquez López; M. Eugenio Vázquez | Stereochemistry; Supramolecular Chemistry (Org.); Analytical Chemistry - General; Bioinorganic Chemistry; Supramolecular Chemistry (Inorg.); Transition Metal Complexes (Inorg.); Chemical Biology; Computational Chemistry and Modeling; Self-Assembly | CC BY NC ND 4.0 | CHEMRXIV | 2020-10-13 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75103337d6c143ce2846d/original/dynamic-stereoselection-of-peptide-helicates-and-their-selective-labeling-of-dna-replication-foci-in-cells.pdf |
65bdfc829138d231615573d9 | 10.26434/chemrxiv-2024-7p3cm | Operando Fe Dissolution in Fe-N-C Electrocatalysts during Acidic Oxygen Reduction and Impact of Local pH Change | Atomic Fe in N-doped C (Fe-N-C) catalysts provide the most promising non-precious metal O2 reduction activity at the cathodes of proton exchange membrane fuel cells. However, one of the biggest remaining challenges to address towards their implementation in fuel cells is their limited durability. Fe demetallation has been suggested as the primary initial degradation mechanism. However, the fate of Fe under different operating conditions varies. Here, we monitor operando Fe dissolution of a highly porous and >50% FeNx electrochemical utilization Fe-N-C catalyst in 0.1 M HClO4, under O2 and Ar at different temperatures, in both flow cell and gas diffusion electrode (GDE) half-cell coupled to inductively coupled plasma mass spectrometry (ICP-MS). By combining these results with pre- and post-mortem analyses, we demonstrate that in the absence of oxygen, Fe cations diffuse away within the liquid phase. Conversely, at -15 mA cm-2geo and more negative O2 reduction currents, the Fe cations reprecipitate as Fe-oxides. We support our conclusions with a microkinetic model, revealing that the local pH in the catalyst layer predominantly accounts for the observed trend. Even at a moderate current density of -15 mA cm-2geo and under O2 at 25 oC, a significant H+ consumption and therefore pH increase (pH = 8-9) within the bulk Fe-N-C layer facilitate precipitation of Fe cations. This work provides a unified view on the Fe degradation mechanism for a model Fe-N-C in both high-throughput flow cell and practical operating GDE conditions, underscoring the crucial role of local pH in regulating the stability of the active sites. | Angus Pedersen; Kavita Kumar; Yu-Ping Ku; Vincent Martin; Laetitia Dubau; Keyla Teixeira Santos; Jesús Barrio; Viktoriia Saveleva; Pieter Glatzel; Vinod Paidi; Xiaoyan Li; Andreas Hutzler; Maria-Magdalena Titirici; Antoine Bonnefont; Serhiy Cherevko; Ifan Stephens; Frédéric Maillard | Materials Science; Catalysis; Energy; Carbon-based Materials; Electrocatalysis; Fuel Cells | CC BY 4.0 | CHEMRXIV | 2024-02-05 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65bdfc829138d231615573d9/original/operando-fe-dissolution-in-fe-n-c-electrocatalysts-during-acidic-oxygen-reduction-and-impact-of-local-p-h-change.pdf |
67378192f9980725cf4c657c | 10.26434/chemrxiv-2024-6j5md | Cheminformatic Analysis of Core-Atom Transformations in Pharmaceutically Relevant Heteroaromatics | Heteroaromatics are the basis for many pharmaceuticals. The ability to modify these structures through selective core-atom transformations, or "skeletal edits", can dramatically expand the landscape for drug discovery and development. However, despite the importance of core-atom modifications, the quantitative impact of such transformations on accessible chemical space remains undefined. Here, we report a cheminformatic platform to analyze which skeletal edits would most increase access to novel chemical space. This study underscores the significance of emerging single and multiple core-atom transformations in heteroaromatics in enhancing chemical diversity, for example, at a late-stage of a drug discovery campaign. Our findings provide a quantitative framework for prioritizing core-atom modifications in heteroaromatic structural motifs, calling for the development of new methods to achieve these types of transformations. | G. Logan Bartholomew; Lucas J. Karas; Reilly M. Eason; Charles S. Yeung; Matthew S. Sigman; Richmond Sarpong | Organic Chemistry | CC BY 4.0 | CHEMRXIV | 2024-11-19 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67378192f9980725cf4c657c/original/cheminformatic-analysis-of-core-atom-transformations-in-pharmaceutically-relevant-heteroaromatics.pdf |
61e010d27110e66a6b62937e | 10.26434/chemrxiv-2022-d5x5j-v2 | A photo-responsive modulation of trans-zeatin | Photo-irradiation of an appropriately designed caged hormones enables the control and manipulation of the corresponding biological processes with high spatial and temporal resolution. Caged trans-zeatin of various types of nitrobenzene carbonate related photoremovable protecting groups have been synthesized. A rapid irradiation liberates the trapped trans-zeatin molecule, permitting targeted perturbation of biological processes including degradation, glucosylation and recognition by appropriate enzymes. | Liang Cheng; Xin Sun; Li Liu | Biological and Medicinal Chemistry; Organic Chemistry; Agriculture and Food Chemistry; Photochemistry (Org.); Chemical Biology; Plant Biology | CC BY NC ND 4.0 | CHEMRXIV | 2022-01-17 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61e010d27110e66a6b62937e/original/a-photo-responsive-modulation-of-trans-zeatin.pdf |
60c74a08337d6c4a5ee277e6 | 10.26434/chemrxiv.12122763.v1 | Visualizing Semipermeability of Cell Membrane by a pH-responsive Ratiometric AIEgen | In clinical chemotherapy, some basic drugs cannot enter the hydrophobic cell membrane
because of ionization in acidic tumor microenvironment, a phenomenon known as ion
trapping. In this study, we developed a method to visualize this ion trapping
phenomenon by utilizing a pH-responsive ratiometric AIEgen, dihydro berberine
(dhBBR). By observing the intracellular fluorescence of dhBBR, we found that
non-ionized dhBBR can enter cells easier than ionized forms, which is in
accordance with the concept of ion trapping. In addition, dhBBR shows superior
anti-photobleaching ability than Curcumin thanks to its AIE property. These
results suggest that dhBBR can serve as a bioprobe for ion trapping. | Yuan Gu; zheng zhao; Guangle Niu; Han Zhang; Yiming Wang; Ryan Tsz Kin Kwok; Jacky W. Y. Lam; Ben Zhong Tang | Analytical Chemistry - General; Imaging; Microscopy | CC BY NC ND 4.0 | CHEMRXIV | 2020-04-20 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74a08337d6c4a5ee277e6/original/visualizing-semipermeability-of-cell-membrane-by-a-p-h-responsive-ratiometric-ai-egen.pdf |
60c7546abdbb89c19ea3a63e | 10.26434/chemrxiv.13567157.v2 | Solvent-Dependent Stability of Highly Defective UiO-66 to Acids and Bases | UiO-66 is one of the most chemically stable Metal-organic frameworks (MOFs) available. However, little is known about its stability in organic solvents. In this study, we synthesized a highly defective UiO-66 (HD-UiO-66) and explored how its textural properties change when exposed to weak and strong acids, both organic and inorganic in nature, and dissolved in different solvents, water, dichloromethane (DCM), and tetrahydrofuran (THF). Exposing defective UiO-66 to weak acids and bases, such as acetic acid and triethylamine, maintains its crystalline structure and porosity, irrespective of the solvent. Sulphuric acid decomposes HD-UiO-66 in organic solvents but not in water, trifluoroacetic acid decomposes the framework only in DCM. Tetramethylguanidine decomposes HD-UiO-66 in organic solvents but mantains some of the MOFs porosity and crystalline structure in water, whereas potassium carbonate damages the MOF to a greater extent in water than in organic solvents. Our results show that the acid/base properties of the solvent modulate the strength of acids and bases and its polarity determines the extent of their solvation, thus playing a crucial role in altering the MOF’s textural properties. This systematic investigation highlights the central role played by the solvent in tuning the stability of MOFs, which is relevant for liquid-phase applications in acidic and basic environments, such as catalysis and adsorption. | Daniele Cartagenova; Fabio A. Peixoto Esteves; Nathan T. Fischer; Jeroen A. van Bokhoven; Marco Ranocchiari | Coordination polymers; Coordination Chemistry (Inorg.) | CC BY NC ND 4.0 | CHEMRXIV | 2021-01-22 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7546abdbb89c19ea3a63e/original/solvent-dependent-stability-of-highly-defective-ui-o-66-to-acids-and-bases.pdf |
66c42130a4e53c4876e86a56 | 10.26434/chemrxiv-2024-4qb0x | Operando insights on CO2 electrolysis on Pr/Gd-doped ceria electrodes : the role of H2 | Ceria-based mixed ionic electronic conductors (MIEC) provide a lucrative electrode material for high temperature (800 oC) CO2 electrolysis. Doping the CeOx electrodes with Gd or Pr improves both the electrochemical and thermochemical processes on the catalyst surface. Our study provides an in-depth analysis of the effects of reactant gas concentration and applied reducing bias on the nature of the products formed. The electrodes were stable under strong reducing biases (-2 A/cm2), and could operate without incurring any major overpotential penalties. Operando Raman spectroscopy and online mass spectrometry (MS) were utilised in conjunction with electrochemical measurements to help establish a relationship between the catalyst structure and its chemical behaviour. The reduction of Ce4+ sites to Ce3+ (creation of oxygen defects) was found to be correlated with the production of CO on applying reducing bias. The doped materials (Ce{Pr}Ox and Ce{Gd}Ox), in general, demonstrated enhanched defect formation. In the presence of H2, Ce{Pr}Ox was found to oxidise, whereas, both CeOx and Ce{Gd}Ox exhibited reduction. In Ce{Pr}Ox, the oxidation by H2 and reduction by bias were found to compete. Coke formation was observed on the catalyst surface at high CO2 concentrations for the doped ceria electrodes. This coke formation co-incided with the removal of carbonyl peaks and Ce3+ enrichment in the Raman spectra. We have observed that increasing H2 concentration affects coke formation differently for Ce{Pr}Ox and Ce{Gd}Ox: it delays the onset bias for coke formation for the former, while expediting it for the latter with increasing H2 concentration. Through first principles-based calculations, we have correlated the counter-intuitive behaviour of Ce{Pr}Ox in H2 to the nature of the incorporated hydrogen in the Ce{Pr}Ox-H adduct in a reducing environment. Incorporation of H is found to stabilise the nearby oxygen sites for Ce{Pr}Ox, whereas it makes oxygen vacancy formation (and thereby, Ce3+ formation) easier for CeOx, Ce{Gd}Ox remains largely unaffected. We have demonstrated the role of hydrogen in improving the nearby metal-oxygen bonding. Our study provides a first account of the nature of interaction of hydrogen with doped ceria-based materials through both experimental techniques and theoretical calculations, which in turn affect their activity towards CO2 electrolysis. | Vipin Kamboj; Soham Raychowdhury; chinmoy ranjan | Catalysis; Energy; Electrocatalysis; Materials Chemistry | CC BY NC ND 4.0 | CHEMRXIV | 2024-08-21 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66c42130a4e53c4876e86a56/original/operando-insights-on-co2-electrolysis-on-pr-gd-doped-ceria-electrodes-the-role-of-h2.pdf |
60c755274c8919ff9aad4629 | 10.26434/chemrxiv.14046296.v1 | Heavy-Atom Effect Promotes Multi-Resonance Thermally Activated Delayed Fluorescence | As
one type of latest emitters with simultaneous high efficiency and color-purity,
the development of multi-resonance thermally activated delayed fluorescence (MR-TADF)
materials represents an important advancement for organic light-emitting diodes
(OLEDs). We herein present a new strategy to improve the performance of MR-TADF
emitters by fusing sulfur element into the B-N based framework, aiming to
utilize the non-metal heavy-atom effect in accelerating the reverse intersystem
crossing (RISC) process of the emitter. Two compounds, namely 2PTZBN and
2PXZBN, were developed in this work through rigidifying the DABNA-1 skeleton by
sulfur or oxygen atoms. The theoretical calculations and photoluminescence
studies revealed that the sulfur-incorporated 2PTZBN enabled considerable rate
constant of RISC (<i>k</i><sub>RISC</sub>)
up to 2.8 × 10<sup>5</sup> s<sup>-1</sup> in toluene due to larger spin-orbital
coupling (SOC) values and smaller singlet-triplet energy splitting (Δ<i>E</i><sub>ST</sub>) compared with 2PXZBN.
Consequently, organic light-emitting diodes based on 2PTZBN exhibited highly
efficient green emission with maximum external quantum efficiency (EQE) of
25.5%. | Tao Hua; Lisi Zhan; Nengquan Li; Zhongyan Huang; Xiaosong Cao; Zhengqi Xiao; Shaolong Gong; Changjiang Zhou; Cheng Zhong; Chuluo Yang | Optical Materials | CC BY NC ND 4.0 | CHEMRXIV | 2021-02-18 | https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c755274c8919ff9aad4629/original/heavy-atom-effect-promotes-multi-resonance-thermally-activated-delayed-fluorescence.pdf |
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