ChemRxiv最新文献

{"title":"Lipoic acid/ethyl lipoate as cleavable comonomers for synthesis of degradable polymer networks","authors":"Maciej, Kopeć, Frances, Dawson","doi":"10.26434/chemrxiv-2024-3f6vk-v2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-3f6vk-v2","url":null,"abstract":"α-Lipoic acid, and its derived ester ethyl lipoate, can copolymerise with n-butyl acrylate to install labile disulfide bonds within the polymer backbone. Covalently crosslinked gel networks containing these comonomers were synthesised by conventional (FRP) and reversible addition fragmentation chain transfer (RAFT) polymerisation. Gels synthesised by both methods and using both comonomers could be degraded by thiol-disulfide exchange to form soluble polymer fragments. The critical comonomer loading for degradation was lower for RAFT synthesised gels due to their more homogenous network structure. As these fragments where thiol functional, they could be oxidised in air with a base catalyst to reform a solid network. However, the presence of the carboxylic acid and the relatively low dispersity of the fragments act to prevent regelation. Therefore, only the gels containing the minimum amount of ethyl lipoate synthesised by RAFT could successfully regel as these fragments had no acid functionality and the highest dispersity value. We suggest that uniform comonomer incorporation leading to lower dispersity of the degraded fragments can be detrimental for the efficient reformation of the degraded network. However, the large amounts of the lipoate comonomer allow the dynamic exchange properties of the disulfide bonds within the polymer backbone, in the presence of DBU catalyst, to impart the networks with self-healing ability with no external pressure or heat.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"119 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Realization of a photoelectrochemical cascade for the generation of methanol, a liquid solar fuel","authors":"Ann L., Greenaway, Thomas, Chan, Calton J. , Kong, Grace A., Rome, Darci, Collins, Alex J., King, Rajiv Ramanujam, Prabhakar, Sarah A. , Collins, Michelle S., Young, Mickey J., Wilson, Myles A., Steiner, Adele C., Tamboli, Emily L., Warren, Clifford P., Kubiak, Joel W., Ager","doi":"10.26434/chemrxiv-2024-kxf6j-v2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-kxf6j-v2","url":null,"abstract":"Biochemical networks use reaction cascades to selectively reduce CO2 using energy from sunlight, but can similar selectivity be achieved by applying a cascade approach to an engineered system? Here, we report the design and implementation of a two-step photoelectrochemical (PEC) cascade to a liquid solar fuel: reduction of CO2 to CO and subsequent reduction of CO to methanol. The potentials required to perform the reductions were generated using custom-made III-V-based three-terminal tandem (3TT) solar cells. Cobalt phthalocyanine immobilized on multi-walled carbon nanotubes (CoPc/MWCNT) catalyzed both reactions. Multiphysics simulations of electrolyte flow and non-illuminated electrochemical measurements were used to narrow the operating parameters for the CoPc/MWCNT 3TT photocathodes. The champion integrated photocathode produced methanol with 3.8 ± 0.4% Faradaic efficiency (FE), with tested photocathodes having 0.7-3.8% methanol FE. Products were quantified by nuclear magnetic resonance spectroscopy and gas chromatography. The current output of the tested photocathodes was highly stable, and methanol production continued over multiple experiments. The low methanol yield is attributed to insufficient CO flux to, and CO2 depletion at, the methanol-producing subcell when both contacts are active, which is supported by the observation that a control photoelectrode slightly outperformed the methanol production of the 3TT device. Methanol production ceased when the 3TT subcell driving CO reduction was deactivated, supporting the assignment of a cascade mechanism. The major factors resulting in low methanol FE by the CoPc/MWCNT 3TT photocathodes are insufficient CO2 depletion at the methanol-producing contact and uncertainty in operating potential selection using the 3TT design. Although the CoPc/MWCNT 3TT photocathode is not yet highly selective, this work develops the basic science principles underlying the PEC cascade, demonstrates the co-design of a 3TT-based photoelectrode to produce carbon-based fuels, and finally discusses routes for improving product yields with this concept, including CO2 supply optimization and alternative photoelectrode and catalyst materials.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"250 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dearomative Skeletal Editing of Benzenoids via Diradical","authors":"Qing-An, Chen, Xiang-Xin, Zhang, Shan-Tong, Xu, Xue-Ting, Li, Ting-Ting, Song, Ding-Wei, Ji","doi":"10.26434/chemrxiv-2024-b5s8r","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-b5s8r","url":null,"abstract":"Dearomative skeletal editing of benzenoids represents a promising yet challenging strategy for the rapid construction of high-value carbon frameworks from readily accessible starting materials. Büchner reaction is a unique type of dearomatizative ring expansion that transforms benzenoids into functionalized cycloheptatrienes (CHTs). However, due to challenges in compatibil-ity and selectivity, achieving seamless integration of this reaction with upgrading transformations within a unified system re-mains undeveloped. Here, we demonstrated an energy transfer–induced intermolecular dearomative skeletal editing reaction of benzenoids with a range of electronically diverse alkynes. This protocol employed N-acylimines as diradical precursors to efficiently construct various formally rearranged heteropropellanes in high chemo-, regio- and diastereoselectivities that have been previously inaccessible. The challenges related to general reactivity and selectivity issues were circumvented through smooth merging of the photoinduced Büchner reaction with radical [6+2] cycloaddition. Experimental and computational stud-ies have been performed to support diradical mechanism and interpret the origins of the observed chemo-, regio- and dia-stereoselectivities.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of an Automated Workflow for Screening the Assembly and Host-Guest Behaviour of Metal-Organic Cages towards Accelerated Discovery","authors":"Annabel, Basford, Aaron Hero, Bernardino, Paula, Teeuwen, Benjamin, Egleston, Joshua, Humphreys, Kim, Jelfs, Jonathan, Nitschke, Imogen, Riddell, Rebecca, Greenaway","doi":"10.26434/chemrxiv-2024-hl427-v4","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-hl427-v4","url":null,"abstract":"Metal-organic cages (MOCs) are a class of self-assembled materials with promising applications in chemical purifications, sensing, and catalysis. Their potential is, however, hampered by challenges in the targeted design of MOCs with desirable properties. MOC discovery is thus often reliant on trial-and-error approaches and brute-force manual screening, which are time-consuming, costly and material-intensive. Translating the synthesis and property screening of MOCs to an automated workflow is therefore attractive, to both accelerate discovery and provide the datasets crucial for data-led approaches to accelerate MOC discovery and to realize their targeted properties for specific applications. Here, an automated workflow for the streamlined assembly and property screening of MOCs was developed, incorporating automated high-throughput screening of variables pertinent to MOC synthesis, data curation and automated analysis, and development of a host:guest assay to rapidly assess binding behavior. Computational modelling supplemented this automated experimental workflow for post priori rationalization of experimental outcomes. This study lays the groundwork for future large-scale MOC screening: from a relatively modest screen of 24 precursor combinations under one set of reaction conditions, 3 clean MOC species were identified, and subsequent screening of their host:guest behavior highlighted trends in binding and the identification of potential applications in molecular separations.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancing Vapor Pressure Prediction: A Machine Learning Approach with Directed Message Passing Neural Networks","authors":"Yen-Hsiang, Lin, Yi-Pei, Li, Hsin-Hao, Liang, Shiang-Tai, Lin","doi":"10.26434/chemrxiv-2024-nmnlk-v2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-nmnlk-v2","url":null,"abstract":"Background:\u0000Vapor pressure is a critical property in chemical and environmental engineering. Accurately predicting vapor pressure across a range of temperatures is vital for various applications, but traditional methods rely on critical property measurements or quantum mechanical calculations, which can be limiting, especially for new or under-characterized chemicals.\u0000Methods:\u0000This study employs a machine learning model based on the directed message passing neural network (D-MPNN) architecture to predict the vapor pressure of organic molecules. Various strategies to incorporate temperature effects into the model are explored to improve prediction accuracy.\u0000Significant findings:\u0000The D-MPNN model achieves significantly better accuracy than the traditional PR + COSMOSAC method, with a lower average absolute relative deviation (AARD) of 0.617 compared to 1.36 for the traditional method, using a dataset of 19,079 molecules. The machine learning approach offers a robust alternative that does not require additional critical property data or quantum mechanical calculations.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis, characterization and reactivity of a series of alkaline earth and rare earth iminophosphoranomethanide complexes","authors":"Fabrizio, Ortu, Matthew, Stevens, Yu, Liu, Rebecca, Hawker, Luis, Lezama, Daniel, Reta","doi":"10.26434/chemrxiv-2024-d2cb2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-d2cb2","url":null,"abstract":"Herein we report the use of the methanide ligand {CH(SiMe3)P(Ph)2=NSiMe3}– (NPC-H) in the stabilization of alkaline earth and rare earth complexes. Protonolysis of the proligand with nBu2Mg or dibenzyl precursors [M(CH2Ph)2(THF)x] (M = Ca–Ba, Eu, Yb) afforded bis-methanide complexes [M(NPC-H)2(THF)x] (1-M·(THF)x; M = Mg, Eu, Yb, x = 0; M = Ca, x = 0, 1; M = Sr, x = 0, 2; M = Ba, x = 2). The same reaction protocol with SmⅡ afforded oxidation product [Sm(NPC-H)3] (2-Sm) reproducibly, which could also be obtained via salt metathesis reaction between [{K(NPC-H)}2] and SmI3(THF)3.5. This salt metathesis methodology was also extended to [REI3(THF)x] (RE = Y, La, Pr), affording tris-methanides, [RE(NPC-H)3] (2-RE; RE = Y, La, Pr). 1-M and 2-RE were characterized by multinuclear NMR, IR spectroscopy, elemental analysis, UV-vis-NIR spectroscopy and single crystal X-ray diffraction; additionally, reactivity of 1-Yb, 2-Y and 2-La as potential synthetic precursors was probed with HN(SiMe3)2 and HOC6H3tBu2-2,6. NMR studies of the 1-M family reveal some underlying changes in the M–C bond character and bonding parameters in the ligand. We also report the first 171Yb{1H} NMR chemical shift (1046.5 ppm) of an ytterbium complex with an iminophosphoranomethanide ligand. Finally, the electronic structure of 1-Eu was studied by means of electron paramagnetic resonance and ab initio calculations.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Redox-innocent scandium(III) as the sole catalyst in visible light photooxidations","authors":"Radek, Cibulka, Amal, Tolba, Ahmed M., El-Zohry, Jafar Iqbal , Khan, Eva, Svobodová, Josef, Chudoba, Jiří, Klíma, Karol, Lušpai, Jiří, Šturala","doi":"10.26434/chemrxiv-2024-m0xw7","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-m0xw7","url":null,"abstract":"In recent years, the catalytic activity of scandium triflate [Sc(OTf)3] has attracted significant attention due to its robust Lewis acidity and the oxophilicity of Sc3+. These features have led to impressive progress in developing diverse organic reactions, including C-C bond formation. The Sc3+ cation also facilitates single electron transfer (SET) processes in photoinduced reactions either by coordination to an organophotoredox catalyst, which substantially modifies its redox reactivity, or by the formation of a scandium–superoxide anion complex (Sc3+-O-O•−) after electron transfer from a light-absorbing redox-active compound. The prior consideration of Sc3+ as a redox-inactive/innocent metal ion initially hampered the investigation of the possibility of using Sc(OTf)3 as a sole visible light photoredox catalyst. This research breaks new ground by demonstrating the inaugural use of Sc(OTf)3 as a visible light photocatalyst capable of direct and mild aerobic oxidative C-H functionalisation of aromatic substrates by oxidation of the benzylic position and direct cyanation of the aromatic ring.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Entangled excited state branching processes in a Ru(II)-based push-pull triad","authors":"Stephan, Kupfer, Guangjun, Yang, Louis , Blechschmidt, Linda , Zedler, Clara, Zens, Kamil , Witas, Georgina E. , Shillito, Sven , Rau, Benjamin, Dietzek-Ivanšić","doi":"10.26434/chemrxiv-2024-9fds6","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-9fds6","url":null,"abstract":"Compared with triplet metal-to-ligand charge transfer (3MLCT) states, charge-separated (3CS) excited states involving organic moieties, such as triplet intra-ligand or ligand-to-ligand charge transfer (3ILCT and 3LLCT) states, tend to possess longer-lived excited states due to the weak spin-orbit coupling with the closed-shell ground state (GS). Thus, the combination of both inorganic and organic chromophores enables the isolation of triplet excited states onto the organic chromophore. Herein, we aim to elucidate the entangled excited-state relaxation processes in a Ru(II)-terpyridyl push-pull triad (RuCl) in a joint spectroscopic-theoretical approach combining steady-state and time-resolved spectroscopy as well as quantum chemical simulations and dissipative quantum dynamics. The kinetics of the underlying electron transfer (ET) processes involving the low-lying 3MLCT, 3ILCT and 3LLCT excited states were investigated experimentally and computationally within a semi-classical Marcus picture, which allowed us to evaluate the ET processes between along the 3MLCT-3ILCT and the 3MLCT-3LLCT channels. Finally, dissipative quantum dynamical simulations – capable of describing incomplete ET processes involving all three states of interest – enabled us to unravel the competitive excited state relaxation channels at the short timescale vs. at the long timescale among the strongly coupled 3MLCT-3ILCT states as well as the weakly coupled 3MLCT/3ILCT-3LLCT states.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adapted DFTB3 repulsive potentials reach DFT accuracy for hydride transfer reactions in enzymes","authors":"José Luís, Velázquez-Libera, Rodrigo, Recabarren, David, Adrian Saez, Carlos, Castillo, J. Javier , Ruiz-Pernía, Iñaki , Tuñón, Esteban , Vöhringer-Martinez","doi":"10.26434/chemrxiv-2024-kkwwg-v2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-kkwwg-v2","url":null,"abstract":"Enzymatic hydride transfer reactions play a crucial role in numerous metabolic pathways, yet their accurate computational modeling remains challenging due to the trade-off between accuracy and computational efficiency. Ideally, molecular dynamics simulations should sample all enzyme configurations along the reaction path using post Hartree-Fock or DFT QM/MM electrostatic embedding methods, but these are computationally expensive. Here, we introduce a simple approach to improve the third-order density functional tight binding (DFTB3) semi-empirical method to model hydride transfer reactions in enzymes. We identified deficiencies in DFTB3's description of the potential energy surface for the hydride transfer step in Crotonyl-CoA Carboxylase/Reductase (Ccr) and developed a systematic methodology to address these limitations. Our approach involves modifying DFTB3's repulsive potential functions using linear combinations of harmonic functions, guided by analysis of C-H and C-C distance distributions along the reaction path. The optimized DFTB3 Hamiltonian significantly improved the description of the hydride transfer reaction in Ccr, reproducing the reference DFT activation barrier within 0.1 kcal/mol. We also addressed the transferability of our method by applying it to another hydride transfer reaction bearing the 1,4-dihydropyridine motif but exhibiting distinct structural features of the reactant, as well as the hydride transfer reaction in Dihydrofolate Reductase (DHFR). In both cases our adapted DFTB3 Hamiltonian correctly reproduced the DFT reference and experimentally observed activation barriers. The low computational cost and transferability of our method will enable more accurate and efficient QM/MM molecular dynamics simulations of hydride transfer reactions, potentially accelerating research in enzyme engineering and drug design.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards Self-Driving Labs for Better Batteries: Accelerating Electrolyte Discovery with Automation and Bayesian Optimization","authors":"Jackie T., Yik, Carl, Hvarfner, Jens, Sjölund, Erik J., Berg, Leiting, Zhang","doi":"10.26434/chemrxiv-2024-mqb6s-v2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-mqb6s-v2","url":null,"abstract":"The integration of automation and data-driven methodologies offer a promising approach to accelerating materials discovery in energy storage research. Thus far, in battery research, coin-cell assembly has advanced to become near fully-automated but remains largely disconnected from data-driven methods, which have been primarily developed for computational or multi-fidelity datasets. To bridge the disconnect, this work presents a self-driving laboratory framework designed to accelerate electrolyte discovery by integrating automated coin-cell assembly, galvanostatic cycling of LiFePO4||Li4Ti5O12 organic-aqueous full-cells, and Bayesian optimization for selecting subsequent experiments based on prior results. The integration of Bayesian optimization highlights machine-intelligent decision-making, enabling closed-loop experimentation-analysis workflow. The study focuses on an organic-aqueous hybrid electrolyte system comprising four co-solvents—dimethyl sulfoxide, trimethyl phosphate, acetonitrile, and water—and two salts, lithium perchlorate and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Using this framework, electrolyte formulations with at least 94% Coulombic efficiency were identified. Additionally, quantification of hydrogen evolution by online electrochemical mass spectrometry revealed a direct correlation between the electrolyte water content and the hydrogen evolution kinetics, irrespective of the electrolyte co-solvent compositions. The results highlight the potential of combining Bayesian optimization with autonomous experimentation, while contributing new insights into electrolyte design for next-generation sustainable aqueous batteries.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"250 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}