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Lipoic acid/ethyl lipoate as cleavable comonomers for synthesis of degradable polymer networks
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-3f6vk-v2
Maciej, Kopeć, Frances, Dawson
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.
α-硫辛酸及其衍生酯硫辛酸乙酯可与丙烯酸正丁酯共聚,从而在聚合物骨架中安装可变二硫键。含有这些共聚物的共价交联凝胶网络是通过传统(FRP)和可逆加成片段链转移(RAFT)聚合法合成的。用这两种方法合成的凝胶和使用的两种共聚单体都可以通过硫醇-二硫交换降解,形成可溶性聚合物片段。RAFT 合成凝胶的降解临界共聚单体含量较低,这是因为它们的网络结构更均匀。由于这些片段具有硫醇功能,因此可以在空气中用碱催化剂进行氧化,重新形成固体网络。然而,羧酸的存在和片段相对较低的分散性阻碍了重新凝胶化。因此,只有通过 RAFT 合成的含脂酸乙酯量最少的凝胶才能成功重新凝胶,因为这些片段不含酸官能团,且分散度值最高。我们认为,共聚单体的均匀加入会导致降解片段的分散度降低,不利于降解网络的有效重组。然而,大量的脂酸共聚单体使得聚合物骨架中的二硫键在 DBU 催化剂的作用下具有动态交换特性,从而赋予网络自我修复能力,而无需外部压力或热量。
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引用次数: 0
Realization of a photoelectrochemical cascade for the generation of methanol, a liquid solar fuel 实现光电化学级联,生成甲醇这种液体太阳能燃料
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-kxf6j-v2
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
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.
生化网络使用级联反应利用太阳光的能量选择性地还原二氧化碳,但将级联方法应用于工程系统能否实现类似的选择性呢?在此,我们报告了一种液态太阳能燃料两步光电化学(PEC)级联反应的设计与实施:将 CO2 还原成 CO,再将 CO 还原成甲醇。进行还原所需的电位是通过定制的基于 III-V 的三端串联(3TT)太阳能电池产生的。固定在多壁碳纳米管(CoPc/MWCNT)上的酞菁钴催化了这两个反应。通过对电解质流动的多物理场模拟和非照明电化学测量,缩小了 CoPc/MWCNT 3TT 光电阴极的工作参数范围。冠军集成光电阴极产生甲醇的法拉第效率(FE)为 3.8 ± 0.4%,测试光电阴极的甲醇法拉第效率为 0.7-3.8%。通过核磁共振光谱和气相色谱法对产品进行了定量。受测光电阴极的电流输出高度稳定,甲醇产量可持续多次实验。甲醇产量低的原因是,当两个触点都处于激活状态时,甲醇产生子电池的 CO 通量不足,二氧化碳耗尽,而对照光电阴极的甲醇产量略高于 3TT 装置,也证明了这一点。当驱动一氧化碳还原的 3TT 子电池失活时,甲醇生产停止,这支持了级联机制的假设。导致 CoPc/MWCNT 3TT 光阴极甲醇产率低的主要因素是甲醇产生接触处的二氧化碳耗尽不足,以及使用 3TT 设计选择工作电位时的不确定性。尽管 CoPc/MWCNT 3TT 光电阴极的选择性还不高,但这项研究工作发展了 PEC 级联的基本科学原理,展示了生产碳基燃料的基于 3TT 的光电阴极的联合设计,最后讨论了利用这一概念提高产品产量的途径,包括二氧化碳供应优化和替代光电阴极和催化剂材料。
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引用次数: 0
Dearomative Skeletal Editing of Benzenoids via Diradical
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-b5s8r
Qing-An, Chen, Xiang-Xin, Zhang, Shan-Tong, Xu, Xue-Ting, Li, Ting-Ting, Song, Ding-Wei, Ji
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.
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引用次数: 0
Development of an Automated Workflow for Screening the Assembly and Host-Guest Behaviour of Metal-Organic Cages towards Accelerated Discovery
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-hl427-v4
Annabel, Basford, Aaron Hero, Bernardino, Paula, Teeuwen, Benjamin, Egleston, Joshua, Humphreys, Kim, Jelfs, Jonathan, Nitschke, Imogen, Riddell, Rebecca, Greenaway
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.
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引用次数: 0
Advancing Vapor Pressure Prediction: A Machine Learning Approach with Directed Message Passing Neural Networks
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-nmnlk-v2
Yen-Hsiang, Lin, Yi-Pei, Li, Hsin-Hao, Liang, Shiang-Tai, Lin
Background:Vapor 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.Methods:This 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.Significant findings:The 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.
背景:蒸气压是化学和环境工程中的一项关键特性。准确预测各种温度范围内的蒸气压对各种应用都至关重要,但传统方法依赖于临界性质测量或量子力学计算,这可能具有局限性,尤其是对于新化学品或特征描述不足的化学品。重要发现:与传统的 PR + COSMOSAC 方法相比,D-MPNN 模型实现了更高的准确度,使用 19,079 个分子的数据集,平均绝对相对偏差(AARD)为 0.617,低于传统方法的 1.36。机器学习方法提供了一种无需额外关键属性数据或量子力学计算的稳健替代方法。
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引用次数: 0
Synthesis, characterization and reactivity of a series of alkaline earth and rare earth iminophosphoranomethanide complexes 一系列碱土和稀土亚氨基磷甲烷络合物的合成、表征和反应活性
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-d2cb2
Fabrizio, Ortu, Matthew, Stevens, Yu, Liu, Rebecca, Hawker, Luis, Lezama, Daniel, Reta
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.
{"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}
引用次数: 0
Redox-innocent scandium(III) as the sole catalyst in visible light photooxidations 氧化还原无辜的钪(III)作为可见光光氧化反应的唯一催化剂
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-m0xw7
Radek, Cibulka, Amal, Tolba, Ahmed M., El-Zohry, Jafar Iqbal , Khan, Eva, Svobodová, Josef, Chudoba, Jiří, Klíma, Karol, Lušpai, Jiří, Šturala
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.
{"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}
引用次数: 0
Entangled excited state branching processes in a Ru(II)-based push-pull triad 基于 Ru(II)的推挽三元组中的纠缠激发态分支过程
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-9fds6
Stephan, Kupfer, Guangjun, Yang, Louis , Blechschmidt, Linda , Zedler, Clara, Zens, Kamil , Witas, Georgina E. , Shillito, Sven , Rau, Benjamin, Dietzek-Ivanšić
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.
与三重金属-配体电荷转移(3MLCT)态相比,涉及有机分子的电荷分离(3CS)激发态,如三重配体内或配体-配体电荷转移(3ILCT 和 3LLCT)态,由于与闭壳基态(GS)的自旋轨道耦合较弱,往往具有较长的激发态寿命。因此,将无机发色团和有机发色团结合起来,可以将三重激发态分离到有机发色团上。在此,我们采用光谱-理论联合方法,结合稳态和时间分辨光谱以及量子化学模拟和耗散量子动力学,旨在阐明 Ru(II)-terpyridyl 推挽三元体(RuCl)中的纠缠激发态弛豫过程。我们在半经典马库斯图景中对涉及低洼 3MLCT、3ILCT 和 3LLCT 激发态的基本电子转移(ET)过程的动力学进行了实验和计算研究,从而评估了 3MLCT-3ILCT 和 3MLCT-3LLCT 通道之间的 ET 过程。最后,耗散量子动力学模拟--能够描述涉及所有三种相关状态的不完全 ET 过程--使我们能够揭示强耦合的 3MLCT-3ILCT 状态和弱耦合的 3MLCT/3ILCT-3LLCT 状态之间在短时间尺度和长时间尺度上竞争性的激发态弛豫通道。
{"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}
引用次数: 0
Adapted DFTB3 repulsive potentials reach DFT accuracy for hydride transfer reactions in enzymes 改编后的 DFTB3 斥力势达到了酶中氢化物转移反应的 DFT 精确度
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-kkwwg-v2
José Luís, Velázquez-Libera, Rodrigo, Recabarren, David, Adrian Saez, Carlos, Castillo, J. Javier , Ruiz-Pernía, Iñaki , Tuñón, Esteban , Vöhringer-Martinez
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.
酶促氢化物转移反应在众多新陈代谢途径中起着至关重要的作用,但由于需要在准确性和计算效率之间权衡,因此对其进行精确计算建模仍具有挑战性。理想情况下,分子动力学模拟应使用后 Hartree-Fock 或 DFT QM/MM 静电嵌入方法对反应路径上的所有酶构型进行采样,但这些方法计算成本高昂。在此,我们介绍一种简单的方法来改进三阶密度泛函紧密结合(DFTB3)半经验方法,以模拟酶中的氢化物转移反应。我们发现了 DFTB3 在描述巴豆酰-CoA 羧化酶/还原酶(Ccr)中氢化物转移步骤的势能面时存在的不足,并开发了一种系统方法来解决这些局限性。我们的方法包括使用谐函数的线性组合修改 DFTB3 的斥势函数,并以沿反应路径的 C-H 和 C-C 距离分布分析为指导。优化后的 DFTB3 哈密顿改进了对 Ccr 中氢化物转移反应的描述,在 0.1 kcal/mol 的范围内重现了参考 DFT 活化障碍。我们还将我们的方法应用于另一个含有 1,4-二氢吡啶基团但反应物结构特征明显的氢化物转移反应,以及二氢叶酸还原酶(DHFR)中的氢化物转移反应,从而解决了方法的可转移性问题。在这两种情况下,我们改编的 DFTB3 哈密顿都正确地再现了 DFT 参考和实验观察到的活化障碍。我们方法的低计算成本和可移植性将使氢化物转移反应的 QM/MM 分子动力学模拟更加精确和高效,从而有可能加速酶工程和药物设计方面的研究。
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引用次数: 0
Towards Self-Driving Labs for Better Batteries: Accelerating Electrolyte Discovery with Automation and Bayesian Optimization 实现更好电池的自动驾驶实验室:利用自动化和贝叶斯优化加速电解质的发现
Pub Date : 2024-12-13 DOI: 10.26434/chemrxiv-2024-mqb6s-v2
Jackie T., Yik, Carl, Hvarfner, Jens, Sjölund, Erik J., Berg, Leiting, Zhang
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.
自动化与数据驱动方法的整合为加速储能研究中的材料发现提供了一种前景广阔的方法。迄今为止,在电池研究中,纽扣电池组装已接近全自动化,但在很大程度上仍与数据驱动方法脱节,而数据驱动方法主要是针对计算或多保真度数据集开发的。为了弥合这种脱节,这项研究提出了一种自动驾驶实验室框架,旨在通过整合自动纽扣电池组装、LiFePO4||Li4Ti5O12 有机水性全电池的电静力循环以及根据先前结果选择后续实验的贝叶斯优化,加速电解质的发现。贝叶斯优化的集成突出了机器智能决策,实现了闭环实验-分析工作流程。研究重点是有机-水混合电解质系统,包括四种共溶剂--二甲基亚砜、磷酸三甲酯、乙腈和水,以及两种盐--高氯酸锂和双(三氟甲磺酰基)亚胺锂(LiTFSI)。利用这一框架,确定了库仑效率至少为 94% 的电解质配方。此外,通过在线电化学质谱对氢演化进行定量,发现无论电解质助溶剂成分如何,电解质含水量与氢演化动力学之间都存在直接关联。这些结果凸显了贝叶斯优化与自主实验相结合的潜力,同时为下一代可持续水性电池的电解质设计提供了新的见解。
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引用次数: 0
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