Chemical Science最新文献

Solid electrolytes (SEs) are crucial for advancing next-generation rechargeable battery technologies, but their commercial viability is partially limited by expensive precursors, unscalable synthesis, or low ionic conductivity. Lithium tetrahaloaluminates offer an economical option but exhibit low Li⁺ conductivities with high activation energy barriers. This study reports the synthesis of lithium aluminum chalcohalide (Li_1.6AlCl_3.4S_0.6) using inexpensive precursors via one-step mechanochemical milling. The resulting Cl-S mixed-anion sublattice significantly improves the ionic conductivity from 0.008 mS cm^-1 for LiAlCl₄ to 0.18 mS cm^-1 for Li_1.6AlCl_3.4S_0.6 at 25 °C. Structural refinement of the high-resolution XRD patterns and ⁶Li magic-angle-spinning (MAS) NMR quantitative analysis reveals the formation of tetrahedrally-coordinated, face- and edge-shared LiCl _x S _y octahedra that facilitate 3D Li⁺ transport. Ab initio molecular dynamics (AIMD) simulations on Li_1.6AlCl_3.4S_0.6 support an enhanced 3D network for Li⁺ migration with increased diffusivity. All-solid-state battery (ASSB) half-cells using Li_1.6AlCl_3.4S_0.6 exhibit high-rate and long-term stable cycling performance. This work highlights the potential of Li_1.6AlCl_3.4S_0.6 as a cost-effective and high-performance SE for ASSBs.

Understanding the adsorption behavior of intermediates at interfaces is crucial for various heterogeneous systems, but less attention has been paid to metal species. This study investigates the manipulation of Co³⁺ spin states in ZnCo₂O₄ spinel oxides and establishes their impact on metal ion adsorption. Using electrochemical sensing as a metric, we reveal a quasi-linear relationship between the adsorption affinity of metal ions and the high-spin state fraction of Co³⁺ sites. Increasing the high-spin state of Co³⁺ shifts its d-band center downward relative to the Fermi level, thereby weakening metal ion adsorption and enhancing sensing performance. These findings demonstrate a spin-state-dependent mechanism for optimizing interactions with various metal species, including Cu²⁺, Cd²⁺, and Pb²⁺. This work provides new insights into the physicochemical determinants of metal ion adsorption, paving the way for advanced sensing technologies and beyond.

Although supported Mo-containing catalysts have been extensively investigated in the metathesis of ethylene with 2-butene to propene, the mechanisms of the formation and transformation of catalytically active Mo-carbenes in the course of the reaction are still not fully understood. The difficulties arise because only a tiny fraction of MoO _x species can form Mo-carbenes in situ, making the detection of the latter by spectroscopic means very unlikely. Herein, purposefully designed steady-state and transient experiments including their kinetic evaluation and density functional theory calculations enabled us to elucidate mechanistic and kinetic details of the above reaction-induced processes in the metathesis reaction over a Mo/P/SiO₂ catalyst at 50 °C. We established that, in parallel with the desired reaction cycle, molybdacyclobutanes also undergo reversible structural transformations which might be one of the reasons for low steady-state catalyst activity. Based on the results obtained, strategies for controlling the concentration of the inactive species and accordingly catalyst activity have been suggested and experimentally validated.

Single-cell multi-dimensional analysis enables more profound biological insight, providing a comprehensive understanding of cell physiological processes. Due to limited cellular contents, the lack of protein and metabolite amplification ability, and the complex cytoplasmic environment, the simultaneous analysis of intracellular proteins and metabolites remains challenging. Herein, we proposed a multi-dimensional bio mass cytometry platform characterized by protein signal conversion and amplification through an orthogonal exogenous enzymatic reaction. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene editing technology was applied in the quantification of endogenous intracellular protein glycer-aldehyde-3-phosphate dehydrogenase (GAPDH) through exogenous luciferase Nanoluc (Nluc). The simultaneous detection of GAPDH and hundreds of metabolites at the single-cell level was realized for the first time. Semiquantitative analysis of GAPDH together with single-cell metabolomes under S-nitrosoglutathione (GSNO)-induced oxidative stress was investigated. Bioinformatics analysis revealed 16 metabolites that correlated positively with GAPDH expression upon oxidative stress, including long-chain fatty acids (palmitoleic acid, myristic acid, etc.) and UDP-N-acetylglucosamine (UDP-GlcNAc). Potential synergetic functions of GAPDH and UDP-GlcNAc-mediated oxidative stress responses were also elucidated. Our work proposes a novel strategy for the simultaneous quantitative analysis of single-cell intracellular proteins and metabolites, deepens the understanding of inherent anti-oxidative stress response mechanisms, and provides the molecular fundamentals for the study of inherent biological processes.

Network measures have proven very successful in identifying structural patterns in complex systems (e.g., a living cell, a neural network, the Internet). How such measures can be applied to understand the rational and experimental design of chemical reaction networks (CRNs) is unknown. Here, we develop a procedure to model CRNs as a mathematical graph on which network measures and a random graph analysis can be applied. We used an enzymatic CRN (for which a mass-action model was previously developed) to show that the procedure provides insights into its network structure and properties. Temporal analyses, in particular, revealed when feedback interactions emerge in such a network, indicating that CRNs comprise various reactions that are being added and removed over time. We envision that the procedure, including the temporal network analysis method, could be broadly applied in chemistry to characterize the network properties of many other CRNs, promising data-driven analysis of future molecular systems of ever greater complexity.

The layer-stacking mode of a two-dimensional (2D) material plays a dominant role either in its topology or properties, but remains challenging to control. Herein, we developed alkali-metal ion-regulating synthetic control on the stacking structure of a vinylene-linked covalent triazine framework (termed sp²c-CTF) for improving hydrogen peroxide (H₂O₂) photoproduction. Upon the catalysis of EtONa in Knoevenagel polycondensation, a typical eclipsed stacking mode (sp²c-CTF-4@AA) was built, while a staggered one (sp²c-CTF-4@AB) was constructed using LiOH. The AB stacking might be induced by the Li⁺ promoted Lewis acid-base interactions with the nitrogen atoms of s-triazine units which would endow the s-triazine units with a charged state and enlarge the total crystal stacking energy. Specifically, the shift in the stacking mode speeds up electron transfer within each layer and along interlayers, thereby improving the photocatalytic activity. sp²c-CTF-4@AB features superior activity over the eclipsed stacking counterpart (sp²c-CTF-4@AA) in sacrificial agent-free H₂O₂ generation, comparable to the state-of-the-art COF photocatalysts, which has not been demonstrated in this field before. This work demonstrates that regulating the interlayer-stacking mode of COFs can endow them with high photocatalytic activity, further inspiring the development of heterogeneous catalysis.

Proton-coupled electron transfer (PCET) is a crucial chemical process involving the simultaneous or sequential transfer of protons and electrons, playing a vital role in biological processes and energy conversion technologies. This study investigates the use of an organic photoredox catalyst to facilitate a unimolecular PCET process for the generation of alkyl radicals from benzylic alcohols, with a particular focus on alcohols containing electron-rich arene units. By employing a benzophenone derivative as the catalyst, the reaction proceeds efficiently under photoirradiation, achieving significant yields without the need for a Brønsted base. The findings highlight the potential of this unimolecular PCET mechanism to streamline radical generation in organic synthesis, offering a more efficient and flexible alternative to conventional methods.

Must excimers quench fluorescence? This study aims to clarify the misconception that excimers are defective species with weak fluorescence. For this purpose, we utilized a rigid xanthene template to connect anthracene units for constructing an inter-excimer and an intra-excimer. Their photophysical properties were systematically investigated in solution and crystal forms, representing dynamic and static environments, respectively. In solutions, the inter- and intra-excimers exhibited low fluorescence efficiencies due to the limited formation and ease of dissociation of the excimers. In crystals, the inter- and intra-excimers both demonstrated a significant increase in fluorescence efficiency, which was ascribed to the greatly suppressed non-radiation for the static excimer in a rigid environment. Furthermore, the efficiency of the inter-excimer was higher than that of the intra-excimer, which arose from the more stable excited state for more effective non-radiative suppression. Therefore, it was concluded that the probability and stability of excimer formation are the key factors for improving excimer fluorescence efficiency. Overall, their fluorescence efficiencies can be ranked as follows: dynamic inter-excimer < dynamic intra-excimer < static intra-excimer < static inter-excimer, which is subjected to environmental rigidity and excimer stability. This work will provide a comprehensive understanding of excimers and propose a novel design strategy to achieve high-efficiency fluorescent materials for innovative organic photo-functional applications.

Mycobacterial hemerythrin-like proteins (HLPs) are important for the survival of pathogens in macrophages. Their molecular mechanisms of function remain poorly defined but recent studies point to their possible role in nitric oxide (NO) scavenging. Unlike any nonheme diiron protein studied so far, the diferric HLP from Mycobacterium kansasii (Mka-HLP) reacts with NO in a multistep fashion to consume four NO molecules per diiron center. HLPs are largely conserved across mycobacteria and we argued that comparative studies of distant orthologs may illuminate the role of the protein scaffold in this reactivity and yield intermediates with properties more favorable for detailed spectroscopic characterization. Herein, we show that HLP from Azotobacter vinelandii (Avi-HLP) requires a single T47F point mutation in the outer sphere of its diferric center to adopt a bridging μ-oxo diferric structure as in Mka-HLP and makes it reactive toward NO. Radical combination of NO with the μ-oxo bridge yields nitrite and a mixed valent Fe(iii)Fe(ii) cluster that further react with NO to produce a stable magnetically coupled Fe(iii){FeNO}⁷ cluster. We report characterization of this stable cluster by electronic absorption, EPR, FTIR and resonance Raman spectroscopies and suggest ways Phe 46 (Mka numbering) might control the Fe(iii) reduction potential and the NO reactivity of HLPs.

Recent advancements in 3D structure-based molecular generative models have shown promise in expediting the hit discovery process in drug design. Despite their potential, efficiently generating a focused library of candidate molecules that exhibit both effective interactions and structural diversity at a large scale remains a significant challenge. Moreover, current studies often lack comprehensive comparisons to high-throughput virtual screening methods, resulting in insufficient evaluation of their effectiveness. In this study, we introduce Topology Molecular Type assignment (TopMT-GAN), a novel approach using Generative Adversarial Networks (GANs) for direct structure-based design. TopMT-GAN employs a two-step strategy: constructing 3D molecular topologies within a protein pocket with one GAN, followed by atom and bond type assignment with a second GAN. This integrated approach enables TopMT-GAN to efficiently generate diverse and potent ligands with precise 3D poses for specific protein pockets. When tested on five diverse protein pockets, TopMT-GAN exhibits promising and robust performance, demonstrating a potential enrichment of up to 46 000 fold compared to traditional high-throughput virtual screening methods. This highlights its potential as a powerful tool in early-stage drug discovery, such as hit and lead generation.