Precision Chemistry最新文献

Hydrogen sulfide (H₂S) is a signaling molecule with a plethora of biological functions, yet precision tools for modulating its intracellular flux remain scarce. Conventional small-molecule donors and enzymatic systems often suffer from off-target reactivity, uncontrolled release kinetics, and redox crosstalk, confounding mechanistic studies. Here, we establish a Salmonella typhimurium d-cysteine desulfhydrase (stDCyD)-derived chemogenetic tool for controlled H₂S manipulation in living cells. stDCyD catalyzes the α,β-elimination of d-cysteine to selectively yield bioavailable H₂S. We term this tool H₂SWITCH. Our approach exhibits pronounced enantioselectivity for d-cysteine, robust catalytic efficiency at physiological temperatures, and temporal tunability through substrate dosing. This chemogenetic tool provides a chemically defined and interference-free method to unravel the physiological and pathological roles of H₂S with unprecedented precision in complex biological systems.

Macrolactones are structurally important motifs that are found in a variety of natural products. While conventional approaches to their synthesis involve the use of seco acids with condensing agents or activators, methods based on hydroxyaldehydes as substrates remain relatively unexplored. Furthermore, the development of macrolactonization reactions that proceed via radical processes is still in its infancy, and to date, examples that use hydroxyaldehydes have not yet been reported. In this study, a photochemical macrolactonization of hydroxyaldehydes via in-situ-generated acyl bromide intermediates has been developed. Lactones with ring sizes ranging from 7-21 were successfully obtained in a good yield. The present photochemical radical macrolactonization therefore represents a promising tool for the synthesis of natural products.

The widespread use of polymeric materials has brought unparalleled convenience and utility, but their environmental persistence presents a critical and growing challenge. As demand increases for sustainable solutions to polymer waste, depolymerization continues to be a promising strategy for achieving true circularity. In this Perspective, we examine depolymerization from a fundamental standpoint, aiming to rationalize the advantages, limitations, and future directions of state-of-the-art technologies. We advocate for standardized reporting practices to enable meaningful comparisons across studies and, in alignment with this goal, we provide key metrics and contextual information throughout the article to support consistent evaluation of different depolymerization strategies. Ultimately, we hope to inspire readers to explore innovative and scalable solutions that advance the transformative potential of depolymerization toward the realization of a circular polymer economy.

Two dimensional (2D) materials have transitioned from lab findings to potential applications. Starting with the isolation of graphene, the field has rapidly expanded to encompass a broad spectrum of materials, including transition metal dichalcogenides, MXenes, and so on. Each of them offers unique structural, electronic, optical, and electrochemical properties. These materials have been recognized as candidates for applications in energy storage and conversion including electrocatalysts. As we approach the limits of traditional "trial-and-error" methods, the integration of statistical analysis, machine learning (ML), live (real-time) electrochemistry, and generative AI presents a compelling path forward. These tools are no longer aspirational; they are becoming essential to navigating the vast and complex design space of 2D materials for electrochemical applications in the future.

This study presents an unconventional approach for the gas-phase synthesis of ultrahigh molecular weight polyethylene (UHMWPE) using sterically hindered 2,6-bis-(diarylmethyl) α-diimine palladium-(II) catalysts. By leveraging a self-supported chain-walking polymerization mechanism, the catalysts form thin films on reactor walls, enabling efficient ethylene polymerization without solvents. The gas-phase chain-walking mechanism facilitates the migration of palladium species within the porous polymer matrix, enabling them to locate and access optimal sites for ethylene capture and subsequent insertion. The distal substituents on the catalysts were systematically varied to investigate their electronic and steric effects on polymerization activity, molecular weight, and branching density. Under optimized conditions (6 atm ethylene, 25 °C), the catalysts achieved high activity (up to 3.90 × 10⁵ g/(mol·h)) and produced UHMWPE with molecular weights exceeding 1600 kg/mol. Kinetic studies revealed a unique three-stage polymerization process, while branching densities (29-131 branches/1000 C) were tunable via catalyst design. The resulting polyethylene exhibited a porous network morphology and balanced mechanical properties, combining high impact resistance with processability. This work highlights the potential of gas-phase polymerization as an environmentally friendly and cost-effective route to UHMWPE with tailored microstructures.

Formaldehyde (FA) emissions seriously influence the environment and human health, while traditional adsorbents are restricted by low capacity and poor selectivity. To address these limitations, amino-functional hyper-cross-linked copolymer ionic compounds (HPIL-Cl-Xs) were designed and synthesized through a one-step hyper-cross-linking and quaternization reaction involving benzimidazole, dichloro-p-xylene, and functional monomers. These polymers provide an ionic environment, active adsorption sites, and a microporous structure, offering abundant adsorption sites. The synthesis parameters were studied to optimize the preparation conditions. Under conditions of 8.6 ppm and WHSV of 54,000 h^-1, the equilibrium adsorption capacity of HPIL-Cl-Phe (phenylalanine) reached 11.3 mg/g with a partitioning coefficient (PC) of 0.44 mol·kg^-1·Pa^-1, surpassing that of conventional adsorbents. The impacts of the adsorption temperature, WHSV, and relative humidity on adsorption were explored, confirming the adaptability of HPIL-Cl-Xs to various environmental conditions. DFT calculations, XPS, and FT-IR confirmed the existence of hydrogen bond interactions and nucleophilic addition reactions. HPIL-Cl-Phe demonstrated an excellent cycling performance with stable adsorption over multiple cycles.

Hydrogen sulfide (H₂S) is a hazardous byproduct of industrial processes and poses significant environmental and health risks. Conventional methods for H₂S removal are not cost-effective, motivating the exploration of photocatalytic splitting of H₂S to both remove H₂S and generate hydrogen. Recent advancements in the use of graphitic carbon nitride materials (g-CN), consisting of heptazine units, have shown impressive progress in the photocatalytic splitting of H₂S. This study employs excited-state nonadiabatic dynamics simulations to investigate the molecular-level mechanisms of photoinduced H₂S splitting in both gas-solid and aqueous phases. Using a H₂S···heptazine model, the gas-solid phase reaction reveals an electron-driven proton transfer (EDPT) process as the key reaction pathway. In the aqueous phase, the photocatalyst significantly improves light absorption efficiency, as the H₂S···(H₂O)₄ cluster absorbs only a limited range of ultraviolet light. Moreover, the study demonstrates that the photoinduced holes transfer from the photocatalyst to H₂S and water molecules, which is a crucial step in enhancing the detachment of hydrogen atoms and their subsequent possible combination to form hydrogen gas. These findings provide valuable insights into the charge carrier dynamics and reaction mechanisms, elucidating the potential for efficient hydrogen production from the photocatalytic splitting of hazardous H₂S.

The discovery of electrode materials with improved cyclic stability and a high rate of performance has been in great demand for the fast growth of energy storage technologies. MXene hybrids have high electrical conductivity, large surface area, layered structure, variable surface chemistry, and hydrophilicity, which make them appropriate for the use. This review aims to provide an overview of recent advancements and the evolution of MXene hybrids, including various synthesis strategies, structural characterization, and their use in energy storage. The current trends in MXene hybrids and their application in electrochemical performance and energy storage applications have been summarized. Overall, this review offers valuable insights, identifies potential opportunities, and provides key suggestions for the future advancement of MXene hybrid and energy storage/supercapacitor applications.