Chemistry methods : new approaches to solving problems in chemistry最新文献

With the growing emphasis on environmentally friendly analytical practices, green approaches to chiral separation have become vital for assessing the enantiomeric purity of chiral pharmaceutical agents. This study aimed to develop a green HPLC method for the enantioseparation of crizotinib, a tyrosine kinase inhibitor targeting anaplastic lymphoma kinase. The enantioselective performance of seven polysaccharide-based chiral stationary phases was systematically evaluated under polar organic conditions. Two chiral stationary phases—Lux Cellulose-3 and Lux Amylose-1—were identified as providing excellent enantiorecognition. Using experimental design-based approaches, we optimized three methods and retained them as final: (i) Lux Cellulose-3 with a methanolic mobile phase, (ii) Lux Cellulose-3 with an ethanol–water mobile phase, and (iii) Lux Amylose-1 with an ethanolic mobile phase. All three methods met ICH criteria: linearity (r²≥ 0.9996), precision (RSD ≤ 2%), and accuracy (~98%–101%), allowing quantification of the 0.02% distomer relative to the active enantiomer. Environmental performance was benchmarked using AGREE, Complex MoGAPI, Eco-Scale/Modified Eco-Scale, AMGS, and RGB-fast. All the developed methods showed superior environmental performance compared to the one method previously reported in the literature. However, it is also evident that applying green solvents does not inherently guarantee a cost-effective or sustainable approach. Overall, the developed methods provide an analytically robust and environmentally sustainable framework for the enantioseparation of crizotinib.

The fluorine (¹⁹F) nucleus has several properties that makes it exceptionally powerful for biological NMR, and these have been exploited for decades. However, in recent years, there has been a strong resurgence in ¹⁹F NMR spectroscopy, particularly for the study of large and complex biological systems that remain challenging for conventional approaches. This renewed interest has been enabled by advances in fluorine-labelling strategies together with a growing toolkit of NMR experiments. In this review, we first outline new labelling strategies that permit the site-specific incorporation of fluorine at strategic positions in proteins, including probes with very high signal intensity, enhanced sensitivity to the chemical environment, and tags that exploit the high-resolution ¹⁹F–¹³C TROSY effect. We then cover the expanding set of ¹⁹F NMR experiments that use these probes to investigate both structure and dynamics across a wide range of timescales. Throughout the review, we highlight recent studies that exemplify these approaches, including work that integrates ¹⁹F NMR measurements with complementary techniques to provide deeper insight into biomolecular mechanisms.

Modulation excitation spectroscopy (MES) is a powerful method to provide information on active species and sites in catalytic reactions. We present the design of a diffuse-reflectance IR Fourier transform spectroscopy (DRIFTS) cell, which is suitable for MES but also applicable to other in situ and operando DRIFTS studies on catalytic materials. The cell is characterized by a low void volume to allow for sufficiently fast gas exchange during MES experiments, even at high gas pressures. The potential of the cell is illustrated for the mechanistic analysis of CO₂ hydrogenation over a ceria-supported copper catalyst (Cu/CeO₂) at 10 bar using ME-DRIFTS combined with phase-sensitive detection (PSD). Using MES/PSD key intermediates of methanol formation could be identified, that is, carbonates and formates, as well as methoxy groups, which are immediate precursors of methanol. By comparison of the mechanistic behavior of Cu/CeO₂ with bare ceria, the crucial role of copper for the reaction toward methanol was demonstrated. The presented DRIFTS cell offers high versatility for steady-state and transient spectroscopic analysis under in situ/operando conditions, providing detailed mechanistic information, including the identification of intermediates during surface reactions over catalytic materials, facilitating their rational design.

Modulation excitation spectroscopy (MES) is a powerful method to provide information on active species and sites in catalytic reactions. We present the design of a diffuse-reflectance IR Fourier transform spectroscopy (DRIFTS) cell, which is suitable for MES but also applicable to other in situ and operando DRIFTS studies on catalytic materials. The cell is characterized by a low void volume to allow for sufficiently fast gas exchange during MES experiments, even at high gas pressures. The potential of the cell is illustrated for the mechanistic analysis of CO₂ hydrogenation over a ceria-supported copper catalyst (Cu/CeO₂) at 10 bar using ME-DRIFTS combined with phase-sensitive detection (PSD). Using MES/PSD key intermediates of methanol formation could be identified, that is, carbonates and formates, as well as methoxy groups, which are immediate precursors of methanol. By comparison of the mechanistic behavior of Cu/CeO₂ with bare ceria, the crucial role of copper for the reaction toward methanol was demonstrated. The presented DRIFTS cell offers high versatility for steady-state and transient spectroscopic analysis under in situ/operando conditions, providing detailed mechanistic information, including the identification of intermediates during surface reactions over catalytic materials, facilitating their rational design.

In this study, a new methodology for microfluidic acid–base titration is developed using a cross-shaped microfluidic channel. Multiphase laminar flow forms within the channel, where the sample solution is sandwiched between the two laminar flows of titrant solutions. Lateral diffusion between the sample and titrant creates two equivalent points across the channel, and the distance between these points is defined as the titration parameter. Simulations based on Fick's diffusion equation show that this parameter increases with higher sample concentration. Compared with conventional microfluidic-based titration systems, this approach features a simple channel design that enables multiple titrations on a single microfluidic channel. A computational study of the diffusion process of protons and hydroxide ions in a microfluidic channel is conducted based on a diffusion equation, along with experimental studies on the titration of both strong and weak acids using a sodium hydroxide solution. The acid determination of hot spring samples and vinegar proves the robustness and feasibility of the present methodology. The findings demonstrate a simple and portable titration method that enables accurate, instrument-free concentration analysis, with potential for on-site, inline, and point-of-care applications.

The commercialization of aqueous zinc-ion batteries (ZIBs) remains hindered by poor Zn electrodeposition efficiency in mild-acidic electrolytes, mainly due to the parasitic hydrogen evolution reaction (HER). The use of metallic substrates, such as copper or indium, has proven to be one of the most effective and potentially industrially viable strategies for kinetically promoting zinc electrodeposition over hydrogen evolution, while simultaneously ensuring a uniform deposit morphology. Here, a scalable strategy to fabricate indium-containing substrates via galvanic displacement, offering a simple, cost-effective, and environmentally sustainable alternative to conventional production methods has been presented. The prepared substrates demonstrate average efficiencies exceeding 99% over 150 Zn stripping/plating cycles at a realistic depth of discharge, requiring a fraction of Zn reservoir compared to standard Zn electrodes. A multivariate design of experiment (DOE) approach is employed to optimize both electrode fabrication and electrolyte parameters, highlighting key variables affecting Zn deposition efficiency and uncovering critical synergistic and antagonistic effects otherwise hidden in traditional one-variable-at-a-time (OVAT) methods. Overall, this work not only demonstrates the feasibility of upscaling indium-modified substrates for high-performance ZIBs but also emphasizes the power of DOE in accelerating material optimization and deepening the understanding of complex electrochemical systems.

Phenomena occurring in the electrolyte as well as the interfaces with the electrodes, such as Li⁺ solvation/desolvation and solid–electrolyte interphase formation, govern the performance and safety of Li-ion batteries. In this article, a dedicated, spring-loaded operando attenuated-total-reflectance Fourier-transform infrared cell is presented, enabling quantitative, time-resolved probing of the electrode–electrolyte processes under electrochemical examination. The optical design is based on a 45^∘ incidence diamond waveguide, while the electrochemical setup comprises a gas-tight stainless steel body. The procedure for preparing the self-supported electrode and the acquisition protocol are also presented, together with a reproducible analysis workflow for tracking solvated versus free electrolyte solvent species without baseline subtraction. Representative measurements on composite tin electrodes validate the ability of the setup to resolve band shifts and intensity changes linked to Li⁺ coordination and electrolyte reduction. The methodology generalizes to diverse negative-electrode chemistries and provides molecular-level insight into battery phenomena under electrochemical operating conditions.

Zeolites are widely studied as promising catalysts for the chemical recycling of plastics due to their inherent microporosity and shape-selective properties. The accessibility of polymer chains to internal acid sites is limited, and initial reactions are supposed to occur near the external surface. A deeper understanding of the role of external acid sites is required to optimize the structure and morphology of the zeolites. In this study, a novel ZSM-5 zeolite catalyst with Brønsted acid sites selectively localized only on the external surface (ZSM-5-SA) is synthesized via selective ion exchange using bulky tetrapropylammonium ions, followed by calcination. Catalytic testing of low- and high-density polyethylene revealed that the initial degradation is mainly triggered at Brønsted acid sites located on the external surface and near-surface internal regions. Once protonated, the polymer chains undergo β-scission, leading to similar product distributions regardless of the acid site density. These findings highlight that a small number of spatially accessible acid sites can effectively initiate and propagate the cracking reaction. These findings establish a direct link between the acid site location and reaction pathway and offer a rational design principle for advanced zeolite catalysts tailored for polymer cracking and chemical upcycling.

Metal–organic frameworks (MOFs) are promising materials for photocatalytic hydrogen production. However, their efficiency is often limited by the optical properties of conventional organic linkers, such as terephthalic acid (TA). In this work, the synthesis of two novel triphenylamine-based organic dyes (L0-TA and L1-TA) featuring a donor–π–acceptor (D–π–A) structure is reported. These dyes are functionalized with a terminal moiety analogous to aminoterephthalic acid, which serves as visible-light-absorbing linkers. These dyes retain the coordination ability required for MOF assembly while enhancing light-harvesting properties. Crystallographic simulations confirm the structural compatibility of these colinkers in hybrid MOFs, providing a viable strategy to maintain MOF crystallinity while improving photocatalytic performance.

The Cover Feature illustrates the vapour-phase metalation of ML-(NH₄)₂V₇O₁₆ squares by atomic layer deposition (ALD) using diethylzinc (DEZ) as precursor, transforming them into zinc vanadate. The image reflects angstrom-scale precision, morphological preservation, and solvent-free sustainability. Directional motifs and layered textures evoke chemisorption, structural metamorphosis, and a rocket-like ascent toward magnetic and functional properties. More information can be found in the Research Article by M. A. Moreno and co-workers (DOI: 10.1002/cmtd.202500066).