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

Tall oil fatty acid (TOFA) represents an important byproduct obtained from processing of lignocellulosic biomass, mainly in the pulp and paper industry. In this work, TOFA is first transformed into its soap form under optimized alkaline conditions. TOFA-based soap is then employed as feedstock for the production of long-chain alkenes through photocatalysis, using a photoreactor equipped with a ultraviolet a-light emitting diode source. The photocatalytic efficiency of TiO₂ is improved by surface modification with NH₄⁺ species. A response surface methodology (RSM) approach is applied to examine the influence of reaction duration (135, 180, and 225 min), photocatalyst loading (80, 110, and 140 mg), and the amount of TOFA-based soap (50, 100, and 150 mg). The maximum yield of C_n−1 long-chain alkenes (77.7 mg) is achieved at nearly 1:1 ratio of TOFA-based soap to NH₄-TiO₂ after 180 min irradiation at 365 nm. Under these optimized conditions, approximately 55% of the TOFA-based soap could be converted into long-chain alkenes. Hydration of these alkenes with sulfuric acid yields corresponding long-chain alcohols, which may act as precursors for bio-based extended surfactants and related applications. This study emphasizes the potential of TOFA, a byproduct of lignocellulosic waste streams, as a renewable feedstock for generating high-value chemicals.

High-temperature chemical-kinetics play an important role in the development of next-generation combustion systems. Toward this goal, a shock-tube facility capable of handling pressures up to 100 atm is constructed. It consists of an 8 m long driven section with an 18 cm internal diameter. The driver section measures 2.9 m in length, extendable to 6.5 m using a U-bend tube. The test section of the shock tube features eight optical windows, facilitating the application of multiple optical diagnostics. Shock-tube tests are performed to characterize the test time and non-·ideal pressure-rise phenomena. Typical test times are in the order of 3–4 ms, with longer durations of 21 ms achieved using tailoring techniques. To validate the shock-tube performance, ignition delay time measurements of stoichiometric methane/air mixtures are conducted, and the results show excellent agreement with literature data. Furthermore, experiments are conducted for stoichiometric methane/oxygen/argon mixtures to perform simultaneous carbon monoxide and carbon dioxide time-history measurements using laser absorption spectroscopy. These species time-history measurements show discrepancies with predictions from kinetics mechanisms, highlighting the need for such data for further mechanisms’ refinement. To the best of the authors’ knowledge, the present study reports the first CO₂ species time histories during methane oxidation behind reflected shock waves. The presented facility will be utilized in future chemical-kinetics studies, particularly for low-carbon and carbon-free fuels.

Chemical protein synthesis is a powerful tool that combines solid-phase peptide synthesis with protein ligations to join synthetic protein segments together. This technology allows for the incorporation of site-specific native and artificial modifications required for chemical biology research and therapeutic applications. Native chemical ligation (NCL), in which protein segments are joined together through a native amide bond, is the most widely used protein ligation strategy and has been employed in the synthesis and semi-synthesis of many modified proteins. Whilst recent advances have extended the range of chemical strategies and ligation junctions available, the selection and optimization of an efficient route to a target protein can be challenging and time-consuming. For most target proteins, several different approaches are possible, and their efficiency and sequence compatibility, as well as the protein properties and purpose of the target protein, must be evaluated. Here, several approaches to the synthesis of a target case study protein, the histone H2A.B variant are demonstrated, illustrating some of the potential challenges and troubleshooting options. This work provides a demonstration of the leading tools for NCL, to guide new users in the selection and optimization of appropriate strategies for targeting a diverse range of protein sequences and properties.

This study explores the chemical and physical mechanisms behind the distinct cracking patterns observed in the black-painted areas of five works by Antonio Saura, a key figure in 20th-century Spanish Informalist art. The investigation is prompted by the widespread presence of degradation phenomena—such as cracking, flaking, and delamination—affecting all black surfaces. The research aims to elucidate the correlation between Saura's material choices and the observed deterioration. A combination of multiband imaging and portable digital microscopy is employed to document the morphology and distribution of crack patterns. Additionally, elemental analysis such as XRF and microinvasive analytical techniques, including µ-Raman spectroscopy, ATR-FTIR, and GC–MS, was used to characterize pigments, binding media, paint additives, and degradation products. Findings reveal that Saura primarily employs commercial oil-based paints with opaque, glossy finishes. Variations in crack morphology are linked to the intrinsic properties of specific pigments—such as zinc white, titanium white, cerussite, hydrocerussite, bone black, and iron oxides—and their interactions with binding media (drying oils and alkyd resins), as well as environmental conditions. This research provides new insights into Saura's materials and highlights key issues, while proposing a methodological framework applicable to studying degradation phenomena in modern and contemporary artworks.

The Front Cover provides Chemistry Methods readers with a glimpse into the decision-making process that takes place during a mass spectrometry-driven natural products discovery workflow. To address this challenge, M. A. Beniddir and co-workers developed MS2DECIDE, a Python library that applies decision theory and expert knowledge to integrate the outputs of three widely used annotation tools–GNPS, SIRIUS, and ISDB-LOTUS–and generate recommendations for prioritizing natural products according to their potential novelty. For more details, see Research Article (DOI: 10.1002/cmtd.202400088).

Herein, the use of solvatochromic fluorescent probes for detecting polarity in cellular microenvironments, a complex physicochemical parameter that influences various biological processes, is reviewed. The nature of polarity itself is related to the physicochemical properties of the environment that affect the spectroscopic properties of luminophores. The mechanisms of solute–solvent interactions and photophysical processes, such as intramolecular charge transfer and photoinduced electron transfer, which are fundamental to understanding the response of the probes to polarity changes are discussed. In the intracellular context, solvatochromic probes have been used to determine polarity in different organelles and subcellular structures. The review puts emphasis on the various targeting strategies and the most commonly utilized photophysical parameters for estimating polarity are focused here. A special attention is paid to those approaches capable of providing absolute quantification of intracellular polarity, for instance, through ratiometric measurements or the use of fluorescence lifetime imaging to improve the accuracy of measurements. Reliable intracellular polarity measurements may provide invaluable information to understand physiological and pathological processes, including neurodegenerative diseases or cancer.

Atomically precise metal clusters have demonstrated significant advantages in homogeneous catalysis, heterogeneous catalysis, electronic catalysis, and photocatalysis. As much, electrocatalytic reduction of nitrate pollution into valuable compounds is a low-energy consumption and environmentally friendly route, which combines environmental and economic advantages by efficiently eliminating pollutant and recycling waste. This review systematically summarizes the current researches on atomically precise metal clusters in the electroreduction of nitrate to produce high-valued chemicals such as ammonia, urea, cyclohexanone oxime, and amino acids. The emphasis on the complexed reaction pathways and key intermediates involved in the conversion of nitrate into different target products is studied. The relationship between the structure of metal clusters and catalytic properties is delved into. This review aims to provide valuable insights for the design of high-performance metal cluster catalysts to achieve efficient conversion from nitrate to high-value-added chemicals.

Vapor phase metalation (VPM) via atomic layer deposition is emerging as a sustainable, solvent-free method for precise material functionalization. This study demonstrates selective zinc metalation of multilayered (NH₄)₂V₇O1₁₆ nanostructured squares using diethylzinc (DEZ) as a volatile precursor. A sequence of samples—(HDA)V₇O₁₆·nH₂O (S-1), (NH₄)₂V₇O₁₆·nH₂O (S-2), iodine-functionalized (S-3), and Zn-metalated (S-4)—was characterised via XRD, HRTEM/SAED, FIB-SEM, ESEM, ATR-FTIR, Raman microscopy, and XPS. The V7₇O₁₆ bilayer framework revealed a triclinic crystal structure (P-1 space group) for the first time. VPM enabled the transformation into Zn₃V3₃O₈ and wurtzite ZnO nanoparticles with structural precision and minimal waste. Metalation was achieved from a single half-cycle (210 seconds total), allowing fine control over deposition dynamics. This process also induced a magnetic transition from spin-frustrated semiconducting behavior to ferrimagnetism. The results underscore VPM's potential for low-impact, high-precision synthesis of multifunctional oxides, aligning with circular economy principles by reducing waste and enhancing recyclability. Applications span spintronics, neuromorphic computing, and sustainable catalysis.

Lipidation, such as S-palmitoylation, is an important, reversible post-translational modification of proteins determining not only their stability and folding but also their interactions with other proteins or membranes. However, in contrast to other post-translational modifications, lipidation is less explored, and lipidated proteins are underrepresented in large-scale studies. To advance the analysis of S-palmitoylation by mass spectrometry (MS), a model peptide containing four potential modification sites is selected. By selectively introducing S-palmitoylation, a set of multiply modified peptides is generated, differing in the sites as well as the degree of modification. Importantly, the solubility of the peptides decreased tremendously with increasing degree of modification, requiring the use of alternative solvents. Nonetheless, using direct-infusion MS, the ionization and fragmentation behavior of the differently modified peptides is characterized. Lipidation is found to be stable during tandem MS, and the sites of modification can be unambiguously identified. The use of dimethyl sulfoxide during electrospray ionization further improves the signal intensity of multiply modified peptides. In summary, the identification of S-palmitoylation even in multiply modified peptides is possible; however, further improvements are required for large-scale analyses.

Knowledge-based catalyst design requires the identification of the active structure during reaction, i.e., by operando spectroscopy, and at different conversion levels. However, for reactions that run at elevated pressure, such as methanol, Fischer–Tropsch, or ammonia synthesis, obtaining spectroscopic data at realistic conditions remains a major challenge. In particular, standard operando setups often fail to replicate the high-pressure, high-conversion regimes relevant to industrial processes. This requires specially designed reactors, and here, how additive manufacturing enables the development of spectroscopic reactors for operando studies of catalysts under high-pressure conditions at different conversion levels up to equilibrium is reported. The reactor has two consecutive zones with independent temperature control and individual catalyst loading. An X-ray-transparent window in the latter zone allows for spatially resolved spectroscopic monitoring of the catalyst structure. A mobile setup is constructed for operation at a synchrotron source, and the functionality of the reactor is demonstrated in an operando X-ray absorption spectroscopy study using a Cu/ZnO/ZrO₂ catalyst during CO₂ hydrogenation to methanol. The dual-zone design enabled simulation of an end-of-catalyst-bed environment, including condensation, which is highly critical for industrial relevance yet difficult to realize in conventional operando experiments.