Communications Chemistry最新文献

Effective chemical catalysts can artificially control intracellular metabolism. However, in conventional catalytic chemistry, activity and cytotoxicity have a trade-off relationship; thus, driving catalysts in living cells remains challenging. To overcome this critical issue at the interface between catalytic chemistry and biology, we developed cell-driven allosteric catalysts that exert catalytic activity at specific times. The synthesized allosteric redox catalysts up- and downregulated their foldase- and antioxidase-like activities in response to varying Ca²⁺ concentrations, which is a key factor for maintenance of the redox status in cells. In the absence of Ca²⁺ or at low Ca²⁺ concentrations, the compounds were mostly inactive and hence did not affect cell viability. In contrast, under specific conditions with elevated cytosolic Ca²⁺ concentrations, the activated compounds resisted the redox imbalance induced by the reactive oxygen species generated by Ca²⁺-stimulated mitochondria. Smart catalysts that crosstalk with biological phenomena may provide a platform for new prodrug development guidelines.

Diketopyrrolopyrrole-based blue dyes in dye-sensitized solar cells (DSCs) exhibit promise for building-integrated photovoltaics, but their efficiency is compromised by dye aggregation-induced charge recombination. Novel bile acid derivative co-adsorbents featuring bulky hydrophobic substituents at the 3-β position were synthesized to address this challenge. These molecules, designed to modulate intermolecular electronic interactions, effectively altered the TiO₂ surface coverage dynamics, as evidenced by UV-Vis spectroscopy and dye-loading kinetics. Systematic variation of hydrophilic substituents revealed structure-function relationships in dye separation efficacy. Devices incorporating these co-adsorbers achieved power conversion efficiencies (PCE) of 7.6%, surpassing reference devices (5.2%) and those using conventional chenodeoxycholic acid co-adsorbers (6.4%). The optimized devices exhibited a 30% increase in short-circuit current density, 30 mV enhancement in open-circuit voltage, and 60% peak external quantum efficiency at 550 nm. Time-resolved photoluminescence spectroscopy confirmed suppressed non-radiative recombination, while transient absorption spectroscopy revealed accelerated electron injection rates from 6.4 ps to 4.6 ps. Electrochemical impedance spectroscopy elucidated the mechanism of reduced interfacial recombination. These findings present a molecular engineering strategy for mitigating lateral charge transfer in planar dye systems, advancing semi-transparent hybrid photovoltaics.

The isoaspartate residue is a spontaneous, time-dependent post-translational modification (PTM) of proteins and peptides, associated with in vivo protein aggregation and changes in molecule lifetime. While this is considered a slow modification impacting long lived proteins, surprisingly, we observed this PTM at high levels within the relatively short-lived neuropeptide galanin (Gal). The combination of liquid chromatography-trapped ion mobility mass spectrometry and protein Isoaspartyl methyltransferase assays demonstrated that 20 ± 2% of the mature Gal contain L-Isoaspartate residue in the hypothalamus of Rattus norvegicus. Aspartate in Gal isomerizes spontaneously under mildly acidic conditions within 48 h in vitro, much faster than previously assumed. Gal with the L-isoaspartate PTM significantly enhanced fibril formation. Transmission electron microscopy revealed differences in morphology of fibrils formed by D17Isoasparte Gal compared to the unmodified peptide. Observed characteristics of D17Isoasparte Gal suggest a potential mechanism for the development of in vivo Gal fibril deposits previously reported in the brain.

Protonic ceramic fuel cells (PCFCs) should exhibit high performance at intermediate temperatures in the range of 400-600 °C. To reduce the operating temperature, more active air electrodes (positrodes) are needed. In the present work, BaCo_0.4Fe_0.4Mg_0.1Y_0.1O_3-δ (BCFMY) is investigated as a positrode material for application in PCFCs as well as solid oxide fuel cells (SOFCs). For SOFCs, the polarization resistance ascribed to the oxygen reduction reaction is proportional to p_O2^-1/4 (p_O2: oxygen partial pressure), suggesting that the rate-determining process is the charge transfer on the mixed ionic-electronic conductors. For PCFCs, this polarization resistance is proportional to p_O2^-1/2, suggesting that the rate-determining process is the oxygen dissociation. The total polarization resistance for the PCFCs using the BCFMY positrode is 0.066 Ωcm² at 600 °C, lower than that using the BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ (BCFZY) positrode. The higher oxygen nonstoichiometry of BCFMY promotes the oxygen dissociation process on the PCFC positrode surface.

Non-ionic detergents enable the investigation of cell membranes, including biomolecule purification and drug delivery. The question of whether non-ionic detergents associated with satisfying protein yields following extraction and affinity purification of proteins from lysed E. coli membranes can amplify antibiotics on whole-cell E. coli remains to be addressed. We unlock the modular chemistry of linear triglycerol detergents to reveal that more polar, non-ionic detergents that form globular micelles work better in amplifying antimicrobial activities of antibiotics than in purifying the membrane proteins mechanosensitive channel and aquaporin Z. Less polar detergents that form worm-like micelles indicate poor performances in both applications. With chromatography we demonstrate how fine-tuning the polarity of chemical linkers between detergent headgroups and tails can switch the utility of detergents from protein purification to antibiotic amplification. We anticipate our findings to be a starting point for structure-property studies to better understand detergent designs in supramolecular chemistry and membrane research.

Carbon-heteroatom bonds are of great importance due to their prevalence in pharmaceuticals, agrochemicals, materials, and natural products. Despite the effective use of metal-catalyzed cross-coupling reactions between sp²-hybridized organohalides and soft heteroatomic nucleophiles for carbon-heteroatom bond formation, the use of sp³-hybridized organohalides remain limited and the coupling with thiols remains elusive. Here, we report the coupling of sp³-hybridized benzyl or tertiary halides with soft thiol nucleophiles catalyzed by iron and extend the utility to alcohol and amine nucleophiles. The reaction is broad in substrate scope for both coupling partners and applicable in the construction of congested tri- and tetrasubstituted carbon centers as well as β-quaternary heteroatomic products. The synthetic utility is further emphasized by gram-scale synthesis and rapid herbicide library synthesis. Overall, we provide an efficient method to prepare pharmaceutically and materially relevant carbon-heteroatom bonds by expanding iron-catalyzed cross-coupling reactions to the coupling of sp³-hybridized organohalides with soft nucleophiles.

Sulfur mustard (HD) alkylates biomolecules such as proteins, generating specific biomarkers. This study employs steric hindrance, electronic effects, and solvent effects through an occupancy-removal strategy to synthesize regioisomers [N1-HETE]-His and [N3-HETE]-His, overcoming isomer separation challenges in conventional methods. Density functional theory (DFT) calculations revealed hexafluoroisopropanol (HFIP)'s critical role in directing HD's regioselective alkylation: HFIP modulates steric and electronic environments to preferentially target N1 or N3 sites of histidine imidazole rings, with predictions validated experimentally. The method further enables selective detection of the isomers in HD-contaminated plasma via standard addition, advancing absolute quantification. This work not only establishes a precision synthesis platform for biomarkers but also elucidates HFIP's unique role in imidazole regioselectivity, offering insights for medicinal chemistry and HD toxicology. These findings hold implications for HD exposure tracking, mechanism analysis, clinical diagnostics, and antidote development.

A μSPEed microextraction combined with ultra-performance liquid chromatography (UHPLC) with UV detection was developed for analysing six veterinary antibiotics (tetracycline, chlortetracycline, oxytetracycline, doxycycline, sulfamethoxazole, and trimethoprim) in environmental samples. To optimise extraction, 12 sorbent cartridges, sample loading cycles, volumes, and pH were assayed. The PS/DVB-RP cartridge, three 250 μL sample loading cycles, and two 50-µL elutions with acidified methanol yielded maximum efficiency. The method was validated with optimised fast chromatographic separation, showing good linearity (R2 > 0.99), precision (RSD < 20%), and recoveries between 46-86%. Detection and quantification limits ranged from 0.30-1.23 μg L^-1 and 0.92-3.73 μg L^-1, respectively. The optimised μSPEed/UPLC-PDA efficiently analysed environmental water samples, requiring only 6 min extraction, 6 min analysis, and 500 μL sample, surpassing alternative methods in speed, workloads and reproducibility. The cost-effective, commercially available equipment facilitates accessibility for laboratories and adaptability for analysing selected antibiotics in diverse matrices, including food and environmental samples.

The stereoselective introduction of glycosidic bonds is one of the greatest challenges in carbohydrate chemistry. A key aspect of controlling glycan synthesis is the glycosylation reaction in which the glycosidic linkages are formed. The outcome is governed by a reactive sugar intermediate - the glycosyl cation. Glycosyl cations are highly unstable and short-lived, making them difficult to study using established analytical tools. However, mass-spectrometry-based techniques are perfectly suited to unravel the structure of glycosyl cations in the gas phase. The main approach involves isolating the reactive intermediate, free from external influences such as solvents and promoters. Isolation of the cations allows examining their structure by integrating orthogonal spectrometric and spectroscopic technologies. In this perspective, recent achievements in gas-phase research on glycosyl cations are highlighted. It provides an overview of the spectroscopic techniques used to probe the glycosyl cations and methods for interpreting their spectra. The connections between gas-phase data and mechanisms in solution synthesis are explored, given that glycosylation reactions are typically performed in solution.

Multiple DNA damage resulting from different nearby ionizations of water molecules is an important process of the initial step of radiobiological effects. Several important characteristics of the damaged DNA site such as the critical size and types of chemical lesions are not well-known. We investigated this long-term issue by developing a dynamic Monte Carlo code for the chemical process. The reaction probabilities and the spatial distribution of lesions were theoretically solved as a function of the spur radius and distance between DNA and the initial ionisation position. From our previous reported results, we suggest that a hydroxyl radical and a hydrated electron from a single spur can concomitantly react within a 10 base pairs DNA to induce a multiple DNA damage site comprising a DNA single-strand break and reductive nucleobase damage; however, the reaction probability is 0.4% or less. Once this combination arises, it may result in a DNA double-strand break (DSB). DSBs are difficult to repair, which may lead to cell death or misrepair, and could lead to point mutations in the genome.