Israel Journal of Chemistry最新文献

Herein, we report a minimalistic protocol for the solvent-free, mechanochemical difluoromethylation of (thio)phenols and N-heteroarenes using non-ozone depleting chlorodifluoromethyl phenyl sulfone as a difluorocarbene source. This mechanochemical difluoromethylation features a short reaction time, excellent functional group tolerance, and compatibility with complex biologically active scaffolds.

Transition metal catalysts with modified second-coordination sphere employed in the electrocatalytic CO₂ can result in increased activity or directed product selectivity. Calixarenes can form metal complexes and potentially catalyze reactions within its cavity, taking advantage of the surrounding phenols groups to tune the reactivity by second-coordination sphere effects. Here, we present a Mn(I) bromotricarbonyl complex with phenanthroline-functionalized calix[8]arene ligands capable of electrocatalytically reducing CO₂ into different products with 2,2,2-trifluoroethanol as proton donor. The selectivity of the reaction seems to be affected by the calixarene cavity: two calixarene-free analogous complexes reduce CO₂ to CO almost exclusively, while the calixarene complexes produce primarily CO, H₂. Interestingly, in some cases the less frequently observed CH₄ was also detected, albeit with low Faradaic efficiency. Thus, the manganese center placed within the calixarene cavity promotes the formation of reduced CO₂ products by more than two electrons and two protons, affording CH₄ in some cases.

There is an urgent need to develop new antibacterial agents against multidrug resistant bacteria. Herein we report our investigation of antimicrobial peptide dendrimers (AMPDs) active against Gram-negative bacteria, whose sequences were designed using a genetic algorithm optimizing molecular similarity to the previously reported AMPD T7 with sequence (KL)₈(KKL)₄(KKLL)₂KKKL. Our computational approach selected analogues unlikely to emerge from a systematic study, including AMPD X66 with a non-conservative Leu→Glu mutation at the dendrimer core which proved compatible with antibacterial effects. Circular dichroism showed that this AMPD is α-helical. Molecular dynamics suggest that its α-helical structure is stabilized by an intramolecular salt bridge involving the core glutamate side chain and a lysine side chain in the dendrimer branches. More substantial variations at the dendrimer core were also tolerated such as the installation of the dianionic pegylated fatty acid side chain of the drug semaglutide potentially useful for in vivo studies.

The Annual Wolf Prize Symposia of the Israel Chemical Society (ICS) have become a significant component of the scientific landscape of the State of Israel. These highly attended events occur annually in late May or early June as part of the Wolf Prize week, usually one day before the award ceremony in the Knesset. This account covers the one-day symposium at the Weizmann Institute of Science on June 14, 2023, the Wolf Prize ceremony in the Knesset on June 15, and several other events in Israel that week, all honoring Chuan He, Jeffrey W. Kelly, and Hiroaki Suga.

Despite substantial advancements in thermal and photochemical catalysis, the evolution of similar processes within the realm of organic electrochemistry has seen a slower pace. However, recent years have heralded a remarkable surge in molecular electrocatalysis. This innovative technique harnesses the power of molecular catalysts to expedite electrochemical transformations. This article underscores the application of ferrocene (Fc) as a redox catalyst in organic electrosynthesis. It delves into the extensive utilization of Fc in organic electrosynthesis, particularly emphasizing its role in the electrocatalytic generation and reactions of heteroatom- and carbon-centered radicals, among various other reactions.

This mini review provides an overview of a range of Ni-, Co- and Pd-catalyzed electroreductive cross-coupling reactions. The combination of homogeneous transition-metal catalysis and electrochemistry are green alternatives to traditional reductive cross-coupling reactions to form Csp²-Csp², Csp²-Csp³ and some Csp³-Csp³ bonds in one step. Most of these reactions use the sacrificial anode process.

A one-pot synthesis of 2-acylidene-3-oxindole and azaaurone derivatives starting from O-alkynylanilines and alkynes is presented. By means of oxidative gold catalysis the two starting materials are transferred to reactive intermediates that in situ form the target products. This double oxidation strategy enables a protecting group-free step-economic strategy towards these valuable substrate classes.

Mass spectrometry (MS) is a central analytical technique used to study proteins and biomolecules. It measures mass-to-charge ratio of ions to identify and quantify molecules in simple and complex mixtures. Technological advancement in instrumentation, sample preparation methodologies, and data analysis workflows continue to push the capabilities of MS to answer more complicated questions and vice versa. Structural proteomics uses MS-based methodologies to characterize protein structure. Specifically, but not limited to, hydrogen deuterium exchange MS (HDX-MS) and crosslinking MS (XL-MS) are complementary techniques that capture the structural plasticity inherent to proteins in solution. This review is intended to present recent progress in HDX-MS and XL-MS that have allowed these techniques to be used not only for simple recombinant protein systems but with complex cellular systems.

The cover art presents Helmut Schwarz surrounded by his favorite chemistry - a collage of graphical display items selected from several papers previously published by Helmut Schwarz and his research group.

Calix[4]arenes and calix[4]resorcinarenes are well-known macrocyclic hosts that can be tailored to bind guests of very different natures, including anions, cations, and various neutral molecules. The molecular architectures of the hosts can be altered in many ways: by attaching polar or hydrophilic groups, extending inner cavities with enlarged aromatic side walls, and adding H-bonding sites to promote the formation of molecular capsules. The attachment of different types of redox-active moieties renders calix[4]arene and calix[4]resorcinarene derivatives electrochemically active, enabling them to either control the guest-binding properties of the receptors or be used as electrochemical sensors. This review will focus on calix[4]arene and calix[4]resorcinarene macrocyclic hosts with appended redox-active groups, such as ferrocene, tetrathiafulvalene, and quinone. We will discuss molecular receptors that can serve as redox sensors for cations or electron-deficient molecules or can bind and release their guests controlled by redox or electrochemical stimuli.