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1,2‐benzisothiazol‐3(2H)‐one derivatives are highly active against a broad spectrum of fungi as well as Gram positive and Gram negative bacteria. For this reason they are extensively used, for example, as additives in detergents, leather products, paper coatings, and antifouling paintings. In this paper experimental findings are reported proving that the sulfur atom of benzisothiazolinones have a remarkable tendency to form short and directional chalcogen bondings on the extension of the covalent N−S bond and, to a lesser extent, of the C−S bond. Analyses of the Cambridge Structural Database confirm the interaction as a primary recognition motif of these systems. The electrophilicity of sulfur is crucial in the chemical reactions initiating the cascade of events resulting in the biopharmacological activities of benzisothiazolinones. The reported results suggest that the electrophility of sulfur may play a role also at earlier stages than the reactive ones, namely it may pin the compounds at the active site of target enzymes via chalcogen bondings that preorganize the system in the conformation required for the bonds formation/cleavage determining the biopharmacological activity [ABSTRACT FROM AUTHOR]

Free radicals are increasingly recognized as active intermediate reactive species that can participate in various redox processes, significantly influencing the mechanistic pathways of reactions. Numerous researchers have investigated the generation of one or more distinct photogenerated radicals, proposing various hypotheses to explain the reaction mechanisms. Notably, recent research has demonstrated the emergence of photogenerated radicals in innovative processes, including organic chemical reactions and the photocatalytic dissolution of precious metals. To harness the potential of these free radicals more effectively, it is imperative to consolidate and analyze the processes and action modes of these photogenerated radicals. This conceptual paper delves into the latest advancements in understanding the mechanics of photogenerated radicals. [ABSTRACT FROM AUTHOR]

Hydrogen bonding greatly influences rates and equilibrium positions of chemical reactions, conformations, and sometimes even stereochemistry. This study reports on tetranitrofluorenone oximate, a novel dye capable of naked‐eye detection of hydrogen‐bond donating species (HBDs) and of rapid determination of H‐bond donation strength by hypsochromic shift monitoring. In addition, the molecule possesses atropisomeric conformations, of M and P configuration, as evidenced in solid and solution state studies by X‐ray diffraction and electronic circular dichroism (ECD), respectively. In the latter case, enantiopure bis‐thioureas were the most effective HBDs to promote a chiral induction (diastereoselective recognition, Pfeiffer effect); the ECD results being rationalized by time‐dependent density functional theory (TDDFT) calculations. Based on these experiments, bis‐thioureas were used as chiral reagents in asymmetric 1,3‐dipolar cycloadditions of structurally‐related nitrones; the ECD sensing of the stereoinduction between bis‐thioureas and the oximate serving as an indirect method of selection of the most effective HBD for asymmetric synthesis. [ABSTRACT FROM AUTHOR]

Molecular quantum mechanical modeling, accelerated by machine learning, has opened the door to high‐throughput screening campaigns of complex properties, such as the activation energies of chemical reactions and absorption/emission spectra of materials and molecules; in silico. Here, we present an overview of the main principles, concepts, and design considerations involved in such hybrid computational quantum chemistry/machine learning screening workflows, with a special emphasis on some recent examples of their successful application. We end with a brief outlook of further advances that will benefit the field. [ABSTRACT FROM AUTHOR]

The stereochemistry of the addition of NH3 to the stereoisomers of 1,2‐di‐tert‐butyl‐1,2‐bis(2,4,6‐triisopropylphenyl)disilene (Z‐5 or E‐5) is 100 % stereospecific giving two isomeric disilylamines 6 and 7, respectively, derived from syn‐addition to the stereoisomeric disilenes. Variable time normalization analysis studies of the reaction of tetramesityldisilene (3) with isopropylamine (iPrNH2) revealed that the order in both amine and disilene is 1. The kinetic isotope effect for the addition of iPrNH2/iPrND2 to tetramesityldisilene was determined to be 3.04±0.06 at 298 K, a primary KIE, indicating that the proton is transferred in the rate determining step. Competition studies between the addition of PrNH2 and iPrNH2 to tetramesityldisilene resulted in the exclusive formation of the PrNH2 adduct consistent with a nucleophilic addition. Computational studies of the mechanism of the addition of ammonia to E‐5 revealed the lowest energy pathway involves the formation of the donor adduct derived from syn‐addition, followed by intramolecular syn‐transfer of the proton. The formation of the donor adduct is the rate determining step. The results of this study, together with previous studies on the addition of ammonia and amines to disilenes, allow for a refinement of our understanding of the mechanism of this important fundamental reaction in disilene chemistry, and allow us to understand our ability to reliably predict the stereochemical outcomes of future NH σ‐bond activation reactions. [ABSTRACT FROM AUTHOR]

The parameters that determine the formation of linear peptides and cyclic dimers (diketopiperazine, DKP) on silica surfaces of different surface area, silanol and siloxane ring populations, controlled by thermal treatments, are investigated upon glycine deposition from gas and liquid phases. The formed products were characterized by infrared and Raman spectroscopies, X‐ray diffraction and thermogravimetric analysis. The results reveal the importance of "nearly‐free" silanols to form ester centers as primers for the formation of linear peptides over DKP, on surfaces with medium silanol density (1.4 to 2.7 nm−2). Quenched reactivity is seen on isolated silanols (density≤0.7 nm−2), while silanols involved in hydrogen bonding (density of 4.5 nm−2) weakly interact with Gly resulting in its cyclization to DKP. Deposition of glycine from liquid phase may also form both DKP and linear polymers, depending on its loading and silica surface. These conclusions demonstrate the complexity of glycine surface chemistry in the polymerization reaction and highlight the interest of a surface science approach to evaluate geochemical prebiotic scenarios. [ABSTRACT FROM AUTHOR]

Online monitoring by flow NMR spectroscopy is a powerful approach to study chemical reactions and processes, which can provide mechanistic understanding, and drive optimisations. However, some of the most useful methods for mixture analysis and reaction monitoring are not directly applicable in flow conditions. This is the case of classic diffusion‐ordered NMR spectroscopy (DOSY) methods, which can be used to separate the spectral information for mixture's components. We describe a fast and flow‐compatible diffusion NMR experiment that makes it possible to collect accurate diffusion data for samples flowing at up to 3 mL/min. We use it to monitor the synthesis of a Schiff base with a flow‐tube with a time resolution of approximately 2 minutes. The one‐shot flow‐compatible diffusion NMR described here open many avenues for reaction monitoring applications. [ABSTRACT FROM AUTHOR]

A spin‐selective tribo‐chemical reaction using a dinuclear lanthanide complex is demonstrated for the first time. The dinuclear complex is composed of two EuIII ions, hexafluoroacetylacetonato ligands, and anthracene‐based phosphine oxide bridges. Single‐crystal analysis revealed a face‐to‐face‐type anthracene dimer structure in the dinuclear EuIII complex. Mechanical stimulus on the dinuclear EuIII complex induced selective formation of oxidized anthracene. The tribo‐chemical reaction is based on a characteristic energy‐transfer pathway for the selective formation of an excited triplet state. [ABSTRACT FROM AUTHOR]

Extremely high electrophilic metal complexes, composed by a metal cation and very electron poor σ‐donor ancillary ligands, are expected to be privileged catalysts for oxidation reactions in organic chemistry. However, their low lifetime prevents any use in catalysis. Here we show the synthesis of fluorinated pyridine‐Pd2+ coordinate cages within the channels of an anionic tridimensional metal‐organic framework (MOF), and their use as efficient metal catalysts for the aerobic oxidation of aliphatic alcohols to carboxylic acids without any additive. Mechanistic studies strongly support that the MOF‐stabilized coordination cage with perfluorinated ligands unleashes the full electrophilic potential of Pd2+ to dehydrogenate primary alcohols, without any base, and also to activate O2 for the radical oxidation to the aldehyde intermediate. This study opens the door to design catalytic perfluorinated complexes for challenging organic transformations, where an extremely high electrophilic metal site is required. [ABSTRACT FROM AUTHOR]

Fused-imidazoles, Groebke-Blackburn-Bienaymé (GBB) reaction, Isocyanide Chemistry, Multicomponent reactions, [2.2]Paracyclophane Cover Feature: Diversity-Oriented Synthesis of [2.2]Paracyclophane-derived Fused Imidazo[1,2-a]heterocycles by Groebke-Blackburn-Bienaymé Reaction: Accessing Cyclophanyl Imidazole Ligands Library (Chem. Eur. J. 3/2022) Keywords: Fused-imidazoles; Groebke-Blackburn-Bienaymé (GBB) reaction; Isocyanide Chemistry; Multicomponent reactions; [2.2]Paracyclophane EN Fused-imidazoles Groebke-Blackburn-Bienaymé (GBB) reaction Isocyanide Chemistry Multicomponent reactions [2.2]Paracyclophane 1 1 1 01/18/22 20220113 NES 220113 B The Groebke-Blackburn-Bienaymé three-component reaction b (GBB-3CR) has contributed enormously to the progress of organic synthesis, medicinal chemistry, and materials science. [Extracted from the article]

Electron transfer plays a major role in chemical reactions and processes, and this is particularly true of catalysis by nanomaterials. The advent of metal nanoparticle (NP) catalysts, recently including atomically precise nanoclusters (NCs) as parts of nanocatalyst devices has brought increased control of the relationship between NP and NC structures and their catalytic functions. Consequently, the molecular definition of these new nanocatalysts has allowed a better understanding and management of various kinds of electron transfer involved in the catalytic processes. This Minireview brings a chemist's view of several major aspects of electron‐transfer functions concerning NPs and NCs in catalytic processes. Particular focus concerns the role of NPs and NCs as electron reservoirs and light‐induced antenna in catalytic processes from H2 generation to more complex reactions and sustainable energy production. [ABSTRACT FROM AUTHOR]

Chemical gardens are self‐assembled tubular precipitates formed by a combination of osmosis, buoyancy, and chemical reaction, and thought to be capable of catalyzing prebiotic condensation reactions. In many cases, the tube wall is a bilayer structure with the properties of a diaphragm and/or a membrane. The interest in silica gardens as microreactors for materials science has increased over the past decade because of their ability to create long‐lasting electrochemical potential. In this study, we have grown single macroscopic tubes based on calcium carbonate and monitored their time‐dependent behavior by in situ measurements of pH, ionic concentrations inside and outside the tubular membranes, and electrochemical potential differences. Furthermore, we have characterized the composition and structure of the tubular membranes by using ex situ X‐ray diffraction, infrared and Raman spectroscopy, as well as scanning electron microscopy. Based on the collected data, we propose a physicochemical mechanism for the formation and ripening of these peculiar CaCO3 structures and compare the results to those of other chemical garden systems. We find that the wall of the macroscopic calcium carbonate tubes is a bilayer of texturally distinct but compositionally similar calcite showing high crystallinity. The resulting high density of the material prevents macroscopic calcium carbonate gardens from developing significant electrochemical potential differences. In the light of these observations, possible implications in materials science and prebiotic (geo)chemistry are discussed. [ABSTRACT FROM AUTHOR]