Developing strategies to study reactivity and selectivity in flexible catalyst systems has become an important topic of research. Herein, we report a combined experimental and computational study aimed at understanding the mechanistic role of an achiral DABCOnium cofactor in a regio- and enantiodivergent bromocyclization reaction. It was found that electron-deficient aryl substituents enable rigidified transition states via an anion- interaction with the catalyst, which drives the selectivity of the reaction. In contrast, electron-rich aryl groups on the DABCOnium result in significantly more flexible transition states, where interactions between the catalyst and substrate are more important. An analysis of not only the lowest-energy transition state structures but also an ensemble of low-energy transition state conformers via energy decomposition analysis and machine learning was crucial to revealing the dominant noncovalent interactions responsible for observed changes in selectivity in this flexible system.
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http://dx.doi.org/10.1021/acscatal.2c03077 | DOI Listing |
Chemistry
December 2024
Lanzhou University, College of Chemistry and Chemical Engineering, Lanzhou Tianshui south street 222, 730000, Lanzhou, CHINA.
Dual single-atom catalysts have attracted considerable research interest due to their higher metal atom loading and more flexible active sites compared to single-atom catalysts (SACs). We pioneered the one-step synthesis of sheets copper-cobalt graphitic carbon nitride dual single-atom (S-Cu/Co-g-C3N4) using folding fan-shaped aluminum foil as a template, and used them as catalysts in the epoxidation of styrene respectively. Through XAFS(X-ray Absorption Fine Structure) and other characterizations, it is found that Cu and Co single atoms are stabilized separately on g-C3N4 via coordination with nitrogen (N), hindered the ordered growth of sheets, and formed more pore structures, which not only increased more catalytically active sites, but also effectively prevented the flakes re-aggregate during the catalytic process.
View Article and Find Full Text PDFJ Phys Chem B
December 2024
Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
This study addresses a critical gap in the existing literature on carbon dioxide and ionic liquid (IL) mixtures, where fragmented and incomplete data, particularly for flow properties, hinder practical applications. Therefore, this work aimed to establish a robust and efficient method for predicting the density of the CO-IL mixtures across diverse operating conditions and IL families using novel validation techniques. Both linear and symbolic regression models provided relevant insights but failed to accurately capture the IL-CO interactions in a mixture that determine the molar volume of CO at infinite dilution when solubilized by a given IL.
View Article and Find Full Text PDFChem Commun (Camb)
December 2024
Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, P. R. China.
In light of the extensive applications of sulfur-containing heterocyclic compounds in drug discovery, agrochemicals, and advanced materials, the construction of complex sulfur-containing molecular scaffolds has flourished in recent years. There is a profound interest in synthetic methods for forming carbon-sulfur bonds. Regarding this, transition metal (TM)-catalyzed C-H bond activation has emerged as a valuable means for the rapid formation of C-S bonds, although it is comparatively less explored than C-N or C-C bonds.
View Article and Find Full Text PDFACS Omega
December 2024
Center for Quantum Information and Quantum Biology, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Photosynthetic water oxidation is a vital process responsible for producing dioxygen and supplying the energy necessary to sustain life on Earth. This fundamental reaction is catalyzed by the oxygen-evolving complex (OEC) of photosystem II, which houses the MnCaO cluster as its catalytic core. In this study, we specifically focus on the D1-Glu189 amino acid residue, which serves as a direct ligand to the MnCaO cluster.
View Article and Find Full Text PDFThe explosion of next-generation sequencing technologies has allowed researchers to move from studying single genes, to thousands of genes, and thereby to also consider the relationships within gene networks. Like others, we are interested in understanding how developmental and evolutionary forces shape the expression of individual genes, as well as the interactions among genes. To this end, we characterized the effects of genetic background and developmental environment on brain gene coexpression in two parallel, independent evolutionary lineages of Trinidadian guppies ( ).
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