Electron delocalization in defect-containing graphene and its influence on tetrel bond formation.

Using the advanced analyses of electron density and fermionic potential, we show how electron delocalization influences the ability of defect-containing graphene to form tetrel bonds. The C atoms of a vacancy defect can produce one nonpolar interaction, alongside a peculiar polar C⋯C bond. The latter stems from the presence of a localized electron pair on a vacancy defect C atom and the local depletion of electron localization on another C atom.

DFT potentials from a chemical perspective: Anatomy of electron (de)localization in molecules and crystals.

We introduce a fermionic potential, , as a comprehensive measure of electron (de)localization in atomic-molecular systems. Unlike other common descriptors as ELF, LOL, etc., it characterizes all physical effects responsible for (de)localization of electrons, namely: an exchange hole depth, its tendency to change, a sensitivity of an exchange correlation hidden in a pair density and kinetic potential to local variations in electron density.

Keto-enol tautomerism from the electron delocalization perspective.

The equilibrium between keto and enol forms in acetylacetone and its derivatives is studied using electron delocalization indices and delocalization tensor density. We demonstrate how electron delocalization governs the equilibrium between keto and enol forms. The less stable enols have more distinct double and single bond character in the CCC fragment, while electron delocalization in this fragment is more pronounced in more stable enols.

Metallo-β-Lactamases: Influence of the Active Site Structure on the Mechanisms of Antibiotic Resistance and Inhibition.

The review focuses on bacterial metallo-β-lactamases (MβLs) responsible for the inactivation of β-lactams and associated antibiotic resistance. The diversity of the active site structure in the members of different MβL subclasses explains different mechanisms of antibiotic hydrolysis and should be taken into account when searching for potential MβL inhibitors. The review describes the features of the antibiotic inactivation mechanisms by various MβLs studied by X-ray crystallography, NMR, kinetic measurements, and molecular modeling.

The explicit role of electron exchange in the hydrogen bonded molecular complexes.

We applied a set of advanced bonding descriptors to establish the hidden electron density features and binding energy characteristics of intermolecular DH∙∙∙A hydrogen bonds (OH∙∙∙O, NH∙∙∙O and SH∙∙∙O) in 150 isolated and solvated molecular complexes. The exchange-correlation and Pauli potentials as well as corresponding local one-electron forces allowed us to explicitly ascertain how electron exchange defines the bonding picture in the proximity of the H-bond critical point. The electron density features of DH∙∙∙A interaction are governed by alterations in the electron localization in the H-bond region displaying itself in the exchange hole.

Revealing electronic features governing hydrolysis of cephalosporins in the active site of the L1 metallo-β-lactamase.

The QM/MM simulations followed by electron density feature analysis are carried out to deepen the understanding of the reaction mechanism of cephalosporin hydrolysis in the active site of the L1 metallo-β-lactamase. The differences in reactivity of ten similar cephalosporin compounds are explained by using an extended set of bonding descriptors. The limiting step of the reaction is characterized by the proton transfer to the nitrogen atom of the cephalosporin thiazine ring accompanied with formation of the C[double bond, length as m-dash]C double bond in its N-C-C fragment.

Solving the enigma of weak fluorine contacts in the solid state: a periodic DFT study of fluorinated organic crystals.

The nature and strength of weak interactions with organic fluorine in the solid state are revealed by periodic density functional theory (periodic DFT) calculations coupled with experimental data on the structure and sublimation thermodynamics of crystalline organofluorine compounds. To minimize other intermolecular interactions, several sets of crystals of perfluorinated and partially fluorinated organic molecules are considered. This allows us to establish the theoretical levels providing an adequate description of the metric and electron-density parameters of the C-F⋯F-C interactions and the sublimation enthalpy of crystalline perfluorinated compounds.

Hydration of the Carboxylate Group in Anti-Inflammatory Drugs: ATR-IR and Computational Studies of Aqueous Solution of Sodium Diclofenac.

Diclofenac (active ingredient of Voltaren) has a significant, multifaceted role in medicine, pharmacy, and biochemistry. Its physical properties and impact on biomolecular structures still attract essential scientific interest. However, its interaction with water has not been described yet at the molecular level.