On the influence of water molecules on the outer electronic shells of R-SeH, R-Se(-) and R-SeOH fragments in the selenocysteine amino acid residue

Unveiling the electronic structure peculiarities of phosphine selenides as NMR probes for non-covalent interactions: an experimental and theoretical study

In this work, R3PSe (R = Me, Et, n-Bu, t-Bu and Ph) were studied experimentally using NMR spectroscopy in solution and the solid-state in combinaton with quantum chemical methods. The study shows that the NMR parameters of these phosphine selenides, such as δP, δSe, and 1JPSe, are sensitive to subtle changes in the electronic environment of the P and Se atoms. Consequently, phosphine selenides R3PSe can serve as promising spectral probes for the detection and quantitative investigation of various non-covalent interactions. Additionally, the variations of R in phosphine selenides influence the observed NMR spectral parameters, primarily through effects such as π-backdonation and hyperconjugation, which have been observed experimentally and confirmed theoretically.

Non-covalent interactions in the glutathione peroxidase active center and their influence on the enzyme activity

In this computational work, the structure of the active center of the enzyme glutathione peroxidase (in three forms -SeH, -SeOH and -Se(O)OH) and the non-covalent interactions in it were investigated using modern quantum chemistry methods. The non-covalent interactions are described in detail. The presence of σ-hole interactions (chalcogen, tetrel and pnictogen bonds) formed mostly by a selenium atom as an electrophile in the glutathione peroxidase active center is confirmed for the first time. It is shown that a number of non-covalent interactions stabilize intermediates along the catalytic cycle and that modelling of the whole enzyme active center is necessary for accurate predictions of thermodynamic parameters, in particular, activation barriers.

Hydration of selenolate moiety: Ab initio investigation of properties of O-H⋯Se(-) hydrogen bonds in CH3 Se(-)⋯(H2 O)n clusters

This work is devoted to investigations of the influence of O-H···Se(-) hydrogen bonds on the electronic shells of selenolate R-Se(-) fragment (R═CH₃ ). The geometric, energetic and nuclear magnetic resonance (NMR) spectral parameters for various conformers of CH₃ Se(-)⋯(H₂ O)_n clusters with n = 0-6 were calculated at CCSD/aug-cc-pVDZ level of theory. For selenolate anion CH₃ Se(-) solvation free energy was calculated, and for water media it is equal to -71.41 kcal/mol. For O-H···Se(-) hydrogen bonds the proportionality coefficients between QTAIM parameters at (3; -1) bond critical point and the strength of an individual hydrogen bond ∆E were proposed. It was shown, that despite a relative weakness of O-H···Se(-) hydrogen bonds, the outer electronic shell of the selenium atom changes significantly upon formation of each hydrogen bond. This, in turn, cause the dramatic change of NMR parameters of selenium nuclei.