0000000000082689
AUTHOR
Juan C. Garro Martinez
Thermodynamics of competing oxidation reactions of allyl methyl disulfide by hydrogen peroxide: a first principle molecular computational study on the conformations of allyl methyl disulfide and its oxidized products
Allyl methyl disulfide, a peroxide scavenger, was studied together with three isomeric (two sulfoxides and one epoxide) forms of its mono-oxidized products. After a full conformational study of the reactant and three isomeric oxidized forms, the geometries were optimized at B3LYP/6-31G (d) level of theory. The epoxide form turned and to be more stable than either one of the two isomeric sulfoxides. Changes for Thermodynamic functions of oxidation reactions were calculated and from the δGreaction values the equilibrium constant for the interconversions of the oxidized products were estimated. Bader-type AIM analyses were performed on the electron density, computed at the B3LYP/6-311++G (d,p)…
A full conformational space analysis of bilirubin
Ab initio methods were utilized in a gas-phase systematic conformational search of bilirubin conformers. The whole molecule was divided into four fragments. Most stable conformers of them were employed to build 196 conformers of the complete bilirubin molecule. Initial geometries were optimized using HF/3-21G level of theory and the minimum energy conformers were then reoptimized at B3LYP/6-31G(d) level. Ridge-tile conformer was the most stable one, in perfect agreement with X-ray data. We found that while tetrapyrrole backbone shows some flexibility, propionic acid side chains have a greater influence in bilirubin conformation because they can interact through different hydrogen bond patte…