Maxim V. Arsenyev

Synthesis and structure of Schiff bases based on 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde. New sterically hindered bis-catecholaldimines

A reaction of 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde with aliphatic (ethylenediamine, propylene-1,3-diamine, 1,4-diaminobutane) and aromatic (o-, m-, p-phenylenediamines, 1,8-diaminonaphthalene, benzidine) diamines leads to the Schiff bases containing fragments of sterically hindered catechols in high yields (up to 97%). The products exist in two tautomeric forms in solutions and in the crystalline state. In the case of aliphatic diamines, catecholaldimines exist in solutions in the quinomethide form, whereas in the case of aromatic, in the catechol form. In the crystalline state, the position of the hydrogen atom in the O-H…N fragment is also affected by the intermolecular hydrogen bonds, which promote stabilization of the quinomethide form of catecholaldimines.

Optically controlled distribution of o -quinonemethacrylate metal complexes in polymer materials

The complexation ability of photoreduction products of 2-(2,5-di-tert-butyl-3,4-dioxycyclohexa-1,5-dienyl)ethyl methacrylate in tetrahydrofuran (THF) solution and in its copolymer films with dimethacrylate and ethylene glycol monomethacrylate was studied. The product of photochemical reduction – catechol – reacts with (NH4)6Mo7O24·4H2O, NH4VO3 and (NH4)2Fe(SO4)2 with the formation of corresponding metal complexes in solution and in the polymer bulk. The concentration of the molybdenum complexes in the polymer matrix was proportional to the exposure and holding time in solution of molybdate salt. Polymer film with optically controlled distribution of o-quinonemethacrylate molybdenum complexes was prepared. A film containing antimony and molybdenum complexes together in the polymer structure in predetermined ratio was obtained by sequential treatment of irradiated copolymer film (50% conversion) by THF solution of SbPh3, and water solution of (NH4)6Mo7O24·4H2O.

Synthesis, structures, and properties of new sterically hindered hydrazine-based catecholaldimines

New sterically hindered catecholaldimines derived from hydrazine were synthesized in high yields. Two procedures for the synthesis of sterically hindered catecholaldimines were developed: by the reaction of 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde with hydrazines (hydrazine hydrate, phenyl-, 1,1-diphenyl-, and (diphenylmethylene)hydrazines, acetyl and benzoyl hydrazides) or by the reaction of 3,5-di-tert-butyl-6-(hydrazonomethyl)catechol with a carbonyl compound (the reaction with 4-N,N-dimethylaminobenzaldehyde). The X-ray diffraction analysis and IR, UV, and NMR spectroscopic studies showed that these compounds exist in the catecholic form both in solution and the crystalline state.

Electrochemical transformations and anti/prooxidant activity of sterically hindered o -benzoquinones

The electrochemical properties of a series of sterically hindered o-benzoquinones in aprotic solvents were examined. The reaction of O2 and KO2 with o-benzoquinones and electrogenerated o-semiquinone radical anions was studied. The formation of o-semiquinone radical anions in the reactions of KO2 with the studied o-quinones was detected using UV-visible and ESR spectroscopy. The influence of the test compounds on lipid peroxidation was considered at the molecular and tissue levels in vitro. In the most cases, o-quinones exhibit antioxidant activity, which varies depending on the type of lipid substrate.