I. V. Fedorova

Structure of orthophosphoric Acid-N,N-dimethylformamide complexes

Ab initio calculations weere used to obtain the characteristics of the most stable configurations of the (H3PO4)2, DMFA-H3PO4, and DMFA-(H3PO4)2 complexes in a vacuum. The changes in the geometric parameters in this series of complexes were analyzed and the energies of intermolecular interactions were estimated. The DMFA-(H3PO4)2 complex was found to be most stable. It was established that the hydrogen bond between the DMFA and H3PO4 molecules is formed with the participation of both lone pairs of the oxygen atom of the DMFA molecule.

Membrane-protective properties of isobornylphenols-a new class of antioxidants

The membrane protective and membrane active properties and the antioxidative activity of new semisynthetic antioxidants—isobornylphenols were studied. The presence of oxidant and cytotoxic properties of the compounds were evaluated considering the degree of hemolysis of erythrocytes, either spontaneous or induced by hydrogen peroxide. All the studied compounds were found to have significant antioxidative activity in certain conditions. But their capacity to protect membrane erythrocytes from oxidative stress substantially depended on the structure and concentration of the compound. The highest membrane protective activity was observed for 2,6-diisobornyl-4-methylphenol, which has isobornyl in both of its ortho-positions. Scanning electron microscopy of blood erythrocyte surface architectonics confirmed the ability of the studied compounds to interact with the cell membrane and to change its structure. A relationship between erythrocyte morphological transformation according to bilayer-couple hypothesis depending on isobornylphenols membrane behavior and the cytotoxic effect of certain compound high concentrations reflected in low membrane protective activity in the model cell system was shown. The data obtained allow us to conclude that the biological activity of isobornylphenols is due to both their antioxidative properties and their ability to interact with the cell membranes.

A molecular dynamics simulation of H3PO4, H2PO4−, and the protonated form of N,N-dimethylformamide in liquid N,N-dimethylformamide

The molecular dynamics simulation method was for the first time used to study the structural and energy parameters of H3PO4, H2PO4−, and (DMFA)H+ (protonated dimethylformamide) in liquid N,N-dimethylformamide. The predominant orientation of the nearest neighbors of H3PO4, H2PO4−, DMFA, and (DMFA)H+ was determined from ranked distribution functions. The most probable structure of H-bonded complexes was obtained. It was shown that H3PO4 formed H-bonds with two DMFA molecules, and and (DMFA)H+ formed H-bonds with one molecule. The dependence of Coulomb interaction energies on the distance between H3PO4, H2PO4−, (DMFA)H+, and DMFA had the form of damped oscillations, as is characteristic of intermolecular interactions in pure DMFA. The molecular dynamics simulation of the H2PO4−-(DMFA)H+-DMFA ternary system showed a high probability of the formation of contact ion pairs.

Hydrogen bonds in complexes of phosphonic and metylphosphonic acids with dimethylformamide

The structures of the hydrogen-bonded complexes of phosphonic and metylphosphonic acids with dimethylformamide (DMF) were calculated by the DFT/B3LYP, DFT/M06, and MP2 methods in the 6-31++G(d, p), 6-311++G(d, p), and cc-PVTZ basis sets. The geometrical parameters of hydrogen bonds, intermolecular interaction energies, and frequency shifts of hydroxyl group vibrations of the acid during hydrogen bonding were calculated. An NBO analysis was performed; the stabilization energy Estab and the charge qct transferred from the orbitals of the lone electron pairs of the oxygen atom of the DMF molecules to the antibonding orbital of the hydroxyl groups of phosphonic and metylphosphonic acids were determined. The obtained values were compared with the corresponding literature data for phosphoric acid complexes.

Inhibiting activity of isocamphyl substituted phenols and their mixtures with 2,6-di- tert -butylphenol in the initiated oxidation of ethylbenzene

The stoichiometric coefficients of inhibition and rate constants for the reaction of several terpenephenols (isocamphyl substituted phenols) with ethylbenzene peroxy radicals were measured. Their reactivity was found to increase as the number of alkyl substituents grew and decreased with an o-alkoxyl compared with o-alkyl substituent because of the formation of an intramolecular H-bond. In spite of similar antiradical activities of terpenephenols with isocamphyl and isobornyl substituents, the reactivities of phenoxyl radicals formed from them in the interaction with sterically hindered phenol molecules are substantially different. They are higher for isocamphylphenols with substituents turned with respect to the aromatic ring plane.

Alkylation of resorcinol with camphene in the presence of aluminum phenolate and aluminum isopropoxide

Alkylation of resorcinol with camphene using aluminum phenolate and aluminum isopropoxide as catalysts was investigated. The conditions of the direct synthesis of ortho-alkylated resorcinol containing the isobornyl moiety were developed. The diastereomers of the symmetrically dialkylated resorcinol were examined by the high performance liquid chromatography and X-ray analysis.

C-PCM based calculation of energy profiles for proton transfer in phosphorus-containing acid–N,N-dimethylformamide complexes

Proton transfer along the hydrogen bond in complexes of DMF with Н3РО4, Н3РО3, СН3Н2РО3, and their dimers has been investigated by the B3LYP/6-31++G** method in combination with the C-PCM model. When the Оacid···ОDMF distance (R) in the scanning procedure is not fixed, the energy profile in all cases has a single well. When this distance is fixed, there can be a proton transfer in all of the complexes in the gas phase at R > 2.6 Å; if solvation is taken into account, proton transfer can take place at R > 2.4 Å (R > 2.5 Å for DMF complexes with СН3Н2РО3 and its dimer). The height of the energy barrier to proton transfer increases with increasing R. Proton transfer is energetically most favorable in the DMF–phosphoric acid complexes. The structural and energetic characteristics of the hydrogen-bonded complexes calculated on the basis of the solvation model are compared with the same parameters for the complexes in the gas phase.

Kinetic characteristics and physicochemical properties of isobornyl phenols with different alkyl substituents in the ortho -position

The rate constants were measured for the reactions of isobornyl phenols (IBPs) containing methyl and tert-butyl substituents in the ortho-position with peroxide radicals in the initiated oxidation of ethylbenzene. The IR spectra of IBPs were analyzed, and the influence of IBPs on phosphatidylcholine aggregation in hexane was studied. The influence of the structure of substituents on the kinetic characteristics and physicochemical properties of the studied phenols is ambiguous. The data obtained indicate the competitive influence of the donor ability and shielding effects of the alkyl substituent in the ortho-position to the hydroxy group on the kinetic characteristics and physicochemical properties of IBPs.

Alkylation of Phenol And Hydroquinone by Prenol in the Presence of Organoaluminum Catalysts

Prenylphenols and 2,2-dimethylbenzopyrans were synthesized via alkylation of phenol and hydroquinone with prenol in the presence of organoaluminum catalysts, i.e., aluminum phenoxide and isopropoxide. Reaction products were isolated and characterized. Several reaction features were determined.

Computer simulation study of the intermolecular structure of phosphoric acid-N,N-dimethylformamide mixtures.

AbstractThe structures and energies of the complexes (H3PO4)2, H3PO4–DMF, and (H3PO4)2–DMF were analyzed at the B3LYP level of approximation. It was found that H-bonds form between H3PO4 and DMF molecules, but the strength of the H-bond depends strongly on its molecular environment. Effects of the solvent were taken into account via the CPCM approach. According to the B3LYP–СPCM calculations, the O···O distance in (H3PO4)2–DMF is shorter and its H-bonds are stronger than in the other complexes studied. In order to study the effects of concentration on the intermolecular structure, molecular dynamics simulations of H3PO4–DMF mixtures with mole fractions of acid of <0.1 were performed. The calculations indicated that the largest fraction of the acid protons are involved in hydrogen bonding with oxygen atoms of the DMF molecules. An increased probability of acid–acid hydrogen-bond formation at phosphoric acid mole fractions >0.06 was also noted. Graphical AbstractA cubic simulation box with periodic boundary conditions, including both H3PO4 and DMF is presented.