Schepin A.S.
INDUCTION OF ELECTRONIC TRANSITIONS IN COLLISION COMPLEXES [O₂-X], X = CO, NO, CO₂, H2O ^{[№ 8 ' 2016]}
Singlet oxygen — a general term used for the two metastable states (a, b) molecular oxygen (O₂) with higher energy than the triplet state (X), which is the main. It has a very high oxidation activity when interacting with the organic substances involved in the biological processes of living organisms. Mechanisms of generation of singlet oxygen are explained by emerging within the oxygen molecule intense forbidden transitions: a-X, b-a, b-X systems bimolecular collision oksokompeksov. Currently, however, such systems are poorly understood. The method CASSCF / 6-311G ++ (2p, 2d) constructed section of the potential energy surface (PES) complex formation reactions [O₂-X], X = CO, NO, CO₂, H₂O. Taking into account the spin-orbit coupling (SOC) calculated values of the moments of forbidden radiative transitions: M (aX), M (ba), M (bX), the Einstein coefficients A (transition probabilities) in the O₂ molecule in the collision with the molecules of CO, NO, CO₂ , H₂O and the radiative lifetime of singlet oxygen in oxo complex bimolecular collision. According to the results of the work showed that the formation of bimolecular complexes [O₂-X], where X = CO, NO, CO₂, H₂O removed spin prohibitions, whereby it becomes possible manifestation of illicit induced transitions in the oxygen molecule: singlet-singlet ba, characterized by high values compared to intensity molecule pure O₂, and singlet-triplet aX, bX (defined only in the complex [O₂-NO]). Also it found that the geometrical configuration of collisional oxo complexes are directly dependent on the values of the radiative lifetime, as well as the values of the moments induced forbidden transitions.

Schepin A.S., Peshkov S.A., Peshkova T.V.
LIFETIME SINGLET OXYGEN IN THE COLLISIONAL COMPLEX O₂-CO₂ ^{[№ 3 ' 2016]}
One of the most promising emerging in our time method to eliminate malignant tumors is photodynamic therapy. We study the mechanism that explains the increase in the lifetime of singlet oxygen in living organisms when administered by photodynamic therapy using a computer simulation. The methods of self-consistent field (SCF/ROHF) and density functional theory (DFT/B3LYP) held conformational analysis to determine the geometrical characteristics of the oxygen complexes with carbon dioxide and identify among them the most stable structure with minimum energy. Multi-configurationally method CASSCF (14, 11) designed the electronic terms of the complex ^1,3[O₂-CO₂]. The method of spin-orbit interaction (SOC) calculated moments of forbidden transitions a¹Δ_g — X³∑_g^–, b¹∑_g⁺ — a¹Δ_g, Einstein coefficients (transition probabilities), as well as the lifetime of singlet oxygen (a¹Δ_g, b¹∑_g⁺) by complexing with oxygen molecules of carbon dioxide molecule. Identify the most stable structure of the complex [O₂-CO₂] — II, having chiseled C_2v group symmetry. It was revealed that the ground and the excited state of oxygen in complex ^1,3[O₂-CO₂] O₂(X³∑_g^– + CO₂(A¹∑_g⁺), O₂(a¹Δ_g; a'¹Δ'_g) + CO₂(A¹∑_g⁺), O₂(b¹∑_g⁺) + CO₂(A¹∑_g⁺) are low stability, as they have low energy dissociation. The possibility of manifestation forbidden transitions induced moment's a¹Δ_g — X³∑_g^–, b¹∑_g⁺ — a¹Δ_g in the O₂ molecule by the action of carbon dioxide a collision molecules that virtually do not appear in a separate O₂ molecule. The calculated value of the lifetime of singlet oxygen in collision complexes ^1,3[O₂-CO₂] describes the possibility of the formation of complexes of oxygen with carbon dioxide, and other low molecular weight compounds having a membrane transport in the tissues of a living organism in their low-intensity laser irradiation, whereby, increases the lifetime of singlet oxygen O₂(a¹Δ_g, b¹∑_g⁺).

Kobzev G.I., Schepin A.S., Peshkov S.A.
STRUCTURAL AND SPECTRAL PROPERTIES OF THE COMPLEX VALINE IN NEUTRAL AND IONIC FORM WITH CATIONS ZN²⁺, CD²⁺ (QUANTUM CHEMICAL STUDY) ^{[№ 9 ' 2015]}
Heavy metals are involved in the diverse chemical, physico-chemical and biological processes. They can act as toxicants, i. e. substances, which are large concentrations can lead to disorders or disorders of various vital processes of the body. Studying the mechanisms of accumulation and excretion of heavy metals in living cells must be based on a study of the problems with the metal binding amino acids as a component of proteins. Given that the ability of metal ions to interact with the amino acids depends on the presence in their structure of certain atoms and functional groups, this reaction is characterized by the formation of metal complexes of varying strength. Density functional method (DFT), in the framework of self-consistent field (SCF) approximation B3LYP/DZP and taking into account the amendments to the energy perturbation theory MP2 (Moller-Plesset) calculated the geometric parameters of the equilibrium states of complex valine in the neutral and ionic forms cations zinc (II) and cadmium (II) in the gas phase. The influence conformation valine complexes with metals, zinc (II) and cadmium (II), as well as the ionic and neutral forms on their stability. The energies of bond dissociation Val-Me, Me = Zn²⁺, Cd²⁺. A number of valine stability of complexes with cations of zinc and cadmium. For cationic complexes with the anionic form of valine [Val^–-Me²⁺]¹⁺ calculated IR spectra revealed that changes the fundamental stretching and deformation vibration frequencies. The regularities of the fringe shift in the IR spectra of the complexes [Val^–-Zn²⁺]¹⁺, [Val^–-Cd²⁺]¹⁺ in complex combination oscillations.