NATURAL SCIENCES

Journal of fundamental
and
applied researches

Structural and dynamic models and spectral identification of monomers uracil carbonic acids

2013. №4, pp. 190-199

Elkin Mihail D. - D.Sc. (Physics and Mathematics), Professor, Astrakhan State University, 20a Tatishchev Str., Astrakhan, 414056, Russian Federation, elkinmd@mail.ru

Smirnov Vladimir V. - D.Sc. (Pedagogy), Associate Professor, Astrakhan State University, 20a Tatishchev Str., Astrakhan, 414056, Russian Federation, kof@aspu.ru

Dzhalmuhambetova Elena A. - Ph.D. (Physics and Mathematics), Associate Professor, Astrakhan State University, 20a Tatishchev Str., Astrakhan, 414056, Russian Federation, kof@aspu.ru

Alykova Olga M. - Ph.D. (Pedagogy), Associate Professor, Astrakhan State University, 20a Tatishchev Str., Astrakhan, 414056, Russian Federation, kof@aspu.ru

Grechukhina Oksana N. - Ph.D. (Physics and Mathematics), Associate Professor, Astrakhan State University, 20a Tatishchev Str., Astrakhan, 414056, Russian Federation, kof@aspu.ru

Gromovoi Sergei A. - undergraduate student, Astrakhan State University, 20a Tatishchev Str., Astrakhan, 414056, Russian Federation, kof@aspu.ru

Carboxysubstituted conformers of uracil (CU) are an important object of pharmaceutical chemistry. For the compound 6-CU known as orotic acid (vitamin B13) has a theoretical interpretation of experimental data of IR spectra (in an argon matrix). However, in it not taken into account possible presence of intermolecular hydrogen bonds. Hybrid quantum method for DFT/B3LYP density functional allows to take into account the impact. The possibility of using it to calculate the CU confirmed by the good agreement between the calculated parameters of the structural and dynamic models of the mono-substituted uracil (X = F, Cl, CH3, NH2, OH) with the available experimental data. The work provides the optimized geometry of the CG of each of the four possible conformers. The paper shows that optimized geometry CU of each of the four possible conformers. The criterion authenticity of model calculations of conformational structure of the monomers CU was reproduction low-frequency torsional oscillations (such as ?) ties uracil cycle and carboxyl fragment in relation to the plane of the uracil ring. It is shown that for the spectral bands associated with fluctuations carboxyl fragment (qOH, ?OH, ?OH) of monomers CU there was a great difference in the positions of bands in the frequency range, intensity values in the spectra which can be used as reliable indicators of the spectral identification of compounds. As additional traits can be used in the bands, interpreted as the stretching vibrations of the C = O.

Key words: carboxy substituted uracil derivative,conformers,tautomers,vibrational spectrum,anharmonicity,adiabatic potential