A DFT study of inter- and intramolecular proton transfer in 2-selenobarbituric acid tautomers

作者：Tavakol Hossein^*; Keshavarzipour Fariba

来源：Structural Chemistry, 2015, 26(4): 1049-1057.

DOI：10.1007/s11224-015-0567-y

• Selenobarbituric acid
• Tautomer
• Proton transfer
• Solvent-assisted

DFT studies were employed to study proton transfer in selenobarbituric acid tautomers in different environments including gas-phase, polarized continuum model (PCM) of solvent and solvent-assisted models. The calculations were performed using WB97XD, CAM-B3LYP and B3LYP methods with the AUG-CC-PVTZ and 6-311++G** basis sets. Among various tautomeric conversions (between ten tautomers), three systems have been selected to study their thermodynamic and kinetic behaviors via proton transfer. The gas-phase calculations showed that only 2-selenoxodihydropyrimidine-4,6(1H, 5H)-dione is the major tautomer and the rates of converting this tautomer to the other tautomers are small (<2.73 x 10(-14)). Using PCM solvation model, the amount of other tautomers versus the major tautomer is increased but the rate constants for proton transfer are slightly decreased. In the solvent-assisted proton transfer, the concentration of the second tautomer (6-hydroxy-2-selenoxo-2,3 dihydropyrimidin- 4(1H)-one) was increased to 5 % (in methanol) in comparison with the major tautomer. More importantly, the rate constants for the most of intermolecular proton transfer in solvent-assisted models were intensively increased. Calculated values showed that these processes could be done in solvent-assisted models and other minor tautomers (with different chemical and biological behaviors) could be observed in these systems.

• 出版日期2015-8