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paper54

A DFT study of inter- and intramolecular proton transfer
in 2-selenobarbituric acid tautomers
 
 
Hossein Tavakol • Fariba Keshavarzipour
 
Struct Chem
DOI 10.1007/s11224-015-0567-y
 
Abstract 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, CAMB3LYP
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 9 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.

 

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paper54 | Professor Hossein Tavakol

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