Theoretical Investigation of Quantum Chemistry on 2,6-dithiopurine Tautomer IR Spectroscopy

The six possible 2,6-dithiopurine tautomers have been optimized with full geometries by Density Functional Theory(DFT) method at B3LYP/6-311G(d,p) level in the gas phases.The zero point energies,total energy,vibrational frequencies,and infrared spectrum were obtained at the same level.The vibrational frequencies were corrected and IR spectroscopy were compared with the experimental data.The calculation results show that in the gas phases the DTP(1,3,7) is the most stable tautomer and the DTP(1,3,9) will exist in some degree.Comparison has been made with the infrared spectrum empirical datum,and it was confirmed that there possibly exist isomer configuration.