Molecular structures and vibrational frequencies of xanthine and its methyl derivatives (caffeine and theobromine) by ab initio Hartree-Fock and density functional theory calculations


Ucun F. , Saglam A., Guclu V.

SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, cilt.67, ss.342-349, 2007 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 67 Konu: 2
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1016/j.saa.2006.07.029
  • Dergi Adı: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
  • Sayfa Sayıları: ss.342-349

Özet

The molecular structures, vibrational frequencies and corresponding vibrational assignments of xanthine and its methyl derivatives (caffeine and theobromine) have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with 6-31 G(d, p) basis set level. The calculations were utilized to the C-s symmetries of the molecules. The obtained vibrational frequencies and optimised geometric parameters (bond lengths and bond angles) were seen to be well agreement with the experimental data. The used scale factors which have been obtained the ratio of the frequency values of the strongest peaks in the calculated and experimental spectra seem to cause the gained vibrations well corresponding to the experimental ones. Theoretical infrared intensities and Raman activities are also reported. (C) 2006 Elsevier B.V. All rights reserved.