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., Saǧlam A., Güçlü V.

Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, cilt.67, sa.2, ss.342-349, 2007 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 67 Sayı: 2
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1016/j.saa.2006.07.029
  • Dergi Adı: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.342-349
  • Anahtar Kelimeler: Caffeine, DFT, HF, IR spectra, Raman spectra, Theobromine, Vibration, Xanthine
  • İstanbul Gelişim Üniversitesi Adresli: Hayır

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 6-31G(d, p) basis set level. The calculations were utilized to the CS 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. © 2006 Elsevier B.V. All rights reserved.