Theoretical and vibrational spectroscopic approach to keto-enol tautomerism in methy1-2-(4-methoxybenzoyl)-3-(4-methoxyphenyl)-3-oxopropanoylcarbamate

Arı H., Ozpozan T., Büyükmumcu Z., Kabacali Y., Saçmacı M.

JOURNAL OF MOLECULAR STRUCTURE, cilt.1122, ss.48-61, 2016 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 1122
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1016/j.molstruc.2016.05.060
  • Dergi Adı: JOURNAL OF MOLECULAR STRUCTURE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.48-61
  • Anahtar Kelimeler: Carbamate, Keto-enol tautomerism, Transition state, Vibrational analysis, DFT, PI-ELECTRON DELOCALIZATION, DENSITY-FUNCTIONAL THEORY, HOMO-LUMO GAP, CARBONYL DERIVATIVES, PHARMACOLOGICAL ACTIVITY, AB-INITIO, FT-IR, AQUEOUS-SOLUTION, PART 1, X-RAY
  • Yozgat Bozok Üniversitesi Adresli: Evet

Özet

A carbamate compound having tricarbonyl groups, methy1-2-(4-methoxybenzoyl)-3-(4-methoxypheny1)-3-oxopropanoylcarbamate (BPOC) was investigated from theoretical and vibrational spectroscopic point of view employing quantum chemical methods. Hybrid Density Functionals (B3LYP, X3LYP and B3PW91) with 6-311 G(d,p) basis set were used for the calculations. Rotational barrier and conformational analyses were performed to find the most stable conformers of keto and enol forms of the molecule. Three transition states for keto-enol tautomerism in gas phase were determined. The results of the calculations show that enol-1 form of BPOC is more stable than keto and enol-2 forms. Hydrogen bonding investigation including Natural bond orbital analysis (NBO) for all the tautomeric structures was employed to compare intra-molecular interactions. The energies of HOMO and LUMO molecular orbitals for all tautomeric forms of BPOC were predicted. Normal Coordinate Analysis (NCA) was carried out for the enol-1 to assign vibrational bands of IR and Raman spectra. The scaling factors were calculated as 0.9721, 0.9697 and 0.9685 for B3LYP, X3LYP and B3PW91 methods, respectively. The correlation graphs of experimental versus calculated vibrational wavenumbers were plotted and X3LYP method gave better frequency agreement than the others.