Molecular structure and vibrational spectra of N4-acetylcytosine.

The infrared and FT-Raman spectra of N4-acetylcytosine in the solid phase have been recorded, and the molecular geometrical parameters were optimized using B3LYP and MP2 methods with 6-311++G(d,p) basis set. The theoretical calculations indicate the presence of four stable conformers of N4-acetylcytosine, and the one containing an intramoleuclar six-membered ring is the most stable. The vibrational wavenumbers, infrared intensities, Raman scattering activities and the corresponding assignments of the observed bands based on the most optimized conformer were performed by B3LYP methods using the aug-cc-pvtz basis set. The observed and calculated frequencies are found to be in good agreement.