Vibrational studies, barrier height and thermodynamic functions for biomolecules: 5-Trifluoromethyl uracil

Abstract

Laser Raman (50–4000 cm−1) and IR (200–4000 cm−1) spectra of 5-trifluoromethyl uracil have been recorded and analysed. It has been possible to assign all the 39 (26a′+13a″) normal modes of vibration. Consistent assignments have been made for the internal modes of the CF3 group, especially for the antisymmetric CF3 stretching and bending modes. Using thus assigned vibrational frequencies and assumed structural parameters, thermodynamic functions, in the temperature range 100–1000 K, have been computed and the barrier to the internal rotation for the CF3 top has been determined.