Vibrational spectra of 6-methyluracil, 6-methyl-2-thiouracil and their deuterated analogues

FTIR and Raman spectra of 6-methyluracil (6MU), 6-methyl-2-thiouracil (6M2TU) and the deuterated forms were recorded and analysed in the regions 400-4000 cm(-1) and 100-4000 cm(-1), respectively. The vibrational spectra are assigned using the frequency shifts upon N-deuteration, especially for bands due to NH modes. For both molecules, the isotopic ratio frequency was calculated for each NH/ND vibrations. The sulphur substitution at C2 position in the 6MU molecule has an effect on the N1H and N3H vibration frequencies. The assignments of C2=O and C4=O modes were supported by the absence of the C2=O group in the thio-derivative. (C) 2011 Elsevier B.V. All rights reserved.