Raman, FT-IR spectroscopic analysis and first-order hyperpolarisability of 3-benzoyl-5-chlorouracil by first principles

Abstract

3-Benzoyl-5-chlorouracil (3B5CU), a biologically active synthetic molecule, has been analysed at DFT/6-311+ + G(d,p) level and reported for the first time as a potential candidate for nonlinear optical (NLO) applications. The optimised skeleton of 3B5CU molecule is non-planar. The frontier orbital energy gap, dipole moment, polarisability and first static hyperpolarisability have been calculated. The first static hyperpolarisability is found to be almost 15 times higher than that of urea. The high value of first static hyperpolarisability (2.930 × 10− 30 e.s.u.) due to the intra-molecular charge transfer in 3B5CU has been discussed using first principles. A complete vibrational analysis of the molecule has been performed by combining the experimental Raman, FT-IR spectral data and the quantum chemical calculations. In general, a good agreement of calculated modes with the experimental ones has been obtained. The strong vibrational modes contributing towards NLO activity, involving the whole charge transfer path, have been identified and analysed.