Vibrational and Electronic Spectral Study on 3,5-Dihydro-4H-Imidazol-4-One Derivatives Containing Organo-Selenium

ABSTRACT

The Fourier transform infrared, Raman, and UV-visible absorption spectral analyses were carried out on five 3,5-dihydro-4H-imidazol-4-one derivatives containing organo-selenium. The ground-state geometries, vibrational wavenumbers, and infrared and Raman intensities were calculated by density functional theory using the B3PW91 functional and 6-311G(2df,p) basis set. Spectral analysis shows that the large conjugation effect makes the C=N stretching vibration of the skeleton shift by 50–100 cm⁻¹ toward the lower wavenumber. The UV-visible absorption spectra were studied by the time-dependent density functional theory method with the polarizable continuum model using B3LYP and PBE0 functionals. Theoretical calculations reveal that the strong absorption bands at 368–411 nm arise from the n → π* transition, and the sharp bands at 208–211 nm arise from the π → π* transition.