FT-IR, FT-Raman and UV-vis spectra and quantum chemical investigation of carvedilol

The FT-IR and FT-Raman spectra of carvedilol were recorded in the regions 4000-400 and 3500-100 cm(-1), respectively. The electronic absorption spectrum was recorded in the region 400-200 nm. In the present study, AM1 and PM3 semi-empirical molecular orbital methods were employed to study molecular structure as well as to predict infrared spectra. The AM1-optimised geometry was used in the density functional theory (DFT) calculation to predict the oscillator strength, electronic transition energies between the orbitals and wavelength of the transitions. The DFT-based NMR calculation procedure was used to assign the H-1 NMR chemical shift of carvedilol. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in carvedilol.