Spectroscopic studies of some antidiabetic drugs

The infrared absorption spectrum of antidiabetic drugs Pioglitazone and Pioglitazone.HCl has been recorded at high resolution in the spectral region 200-4000 cm(-1). Most of the frequencies in the latter compound are slightly lower in magnitude than corresponding value in the former. The absorption intensities are however slightly larger. In order to confirm the vibrational assignment of the bands obtained from experimental observation, a normal co-ordinate analysis has been carried out using semi empirical AM1 method through MOPAC 5.1 computer program. In addition to these compounds, the vibrational frequencies for some of the intermediate metabolite of Pioglitazone have also been calculated.