Circular dichroism and optical activity of thalidomide in polar aprotic acetonitrile

Abstract Thalidomide is a representative chiral pharmaceutical for which accurate evaluation of its chirality is essential to ensure drug safety, as there are significant differences in biological activity between its enantiomers. In this study, chiroptical properties of TD were systematically investigated through circular dichroism and optical activity measurements in polar aprotic acetonitrile. Kramers–Krönig analysis and quantum chemical calculations revealed that the observed responses mainly originate from monomeric thalidomide and arise from mixed n → π* and π → π* electronic transitions.