X-ray structures and spectroscopic properties of chiral thiosemicarbazides as studied by computational calculations

In the present work, (+)-(R)-1-[2-(benzenesulfonamido)-3-phenylpropanoyl]-4-[(4-methoxy)phenyl]thiose micarbazide (1a) and (−)-(S)-1-[2-(benzenesulfonamido)-3-phenylpropanoyl]-4-[(4-methoxy)phenyl] thiosemicarbazide (1b) were synthesized starting with D-phenylalanine methyl ester and L-phenylalanine ethyl ester as a source of chirality. The single crystal structures were characterized by XRD, FTIR and ¹H and ¹³C NMR spectroscopy. Density functional theory (DFT) calculations (B3LYP/6-311G(d,p) were carried out to obtain the ground state optimized geometry, the IR and the NMR spectra of the molecule. Electronic properties (HOMO&LUMO) were calculated using the Time Dependant-DFT/B3LYP/6-311G(d,p) method. Furthermore, NBO, MEP, and Fukui function analyses have been used for the quantitative determination of the chemical activities at various sites of the molecule.