Molecular structures, spectral and computational studies on nicotinohydrazides

The FT-IR and the high resolution 1H and 13C NMR spectra have been recorded for N′-(2-methyl-3-phenylallylidene)nicotinohydrazide (1) and N′-(2-methyl-3-phenylallylidene)isonicotinohydrazide (2) and analyzed. 1H-1H COSY spectra were also recorded for the hydrazides. The spectral studies reveal that both the hydrazides exist in the keto form. Theoretical calculations were performed for some possible conformations of the hydrazide and the minimum energy conformers are predicted to be the one in which the azomethine protons are syn to N-NH bond. From the optimized structures, HOMO-LUMO energy gap and geometrical parameters were derived and these parameters were compared with the XRD measurements of hydrazide 1. The vibrational frequencies in the ground state have been calculated using DFT and HF methods and compared with the observed frequencies. Non-linear optical (NLO) behaviour of the hydrazides was investigated by the determination of the electric dipole moment μ, the polarizability α and the hyperpolarizability β using B3LYP method.