Nuclear magnetic resonance, vibrational spectroscopic studies, physico-chemical properties and computational calculations on (nitrophenyl) octahydroquinolindiones by DFT method

•The theoretical calculations were made using 6-311++G (d,p) method.•Experimental IR and Raman spectra are in agreement with the theoretical results.•Complete wave number assignments are performed on the basis of PED.•Isotropic chemical shifts for 1H and 13C NMR were calculated using GIAO.•Molecular electrostatic potential and thermodynamic functions have been investigated.

In the present study, 2′-nitrophenyloctahydroquinolinedione and its 3′-nitrophenyl isomer were synthesized and characterized by FT-IR, FT-Raman, 1H NMR and 13C NMR spectroscopy. The molecular geometry, vibrational frequencies, 1H and 13C NMR chemical shift values of the synthesized compounds in the ground state have been calculated by using the density functional theory (DFT) method with the 6-311++G (d,p) basis set and compared with the experimental data. The complete vibrational assignments of wave numbers were made on the basis of potential energy distribution using GAR2PED programme. Isotropic chemical shifts for 1H and 13C NMR were calculated using gauge-invariant atomic orbital (GIAO) method. The experimental vibrational frequencies, 1H and 13C NMR chemical shift values were found to be in good agreement with the theoretical values. On the basis of vibrational analysis, molecular electrostatic potential and the standard thermodynamic functions have been investigated.

Graphical abstractComparison of the 2′-nitrophenyl and 3′-nitrophenyl isomers of octahydroquinolindiones.Figure optionsDownload full-size imageDownload as PowerPoint slide