VIBRATIONAL, NMR AND UV VISIBLE SPECTROSCOPIC INVESTIGATION OF THIOSEMICARBAZONE OF 4- CHLORO BENZALDEHYDE USING COMPUTATIONAL CALCULATION

Aims: In this work, the vibrational spectral analysis was carried out by FT-IR spectroscopy in the range 4000-400 cm-1 respectively, for the molecule.

Study Design: The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartree Fock (HF) and density functional theory (DFT) method and different basis set combination.

Methodology: The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The effects due to the substitution of the halogen bond were investigated. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra.

Results: The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), and thermodynamic properties were performed.

Conclusion: On the basis of the thermodynamic properties of the compound at different temperatures have been calculated, revealing the correlations between heat capacity (C), entropy (S), and enthalpy changes (H) and temperatures.