UV-Visible, FT-IR, FT-Raman, NMR Spectra, Molecular Structure, ESP and HOMO–LUMO Investigation of Coumarin Derivative

Author(s)	Dr. Mayadevi V Kalgi, Dr. Shivaleela Basavaraj L, Dr. Mahantesh B B, Prof. Dr. Tipperudrappa J J, Prof. Dr. S M Hanagodimath
Country	India
Abstract	Computational studies on biologically active coumarin derivatives have been studied using Gaussian 16 software. Coumarin molecule with the substitution of benzene and methoxy group Viz., 4IPBC have been used to carry the quantum chemical calculations. Parameters like absorption maxima, oscillator strength and excited state energies, are obtained from UV-Visible absorption maxima. Semi-empirical method is the convenient tool to study optimized geometry. Spectroscopic analysis of NMR, IR and Raman spectra have been studied using DFT method at 6-311++G(d, p)/B3LYP basis set. The ground state dipole moments are smaller than the excited state dipole moment determined by TD-DFT technique. The use of IR and Raman vibrational bands facilitates the study of the bending and stretching modes of vibration in the molecule. H1 and C13 NMR shielding values were evaluated from NMR spectra using GIAO method. HOMO-LUMO, MESP map and Mulliken atomic charges give charge distribution within the molecule.
Keywords	Coumarin derivatives, TD-DFT, GIAO, Mulliken charges, Molecular orbital
Field	Physical Science
Published In	Volume 8, Issue 5, September-October 2026
Published On	2026-09-04
DOI	https://doi.org/10.36948/ijfmr.2026.v08i05.87285

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