Molecular Structure, Spectroscopic Characterization, and Nonlinear Optical Properties of 4-Hydroxycoumarin: A DFT Approach

The present work focusses on computational analysis of the molecular structure, spectroscopic, natural bonding orbital (NBO) and the NLO (non-linear optical) properties of 4-hydroxycoumarin (4HC). With the help of computation DFT and TD-DFT study, the geometrical parameters, molecular orbitals (MOs), electrostatic potential, reactivity parameters and thermodynamic properties of 4-hydroxycumarine (4HC) was explored. Also, the absorption and emission spectra of 4HC in certain polar protic, polar aprotic and non-polar solvents and in gas phase were estimated using TD-DFT method. Theoretically calculated absorption in different solvent lies in 268 to 271 nm range and while the emission lies in 313 nm – 319 nm range depending on the environment. The natural bonding orbital (NBO) and the NLO (non-linear optical) properties including polarizability, first-order hyperpolarizability and dipole moment were also computed. The photophysical behaviour of 4HC is attributed to both specific and non-specific solute-solvent interactions. In this article, Pockel, dc-Kerr, ESHG (electric field induced second harmonic generation), degenerate four-wave mixing coefficients and nonlinear refractive indices from the first and second order hyperpolarizability calculations at Nd:YAG Laser wavelength is reported.