DFT, Electronic absorption spectra and Non-linear optical properties of some 4H-benzo[h]chromene Derivatives. Solvent effect and TD-DFT Approach

The electronic structure of some 4H-benzo[h]chromene derivatives are investigated theoretically at the B3LYP/6-311++G (d,p) level of theory. The extent of delocalization and intramolecular charge transfer are estimated and discussed in terms of natural bond orbital analysis (NBO) and second order perturbation interactions between donor and acceptor MOs. The calculated EHOMO and ELUMO energies of the studied compounds can be used to calculate the global properties; chemical hardness (eta), softness (S) and electronegativity (chi). The equilibrium geometries of the studied compounds are determined, and it was found that these geometries are non -planar. The calculated nonlinear optical parameters (NLO); polarizability (alpha), anisotropy of the polarizibility (Delta alpha) and first order hyperpolarizibility (beta) of the studied compounds show promising optical properties. The molecular electrostatic potential (MEP) and Local reactivity descriptors (fukui function) have been studied for the title compound and its derivatives at the same level of theory. Electronic spectra of 4H-benzo[h]chromene derivatives in different organic solvents such as 1,4-Dioxane and DiChloroEthane as non-polar solvents and Ethanol, Methanol and Acetonitrile as polar solvents, are investigated experimentally and theoretically using the time dependent density functional theory (TD-DFT) method at the B3LYP/6-311++G(d,p) level of the theory. The origin of the spectrum of the parent compound is found to be an additive one. The solvent effect is investigated experimentally and theoretically and a blue shift is discerned.