NON-LINEAR OPTICAL PROPERTIES STUDY OF TWO HETEROCYCLIC COMPOUNDS

In an attempt towards understanding the relation between molecular structure-nonlinear optic activity (NLO) among heterocycles, with special reference to the identity, number and position of the heteroatom, semiempirical calculations were carried out. This paper reports the Non-linear optical properties of two heterocyclic compounds namely 3-[2-Oxo-2-(2-oxo-2H-chromen-3-yl)ethylidene]- 1,3-dihydro-indol-2-one (3OCEDI) and Quinolin-8-ol (QL). To understand the Non-Linear Optical properties of coumarin dyes we computed dipole moment (mu), electronic polarizability (alpha), and the mean was first hyperpolarizability (beta o) using B3LYP density functional theory method in conjunction with 6-31G(d, p) basis set. All the calculations were carried out in gas phase and in acetonitrile medium. The optimized geometry of both compounds shows a 3D helical structure. The results indicate that given the same number and type of atoms and double bonds in a molecule, linear conjugation excels over cyclic or crossed conjugation in enhancing hyperpolarizabilities and it seems to be far more critical than a chiral centre.