First hyperpolarizabilities of ionic octupolar molecules: structure–function relationships and solvent effects

We present a quantum-chemical analysis of the first hyperpolarizabilities of a series of ionic octupolar molecules and comparison of their characteristics with corresponding neutral molecules. The molecular geometries are obtained via BL3YP/6-31G (d,p) optimization including SCRF/PCM approach, while the dynamic NLO properties are calculated with the ZINDO/CV method including solvent effects. The effect of donor or acceptor substitution and elongation of the conjugation path length are established to demonstrate the engineering guidelines for enhancing molecular optical non-linearities. The solvent induced effect on the NLO properties are studied using ZINDO/CV/SCRF method. It was found that solvents play a significant role on the first hyperpolarizabilities of ionic octupolar molecules.