Computational study on non-linear optical property of Wittig based Schiff-Base ligands (both Z & E isomers) & Copper(II) complex

96 new Wittig based Schiff-Base (WSB) ligands (both E & Z conformation) containing fused aromatic rings were designed and screened for NLO property. Wittig based precursor aldehydes were synthesized and spectroscopically confirmed. WSB ligands and their copper(II) complexes were also designed, optimized and their NLO property was studied using a GAUSSIANO9 computer program. For Optimization & Hyperpolarizability (beta) calculations, DFT based B3LYP method was applied with LANL2DZ basis set for metal ion and 6-31G* basis set for C, H, N & O atoms. The study presents the Structure-Activity relationship (SAR) between WSB ligands and beta. The study revealed that WSB Ligands of the category N-2, which are those derived from precursor aldehyde, (2-hydroxy-5-(2-(naphthalen-l-yl)vinyl)benzaldehyde) encoded as PA-2, showed higher,(3 values over N1, which are derived from, 2-hydroxy-5-(2(naphthalen-l-yl)vinyl)benzaldehyde, encoded as PA-1. Among all ligands, Ligand-14, (E-4-(2-Pyren-1-yl-vinyl)-2-([1,2,4]triazol-4-yliminomethyl)-phenol), of N-2 category showed highest beta value (6.968 x 10(-30) e.s.u). After complexing with Cu(II), encoded as Complex-1 ([(4-(2-Pyren-l-yl-vinyl)-2([1,2,4]triazol-4-yliminomethyl)-phenoxy)(2)Cul, which has C-2 symmetry, the beta value (0.310 x 10(-30) e.s.u) unexpectedly decreased. However, it is still high as compared to that of urea (beta = 0.091 x 10(-30) e.s.u). The output of TD-DFT also supports the obtained results. Different factors affecting beta value especially their geometrical isomeric effect were successfully analyzed. (C) 2018 Elsevier B.V. All rights reserved.