Redox-switching second-order nonlinear optical responses of N∧N∧N ruthenium complexes

The second-order nonlinear optical (NLO) properties of ruthenium complexes, including redox-active iminoquinonoid, quinonoid, and dithiolene noninnocent ligands, have been investigated using density functional theory (DFT) combining with the finite field (FF) method. The DFT-FF calculations show that these complexes have excellent second-order NLO responses. According to B3LYP/133P86/CAM-B3LYP/6-31G(d) calculations complex (3e)1(reduced) has the largest beta value among all the complexes studied. The calculations show that the beta value of (3e)1(reduced) is similar to 7.7 times, similar to 10.6 times and similar to 11.6 times larger than those of (2e)1(reduced), (1e)1(reduced) and 1, respectively. Complex 1 can act as the multi-state redox NLO switchable materials through sequential one-electron reduced processes. (C) 2011 Elsevier B.V. All rights reserved.