Quantum mechanics study on the nonlinear optical responses of a series of 4-hydroxy, 4'-cyanoazobenzene dimers

Nonlinear optical (NLO) properties are mainly measured by the first hyperpolarizability β(0) magnitudes. Besides analyzing the NLO behaviours of monomers, dimerization of chromophores has been found of a huge interest for the application in several optical areas. In the present work, a theoretical study has been carried out on a series of dimers constituted by the azo-chromophore 4-hydroxy, 4'-cyanoazobenzene (HCAB). Combinations of vinylic and styrenic oligomers as well as of 1,3-diphenyl propnane (1,3-DPP) to HCAB have been also investigated. No influence of geometrical parameters has been detected. Indeed, after establishing a comparison with β(0) of monomeric entities, results show that the NLO response of these dimers is not guided by any additivity rule.