Nonlinear optical properties of some derivatives of stilbene and vinyl cyanide

Three derivatives of stilbene: 3-hydroxy-4-methoxy-4′-nitrostilbene (HMONS), 3-methoxy-4-hydroxy-4′-nitro-stilbene (MOHNS), 2-cyano-3-indole-propenoic acid ethyl ester (CIP-ethyl), and one derivative of vinyl cyanide: p-1,1-dicyano-vinyl-dimethylaminoaniline (DVDA) were designed and synthesized. The powder second-harmonic generation and absorption spectra of these four compounds were measured. First principle calculation of the molecular first hyperpolarizabilities of HMONS were calculated and compared with those of 3-methyl-4-methoxy-4′-nitrostilbene (MMONS, Appl. Phys. Lett. 56 (1990) 423) in order to elucidate their structural origin of the optical nonlinearity.