NONLINEAR OPTIC PROPERTIES OF P-TRICYANOVINYL-METHYLENEAMINO-ANILINES, P-DICYANOVINYL, AND P-DICYANO-METHYLENEAMINO-ANILINES AND POLY(METHYLMETHACRYLATE)S COVALENTLY FUNCTIONALIZED WITH THEM - SYNTHESES WITH NITRILE-C

Copolymers of methyl methacrylate and chromophores with methacrylate e nd groups were obtained by radical polymerization. Their nonlinear opt ical properties ware examined by electric field induced second-harmoni c generation (EFISH) measurements and compared with corresponding mono meric dyes. All of them had maximum absorption wavelengths between 480 and 510 nm. Values for mu beta (dipole moment mu, molecular hyperpola rizability beta) were remarkably high and reached 530x10(-68) Cm-5 V-1 . According to quantum chemical calculations (ab initio and semiempiri cal) increasing the acceptor strength in going from the dicyanovinyl t o the dicyanomethyleneamino moiety also leads to an increase in the mo lecular hyperpolarizability. In contrast, further increasing the accep tor strength to the tricyanovinyl group is accompanied by a levelling off or, even, a decrease in the calculated beta-value. (C) 1997 Elsevi er Science Ltd.