Donor-linker-acceptor (D-π-A) diazine chromophores with extended π-conjugated cores: synthesis, photophysical and second order nonlinear optical properties.
Abstract
The synthesis of a series of push-pull pyrimidine and quinoxaline chromophores with extended π-conjugated cores is reported. Starting from a bromoarylvinyldiazine deriv., the key step in the prepn. of the chromophores consists of a Sonogashira cross-coupling reaction. The photophys. properties of the compds. are described. A strong pos. emission solvatochromism, typical for dyes presenting Intramol. Charge Transfer (ICT), is obsd., in particular for amino substituted derivs. with larger solvatochromic range than known analogous chromophores with smaller π-conjugated cores. The second order non linear optical (NLO) properties were investigated for some of the compds. and a comparison with the NLO responses of already described diazine chromophores exhibits a significant enhancement of the NLO properties by extension of the π-conjugated core.