Design, synthesis of two-dimensional charge transfer molecules based on pyridinium salts and determination of their first hyperpolarizability

Two new two - dimensional charge transfer (2DCT) chromophore molecules for nonlinear optics (NLO) were designed and synthesized with pyridinium as ele ctron acceptor group. They are trans -4, 4' - di {p - [(N- ethyl - N - hydr oxyethyl) amino] styryl} - N, N' - (1, 2 - ethylene) - 2, 2' - bipyridinium ditetraphenylborate and trans - N - bexyl - carbazole - 3, 6 - di(p - ethe nyl - N - hydoxyethyl - pyridinium) ditetraphenylborate. The first hyperpol arizability (beta) values were determined by Hyper - Rayleigh Scattering (H RS) technique. The large beta values are obtained as 786 x 10(-30) esu and 1770 x 10(-30) esu at 1064 nm and corresponding beta(0) are 215 x 10(-30) e su and 119 x 10(-30) esu calculated according to two - level model, respect ively. The large value of beta was explained qualitatively from the point o f view of molecular structure.