Systematic study of thiazole incorporated NLO gradient bridge chromophores

In an exploration of improving the intrinsic first order hyperpolarizability of organic NLO chromophores, sets of novel chromophores were synthesized. These compounds were designed according to a novel gradient bridge concept. Among these novel compounds, the first experimental example of a thiazole "forward" containing chromophore was synthesized. The first order hyperpolarizabilities of these compounds were examined using hyper-Raleigh scattering (HRS) technique. Results obtained at 1.3mum and 880nm revealed that the regiochemical orientation of the thiazole has a marked effect on the hyperpolarizability. Thiazole "forward" showed a 20% improvement in hyperpolarizability relative to chloroform compared to that of thiazole "backward." An additional examination of two of these compounds with respect to their bulk nonlinear optical activity showed that the novel thiazole "forward" containing chromophore possessed an inherit instability in its structure compared to that of its thiophene analogue. The degradation of the thiazole "forward" chromophore occurred through a [4+2] cycloaddition reaction with DMSO. Recommendations to improve the stability of future thiazole "forward" chromophores were discussed. Overall, the first order hyperpolarizability of thiazole containing chromophores can be tailored, but are not stronger than their thiophene analogue.