The first-order molecular hyperpolarizability and thermal stability of charge-transfer azo diol and azo aldimine

Nonlinear optical chromophores with nitro acceptors have been designed and synthesized. The first-order hyperpolarizability of the chromophores was determined using hyper-Rayleigh scattering; the decomposition temperature was determined using DSC and the absorption spectra of the compounds were measured. The nonlinear optical properties of the chromophores were discussed; the first-order hyperpolarizabilities of chromophores 3 and 4 come from their two-dimensional structure, the length of the conjugation bridge and intramolecular proton transfer. The strong dihydroxyl donor of chromophores 1 and 2 expanded the first-order hyperpolarizabilities, the measured βHRS values of chromophores 1 and 2 at 1064 nm are 211 × 10−30 esu and 177 × 10−30 esu, respectively. These NLO-chromophores exhibit higher decomposition temperature in the range of 290–330 °C.