NLO chromophores containing dihydrobenzothiazolylidene and dihydroquinolinylidene donors with an azo linker: Synthesis and optical properties

We report the synthesis of a series of nonlinear optical chromophores containing either a dihydrobenzothiazolylidene or dihydroquinolinylidene donor with an azo linker. The results demonstrate the versatility of coupling a diazonium salt to a donor–methylidene nucleus in order to access novel materials with good thermal stabilities and high nonlinear optical responses. From hyper-Raleigh scattering studies it was found that the use of the well-known TCF acceptor yields the best performing chromophores, one of which has a dynamic first hyperpolarizability of 1900 × 10−30 esu at 800 nm. The results from this study suggest the use of pro-aromatic donors such as dihydrobenzothiazolylidene or dihydroquinolinylidene results in compounds with higher nonlinear optical responses than those containing donors based on either indoline or aniline.

► A series of chromophores with aromatizable donors and azo linkers are reported. ► The methodology allows for the synthesis of the target molecules in high yield. ► The compounds have first hyperpolarizabilities of up to 1900 × 10−30 esu. ► The compounds have decomposition temperatures between approx 215–250 °C.