Design, synthesis, structure, and photophysical features of highly emissive cinnamic derivatives

New cinnamic derivatives 1a-c were designed starting from the chromophores working in polybenzofulvene derivatives poly-6-DMFL-BF3k, poly-6-MCBZ-BF3k, and poly-6-TPA-BF3k endowed with outstanding optoelectronic performances. This design approach led to the discovery of cinnamic derivatives showing very intriguing photophysical features. For instance, the cinnamic derivative bearing a triphenylamine moiety 1c showed photoluminescence quantum yield (PLQY) values of around 80% both in solution (λem = 540 nm) and in the crystalline state (λem = 470 nm). On the other hand, compounds 1a, b showed slightly lower, but still interesting PLQY values in the order of 57-77% and emission maxima in the range of 407-480 nm. The experimental findings were supported by the results of DFT and TDDFT calculations of the absorption and emission maxima of cinnamic derivatives 1a-c.