Design, synthesise, and evaluate photoluminescent properties of novel 3,6-diphenylpyrazine-2-cyanopyrazine derivatives

Abstract

Seven 2-cyanopyrazine derivatives, including six novel compounds, were designed based on a symmetric donoracceptor-donor (D-A-D) motif, employing 2-cyanopyrazine. The use of this strong acceptor transforms simple phenyl rings into donors aimed to develop new photoluminescent molecules and investigate the effects of substituent modifications on the phenyl rings. This is an uncommon motif with potential for broad application in designing new thermally activated delayed fluorescence (TADF) molecules. The derivatives were efficiently synthesised via Suzuki coupling reactions. Investigation of the photoluminescent properties of these novel compounds revealed that the phenyl-based donor substituents could modulate the photoluminescent characteristics of the molecules in diverse ways. Two new compounds, 3f and 3g, exhibited emission in the visible region, with compound 3g demonstrating
a highly selective emission band. The results suggest that strategically adding various phenyl derivatives as donor substituents to the 2-cyanopyrazine acceptor core yields flexible and easily tunable luminescent properties. The results obtained in this study open up promising prospects for the application of 2-cyanopyrazine derivatives in the fields of optoelectronics and luminescent materials.