Aggregation induced emission properties of cruciform-type conjugated pyrazine molecules with four pendent donor groups

Abstract

Exploration of new fluorescent materials with aggregation-induced emission (AIE) properties is of great significance for practical applications. Tetraphenylpyrazine (TPP) derivatives are the most attractive species for their promising AIE performance and flexible structural modification. In the present work, three D-A type cruciform conjugate chromophores TDMAPP, TDPAPP, and TCPP with rigid X-shaped geometry were elaborately designed and synthesized. Their photophysical properties were systematically investigated to clarify the relationships between their structures and properties. Investigation of their aggregation-induced properties revealed that TDMAPP and TCPP shows aggregation-enhanced emission (AEE) behaviour. In contrast, TDPAPP analogue of TCPP, exhibits an opposite aggregation-caused quenching (ACQ) effect. The differences in their photophysical properties can be mainly ascribed to the substituent effects, which are closely associated with the restriction of intramolecular rotation mechanism.