Isomer Effect Study of Pyridinium-type Cationic Fluorophores: Multiple Functions and Internal Optical Mechanism

Cationic fluorophore (CF) with highly twisted conformation is a kind of very important functional materials in the field of optical sensing and imaging. In this paper, isomers of pyridinium-type CFs (PyrCFs, o-, m-, p-TPA-Pyr-BP) were employed as three models, which share the same electron donor of triphenylamine (TPA) and acceptor of pyridinium (Pyr) but with different link positions. For the purpose to demonstrate the isomer effect of o-, m-, p-TPA-Pyr-BP, extensive research works, including of aggregation-induced emission (AIE) capability, sensing ability and the cell imaging behavior have been systematically evaluated. Furthermore, based on the experimental facts and theoretical calculations, a deeper understanding on the internal optical mechanism was also revealed. Finally, p-TPA-Pyr-BP was verified as a highly powerful multi-functional material, and successfully used in various applications.