Counteranion-Controlled Aggregation-Induced Emission in 10H-Pyrido[1,2-a]-5-indolium Salts: Structure-Property Relationships and Anion-π⁺ Interactions

Abstract

We synthesized fluorescent 10H-pyrido[1,2-a]-5-indolium salts and studied the variations in their optical and structural properties with different counter anions. Spectroscopic and crystallographic analyses revealed anion-dependent changes in absorption coefficients, fluorescence intensity, and intermolecular interactions. Furthermore, the compounds exhibited aggregation-induced emission (AIE) behavior. These findings highlight the potential of anion control for tuning the fluorescence behavior of advanced dyes and photofunctional materials.