Two Imidazo[1,2-a]pyridine Congeners Show Aggregation-Induced Emission(AIE):Exploring AIE Potential for Sensor and Imaging Applications

摘要

Density functional theoretical calculations predicted noncoplanar twisted geometry for two new imidazo[1,2-a]pyridine derivatives,Imp and ImBt.Analysis of single-crystal of Imp asserted the non-coplanar twisted geometry,which is implicated in aggregation induced emission(AIE)of small aromatic molecules.Universal quenching by water was observed in aqueous THF solutions of Imp and ImBt,but they showed AIE effect when the water content was more than 80%.Nonfluorescent solutions of Imp and ImBt in THF-water(7:3 v/v)mixture turned fluorescent on addition of specific metal ions prompting their potential to be explored for turn-on sensor applications.While ImBt showed AIE response to Cd~(2+),Hg~(2+)and Al~(3+),Imp displayed AIE effect only to Cd~(2+)ions,under identical conditions.Absence of interference from common metal ions(including Hg~(2+)and Al~(3+))led to selective formation of Imp-CdCl2(1:1)complex,which offered the limit of detection of Cd~(2+)to be 19.2 μM.The observed selectivity for Cd~(2+)permitted the use of Imp in the imaging of live Rhizoctonia oryze contaminated with Cd~(2+)ions.