AIE‐ESIPT Photoluminescent Probe Based on 3‐(3‐Hydroxypyridin‐2‐yl)isoquinolin‐4‐ol for the Detection of Intracellular Hydrogen Peroxide

Abstract

AbstractExcited‐state intramolecular proton transfer (ESIPT) molecules, which feature large Stokes shifts to avoid self‐absorption, play an essential role in photoluminescent bioimaging probes. Herein, we report the development of an ESIPT molecule 3‐(3‐hydroxypyridin‐2‐yl)isoquinolin‐4‐ol (PiQ). PiQ not only undergoes a distinct ESIPT process unlike the symmetrical 2,2′‐bipyridyl‐3,3′‐diol but also exhibits aggregation‐induced emission (AIE) characteristics. PiQ self‐assembles into aggregates with an average size of 241.0±51.9 nm in aqueous solutions, leading to significantly enhanced photoluminescence. On the basis of the ESIPT and AIE characteristics of PiQ, the latter is functionalized with a hydrogen peroxide‐responsive 4‐pinacoratoborylbenzyl group (B) and a carboxylesterase‐responsive acetyl group (A) to produce a photoluminescent probe B−PiQ−A. The potential of PiQ for applications in bioimaging and chemical sensing is underscored by its efficient detection of both endogenous and exogenous hydrogen peroxide in living cells.