Elegant cooperation of AIE, ESIPT and ICT effects into tetraarylimidazole-based fluorophore and its tuning for ratiometric detection of carbon monoxide

Abstract

Carbon monoxide (CO) is an important gasotransmitter to regulate various physiological processes. Visualization of CO in situ would be conducive to uncover its physiological/pathological role. Unfortunately, most current CO fluorescent probes display aggregation-caused quenching (ACQ) characters. Herein, we reported a new fluorophore (MTPIM-HBT) coupling with aggregation-induced emission (AIE), excited-state intramolecular proton transfer (ESIPT), and intramolecular charge transfer (ICT) characteristics by attaching 2-(2′-hydroxyphenyl)benzothiazole (HBT) on methoxyl-substituted tetraarylimidazole derivative. Because of the synergistic effects, this fluorophore presented an all-purpose platform for developing ratiometric fluorescent probes with promising optimized properties. Hence, two reaction-based fluorescent probes (MTIPIM-AF-CO and MTPIM-AE-CO) for ratiometric detection and imaging of CO were rationally designed based on these unique scaffolds via one-step facilely synthesis. These probes have the merits of superior selectivity and excellent sensitivity with detection limit 47.5 nM and 32.2 nM, respectively. Significantly, the practicability of probes for visual detection of CO in air and ratiometric detection of exogenous and endogenous CO in living cells were successfully elucidated as well.