An aggregation-induced phosphorescent emission-active iridium(III) complex for fluoride anion imaging in living cells

Abstract

Fluoride anion plays a crucial role in bone and tooth growth. However, overdose of fluoride anion can also lead to many chronic diseases and there is no specific medicine for fluorosis so far. Hence, the early detection and accurate estimation of fluoride anion intake are important. In this work, an aggregation-induced phosphorescent emission (AIPE)-active iridium(III) complex as fluoride anion probe (Ir-AF) has been developed by incorporating N-(4-hydroxylphenyl)-rhodol protected by tert-butyldiphenylsilyl onto cyclometalating ligand. As Ir-AF reacts with fluoride anion, the nonradiative transitions of Ir-AF would be promoted by enhanced photoinduced electron transfer effect and intramolecular rotations, leading to its phosphorescence quenching dramatically. Thus, Ir-AF has been used for fluoride anion measurement in the aqueous solution by ratiometric readout. Furthermore, with the utilization of the long-lived phosphorescence from Ir-AF, fluoride anion sensing in living cells with high signal-to-noise ratio has been achieved by time-resolved photoluminescence imaging. This is the first report of AIPE-active probe for fluoride anion.