Sulfonate‐Functionalized AIEgens: Strategic Approaches Beyond Water Solubility for Sensing and Imaging Applications

Abstract The development of water‐soluble aggregation‐induced emission (AIE)‐active “light‐up” probes for sensing and imaging purposes has drawn immense research attention in the recent past. One strategy has been to introduce −SO 3 − groups in AIEgens (AIE‐sulfonates) to increase their hydrophilic properties, and the ionic nature of the corresponding compounds also paves the way for electrostatic interaction with various analytes, in particular, with several biospecies having positively charged surfaces. A significant number of AIE‐sulfonates, many among them having a tetraphenylethylene (TPE) moiety, have been designed and synthesized for the selective detection of a variety of analytes, such as metal ions, small molecules, enzymes, proteins, and bacteria. The strategies for selective detection include, for example, spontaneous complex formation with cations, electrostatic interaction with target‐specific units in the biospecies, and strong hydrophobic interactions. In addition, these AIEgens are used in cell imaging and OLED applications. This Review attempts to provide a summary and discuss recent developments in sulfonate‐functionalized AIE‐active “light‐up” probes in sensing and imaging applications with a focus on the role of the sulfonate functionality in the design and sensing processes.