Multicomponent Stereoselective Polymerizations toward Multifunctional AIE Polymers with α,β-Unsaturated Amidines

<p>Heterochain polymers play an essential role in our daily lives due to their distinctive properties. Among various heteroatom-rich structures, amidine derivatives serve as a synthetically important and pharmacologically useful structural branch and have found wide applications in synthetic chemistry and biomedicine field. In this work, we developed a straightforward and powerful polymerization tool to access diverse heterochain polymers with <i>α</i>,<i>β</i>-unsaturated amidine units. The multicomponent electrophilic polymerizations of readily accessible diynes, disulfonyl azides, and <i>N</i>,<i>N</i>-dimethylformamide dimethyl acetal proceed efficiently at room temperature, producing amidine-containing polymers with high molecular weights (<i>M</i><sub>w</sub> up to 74500) in high yields within merely 1 h. Nuclear magnetic resonance spectra analysis revealed that all the obtained polymers are formed with excellent stereoselectiviy. The introduction of aggregation-induced emission (AIE) luminogen together with the inherent heteroatom-rich structure feature endow these polymers with multiple functionalities. The nanoaggregates of the diethylamino-substituted polymer show remarkable and reversible fluorescence response to acid and base, and the acid-fumed polymer thin film can be used as a sensitive and reusable fluorescent probe for detecting seafood spoilage. This polymer system can also be employed as a highly selective and sensitive Au<sup>3+</sup> sensor, and efficient gold recovery can be achieved based on the excellent gold enrichment capability of the polymer. In addition, the AIE polymers can also be applied in lysosome-specific cell imaging with low cytotoxicity and excellent photostability.</p>