A Highly Selective Fluorescence-Based Polymer Sensor Incorporating an (R,R)-Salen Moiety for Zn2+ Detection

A chiral polymer incorporating an (R,R)‐salen moiety was synthesized by the polymerization of (R,R)‐1,2‐diaminocyclohexane with 2,5‐dibutoxy‐1,4‐di(salicyclaldehyde)‐1,4‐diethynyl‐benzene by a nucleophilic addition–elimination reaction. The fluorescence responses of the (R,R)‐salen‐based polymer toward various metal ions were investigated by fluorescence spectra. Compared with other cations, such as Na+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Cd2+, Hg2+, and Pb2+, Zn2+ can lead to a pronounced fluorescence enhancement as high as 7.8‐fold together with an obvious blue‐shift change of the chiral polymer. More importantly, the fluorescent color of the polymer changed to bright blue instead of weak yellow after addition of Zn2+, which can be easily detected by the naked eye. The results indicate that this kind of chiral polymer, incorporating an (R,R)‐salen moiety as a receptor in the main chain backbone, can exhibit high sensitivity and selectivity for Zn2+ recognition. Sensing sensibility: A chiral polymer incorporating an (R,R)‐salen moiety was synthesized and exhibits an excellent fluorescence response toward Zn2+. The fluorescent color of the polymer changed to bright blue instead of weak yellow after addition of Zn2+, which could be easily detected by the naked eye (see picture).