( R, R)-salen/salan-based polymer fluorescence sensors for Zn 2+ detection

Abstract

( R,R)-salen-based polymer fluorescence sensor P-1 could be synthesized by the polymerization of 5,5′-(isoquinoline-5,8-diylbis(ethyne-2,1-diyl))-bis(3-tert-butyl-2-hydroxybenzaldehyde) ( M-1) with ( R,R)-1,2-diaminocyclohexane ( M-2) via nucleophilic addition–elimination reaction, and ( R,R)-salan-based polymer sensor P-2 could be obtained by the reduction reaction of P-1 with NaBH 4. The fluorescence response behaviors of two chiral polymers P-1 and P-2 on Zn 2+ were investigated by fluorescence spectra. The fluorescence intensities of P-1 and P-2 can exhibit gradual enhancement upon addition of Zn 2+. Compared with other cations, such as Na +, K +, Mg 2+, Ca 2+, Fe 3+, Co 2+, Ni 2+, Cu 2+, Ag +, Cd 2+, Cr 3+ and Pb 2+, Zn 2+ can lead to the pronounced fluorescence enhancement as high as 22.8-fold for P-1 and 3.75-fold for P-2, respectively. The results show that P-1 and P-2 incorporating ( R,R)-salen/salan moieties as receptors in the polymer main chain backbone can exhibit high sensitivity and selectivity for Zn 2+ detection.