Colorimetric naked-eye recognizable anion sensors synthesized via RAFT polymerization

A polymeric sensor (PTH) containing naphthalimide signal moiety and thiourea recognition moiety for the detection of anions was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, which can guarantee controllable molecular weight, narrow molecular weight distribution, and precise polymer structure. Both PTH and its corresponding monomer (TH) showed naked-eye recognizable yellow-to-orange changes upon addition of fluoride (F−), acetate (AcO−), and dihydrogen phosphate (H2PO) of low concentration. However, only F− can result in orange-to-purple change when the aforementioned anions were added at high concentrations, which was attributed to the deprotonation of the thiourea NH groups and the mechanism was supported by the UV-Vis absorption spectra and 1H NMR titration. The effect of these anions on thin PTH films was also investigated, and the addition of F− led to obvious spectra change. It was found that other halide anions (Cl−, Br−, and I−) could hardly induce any variation of absorption spectra. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1551–1556, 2010