A new kind of polymeric chemosensor containing chiral naphthaldimine moiety in the side chain was synthesized by the reversible addition-fragmentation chain transfer polymerization of N-{[2-(4-vinylbenzyloxy)-1-naphthyl]-methylene}-(S)-2-phenylglycinol (VNP). The resulting polymers (PVNP) showed high selectivity for hydrogen sulfate relative to other anions including F-, Cl-, Br-, H2PO?4-, CH3CO?2-, and NO?3- in tetrahydrofuran (THF) solution as judged from UV-vis, fluorescence, and circular dichroism spectrophotometric titrations. Compared with its monomer, the polymer has proven to be more attractive for detection of HSO?4- in terms of sensitivity and reproducibility. Upon addition of the anion it gives remarkable spectral responses concomitant with detectable color change from colorless to pale yellow. Furthermore, the HSO?4--induced CD or fluorescence signal can be totally reversed with addition of base and eventually recovered the initial state, leading to a reproducible molecular switch with two distinguished on and off states. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012