Fluorogenic detection of Hg2+, Cd2+, Fe2+, Pb2+ cations in aqueous media by means of an acrylamide-acrylic acid copolymer chemosensor with pendant rhodamine-based dyes

A monomer 1-acrolyl-2-rhodamine 6G hydrazide (AR6GH) was synthesized by the heterogeneous reaction of acryloyl chloride with rhodamine 6G hydrazide (R6GH) and characterized by 1 H NMR, FTIR and elememtal analyses. Then it was micellar copolymerized with acrylamide (AM), acrylic acid (AA) to obtain a water-soluble fluorescent copolymers (poly(AM-AA-AR6GH)) which were characterized by the method of FTIR and 1 H NMR. The viscosity average molecular weight M η – of poly(AM-AA) and poly(AM-AA-AR6GH)s were 1.76 × 10 6 , 8.58 × 10 4 and 7.68 × 10 4  g/mol, respectively. The fluorescent characteristic of the aqueous solutions of copolymers was investigated both in varied pH and in the presence of metal cations. The poly(AM-AA-AR6GH) was found to be a selective chemosensor for Hg 2+ , Cd 2+ , Fe 2+ , Pb 2+ ions. Obvious fluorescence enhancement was due to the photophysical response of the copolymer to the presence of Hg 2+ , Cd 2+ , Fe 2+ , or Pb 2+ ions. In addition, the ability of the copolymer to detect different metal cations (Ag + , Ba 2+ , Co 2+ , Cd 2+ , Cr 3+ , Cu 2+ , Fe 2+ , Fe 3+ , Hg 2+ , K + , Mg 2+ , Mn 2+ , Na + , Ni 2+ , Pb 2+ , Zn 2+ ) in aqueous solution was studied. The results suggest that copolymer may offer potential application for sensors of Hg 2+ , Cd 2+ , Fe 2+ , or Pb 2+ ions in aqueous solution.