Synthesis and photophysical behaviors of a blue fluorescent copolymer as chemosensor for protons and Ni2+ ion in aqueous solution

An acrylic monomer bearing couamrin moiety, 7-hydroxy-4-methyl-8-(4′-acryloylpiperazin-1′-yl) methylcoumarin (Ac-HMPC) was synthesized from 7-hydroxy-4-methyl-8-(4′-piperazin-1′-yl)methyl coumarin (HMPC) and acryloyl chloride (Ac) in the presence of triethylamine in dry dichloromethane (CH2Cl2) under 0 °C. The synthesized Ac-HMPC was identified by FTIR, MS and 1H NMR spectra, respectively. Then it was copolymerized with acrylamide (AM) using AIBN as initiator in THF under 70 °C. The main photophysical properties of the fluorescent copolymer (poly(Ac-HMPC-co-AM)) were determined viewing its sensor for protons and metal cations. The fluorescent polymer displayed “on-off” switching in its fluorescence intensity over a wide pH scale. In addition, it was found the fluorescence enhancement of poly(Ac-HMPC-co-AM) in the presence of Ni2+ ion. The results suggest that copolymer may offer potential as a reusable polymer for sensor protons and Ni2+ ion in aqueous solution.