Water-soluble polymeric chemosensor for detection of Cu2+ ions with high selectivity and sensitivity

Abstract

Development of water-soluble chemosensors that are selective and sensitive to Cu2+ ions is of tremendous importance owing to their potential applications in biological systems. In the present work, we report the synthesis of a new water-soluble polymer containing pendant rhodamine units that are capable of highly selective and sensitive detection of Cu2+ ions in aqueous medium. Poly(2-pyrrolidinemethyl acrylate) was prepared using RAFT polymerization technique. The pyrrolidine nitrogen group in the polymer was subjected to Aza-Michael type addition with ethyl acrylate that was followed by covalent linking of rhodamine units to the polymer. This polymer was completely water-soluble and found to be capable of sensing Cu2+ ions in aqueous medium. Cu2+-induced opening of the spirolactam ring of the rhodamine units resulted in rapid and easily noticeable colour change, thus enabling a highly selective detection of Cu2+ in μmol range. The ability of these polymeric systems to detect Cu2+ ions in complete aqueous media has more importance than use of organic solvents to solubilize the polymer as reported previously, and thus opened a new window for application of these systems in the detection of copper ions in biological systems.