Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion

A new spiropyran derivative was synthesized and first utilized in a polymeric film-based optical sensor for zinc ion. Spiropyrans, combining the characteristics of metal binding and signal transduction, show potential function in the design of optical chemical sensors (optodes) toward metal ions. When embedded in a plasticized poly(vinyl chloride) (PVC) membrane, the newly synthesized spiropyran derivative 1 exhibits obvious fluorescence enhancement at 630 nm in the presence of zinc ion in aqueous solution. With the optimum condition described, the optode membrane responds to zinc ion over a dynamic range of 4.94 × 10^-7 to 4.15 × 10^-4 mol·L^-1, with a detection limit of 1.51 × 10^-7 mol·L^-1. The membrane not only displays excellent photostability, reproducibility and reversibility, but also exhibits high selectivity toward zinc ion over transition metal ions including Hg²⁺, Cd²⁺, Pb²⁺, Cu²⁺, Fe³⁺ and common cationic ions presented in the physiological fluids.