A quinoline-based Cu2Â + ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells

A quinaldine functionalized probe 1 has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2 + ion over most of the biologically important ions at physiological pH. The binding ratio of the probe 1 and Cu2 + ion was determined to be 1:1 through fluorescence titration, Job's plot and ESI-MS. The binding constant (K) of Cu2 + to probe 1 was found to be 2.12 × 104 M− 1. Further, the Cu2 + ensemble of probe 1 was found to respond H2PO4− and HPO42 − anions among other important biological anions via fluorescence turn-on response in buffered aqueous solution at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe 1 could be used as an effective fluorescent probe for detecting Cu2 + cation and H2PO4− and HPO42 − anions in living cells.275