A coumarin based highly selective fluorescent chemosensor for sequential recognition of Cu2+ and PPi

In this study, we have successfully synthesized a new coumarin based fluorescent chemosensor 1 , in which tren and quinolone are introduced as receptors for sequential recognition of Cu 2+ and PPi. The structure of chemosensor 1 was characterized by 1 H NMR, 13 C NMR and ESI-HR-MS. Sensor 1 showed an obvious “on-off” fluorescence quenching response toward Cu 2+ , and the quenching efficiency reached a maximum of 99.6% with the addition of 20 equiv. of Cu 2+ . The 1 -Cu 2+ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions, especially HPO 4 2− and H 2 PO 4 − . The detection limit of sensor 1 was 1.9 × 10 −6  M to Cu 2+ and 5.96 × 10 −8  M to PPi. In addition, sensor 1 showed a 1:1 binding stoichiometry to Cu 2+ and sensor 1 -Cu 2+ showed a 2: 1 binding stoichiometry to PPi in CH 3 CN/HEPES buffer medium (9:1 v/v, pH = 7.4). The stable pH range of sensor 1 to Cu 2+ and 1 -Cu 2+ to PPi was from 4 to 8.