New fluorescent chemosensors based on mononuclear copper complex for highly selective and sensitive detection of phosphate anion in aqueous solution and living cells.

Three new probes, named, [Cu(L1)]Cl (C1), [Cu(L2)]Cl (C2) and [Cu(L3)]Cl (C3) were synthesized and well characterized. The probes C1, C2 and C3 were successfully achieved for the efficient detection of PO as turn-on fluorescence chemosensors in DMSO/HO (v:v = 2:8, Tris-HCl pH = 7.20). The limit of detection (LOD) of probes C1, C2 or C3 for PO could be as low as 0.029 μM, 0.048 μM, 0.079 μM, respectively, which were effectively applied for the determination of the PO concentration in environmental water of swimming pool. What's more, the binding constant between probes C1, C2, C3 and PO are estimated to be 3.11 × 10 M (R = 0.9992), 1.84 × 10 M (R = 0.9956), 1.93 × 10 M (R = 0.9976), respectively. The proposed mechanism for the "on-off-on" fluorescence response was confirmed by ESI-MS and fluorescence spectrum. Moreover, the membrane-permeable probe C1 was successfully demonstrated in monitoring of PO in cultured HepG2 cells.