A dual-functional MOF for high proton conduction and sensitive detection of ascorbic acid

A new metal-organic framework (MOF), [Eu 2 (HBDPP) 2 (H 2 O) 2 (DMF) 2 ](H 2 O) 2 (H 4 BDPP = 3,5-bis(3,5-dicarboxylphenyl) pyridine; DMF = N , N -dimethylformamide) (Eu-MOF), has been successfully synthesized under solvothermal conditions. A 1D chain was formed by the adjacent Eu 2 (COO) 2 4+ dinuclear cluster and HBDPP 3− , and further connected by HBDPP 3− to form an infinitely extended 3D structure. In order to further improve the proton conductivity of the Eu-MOF, imidazole was encapsulated in its pores to form a composite material named Im@Eu-MOF. AC impedance analysis shows that the highest proton conductivity of the Im@Eu-MOF reaches up to 4.53 × 10 −4 S cm −1 at 348 K and 98% RH, which is about 10 times higher than that of the Eu-MOF. In addition, the Eu-MOF can be considered an excellent luminescence-based sensor with a high sensitivity and low detection limit (0.1 μM) for the detection of trace amounts of ascorbic acid. A new Eu-MOF detects AA with turn off fluorescence and the proton conductivity of the Im@Eu-MOF is ten times higher than that of the En-MOF.