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

Abstract

A new metal–organic framework (MOF), [Eu₂(HBDPP)₂(H₂O)₂(DMF)₂](H₂O)₂ (H₄BDPP = 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 Eu₂(COO)₂⁴⁺ dinuclear cluster and HBDPP³⁻, and further connected by HBDPP³⁻ 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.