A new europium metal–organic framework with both high proton conductivity and highly sensitive detection of ascorbic acid

Abstract

A new metal–organic framework (MOF), [{(H₃O)[Eu (SBDB)(H₂O)₂]}_n] (H₄SBDB = 1,5-disulfo-benzene-2,4-dicarboxylic acid) (1), was successfully synthesized under solvothermal conditions. Ten central Eu³⁺ ions are coordinated by the H₄SBDB ligands and two coordination water molecules. The adjacent Eu³⁺ ions are connected by oxygen atoms from carboxyl groups, forming a 1D chain. 1D chains are linked by H₄SBDB ligands to induce a 2D infinitely extensible planar structure, and then connected by hydrogen bonds to form a 3D supernetwork structure. Complex 1 exhibits excellent thermal and chemical stability. AC impedance analysis shows that the highest proton conductivity of 1 reaches up to 1.0 × 10⁻⁴ S cm⁻¹ (338 K, 98% RH). Furthermore, complex 1 is an excellent luminescence-based sensor with high sensitivity and a low detection limit for ascorbic acid (AA) in aqueous solutions.