A 3D supramolecular framework-based electrochemical sensor for highly sensitive detection of ascorbic acid

A benzimidazole carboxylate ligand with multiple coordination sites has been designed by the aldimine condensation reaction of 2-pyridinecarboxal-dehyde and 3,4-diaminobenzoic acid, 2-(2'-pyridyl)-benzimidazole-6-carboxylic acid (H(2)pybimc), which solvothermally assembled with Ni2+ ions in the mixed solvents of H2O and n-propanol to generate a 3D supramolecular framework, {[Ni(Hpybimc)(NO3)(H2O)]}(n) (CP 1). The chemical composition and structure of CP 1 have been characterized in detail by various tools. Structural analysis demonstrates that the asymmetrical unit of CP 1 consists of one octahedral Ni2+ ion, one Hpybimc(-), one NO3- and one coordinated water molecule. Adjacent Ni2+ ions are linked by Hpybimc(-) to form a 2D 3-connected 'fes'-type topology, which further generates a 3D supramolecular architecture by hydrogen bonds and pi center dot center dot center dot pi stacking interactions. The carbon paste electrode (CPE) modified with CP 1 is fabricated (CPE 1) and applied for the electrochemical sensor of ascorbic acid (AA), which exhibits good linear correlation with AA in the concentration range of 5.0 x 10(-4) to 7.3 mmol L-1 with the limit of detection (LOD) of 0.85 mu mol L-1. Moreover, it has satisfactory stability, repeatability, and selectivity towards AA, which can be successfully used for the detections in real samples.