Synthesis, structure, adsorption and electrochemical properties of the new two-dimensional cobalt coordination polymer based on bifunctional ligand

A novel two-dimensional coordination polymer {[Co(Htia)₂(C₂H₅OH)₂]·H₂O}_n (1) (H₂tia = 5-(1H-1,2,4-triazol-1-yl)isophthalic acid, C₁₀N₃O₄H₇) was successfully synthesized by a solvothermal method using H₂tia containing –COOH and –N bifunctional groups as ligands and transition metal Co as the central ion. 1 was analyzed by XRD, IR, UV and TG. Single-crystal X-ray diffraction analysis shows that Co²⁺ ions in 1 are the hexagonal distorted octahedral geometry. Neighboring Co²⁺ ions form a two-dimensional grid using the Htia ligand as the rigid skeleton. The adjacent 2D layers interact through hydrogen bonds to build a three-dimensional supramolecular crystalline material. Based on the laminar structure of 1, we investigated the adsorption capacity of 1 on two cationic dyes, crystalline violet and Janus green B. The results show that 1 has a certain adsorption capacity and the maximum adsorption amount of the dyes can reach as high as 56 and 176 mg g⁻¹, respectively. The electrochemical experiment shows that 1 has good electrocatalytic activity in the electrolyte solution of 0.01 M KOH not only for the oxidation of H₂O₂, but also for the oxidation of ascorbic acid.