Metal(II)-Induced Coordination Polymer Based on 4‑(5-(Pyridin-4-yl)-4H-1,2,4-triazol-3-yl)benzoate as an Electrocatalyst for Water Splitting

Using a rigid ligand, 4-(5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl) benzoic acid (HL), three metal­(II)–organic frameworks (MOFs) formulated as M2L4·3H2O [M = Co (1), Cu (2), and Zn (3)] were synthesized and characterized by single-crystal X-ray diffraction. The three MOFs are isostructural except for different unsaturated coordinated metal­(II) ions in the structures, and they display a uninodal two-dimensional layer with 44-sql topology. Among the three complexes, the Co and Cu complexes can act as electrocatalysts for water splitting, and the Co complex shows better electrocatalytic activity. The present work shows that the species of metal­(II) ions plays an important role in the electrocatalytic activity for water splitting. The three complexes show different thermal stabilities, UV–vis absorption characteristics, and photoluminescence properties.