Two CoII Metal–Organic Frameworks Based on a Multicarboxylate Ligand as Electrocatalysts for Water Splitting

By using a rigid multicarboxylate ligand, 4,5‐di(4′‐carboxylphenyl)phthalic acid ( H 4 L ), two Co II complexes formulated as [Co 4 L 2 (4,4′‐bpy)(H 2 O) 6 ] ⋅ 3.5 H 2 O (4,4′‐bpy=4,4′‐bipyridine) ( 1 ) and [Co 2 L(azene)(H 2 O) 3 ] ⋅ DMF (azene=( E )‐1,2‐di(pyridin‐4‐yl)diazene, DMF=dimethylformamide) ( 2 ) have been synthesized and structurally characterized by single‐crystal X‐ray diffraction. Complex 1 features a novel three‐nodal (4,5,6)‐connected 2 D framework with an unusual (3 2 .4 2 .5.6 3 .7.8)(3 2 .4 2 .5.6)(3 2 .4 6 .5 2 .6 4 .7) topology. Complex 2 exhibits a novel two‐nodal (4,7)‐connected 3 D framework with an unusual (4 3 .5.6 2 )(4 5 .5 5 .6 9 .7.8) topology. Ligand L 4− displays different coordination modes in the two complexes. The complexes both exhibit electrocatalytic activities toward generating H 2 and O 2 from water with lowered overpotentials and enhanced currents. The different electrocatalytic properties of the two complexes are related to their different ligands and frameworks.