Two cobalt(II) coordination polymers based on 5-i-butoxyisophthalate and dipyridyl: Syntheses, structures and efficient oxygen evolution reaction

Two new cobalt(II) clusters based 3D metal-organic frameworks (MOFs) [Co-2((i)BuOip)(2)(bpa)(2)(H2O)] (1) and [Co-5((i)BuOip)(4)(mu(3)-O)(bPp)(2)(DMF)(H2O)(3)]center dot 2H(2)O (2) ((i)BuOip = 5-i-butoxyisophthalate, bpp = 1,3-bis(4-pyridyl) propane and bpa = 1, 2-bi(4-pyridyl)ethane), were synthesized with 5-i-butoxyisophthalate and bpp/bpa mixture ligands. Compound 1 shows a 3D network constructed from both a dinuclear cluster and mononuclear Co(II) nodes. The mixture of triangular trinuclear and rhombus tetranuclear cluster nodes linked by 5-i-butoxyisophthalate and bpp give rise to a 3D pillared-layer structure of 2. The structural and topological differences of the two complexes demonstrate that the characteristics of the N-donor auxiliary ligands play significant roles in constructing the novel architectures of coordination polymers. Electrochemical measurements reveal that 2 modified electrode is catalytically active to oxygen evolution reaction with a lower overpotential of only 340 mV at 10 mA cm(-2) in neutral solution.