Mixed-ligand strategy affording two 6-connected 3-fold interpenetrated metal-organic frameworks with binuclear CoII2/NiII2 subunits: Synthesis, crystal structures and magnetic properties

Abstract Two 6-connected (6-c) edge-transitive nets, namely, [Co2(2,6-ndc)2(4-bpdb)·2CH3OH·2H2O]n, (1), and [Ni2(2,6-ndc)2(4-bpdb)·(H2O)3·2DMF]n (2) (2,6-H2ndc = 2,6-naphthalenedicarboxylic acid, 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene), were synthesized under solvothermal conditions. The structure of 1 manifests a three-fold interpenetrated 3D pcu topology based on paddle-wheel [Co2(μ2-η1:η1-COO)4] dimers. The structure of 2 possesses a three-fold interpenetrated 3D acs topology based on [Ni2(μ2-OH2)(μ2-η1:η1-COO)2(η1-COO)2] dimeric units. Magnetic analyses indicate that both two compounds show weak antiferromagnetic interactions within binuclear CoII2 and NiII2 units.