Interpenetration, self-catenation, and new topology in metal-organic frameworks of cobalt with mixed organic linkers

Two Co(II) metal-organic frameworks with 2,2′-dinitrobiphenyl-4, 4′-dicarboxylate (dnpdc) and different dipyridyl ligands have been synthesized by hydrothermal methods. They exhibit different three-dimensional mixed-connected net topologies with either interpenetration or self-catenation features. With dnpdc and 4,4′-bipyridine as cobridging ligands, compound 1 displays 3-fold interpenetrated (4,6)-connected nets based on mononuclear and binuclear nodes. With dnpdc and bis(4-pyridyl)ethane as cobridging ligands, compound 2 exhibits a novel (6,8)-connected net based on two different binuclear nodes, with a high degree of self-catenation arising from the interconnection of "interpenetrated" 2D subnets.