Two 3-D Cluster-Based Frameworks: Highly Eight-Connected Molecular Topology and Magnetism

A couple of metal-organic frameworks (MOFs) constructed from rigid bicarboxylates are presented herein, namely, CO3(ndc)(3)(bbi)(CH3CN)(2) (1) and DY2Mn3(ndc)(6)(bipy)(2) (2), where H(2)ndc = 2,6-naphthalenedicarboxylic acid, bipy = 2,2'-pyridine, and bbi = 1,1'-(1,4-butanediyl)bis(imidazole). These two coordination polymers have been prepared through solvo/hydrothermal reactions and characterized by single-crystal X-ray study, TG, IR, and elemental analysis. Polymer 1 features a novel self-penetrating network mediated by flexible long-chain ligand and well defines a unique 4(16)center dot 5(8)center dot 6(4) topology with the treatment of Co-3 unit as an 8-connected node, which equals the highest connectivity for monometallic self-penetrating system so far. Polymer 2 represents the first example of a Mn-II-Dy-III (3d-4f) heteropentanuclear complex showing an intriguing 3-D 3(6)center dot 4(18)center dot 5(3)center dot 6 framework upon the assignment of DY2Mn3 cluster to an 8-connected node. In addition, magnetic studies of 1 reveal that the antiferromagnetic behavior is operative within the trimeric Co-3 Cluster and 2 demonstrates dominant ferromagnetic coupling interactions between Dy-III and Mn-II ions.