Synthesis , Structure and Electrochemical Properties of Metal Cobalt Complexes with Interpenetrating Structures

Using multidenate 4, 4'- (phenylazanediyl) dibenzoic acid (H2L) and 1, 3-bis (imidazol-1-yl) benzene (B), 3, 5-bis (imidazol-1-yl) pyridine (bimp) or 1, 4-bis (imidazol-1-yl) benzene (B') as ligands under solvothermal conditions, three new metal-organic frameworks with interpenetrating structure, {[CoLB]center dot H2O}(n)(1), Co2L2 (bimp)(0.5)center dot 3H(2)O}(n)(2) and {[Co2L2B2 center dot 2DMF}(n)(3), were synthesized. The complexes were characterized by single-crystal X-ray diffraction (XRD), thermal analysis and powder X-ray diffraction (PXRD). Complexes 1-3 all crystallize in the monoclinic system, with C2/c (complex 1), P2/n (complex 2) and P2(1) (complex 3) space group, respectively. In complexes 1 and 3, Co2+ forms a tetracoordinate geometry, whereas it forms a five-coordinated geometric configuration and exists as a dual-core paddleshaped structural unit [Co-2(CO2)(4)] in complex 2. Complexes 1 and 2 give a 2-fold interpenetrating three-dimensional(3D) supramolecular networks, while complex 3 exhibits a 4-fkild interpenetrating 3D framework. The results of electrochemical studies show that complexes 1-3 are electrochemically active substances with good electrochemical reversibility.