Six New Co-Coordination Polymers Based on a Tripodal Carboxylate Ligand

Six new compounds of partially or wholly deprotonated 3,5-bi(4-carboxyphenoxy)-benzoic acid (H(3)BCPBA), namely, {[Co(H(2)BCPBA)(2)(H2O)(4)]}(n) (1), {[Co(HBCPBA)(bipy(0.5))(2)center dot(H2O)]}(n) (bipy = 4,4'-bipyridine) (2), {[Co-3(BCPBA)(2)(dpe)center dot(mu(2)-H2O)(4)]center dot 2H(2)O center dot 2DMF}(n) (dpe = 1,2-di-4-pyridyleth-ene) (3), {[Co-3(BCPBA)(2)(pdp)center dot(mu(2)-H2O)(4)]center dot 2DMF}(n) (pdp = 4-[(E)-4-pyridinylazo]pyridine) (4), {[Co-3(BCPBA)(2)(bpe)center dot(mu(2)-H2O)(4)]center dot 2DMF}(n) (bpe = 1,2-bis(4-pyridyl)ethane) (5), {[Co-2(HBCPBA)(2) (bpp)center dot(mu(2)-H2O)(2)]center dot H2O center dot 2DMF}(n) (bpp = 1, 3-bis(4-pyridyl)propane) (6) were synthesized in the presence or absence of auxiliary ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectroscopy, and thermogravimetric analysis. Compound 1 is a zero-dimensional structure. Compound 2 is a two-dimensional (2D) sheet structure with two 2D -> 2D interpenetration frameworks. Compounds 3-5 are similar and posses three-dimensional (3D) networks with two 3D -> 3D interpenetration frameworks. In compound 6, H(3)BCPBA and bpp ligands link Co centers to generate a 2D sheet structure which is further connected by intermolecular hydrogen bonds to form a 3D supramolecular structure. The photochemical properties are performed in the solid state at room temperature. Magnetic susceptibility measurements indicate that compounds 2-6 exhibit antiferromagnetic coupling between adjacent Co(II) ions.