pH-dependent self-assembly of divalent metals with a new ligand containing polycarboxylate: syntheses, crystal structures, luminescent and magnetic properties

Six new coordination polymers, namely, [Cd(HL)(4,4'-bpy)(H2O)]center dot H2O (1), [Cd-3(L)(2)(4,4'-bpy)(3) (H2O)]center dot 2.5H(2)O (2), [Co(HL)(4,4'-bpy)]center dot H2O (3), [Co-2(L)(4,4'-bpy)(0.5)(mu(3)-OH)(H2O)(2)]center dot H2O (4), [Zn(HL)(BIMB)]center dot 2H(2)O (5), [Zn-3(L)(2)(BIMB)(2)]center dot 3H(2)O (6), where H3L = 5-(4-carboxybenzyloxy) isophthalic acid, 4,4'-bpy = 4,4'-bipyridine, BIMB = 1,4-di(1H-imidazol-1-yl)benzene, have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction. In complexes 1, 3 and 5, H3L ligand is partially deprotonated in the form of HL2-; while in 2, 4 and 6, it is completely deprotonated due to the influence of different pH values. Complexes 1 and 5 are 2D layer structures, the hydrogen bonds between lattice-water molecules and carboxylate groups of HL2- ligands extend the 2D layer into a 3D framework; while complex 3 is a 3D framework with alpha-Po topology. Complex 2 is a 3D fourfold interpenetrating (3,4,4)-connected net with (6(3))(6(2).8(4))(6(4).8(2)) topology. Complex 4 is a twofold interpenetrating (3,8)-connected net with (4(3))(2)(4(6).6(18).8(4)) topology. And complex 6 is a twofold interpenetrating (3,4,6)-connected net with (4.6(2))(6(4).7(2))(4(2).6(6).7(4).8.9(2)) topology. In addition, powder X-ray diffraction and thermogravimetric analyses for 1-6, photoluminescent properties for 1, 2, 5, 6 and magnetic properties for 3, 4 are investigated in detail.