Control formation of rigid linear and flexible zig-zig complexes based on Zn(II) and hydroxyquinoline carboxylate ligand system

Two novel zinc complexes, [Zn(H-hqc)2(bpy)(H2O)2] (1) and [Zn(H-hqc)2(bpe)]∙H2O (2), where H2-hqc = 2-hydroxyquinoline-4-carboxylic acid, bpy = 4,4′-bipyridine and bpe = 1,2-bi(4-pyridyl)ethylene, have been prepared under hydrothermal condition. Complex 1 displays a 1D rigid linear chain structure while complex 2 displays 1D flexible zig-zag chain structure. Coordination number of the central Zn ion in complex 1 is six and in complex 2 is four. The structural differences of these complexes suggest the effect of size of the bridging ligands on the construction of metal organic frameworks with the same metal ion under solvothermal conditions.