Synthesis, Structures And Properties Of Transition Metal Multinucleal Complexes With Pyridine-2,3,5,6-tetracarboxylic Acid

Compared with pyridinedicarboxylic acid, Pyridine-2,3,5,6-tetracarboxylic acid with more coordination sites and some novel structures and coordination modes is desired to be obtained, but was much less used so far. By using H4PTA as bridging ligands, novel 1D chains, 2D and 3D structural complexes have been successfully synthesized. Furthermore, nano-channels and coordination modes are also explained in detail.Five complexes {[Cu₂(PTA)(bpy)(H₂O)₂]·3H₂O}_n (1), {[Cu₂(PTA)(bpy) (H₂O)₂]·2H₂O}_n (2), {[Mn(PTA)(H₂O)]·(bpy)·3H₂O}_n (3), {[Mn(HPTA)(H₂O)₂]·(bpy) 3H₂O·Cl}_n (4) and {[Co₃(HPTA)₂(bpy)₂(H₂O)₄]·4H₂O}_n (5), have been synthesized and characterized by IR spectrum, thermogravimetric (TG) analysis, ultraviolet visible absorption spectrum and single-crystal X-ray diffraction.Complex (1) is a binuclear structure which is assembled into 3D supramolecular network by hydrogen-bond. Complex (2) is particularly interesting in that it contains nano-channels. Complex (3),(4) show the one-dimensional ladder-type chains structure. The chains are connected by hydrogen-bond to form 2D layers, the 2D layers then form 3D supramolecular framework with hydrogen-bond. There exists a (H₂O)₆ water cluster in Complex (3). Complex (5) is a binuclear unit, and then the binuclear molecules are alternatively assembled into 3D supramolecular network. The structures of them are analyzed compared with the other complexes of H₄PTA. The hydrogen bonding of them and the different coordination modes of the carboxylate groups are analyzed in detail.