Syntheses, Structures And Properties Of Novel Dinuclear Schiff Base Complexes Containing N,N'-Bis(2-pyridinylmethylene)-2,3,5,6-tetrafluoro-1,4-benzenedimethanamine

The coordination compounds, self–assemble by transition metal ions and Schiff base ligands, are attracting much attention as their interesting topological structures and properties. The desing and synthesis of novel coordination compounds is of important current interest in supramolecular chemistry and crystal engineering. The potentially applications of these compounds will be intensive in the fields of non–linear, luminescence, magnetism, chemical catalysis, gas separation and storage. In this dissertation, flexible bipyridyl Schiff base ligands based on a tetrafluorinated phenyl ring backbone was selected as the first ligand to synthesize some novel coordination polymers through hydrothermal or solution reactions with oxalamide, tetrafluoroterephthalate as the second ligands. Main conclusions made in this paper are listed as follows:1. Flexible bipyridyl Schiff base (L1), namely N,N'–bis(2–pyridinylmethylene)–2,3,5,6–tetrafluoro–1,4–benzenedime– thanamine (L1), was prepared by reacting 2,3,5,6–tetrafluoro–1,4–benzenedimethanamine with 2–pyridine– carboxaldehyde. The same synthetic procedure as that for L1 was used except the 2–pyridinecarboxaldehyde was replaced by 3–pyridinecarboxaldehyde and 4–pyridinecarboxaldehyde, affording its analogues L2 and L3; By the same methods, the 2,3,5,6–tetrafluoro–1,4–benzenedimethanamine was substituted by 1,4–benzenedimethanamine, giving compounds L4–L6. The structures of L1–L6 were characterized by IR, UV, and 1H–NMR. Compounds L1, L4 and L5 were furthermore studied by X–ray diffraction analysis, and their packing modes and intermoleucular hydrogen bonding interactions were also investigated.2. Two coordiantion polymers with the formula {[(Zn₂)(L₁)(C₂O₄)2]·(H₂O)₄}_n (1) and [Cd(L₁)_0.5(Cl)(C₂O₄)_0.5]_n (2) were synthesized by treating znic(II) chloride and cadmium(II) chloride with L1 and oxalamide under hydrothermal conditions. The same synthetic procedure as that for complexe 1 was used except the L1 was replaced by L4, affording Complex 3, {[Zn₂(L₄)(C₂O₄)2]·(H₂O)}_n. Complex 4, {[Mn(L₁)_0.5(BDC–F₄)(H₂O)₂]·(H₂O)}_n (BDC–F4 = tetrafluoroterephthalate), was obtained by reaction of magnesium chloride with L1 and tetrafluoroterephthalate in a CH₂Cl₂/CH₃OH media at room temperature. Complexes 1–4 were characterized by IR, thermal, and X–ray structure analysis. Notably, complexes 1 and 2 crystallize in the chiral space group P212121 and P3121, respectively. Complexes 1–3 are one–dimensional polymeric coordination chains, while complex 4, {[Mn(L₁)_0.5(BDC–F₄)(H₂O)₂]·(H₂O)}_n, shows a two–dimensional layer structure. Notably, complexes 1, 2 and 4 have unusual helix structures.3. For utilization of colon bacillus, staphylococcus aureus, and bacillus subtilis, the bactericidal activites compounds L1–L6 were tested. It was found that compounds all possesess good bactericidal activity.