Syntheses And Properties Of Coordination Polymers Based On Bifunctional Ligand Of 4-(1,2,4-triazol-4-yl)- Phenylphosphonic Acid

Porous Coordination polymers （PCPs） as novel microporous materials with high surface area, diverse structure and tailorable functionalization, show potential application in adsorption and separation, magnetism, luminescence, catalysis, medicine and so on.The microporous metal-phosphonate framworks hold very high thermal and chemical stabilities, but they are hardly prepared for preferring to form dense phase in the self-assembly of phosphonate and metal salts. Recently some reports showed that a strategy of attaching other coordination group such as hydroxyl, amine, and carboxylate group to the phosphonate ligands would result in some novel porous metal phosphonate frameworks with excellent property. In the thesis a phosphonate ligand attached a 1,2,4-triazol-4-yl group, namely 4-（1,2, 4-triazol-4-yl）-phenylphosphonic acid （H₂ptz） was synthesized. The self-assembly of a ligand of H₂ptz and some metal salts （Cu（II） and Fe（II）） produced 9 new metal-phosphonate coordination polymers in the hydrothermal condition. The structures and properties of these compounds obtained were characterizedIn chapter 1 the basic concept, history and current status of coordination polymers, especially metal-phosphonate frameworks were reviewed. In addition, some problems and research focuses in metal-phosphonate frameworks were outlined. Finally our research aims and projects were given in the charpter.In chapter 3, five metal-phosphonate coordination polymers were prepared by the hydrothermal reaction of H₂ptz and some salts such as Fe²⁺ and Cu²⁺ under different synthesis condition. Cuptz-1 holds a cation layer structure alike to clay. Cuptz-2 and Cuptz-3 exbihit porous hydrogen-bond networks made up of 1-D chain building blocks, and can accommodate a certain amount of waters guests. Compared to copper phosphonate analougues, two ferric phosphanate frameworks are very interesting, Feptz-1 contains a single-molecule-layered ferric phosphate framework built of six-member ring of 7.5 A, and Feptz-2 is a microporous 3D frameworks that directed by the anion of sulphate, and 9.5 A of pore size. Besides that these polymers was indissoluble in some solvents, TGA showed they were stable up to 290℃.In chapter 4, a novel cuprous coordination polymer built of [Cu₄^ⅠCl] cluster has been hydrothermally synthesized, in which the CuⅠ is in-situ generated by the reduction reaction from CuⅡ precursors. Interestingly, this compound exbihits a strong and bright green emission band （λem,max 510 nm） at N₂ atomsphere, while it doesn’t exbihit emission at O₂ atomsphere due to O2 fluorescence quenching. This compound can be used as a kind of potential O₂ sensor material for the fluorescence process is reversible with the atmosphere change from N₂ to O₂. To explore the oxidation state, XPS study was then carried out. The theoretical calculation demonstrated the fluorescence quenching chould result from charge transfer of Cu（I） to O₂.In chapter 5, three microporous metal-phosphonate coordination polymers which contain trinuclear SBUs were hydrothermally synthesized. Cuptz-5 holds a elliptic pore size of 6 x 14 A, while Feptz-3 and Feptz-4 are a pair of isomorphism duo to variant valene metal iron, and show the same pore size of 16 A. N₂ sorption test showed the BET surface area of Feptz-3 and Feptz-4 are 856 m²/g and 689 m²/g, respectively. The CO₂ adsorbed quantity of Feptz-3 and Feptz-4 are compared with HKSTU-1, up to 181 and 145 mg/g, respectively. The catalytic test showed Feptz-4 has highly reactivity and good size-selectivity in the ring opening of styrene oxide with alcohols. When CH3OH was used as a nucleophile, the yield of product is up to 96%.In chapter 6, we summarized some interesting results in this thesis.