Syntheses, Structures And Electro-optical Properties Of Coordination Polymers Based On Flexible Multi-carboxylate Ligand

The new type of porous solid material, metal-organic frameworks（MOFs） with diversified structures and unique structure–property relationship, have attracted many researchers’ attention. The ligands, an element of MOFs, are contained of flexible ligands and rigid ligands. Particularly, the flexible aromatic carboxylate ligands coordinating with metal ions could generate frameworks with excellent properties and diverse structures due to their various coordination models result from their flexible groups（C, O, N, et al）. The potential applications of metal-organic frameworks in gas separation and storage, magnetic, luminescent and electrical materials have been explored gradually. As a critical compoment of fuel cell, the proton conducting material plays a crucial role on the performance of fuel cell. The structural predictability of MOFs has obtained speed development in the field of proton conducting material. Simultaneously, the unique luminescent property of lanthanide-based MOFs shows an attractive practical prospect in fluorescence sensing combined with the advantages of the metal-organic framework materials with porous structures.In this thesis, our work mainly includes the following two parts:1. A flexible aromatic carboxylic acid ligand H4L₁ [H3L₁=5-（4-Carboxy-2-formyl-phenoxymethyl）-isophthalic acid] was synthesized. Then we got two different compounds {[Eu（L₁）（H₂O）4]·H₂O}_n（1）;{[Eu（L₁）（DMF）2]·（DMF）（H₂O）}_n（2） with the ligand H4L₁ and cadmium nitrate by solvothermal method. And the representation was implemented by x-ray single crystal diffraction, infrared spectrum, elemental analysis, powder x-ray diffraction and thermoanalysis. The MOFs were used for detecting the nitro aromatic explosives and metal ions on account of their red emission performance and their peculiar structures.The flsorescence of MOFs were quenched by Fe3+, nitrobenzene（NB）,2-nitrophenol（2-NP） and 2,4,6-trinitrophenol（TNP） respectively. And the mechanism of machine of fluorescence quenching was explored.2. Designed and synthesized a ligand（5-[（Bis-carboxymethyl-amino）-methyl]-isophthalic acid）（H4L₂）, and obtained three MOFs {[M2（L₂）·（L’）·（H₂O）2]}_n（M = Co, L’ = bpe（3）; M = Co, L’ = bpn（4）; M = Fe, L’ = bpe（5）） with the aid of assistant ligand bpe（1,2-bis（4- pyridyl） ethylene） or bpd（1,2-bis（4- pyridyl） azo）.All the three MOFs are prepared under the same conditions（reaction time, solvents,temperature,etc.） with solvothermal proccess and their structures have been charactered through X-ray cristal diffraction, infrared radiation, X-ray powder diffraction and thermal analysis. In addition, crystals packing with tetrahydrofuran,thiophene, pyrrole from the above three MOFs have been prepared through soaking method and tested for alternating-current impedance repectively.