Preparation Of Metal-Organic Framework (MOF) And Azodicarbonamide Loaded MOF Composite

Metal-Organic Framework (MOF) material is a class of new porous material and widely used especially in the catalysis, adsorption, separation, gas storage and other fields. In this thesis, we reported the first synthesis of a new type single-phase metal-organic framework coordination compound 1 by slow diffusing method using terephthalic acid as ligand, zinc nitrate hexahydrate providing metal ion and ammonia for deprotonation. The crystal structure of coordination compound 1 has been determined by single crystal X-ray diffraction. Chemical composition of the crystal is Zn(NH3)2(BDC)]n which belongs to monoclinic, space group P2(1)/m, a=5.253(2) A, b=16.240(6) A, c=6.002(2) A,β=111.168(5)°. The spatial structure of compound 1 containes irregular tetrahedral coordination environment for Zn(II) consisting of two nitrogen donors from two NH3 and of two coordinated oxygen counter donors from BDC ligands. Thermal analysis results showed that compound 1 had two distinct weight loss steps, corresponding to 2 molecules NH3 off and the decomposition of BDC ligands, respectively.We synthesized crystal material using the same reactant in hydrothermal condition at 100℃. The crystal was not single-phase. One phase is the compound 2:[Zn(NH3)2(BDC)]n which belongs to monoclinic, space group P2(1)/m, a=5.2624(2) A,b=16.2214(8) A, c=5.9829(3) A,β=111.322(2)°. We have proved that the content of the compound 2 is neglectiable in the mixture. Crystals (MOF) prepared by hydrothermal method was used as the host matrix to form the nanocomposites with guest molecules such as azodicarbonamide (AC), urea, and hydrazine hydrate. The composites were characterized by means of XRD, solid state NMR, FT-IR, UV-vis and TG-DTA. X-ray diffraction data showed the gradual inversions of the relative intensities of the first two reflexes at 2θ=6.1°and 8.2°as compared with the MOF. These observations were the strong hints for inclusion of guest molecules inside the cavities of MOF. The solid state 13C CP/MAS NMR chemical shift of the carbonyl of AC@MOF was shifted from 159.7 ppm in pure AC to 163.3 ppm. In IR spectra, the characteristic carbonyl absorption band of AC was red-shifted from 1728 to 1688 cm-1.