| As a new type of porous materials, metal-organic frameworks (MOFs) materials have been developed rapidly in the past decade. MOF is a kind of inorganic-organic hybrid materials, which is composed of inorganic metal ions and organic ligands through coordination bonds. Owing to their controllable compositions, predominance of large surface areas, adjustable pore sizes and shapes and other excellent characteristics, MOFs have been applied in many aspects in the field of materials, such as energy storage, selective adsorption and separation of gases/vapors, molecular sensing, optics, bionics, catalysis and so on. Structure research has become a means of characterization in MOFs study, the research focus of this kind of material has transfered from the construction of novel structures to design and synthesis MOFs materials with multifunctions. However there are still a lot of issues need to be discussed, just like how to synthesis porous MOFs with high stability, how to realize the controllable synthesis of functional groups, how to improve the interactions between hosts and guests in order to increase the loading capacity and so on.In this paper, using the strategy of employing mixed ligands, we have designed and synthesized six multi-functional MOFs with large surface areas by choosing the appropriate bidentate or tridentate ligands with different transition metal ions. Through reasonable structure analysis, we have investigated their properties in small molecule capture, fluorescence probe, hydrogen adsorption, organosulfur compounds removal, volatile organic solvent adsorption and so on. The aims of this work can be concluded as follows:First, by employing strategy of mixed ligands, synthesizing non-interpenetrating structures which possess the relatively high surface areas and high stabilities. Second, studying the effect of substituent groups on the properties of MOFs, including hydrogen storage capacity, volatile organic vapor adsorption capacity, organosulfur compounds removal ability and so on. Thirdly, through synthesizing a series of isoreticular MOFs with different substituents, we aim to analysize the interactions between MOFs and guest molecules, expect to obtain MOFs materials with specific functions.A novel non-interpenetrating microporous metal-organic framework (IFMC-15) was successfully constructed based on octahedral cage-like building units by using mixed ligands. There is a 1D quadrilateral channel in this structure. With the merit of microporous, IFMC-15 was carried on I2 adsorption experiment and exhibited a rapidly reversible process. The electrical conductivity value of I2@IFMC-15 is nearly 80 times than IFMC-15, shows a nature of the semiconductor. By loading different rare earth ions with different proportions into IFMC-15, we successfully achieved the tunable fluorescence in MOFs. [NH2(CH3)2]·[Zn40(BPTC)2(BDC)0.5]·8DMF (IFMC-15) H3BPTC=biphenyl-3,4,5-tricarboxylate H2BDC=terephthalic acidAnother novel microporous metal-organic framework, IFMC-16, has been successfully constructed by using suitable combination of two carboxylate ligands with almost equal coordination length. There are three types of open channels along the crystallographic c axis in the structure. IFMC-16 has multipoint interaction sites to the guest molecules. IFMC-16 exhibits H2 uptake capacity as high as 2.80 wt% at 77 K and 1 bar, and furthermore, IFMC-16 has the saturated excess H2 storage capacity of 5.3 wt% at lower pressure in high pressure region of 10 bar. That means IFMC-16 exhibits high hydrogen storage capacity not only at ambient pressure, but also at lower pressure in high pressure region. With the permanent porosity, IFMC-16 has been used for adsorptive desulfurization. The results indicate that IFMC-16 shows excellent adsorption properties for both BT and DBT, good stability, repeatability, and regenerability. [CuU4(BPTC)2(PBA)2(H2O)2]·12DMA·8CH3OH·6H2O (IFMC-16) H3BPTC= biphenyl-3,4,5-tricarboxylate HPBA= 4-(pyridin-4-yl) benzoic acidA series of isoreticular MOFs (NENU-511, NENU-512, NENU-513 and NENU-514) which all have high surface areas and strong adsorption capacities have been successfully constructed by using mixed ligands. NENU-513 has a highest benzene capacity of 1687 mg·g-1 at 298 K which ranks the top one among the MOFs materials reported up to now. This NENU series have been used for adsorptive desulfurization because of their permanent porosity. The results indicate that this NENU series have a higher adsorptive efficiency in the removal of organosulfur compounds than other MOF materials, especially for NENU-511, it has the highest adsorptive efficiency in the ambient atmosphere. This work proves that design and synthesis of targeted MOFs with higher surface areas and functional groups is an efficient method for enhancing benzene storage capacity and adsorption of organosulfur compounds. Zn4O(TDC)(BTB)4/3 (NENU-511)H2TDC= thieno[2,3-b]thiophene-2,5-dicarboxylic acidH3BTB= 5'-(4-carboxyphenyl)-[1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid... |
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