| Over the past decades, the self-assembly of metal-organic framework (MOFs) isof great interest,not only because of their intrinsic aesthetic appeal but also for their potential applications as functional materials in gas storage and separation, luminescence, chemical sensor, magnetism, optics, etc. Generally,the physicochemical properties of the extended coordination framework solids are closely related to their structural features, which means the thorough analysis on the structures is crucial for their potential applications. Not to mention that the structural analysis can help us to understand the formation mechanism of MOFs and provide us the theoretical basis to design and construct new crystalline materials. On the other hand, along with the appearance of various environmental and energy issues, whether MOFs can contribute to solving these problems have proven to be a hot topic. As a result, recently, many reports had demonstrated that MOFs can act as luminescent probes to detect the harmful substances and photocatalysts to degrade the organic pollutants as well as solid electrolyte to conduct protons. Although relevant works had confirmed the feasibility of applications in these fields for MOFs, it still remain great challenge to synthesize such crystalline materials.In this dissertation, we mainly focus on the structural features and several functional applications of MOFs. (i) we synthesized two azole derivatives to connect metal ions to build MOFs and discussed the factors that affect the structural assembly through the careful modulation and comparison of experimental conditions, (ii) The as-synthesized MOFs were thoroughly analyzed to distinguish the fascinating entanglements embedded in the structures including interpenetration, self-penetration, polyrotaxane, polycatenane, polythreading, interdigitation and helices, (iii) The as-synthesized MOFs were tested to be used in separation based on ion-exchange, luminescence sensing of metal ions and nitro explosives, photocatalytic degradation of organic dyes and proton conduction, and the corresponding mechanisms were investigated briefly.1) A novel MOF (1) was prepared via a hydrothermal process which shows the first example of 6-fold polyrotaxane-like interpenetration combined with interdigitation, and exhibits reversible and irreversible guest-dependent structural conversion; Because of the ID channels running along the b axis,1 can serve as a host to encapsulate and sensitize Eu3+ cation in water. Moreover, the framework also shows a proton conductivity of over 10-5 S cm-1 at 298 K and 98% relative humidity due to the methylene hydrogens of the imidazolium moiety are highly acidic and aligned inside the channels which will enhance the proton conductivity. [Cd2L3(DMF)(NO3)]·2DMF·3H2O (1) H2L+Cl-= 1,3-bis(4-carboxyphenyl)imidazolium chloride2) A unique cationic MOF was synthesized by taking the strategy of connectingneutral rod-shaped SBU with cationic imidazolium-based dicarboxylate ligand. The topology of the three-dimensional network features a snub square-like lattice (32.4.3.4) where the triangular and square metal-organic nanotubes alternately arranged in be plane. This framework demonstrated charge- and size-dependent selectivity for the bulky anion dyes adsorption due to the anion-exchange process. [In(OH)L]5(NO3)5·33H2O·14DMF (2) H2L+Cl-= 1,3-bis(4-carboxyphenyl)imidazolium chloride3) A new MAF based on Cu(I) has been synthesized, which contains an tetranuclear copper clusters constructed by six 1,2,4-triazole units where two of them show unusual bridging "crevice" coordination mode with their 1- and 2-positioned sp2 N-atoms as symmetrically bridging centers.The band gap of 1 demonstrates that it can be used as photocatalyst and the photocatalytic activity was tested by degradation of organic dye solutions under ultraviolet and visible light irradiation, respectively. The results showed that the decoloration rate under ultraviolet light is higher than that under the visible light because of the relatively high band gap of compound 1. [Cu5L3(CN)2]·6H2O(3) NH2-L= 4-amino-3,5-bis(4-imidazol-1-ylphenyl)-1,2,4-triazole4) Eight new MOFs (4-11) with novelarchitectures had been synthesized and characterizedusing the mixed-ligandstrategywith N-donor triazole-containing ligand and O-donor aromatic dicarboxylic ligandsas the auxiliary ligands. Structural characters of interpenetration, self-penetration, interdigitation, polythreading, single- and multi-stranded helical chains can be discovered in these structures, and a pair of supramolecular isomers is also discovered. The structural differences between 4-11 demonstratejudicious choice and design of organic ligands as well as the precise modulation of solvents andmetal ions plays an important role in the generation of MOFs. The luminescence properties of compounds 4-11 were also measured and discussed. [Zn3L2(oba)3(H2O)2]·4H2O (4), [Zn(L)(bdc·2H2O (5), [Zn(L)(2-NH2-bdc)]·2H2O (6), [Zn(L)(bdc)]·1.75DMF·0.5H2O(7), [Zn(L)(oba)]·H2O (8), [Co(L)(oba)]·H2O (9), [Cd2(L)2(bdc)(NO3)2]·2DMF (10), [Cd(L)(ndc)(H2O)] (11) L= 4-amino-3,5-bis(4-imidazol-1-ylphenyl)-1,2,4-triazole, H2bdc =1,4-benzenedicarboxylicacid,2-NH2-H2bdc= 2-amino-1,4-benzenedicarboxylicacid, H2oba = 4,4'-oxydibenzoic acid, H2ndc= 1,4-naphthalenedicarboxylic acid5) Two unprecedented homochiral enantiomers 12R and 12L had been synthesizedthrough spontaneous resolution.The resulting framework constructed by four kinds of homo-handed helical chains represents the first 3D self-penetrating framework formed by decoration of single (10,3)-a net with helical chains.Interestingly,12 exhibits fluorescent emission in both the solid and solution phase. The water stability of the framework and uncoordinated nitrogen atom and amino group from the triazole core on the crystal surface make it suitable to detect picric acid in water. The possible quenching mechanisms for PA are also investigated. [Cd(ndc)L]2·H2O (12R and 12L) L= 4-amino-3,5-bis(4-imidazol-1-ylphenyl)-1,2,4-triazole ndc= 2,6-Naphthalenedicarboxylic acid... |
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