Synthesis, Structure And Properties Of Novel Metal-Organic Frameworks Under Solvothermal Conditions

Metal-organic frameworks (MOFs), a new development of polypore's materials, have attracted much attention for their flexible design and various topologies for promising application in ion-exchange, adsorption, molecular recognization, catalysts along with optics, electrics, magnetism and enantioselective separation. MOFs with rigid open frameworks, zeolite-like materials, possess not only porous phases similar to inorganic zeolites, but also better performance in gas sorption and store than traditional zeolites. At the same time, MOFs are also able to be endowed with multifunctional properties by selecting functional metal ions and organic ligands with functional groups.According to the principle of molecular engineering, we have focused our study on the synthesis, topological structures and multifunctional properties of MOFs in this dissertation. We have developed new types of secondary building units, at the same time, study the structure control roles of different type's organic ligands and coordination modes of the metal centers, these will progressively achieve the synthesis of semi-directional and directional for coordination polymers with good functional properties. We have prepared 11 new MOFs by using different organic ligands and metals, meanwhile,analyzed their structures as well as explored their multifunctional properties. These results will be introduced from the following four issues:(1) Rod-shaped secondary building unit is an important type of SBUs for constructing porous rare earth metal-organic frameworks. 1-D channels will be obtained when linking this SBU by organic ligands. Porous rare earth MOFs may be used as functional materials in sorption, separate and catalytic. To address this issue, we selected 1,3-benzenedicarboxylic acid (1,3-BDC) and rare earth metals to synthesis a family novel compounds with rod-shaped SBU: [Eu2(BDC)3(DMF)2]?(DMF)1.7[1], [Pr2(BDC)3(DMF)2]·(DMF)2[2] and [Nd2(BDC)3(DMF)2]·(DMF)2[3]. They have the same topological structures and 1-D hexagonal channels. For thermal study, compound 1 had high nitrogen adsorption after removed gust and coordinated DMF molecules. Compound 1 had fluorescence characteristics for containing Eu3+.(2) The introduction of substituent groups such as amine, amide, methyl and nitro group on organic linker may bring the changes of space, solubility, and coordination modes, these will make it difficult to form structural quasi-invariant MOFs. However, these changes are significant thing when they can achieve the conversion from different types of SBUs. In similar experiment conditions of synthesizing rare earth MOFs, it is still rare that the affect of substituent groups for conversion from different types of SBUs. Here we report three novel lanthanide metal-organic frameworks; both of them show the fascinating conversion from infinite rod-shaped building units in 1-3 to octahedral SBUs for affect of–NO2 substituent group in the similar experiment condition. We prepared three isomorphous 3-D frameworks [Eu2(NIPH)3(DMF)4]?(DMF)2 [4], [Pr2(NIPH)3(DMF)4]?(DMF)2 [5] and [Sm2(NIPH)3(DMF)4]?(DMF)2 [6] which have the same topological structures and octahedral SBUs. Compound 4 had fluorescence characteristics for containing Eu3+.(3) Helical and porous structures are the hot area of reach for synthesis MOFs. It is hard to construct helical or porous rare earth MOFs for high coordinated numbers and flexible coordinated models of rare earth metal ions. We prepared [Y2(H2O)(BDC)3(DMF)]·(DMF)3 [7] with 2-D multi-helix structure using Y3+ and 1,3- benzenedicarboxylic acid (1,3-BDC), meanwhile, [Eu2(NDC)3(DMF)4]·(DMF)3 [8] 3-D porous material with octahedral SBUs using Eu3+ and 2,6-naphthalic acid (2,6-NDC). Compound 7 has two types of helical tubes with opposite chirality and nanoscale windows. Compound 8 had high nitrogen adsorption and fluorescence characteristics of Eu3+. At the same time, activated compound 8 had fluorescence sensing to Cu2+ for containing Eu3+.(4) In order to study the rival roles of ligands to crystal, we prepared a 0-D compound [Zn9(hbtz)12(NO3)6(H2O)6]·8DMF [9] using Zn2+ and 1H-Benzotriazole. Taking the compound 9 as a mother crystal, we prepared [Zn(BDC)(DNA)]·(DMA) [10] and [Zn2(BDC)2(bipy)2]·(H2O)(DMF) [11] by adding new ligands under solvothermal conditions. Compound 10 is similar to MOF-2 but have different coordinated solvent molecules. Compound 11 has a novel structure with interlaced 2-D layer containing binuclear groups. The particular binuclear group limits the location of ligands and noπ-πconjugation in compound 11.