The Sytheses,Properties And Characterizations Of Anthracene-based Metal-Organic Frameworks

With the development of society and the progress of science and technology, the utilization of new functional materials has become a hotspot in the field of energy and material science. Metal-organic framework （MOF） is a new class of inorganic-organic hybrid crystalline material with large surface area, diverse structure and abundant compositions. During past few decades, MOFs have exhibited good performance in the field of gas storage, separation, luminescence and sensor and so on. Recent years, the research direction of MOFs mainly centered on the design and synthesis of unique functionalized MOFs and exploring their new applications.In this paper, we focus on the synthesis of novel photoactive organic ligand and constructing visible-light responsive MOFs with different structural characteristics by solvothermal method. Simultaneously, we detailedly studied the obtained compound in the aspects of light absorption, the characteristic of photoinduced charge generation, the performance in the several photocatalytic system and their possible reaction mechanisms. The main results are as follows:1. We successfully synthesized a two-fold interpenetrated UIO-type zirconium MOFs （denoted as compound 1, [Zr6O4（OH）₄（L）6]·6DMF） by using anthracene based ligands and Zr6 oxo clusters. The Zr-MOF showed desirable characteristics including excellent chemical and thermal stability, high surface area, broad-band visible light absorption and efficient photoinduced charge generation. Remarkably it shows a high efficiency for the visible-light-driven CO2 reduction to produce formate with a formation rate of 183.3 μmol/h·mmolMOF. Both photocatalytic experiments and in situ EPR studies demonstrate clearly that dual catalytic routes exist in the Zr-MOF where both the anthracene-based organic ligand and the inorganic building unit of the Zr6 oxo cluster through the LMCT process contribute to CO2 photoreduction. The existence of dual catalytic routes makes compound 1 show a high performance among the reported Zr-MOFs. This study illustrated a new strategy to design and synthesize novel visible-light-responsive MOFs photocatalysts with high efficiency.2. Considering that compound 1 exhibits enhanced visible light absorption and characteristic of photoinduced charge generation, the promising visible-light-induced photocatalytic reaction of atom transfer radical polymerization （ATRP） initiated by compound 1 is explored. The photoactive Zr-MOF mediated ATRP reaction relies on the in situ generation of Cu（Ⅰ） complex activator from the Cu（Ⅱ） complex deactivator by photoexcited compound 1 through electron transfer process. The visible-light-induced photopolymerization is carried out at room temperature under 520 nm light irradiation. The photopolymerization of methacrylates shows typical characteristics of controlled radical polymerization, where the as-prepared polymers possess narrow molecular weight distributions and high retention of chain-end groups. Besides this Zr-MOF mediated photopolymerization can be easily temporally and spatially controlled by light. This work open a new insight to the field of controlled radical polymerization based on MOF materials.3. A new three-dimensional microporous bimetal MOF （denoted as compound 2, [ZnNa2（L）₂（DEF）₂]·DEF） has been constructed using highly conjugated anthracene-based ligand, Zn²⁺ and Na+ ions. The rarely occurring long-range π-stacking of the ligand in the form of a zigzag chain has been found in the MOF structure, which provides not only a new charge transport pathway but also an electroluminescence property. On the other hand, compound 2 shows a wide-range optical absorption in the visible light region with absorbance edge at ca.600 nm. The SPV and EPR studies demonstrated that its photocatalytic performance arises from photo-induced ligand-based free radical. Compound 2 shows efficient photocatalytic performance for dye degradation under visible light irradiation. This work demonstrates the significance of using photoactive ligand to synthesize multifunctional MOF.4. Conformational supramolecular compounds 3-8 have been prepared through solvothermal method based on a newly designed flexible tetracarboxylate ligand of H4Lb and metal ions (In³⁺ and Cd_<sup>2+).（Me₂NH₂）[In（Lb）]·DMF （3）（Me₂NH₂）₂[In₂（Lb）₂]·（DMF）₃·（H₂O）₂ （4）（Me₂NH₂）₄[Cd₂（Lb）₂]·（DMF）₂ （5）（Et₂NH₂）₂[Cd（Lb）]·H₂O （6）（Et₂NH₂）₃[Cd₂（Lb）₂]·（DEF）₂·（H₂O）₄ （7）（Et₂NH₂）₃[Cd₂（Lb）₂]·（EtNH₂）₂·（H₂O）₂ （8）These compounds possess very similar two-dimensional framework structures with the same （4,4）-net topology. These compounds comprise two groups of conformational supramolecular isomers, owing to identical compositions of the frameworks but different conformations of ligands. It is worth noting that as much as fourteen stereoisomers of ligands have been found in these compounds, which demonstrated that the introduction of multiple single bonds has greatly expanded the flexibility of the ligand. The photoluminescent properties of these compounds have also been investigated where the emission of these supramolecular isomers are from blue （402nm） to green （508nm）.