Study On Synthesis, Structures, And Properties Of Metal-Organic Frameworks Based On Extended Ligands

Metal-Organic Frameworks （MOFs） represent a new class of hybrid organic-inorganicsurpramolecular materials comprised of ordered networks. These compounds are composed ofrigid multidentate bridging struts and the metal nodes. High micropore volume, large poresizes, and a high metal content offering potentially valuable active sites are the key features ofthis new and emerging class of porous materials. Currently, the study on MOFs as catalysts isone of the hot topics. The use of MOFs as heterogeneous catalysts is particularly interesting,since the pore size and functionality of the framework can be adjusted over a wide range for avariety of catalytic reactions, namely MOFs can be designed as shape-, size-, chemo-, orenantio-selective catalysts.As is known to all, the development of rational approaches to the design of MOFs based onelongated carboxylic acids is a subject continually attracting interest in inorganic chemistry.To use these elongated ligands has produced many interesting porous MOFs which possesslarge-sized channels and surface area and shows excellent properties.In this thesis, we have synthesized several extended multicarboxylic acid and mutisulfonate,including9-ethyl-carbazole-3,6-dicarboxylic acid（H₂L）,4,4’-bis（2-sulfonatostyryl）biphenyl（Na2L’）,4,4′-（9,10-anthracenediyl）dibenzoic acid （H₂L’’） and tris（4′-carboxybiphenyl）amine（H3L’’’）. We have used these ligands to react with transition metal ions or lanthanide ions togenerate fourteen new compounds either in a direct way or by adding assistant ligand. Bytuning crystal growth conditions of reaction temperature, solvent etc. All of them werecharacterized by IR spectroscopy, elemental analysis, thermogravimetric analysis andsingle-crystal X-ray diffraction.In chapter2, we have used9-ethyl-carbazole-3,6-dicarboxylic acid （H₂L） to react withtransition metal ions Mn（Ⅱ） and Cd（Ⅱ） to generate three new1D structures, namely{[Mn（L）（bpy）]·2H₂O}∞（1）,{[Mn（L）（phen）]·2H₂O}∞（2）,{[Cd（L）（bpy）]·2H₂O}∞（3）.Subsequently, luminescent and magnetic susceptibility properties of compound1wereinvestigated in detail.In chapter3, this is the first time to use the Na2L’ to synthesize LMOFs. Six newlanthanide metal organic frameworks, namely,[La2（L’）3（phen）3（5H₂O）]·3H₂O （4） and [Ln（L’）（bpdc）0.5（phen）]∞（Ln=Sm（5）, Eu （6）, Gd （7）, Tb （8）, Dy （9）; L’=4,4’-bis（2-sulfonatostyryl）biphenyl; bpdc=4,4’-biphenyldicarboxylate; phen=1,10-phenanthroline）, have been synthesized hydrothermally from the self-assembly of thelanthanide ions （Ln3+） with the fluorescent whitener disodium 4,4’-bis（2-sulfonatostyryl）biphenyl （Na2L’）, the4,4’-biphenyldicarboxylic acid （H₂bpdc） and1,10-phenanthroline. As for4, after coordinated H₂O molecules are removed, compound4showsexcellent properties for heterogeneous selective oxidation of alkylbenzenes with high yieldsand100%selectivity and the catalyst can be recycled and reused. When excited at325nmwavelength, complex6exhibits intriguing fluorescent properties, including strong intensity,bathochromic-shift and the variable and versatile emission bands.In chapter4, three novel three-dimensional （3D） porous metal organic framework,{[Cd（L’’）（H₂O）]·3H₂O}∞（10）、{[Zn4O（L’’）3]·3H₂O}∞（11） and [Cd3（L’’）2（i-pyc）（pyc）]∞（12）（H₂L’’=4,4′-（9,10-anthracenediyl）dibenzoic acid）, was synthesized.10has a3D frameworkformed by L’’ connectors and the infinite {Cd（O₂CR）2}∞secondary building units （SBUs）. Wethen investigated its adsorption, catalysis and luminescent properties. Framework10′exhibitspermanent porosity （Langmuir surface area,324m2/g）, high thermal stability （up to380°C）,highly active properties for oxidation of alkylbenzenes. The catalytic results reveal that10′isindeed an efficient heterogeneous catalyst with100%selectivity. To the best of ourknowledge, it is the first report that oxidation reactions of alkylbenzenes were performedusing Cd （II） with unsaturated coordination sphere as active sites. To the best of ourknowledge, it is the first report that oxidation reactions of alkylbenzenes were performedusing a MOF that contains Cd （II） with unsaturated coordination sphere as a catalyst. Thiswork provides an effective pathway for the future synthesis of heterogeneous catalysts withmany potential catalysis.In chapter5, a tritopic carboxylate ligand, tris（4′-carboxybiphenyl）amine （H3L’’’）, has beensynthesized and applied in the construction of microporous metal-organic frameworks（MOFs）. Two novel metal-organic frameworks （MOFs）,{[Zn2（L’’’）（OH）]·2DMF·H₂O}∞（13）and {[Cu（HL’’’）（DMA）]·DMA·2H₂O}∞（14）, have been constructed out of H3L’’’, Zn2+, andCu2+, respectively.13has a2-fold interpenetrating three-dimensional framework formed byL’’’ connectors and the [Zn2（CO₂）3] secondary building units （SBUs）. As for13, it is worthpointing out that one μ2-OH group links two Zn atoms between two neighboring SBUs toproduce interesting Zn-O-Zn zigzag chains in the structure.14has a two-dimensional gridsheet formed by HL’’’ connectors and the typical paddle-wheel [Cu2（CO₂）4] SBUs.2D sheetsnest each other, which finally forms a3D nested framework. Framework13’ exhibits highpermanent porosity （Langmuir surface area,848m2/g）, high thermal stability （up to450°C）,highly active properties for Friedel-Crafts alkylation reaction, as well as the potentialapplication for the CO₂gas storage （42.0cm3/g） and luminescent material. The catalyticresults reveal that14’ is indeed an efficient heterogeneous catalyst for olefin epoxidation reactions. To the best of our knowledge, it is the first report that olefin epoxidation reactionswere performed using t-BuOOH as an oxidant as well as MOF containing Cu2+as a catalyst.