【作者】 王崇臣；

【导师】 郭广生；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2012， 博士

【摘要】 金属-有机骨架化合物（MOFs）凭借其具有的新颖的拓扑结构及独特的性质，在气体存储、气体选择性吸附及分离、催化、磁学、荧光等领域具有广阔的应用前景。多羧酸是构筑MOFs的理想构件，因为多羧酸配体本身含有的羧基去质子化后可在组装MOFs时自动补偿电荷，因而可避免外来阴离子的影响，而且其多变的配位模式能组装出结构复杂的MOFs。稀土金属元素是形成具有优异光、电、磁等性能的MOFs的模版，其独特的4f外层电子结构和较大的配位数容易与配体中的氧原子配位，且形成的配位键非常稳定，易得到热稳定性好的MOFs。IB族Ag（I）亦为形成MOFs的模版。因为Ag（I）是一种极软的酸，对大多数配位原子具有极好的亲和力，且配位数多变，所以引起了研究者的广泛兴趣。综上所述，本课题选择稀土金属离子和银离子为模板、以多羧酸为构件（或反离子），组装出一系列具有新颖结构的MOFs，并对其热稳定性进行研究。主要的研究成果如下：1.以2,2’-联吡啶-6,6’-二羧酸（2,2’,6,6’-bpdc）作为构件与相应的稀土金属离子组装了5种具有新颖拓扑结构的MOFs，分别是[Ln₃（bpdc）₄（Hbpdc）（H₂O）₂]·12H₂O （Ln=Ce（1）, Nd（2）和Pr（3））和[Ln₂（bpdc）₃（H₂O）₃]·3H₂O （Ln=Er（4）和Tm（5）），并对其晶体结构和热性能进行了测定与分析。结果表明化合物（1）-（3）具有相同的晶体结构，包含一维无限扩展的双之字链[Ln₃（bpdc）₄（Hbpdc）（H₂O）₂]（Ln=Ce（1）,Nd（2）和Pr（3）），并且通过氢键和π-π堆积作用扩展成二维网络结构；而化合物（4）-（5）包含离散的零维[Ln₂（bpdc）₃（H₂O）₃]（Ln=Er（4）和Tm（5）），通过氢键和π-π堆积作用等弱作用力连接成三维框架结构。在化合物（1）-（3）中，Ln呈2种不同的配位环境，分别是八配位畸变十二面体构型和九配位畸变三帽三棱柱构型；而在化合物（4）-（5）中，Ln也呈现2种不同的配位环境，分别为八配位双帽三棱柱构型和八配位十二面体构型。化合物（1）-（5）中，Ln-O和Ln-N键呈现明显的镧系收缩特征，热稳定性逐渐增强。2.以2,2’-联吡啶-4,4’-二羧酸（2,2’,4,4’-bpdc）作为构件与相应的稀土金属离子组装了2种具有新颖拓扑结构的MOFs，分别是Ce₄Ag₂（bpdc）₄（SO₄）₃（H₂O）₆·H₂O （6）和La₂（bpdc）₃（H₂O）₄·2H₂O （7），并对其晶体结构进行了分析。结果表明化合物（6）和（7）包含由bpdc与稀土金属离子构筑的三维框架结构，其中的氢键和π-π堆积作用对其三维结构起到了加强作用；在化合物（6）中，Ce呈2种不同的配位环境，分别是八配位畸变十二面体构型和八配位畸变双帽三棱柱构型；而在化合物（7）中，La为十二配位二十面体构型。化合物（6）和（7）中，2,2’,4,4’-bpdc呈现出了多变的配位模式。3.以1,3-苯二甲酸（1,3-bdc）和1,10-菲啰啉（phen）作为构件与相应的稀土金属离子组装了3种具有新颖拓扑结构的MOFs，分别是[La₂（bdc）₃（phen）H₂O]·H₂O （8）、[Pr₂（bdc）₃（phen）H₂O]·H₂O （9）和[Yb₂（bdc）₃（phen）H2_O]·H₂O （10），并对其晶体结构进行了分析。结果表明化合物（8）-（10）具有相同的晶体结构，包含由bdc、phen与稀土金属离子构筑的二维层状结构，其中的氢键和phen环之间的π-π堆积作用使其形成了三维框架结构；在化合物（8）-（10）中，Ln呈2种不同的配位环境，分别是八配位畸变十二面体构型和七配位五角双锥构型。化合物（8）-（10）中，Ln-O和Ln-N键呈现明显的镧系收缩特征，热稳定性逐渐增强。4.以5-羟基-1,3-苯二甲酸（OH-bdc）、5-甲基-1,3-苯二甲酸（m-bdc）和1,10-菲啰啉（phen）作为构件与相应的稀土金属离子组装了1种具有新颖拓扑结构的MOFs—[Er₂（HO-bdc）₂（m-bdc）（phen）]·3H₂O （11），并对其晶体结构进行了分析。结果表明化合物（11）包含由OH-bdc、m-bdc、phen与稀土金属离子构筑的三维框架结构，其中的氢键和phen环之间的π-π堆积作用进一步巩固了其三维框架结构；在化合物（11）中，Er呈2种不同的配位环境，分别是八配位畸变四方反棱柱构型和九配位畸变三帽三棱柱构型。5.通过均相合成法，以AgNO3为模板，以4,4’-联吡啶（bpy）/1,2-联（4-吡啶基）乙烯（dpe）为构件，以己二酸（ha）/吡啶-3,5-二羧酸（pdc）/3,3’4,4’-联苯四羧酸（bptc）为反离子组装了4种具有三明治夹层结构的MOFs，分别是[Ag₂（bpy）₂]（ha）₂·6H₂O（12）、[Ag₂（bpy）₂（H₂O）]（pdc）·3H₂O（13）、[Ag4（bpy）4]（bptc）·14H2O （14）和[Ag2（dpe）2（H2O）2]（ha）·6H2O （15）。这4种MOFs均包含无限扩展的一维Ag-bpy/dpe阳离子链，有机多羧酸阴离子在此则作为反离子平衡化合物的电荷而存在。化合物（12）-（15）的晶体结构中分布了大量的结晶水，从而存在丰富的氢键，具有进一步稳固晶体结构的作用。本论文分别利用水热法与缓慢扩散法合成了系列稀土金属-有机骨架化合物和银金属-有机骨架化合物，并考察了柔性多羧酸配体（2,2’,6,6’-bpdc和2,2’,4,4’-bpdc）和刚性多羧酸配体（1,3-bdc、OH-bdc和m-bdc）对其所构筑的化合物结构的影响。该系列化合物的成功合成不但丰富了MOFs的种类，为研究其相关性能提供物质基础，同时还为探索其合成规律、定向合成相关材料提供了必要的理论依据。更多还原

【Abstract】 Investigations of the assembly of metal-organic frameworks （MOFs）based on the lanthanide family have become the robust subject of manycurrent studies due to not only their versatile architecture, but also theirpotential applications as gas storage, selective gas absorption andseparation, catalysts, magnetic and luminescent materials. Polycarboxylicacids are the “star ligands” in coordination chemistry of such MOFs at alltimes because of （a） the inherent negative charge of carboxylate groupscompensate for the charge induced by metal cations and can mitigate thecounterion effect;（b） the diverse coordination modes provide thepotential for the formation of metal-organic bridging units, which helpenhance the robustness of the resulting network architectures. Thelanthanide ions have novel4f outermost layer electrons and largecoordination numbers, and the MOFs constructed from lanthanide ionspresent excellent optical, electronic and magnetic properties. In addition,the lanthanide ions prefer to coordinate with oxygen atoms frompolycarboxylic acid ligands to form stable Ln-O bonds. And the MOFsbased on Ag（I） attract many researchers’ interests due to its versatilecoordination environments and diversied coordination numbers. In thisthesis, the lanthanide ions and Ag（I） ions were selected as templates, andpolycarboxylic acids were chosen as linkers/counterions to constructMOFs with novel and fascinating crystal structures, and the thermalproperties of some MOFs were investigated. 1. Five lanthanide-based MOFs,[Ln₃（bpdc）₄（Hbpdc）（H₂O）₂]·12H₂O（Ln=Ce（1）, Nd（2） and Pr（3）） and [Ln₂（bpdc）₃（H₂O）₃]·3H₂O （Ln=Er（4）and Tm（5）） were obtained from2,2’-bipyridine-6,6’-dicarboxylate acidand corresponding lanthanide salts by the hydrothermal synthesis method.Single-crystal X-ray diffraction reveals that compounds1-3areisomorphous and isostructural, composed of one-dimensional （1D）infinite double zigzag chain structure, and further extended totwo-dimensional networks via hydrogen bonds and π-π interactions;while isomorphous and isostructural compounds4-5are zero-dimensionaldiscrete moieties and further joined into three-dimensional （3D）framework by rich intermolecular hydrogen bonds and π-π interactions.In （1）-（3）, there are two distinct lanthanide ions with differentcoordination spheres in the structure, namely eight-coordinateddodecahedron and nine-coordinated tricapped trigonal prism geometries.The temperature of dehydration and decomposition of compounds1-5rises with the increase in the atomic number of lanthanide elements,which resulted from the lanthanide contraction in accordance with thedecrease of Ln-O and Ln-N bond distances.2. Two lanthanide based metal-organic frameworks,Ce₄Ag₂（bpdc）₄（SO₄）₃（H₂O）₆·H₂O （6） and La₂（bpdc）₃（H₂O）₄·2H₂O （7）,were obtained from2,2’-bipyridine-4,4’-dicarboxylate acid andcorresponding lanthanide salts by the hydrothermal synthesis method.The single crystal X-ray diffraction reveals that compounds （6） and （7）are composed of3D frameworks built up of bpdc and lanthanide ions, inwhich the hydrogen-bonding interactions and π-π stacking interactionsplay an important role in strengthening the frameworks. In compound （6）,there are two distinct Ce³⁺atoms with different coordination spheres in thestructure, namely eight-coordinated dodecahedron and eight-coordinated bicapped trigonal prismatic geometries. While in compound （7）, La³⁺atom is in an eleven-coordinated icosahedron environment. In bothcompounds （6） and （7）,2,2’,4,4’-bpdc acts as a multi-dentate ligand.3. Three lanthanide based metal-organic frameworks,[Ln₂（bdc）₃（phen）H₂O]·H₂O （Ln=La（1）, Pr（2） and Yb（3）） were obtainedfrom1,3-benzenedicarboxylic acid （H₂bdc）,1,10-phenanthroline （phen）and corresponding lanthanide（III） salts by the hydrothermal synthesismethod. Single-crystal X-ray diffraction reveals that compounds1-3areisomorphous and isostructural, composed of2D sheets constructed fromdbc and lanthanide ions and further extended to3D supramolecularframework through π-π interactions between phen rings of theneighboring chains. In all of the three MOFs, there are two distinct Ln³⁺ions with different coordination spheres in the structure, namelyeight-coordinated dodecahedron and seven-coordinated pentagonalbipyramidal geometries. The bdc acts as both tetra-monodentate ligand tolink two Ln1and two Ln2ions （Ln=La（1）, Pr（2） and Yb（3））, respectively,and counter-ions to balance the charge of the title complexes.Thermogravimetric analyses of1-3display a considerable thermalstability, and the temperature of dehydration and decomposition ofcompounds1-3raises with the increase in the atomic number oflanthanide elements, which resulted from the lanthanide contraction inaccordance with the decrease of Ln-O and Ln-N bond distances.4. A novel erbium based metal-organic framework,[Er₂（HO-bdc）₂（m-bdc）（phen）]·3H₂O （11）, was obtained by thehydrothermal method from5-hydroxy-1,3-benzenedicarboxylic acid（HO-H₂bdc）,5-methyl-1,3-benzenedicarboxylic acid （m-H₂bdc）,1,10-phenanthroline （phen） and erbium（III） salt. Single-crystal X-raydiffraction reveals that the titled compound is composed of3Dframework of [Er₂（HO-bdc）₂（m-bdc）（phen）], in which three lattice water molecules are situated. The rich hydrogen bonding interactions togetherwith aromatic π-π interactions of phen rings and coordinate-covalentinteractions between metal ions and organic ligands strengthen thestability of the3D erbium-based metal-organic framework. In compound（11）, compound1possesses two crystallographically independent Er（III）atoms, namely eight-coordinated distorted square antiprism andnine-coordinated distorted tricapped trigonal prism.5. The reaction of AgNO₃,4,4’-bipyridine （bpy）/1,2-di（4-pyridyl）ethylene（dpe）, hexanedioic acid （ha）/pyridine-3,5-dicarboxylic acid （pdc）/3,3’4,4’-biphenyltetracarboxylic acid （bptc） in alcohol aqueous solutionproduces block-like crystals of [Ag₂（bpy）₂]（ha）₂·6H₂O（12）,[Ag₂（bpy）₂（H₂O）]（pdc）·3H₂O （13）[Ag₄（bpy）₄]（bptc）·14H₂O （14） and[Ag₂（dpe）₂（H₂O）₂]（ha）·6H₂O （15） at room temperature. All of theabove-stated compounds consist of parallel1-D infinite bpy/dpe-silvercationic chains, interspersed with organic anions which play the role ofcharge compensation in the crystal structure. The lattice water moleculesare situated among the framework of the crystal structure and stabilizedby rich hydrogen-bonding interactions, and lattice water molecules mayplay a role in the orientation of the organic anions in the crystal packing.All of the four complexes contain sandwich-like crystal structures, inwhich anionic sheets built up from different anions (ha^2-, pdc^2-, bptc^4-)and lattice water molecules via rich hydrogen-bonding interactions areinserted between the cationic silver complexes layers.In this paper, eleven lanthanide based metal-organic frameworks（MOFs） were obtained from the hydrothermal syntheses methods and theinfluence of flexible （like2,2’,6,6’-bpdc and2,2’,4,4’-bpdc） and rigid（like1,3-bdc, OH-bdc and m-bdc） polycarboxylic acids on the crystalstructures of MOFs was investigated. And four silver-based MOFs wereharvested via slow evaporation, and the different counterions （anions） play important roles in forming the crystal strucutures. The successfulsyntheses of these fifteen compounds enrich the family of MOFs, and willfacilitate the exploration of new MOFs with charming topologies andversatitle properties.更多还原