| 摘要 | 金属有机配合物是一类重要的有机-无机杂化材料，是由有机配体与金属离子桥联组装而形成的具有高规整度的化合物。此类材料由于具有新奇的晶体结构，并且在催化、发光、磁性材料等领域具有广泛的潜在用途，因此，自上世纪90年代中期以来，一直深受广大科研工作者的关注。而基于羧酸配体的金属有机配合物无疑是众多类型配位聚合物中的一个研究热点，尤其是近年来科学家们发现一些具有永久孔道特征的金属有机框架化合物（Metal-Organic Frameworks, MOFs）在低温或者室温条件下可以有效吸附氢气、甲烷、二氧化碳等气体，可望用作新型气体存储和分离材料，将多孔配位聚合物的研究推向了一个更高的高度。本论文设计并合成了一个含亚氨基修饰的半刚性四羧酸配体，使用水热-溶剂热的合成方法，通过与不同的过渡金属和第二配体自组装，构筑了一系列结构类型丰富的金属有机配合物。并对所得化合物进行了单晶结构解析、热稳定性分析以及红外光谱表征，对部分材料进行了发光及磁性的研究。本论文主要工作包括以下几个部分：第一章主要介绍了基于多羧酸配体的过渡金属有机配合物材料的研究进展。第二章讲述配体2,3,5,6-四甲基-1,4-对苯亚氨基二乙酸（H4L）的设计合成与表征。以1,2,4,5-四甲基苯和亚氨基二乙酸二乙酯等为原料，通过多步有机反应得到配体H4L。我们对其进行了氢核磁共振谱、红外光谱以及元素分析等基本表征。第三章描述了基于H4L配体的过渡金属有机配合物的合成、表征与荧光性质的研究。以H4L为桥连配体，与CuSO4•5H2O、CoCl2•6H2O和CdCl2•0.5H2O三种过渡金属盐在水热/溶剂热的条件下，合成得到了三个配位聚合物：[CuL0.5] (1), [Co(H2L)(H2O)2][H2O] (2)和[Cd0.75Cl0.5(H2L)0.5] (3)。其中配合物1是由四羧酸配体的亚氨基二乙酸与Cu(II)形成-ab平面内的Cu[−N(CH2COO)2]层，层与层之间通过四甲基苯基团连接成层柱状三维框架骨架结构。配合物2中，四羧酸配体的四个羧基均采取单齿配位模式分别与一个Co(II)配位，形成-bc平面内的一个二维层，层内以及层间存在的N−H…O和O−H…O氢键将这些二维层组装成了一个三维超分子结构。配合物3中存在[Cd2(CO2)4Cl2] paddle wheel和[CdO8]十二面体两种构筑单元，通过四羧酸配体的连接形成一个三维骨架结构。从这三个配合物的表征结果，我们可以看出，H4L与过渡金属离子的配位模式具有多样性，且配体中的亚氨基对Cu(II)离子具有亲和性。在紫外光照射下，配合物3在蓝光区存在宽发射峰。第四章描述了在吡啶类辅助配体参与调控的金属有机配合物材料的合成、表征及磁性性质的研究。我们将H4L作为主配体，以2,2'-联吡啶（2,2'-bpy）、2,4'-联吡啶（2,4'-bpy）、4,4'-联吡啶（4,4'-bpy）、1,2-二(4-吡啶基)乙烯（bpe）、1,2-二(4-吡啶基)乙烷（bpa）以及4,4'-三亚甲基二吡啶（4,4'-t-bpy）为辅助配体，分别与Cu(II)盐在水热/溶剂热的条件下反应，得到了六个配合物：[CuL0.5(2,2'-bpy)][(H2O)2] (4), [CuL0.5(2,4'-bpy)(H2O)][H2O] (5), [Cu2L(4,4'-bpy)(H2O)2][(H2O)1.5] (6), [CuL0.5(bpe)0.5(H2O)] (7), [CuL0.5(bpa)0.5(H2O)2][(H2O)3] (8), 和[Cu2L(4,4'-t-bpy)][H2O] (9)。单晶结构分析表明，配合物4和5为双核零维结构，而6、7、8为一维链状结构，9为三维穿插骨架结构。在这些化合物中，四羧酸配体以顺式或者反式构型与Cu(II)离子鳌合或者桥联，而辅助配体则以端基或者桥联的方式与Cu（II）配位，这种配位方式上的差异直接导致了所得配位聚合物结构上的差异。此外，我们还对这六个配合物的磁性质做了初步研究，发现它们均可作为潜在的反铁磁性材料。在本论文中我们较系统地研究了半刚性四羧酸配体的的配位模式、金属种类、反应条件、配体/金属比例、反应温度、pH值、配体的柔性及长度等因素对所形成配合物晶体结构与性能的影响。通过适当增加羧酸配体的柔性，大大丰富了配位聚合物的结构类型，加深了对羧酸类配位聚合物的结构与性能的认识。; Metal organic complexes are an important organic-inorganic hybrid material, with high structural regularity, which is formed by the bridge linking mechanism with organic ligands and metal ions. Since the mid-1990s, this kind of material has aroused great attention all over the world because of the great potentials in the applications such as gas storage and separation, magnetism, catalysis and luminescence, et al. Especially when scientists have found that some permanent pores on the metal organic frameweoks (MOFs) based on multicarboxylic acid ligands, which can used to effectivly adsorb gases such as hydrogen, methane and carbon dioxide under room temperature. Based on the information mentioned above, we first synthesized a semi-rigid four-carboxylate ligand containing the −NH− group. This ligand was later self-assembled with different transition metal ions via the hydrothermal-solvothermal method to form the compounds with multi-dimentional achitetures. We characterized the derived complexes through the single-crystal X-ray diffraction (SXRD), thermo-gravimetric analysis (TGA), and infrared spectroscopy (IR). Moreover, we study the luminescence and magnetic properties of some typical compounds. Main contents of this dissertation are as follows:In chapter 1, we mainly illustrated the recent research progress based on MOFs composed of multi-carboxylic acid ligands.In chapter 2, we synthesized and characterized the ligand of H4L, namely, [2, 3, 5, 6-tetra- methyl-1, 4-phenylenebis (methylenenitrilo)] tetraacetic acid. The 1, 2, 4, 5-tetramethylphenoxy and diethyl iminodiacetate were used as the starting materials. We first designed the multi-step organic reactions with these materials to form the ligand of H4L, and then characterized the ligand in detail through the 1H NMR spectra, IR, and elemental analysis (EA) technique.In chapter 3, we first synthesized three transion-metal organic complexes based on the ligand of H4L and then characterized them in detail. Specifically, we used the H4L as the bridging ligand, via the hydro/solvo-thermal reactions with transition metal salts CuSO4•5H2O, CoCl2•6H2O, and CdCl2•0.5H2O to form three coordination polymers with different structures, namely, [CuL0.5] (1), [Co(H2L)(H2O)2][H2O] (2) and [Cd0.75Cl0.5(H2L)0.5] (3). Complex 1 has a three-dimensional architecture with infinite two-dimensional networks linked together by weak Cu-O interactions. Complex 2 displays a 2D network. And complex 3 exhibits an infinite 3D architecture that has unusual [Cd2(CO2)4Cl2] binuclear paddle-wheel units and [Cd(CO2)4] dodecahedron units. The results showed that the coordination geometry of metal centres and the conformation and coordination mode of organic ligands play an important role in determining the structure of the complexes. The luminescence property of complex 3 was studied in the solid state at room temperature. In chapter 4, we mainly studied the properties of metal organic complexes obtained via using bipyridyl as the ancillary ligands. Six new coordination complexes, namely, [CuL0.5(2,2'-bpy)][(H2O)2] (4), [CuL0.5(2,4'-bpy)(H2O)][H2O] (5), [Cu2L(4,4'-bpy)(H2O)2] [(H2O)1.5] (6), [CuL0.5(bpe)0.5(H2O)] (7), [CuL0.5(bpa)0.5(H2O)2][(H2O)3] (8), [Cu2L(4,4'-t-bpy)] [H2O] (9), were synthesized under hydrothermal conditions by reactions of Cu(II)(OH)2 with multidentate carboxylic ligand H4L and some N-donor second ligand, including 2,2'-bipyridine (2,2'-bpy), 2,4'-bipyridine (2,4'-bpy), 4,4'-bipyridine (4,4'-bpy), 1,2-bi(4-pyridyl)ethylene (bpe), 1,2-bi(4-pyridyl)ethane (bpa) and 4,4'-trimethylene-bipyridine (4,4'-t-bpy). These complexes were thoroughly characterized by single crystal X-ray diffraction, IR, thermogravimetric and elemental analyses. The semi-rigid tetracarboxylic ligands are all fully deprotonated, chelate two copper ions through their two iminoacetate moieties with either cis or trans conformation. The copper ions are five- or six-coordinated by carboxy oxygen atoms and tertiary imine nitrogen atom of H4L and nitrogen atoms of second ligand and aqua ligands, forming square pyramidal coordination sphere in compounds 4-8 and octahedral coordination geometry in compound 9. 2,2'-bpy and 2,4'-bpy behave as terminal group, as a result compounds 4 and 5 have a zero-dimensional dimer structure. Whereas 4,4'-bpy, bpe and bpa function as bridging linker which is responsible for the formation of 1D infinite zigzag chain structure for compounds 6-8 and 3D network structure for 9. The results showed that the coordination geometry of metal centres, the conformation and coordination mode of organic ligands and bipyridyl ligands play important roles in determining the structure of the complexes. The differences among the structures were directly influenced by the bipyridyl second ligands, while all conditions are the same except bipyridyl second ligands. Moreover, the magnetic properties of these complexes was also briefly investigated and we found that all these complexes have the potentials in the applications as the anti-ferromagnetic materials.In this paper, we systematically studied the factors, including the coordination modes of the semi-rigid tetracarboxylic acid ligand, the type of metal ions, the reaction conditions, the ratio of ligand and metal ratios, reaction temperature, pH value, the flexibility and length of the second ligands, which greatly affect the crystal structure and properties of the formed metal coordination compounds. Based on our experiments results, we find that the kinds of coordination structures of polymers will be greatly enriched via appropriately increase the flexibility of the carboxylic acid ligands. All the above mentioned studies made us to learn more about the structures and properties for the coordination polymers of carboxylic acids. |
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