节点文献
新型过渡金属—含氮芳环配体的配位聚合物设计、组装与结构研究
Design, Assembly and Crystal Structures of Novel Coordination Polymers of Transition Metal-azaaromatic Ligands
【作者】 韩克飞；
【导师】 郭洪猷；
【作者基本信息】 北京化工大学 ， 应用化学， 2008， 博士
【摘要】 本文依据晶体工程学原理，充分利用配位键和其他弱的分子间作用力，合成并测定了一系列新型的具有不同结构的配位聚合物，探讨了其与剑桥晶体数据库中相关结构的相应规律，本研究工作取得了以下成果。1、对影响配位聚合物结构的众多因素进行了简要概括，并结合剑桥晶体数据库，对已有的配位聚合物和与本论文密切相关的含氮芳香配体的配位聚合物的结构进行了分类性评述。2、利用小的配位单元通过氢键等弱相互作用构筑新的超分子聚集体。（1）、以配体和水分子作为氢键的给体进行超分子聚集体的构筑。阴离子选用体积较小的氯离子、硝酸根离子，配体选取结构中同时包含有羧基和螯合氮原子的配体2，2’-联吡啶-4，4’-二羧酸（H2bpdc），在强酸性环境得到了配合物[Cu（H2bpdc）（NO3）（H2O）Cl]2并解析了相应的晶体结构。通过剑桥晶体数据库检索表明，与铜（Ⅱ）的配位能力不同的水分子、硝酸根和氯离子同时与铜（Ⅱ）配位的情况是较为罕见的。阴离子能否参与配位的种类和数量与它们和金属离子配位的热力学稳定性相关。（2）、单独以水分子作为氢键的给体进行超分子聚集体的构筑。阴离子选用配位能力较弱、有较大体积的1，5-萘二磺酸根（1，5-nds）和2,6-萘二磺酸根（2,6-nds），配体选用具有柔韧性连接臂的1，3-二（4-吡啶）丙烷（bpp），获得了两个分子式相同而结构完全不同的配合物[Co（bpp）2（H2O）]（1，5-nds）·2H2O和[Co（bpp）2（H2O）]（2,6-nds）·2H2O的晶体结构。前者为氢键主导的三维结构自组装结构，后者为二维层状结构。表明大体积阴离子作为超分子聚集体网络结构的重要组成部分，它不仅能维持整个网络结构电荷平衡，同时也对整个网络结构产生重要影响。3、以水分子作为氢键的给体，将一维的配位聚合物同氢键等弱相互作用结合起来，构筑新型的超分子聚集体。（1）、在这个系列获得了Ag（Ⅰ）、Ni（Ⅱ）、Zn（Ⅱ）的配位聚合物{[Ag（bpp）]·0．5（1，5-nds）·H2O}n、{[Ni（bpp）2（H2O）2]·（1，5-nds）}n和{[Zn（bpp）（2,6-nds）（H2O）2]·2H2O}n的晶体结构。通过剑桥晶体数据库检索发现Zn（Ⅱ）直接与萘二磺酸根配位，{[Zn（bpp）（2,6-nds）（H2O）2]·2H2O}n是目前发现的第一个例子。在结构方面，对于直线型配位的如Ag（Ⅰ），很容易通过柔性的连接臂形成一维正弦结构的配位聚合物，对于八面体配位的如Ni（Ⅱ）、Co（Ⅱ）、Cd（Ⅱ）等，更容易形成一维的双链配位聚合物。在这些一维链之间，萘二磺酸根利用其对称性形成架桥氢键，并进一步拓展为三维结构。（2）、作为对比研究，将柔性bpp换为刚性的4，4’-联吡啶（bpy）作为中心配体，获得了Co（Ⅱ）的两个配位聚合物{[Co（bpy）（H2O）4]·（1，5-nds）}n和{[Co（bpy）2（H2O）4]·[Co（bpy）（H2O）4]·（2，6-nds）2·2H2O}n的晶体结构。通过我们的例子和剑桥晶体数据库检索发现，当把柔性配体换成刚性配体，仍然可以得到一维结构，但是由双链结构变为线状结构，所涉及到的配体数量减少，而金属离子上配位水分子增多。在这些一维线状结构之间，萘二磺酸根还能利用其对称性形成架桥氢键。在{[Co（bpy）2（H2O）4]·[Co（bpy）（H2O）4]·（2，6-nds）2·2H2O}n中，一个配位单元通过氢键网络组装成一个二维层状结构，该层状结构的上下外缘的氢键受体层进一步与另一个配位单元的一维线状结构配位聚合物形成由氢键主导的三维空间自组装结构，这是一种新颖的组装方式，尚未见文献报道。4、以水分子作为氢键的给体，将二维、三维的配位聚合物同氢键等弱相互作用结合起来，构筑新型的超分子聚集体。仍以bpp作为中心配体，阴离子选取有一定配位能力的2，5-噻吩二甲酸阴离子（tda），金属离子分别选取具有四面体配位的Zn（Ⅱ）和八面体配位的Ni（Ⅱ），获得了相应的配位聚合物[Zn（bpp）（tda）2（H2O）]n和[Ni（bpp）（tda）（H2O）2]n。（1）、在[Zn（bpp）（tda）2（H2O）]n的结构中，虽然Zn（Ⅱ）采取四面体构型，但是其中一个位置被不具有拓展性的水分子占据。在水分子和tda的羰基氧之间的氢键为配位聚合物分子的结构互穿应该有重要作用。当以Zn（Ⅱ）为结点时，[Zn（bpp）（tda）2（H2O）]n的拓朴学特征为极其少见的（10,3）-b（ThSi2型），表现为8重互穿，经检索证实对具有这类拓朴学特征的配位聚合物，我们的例子[Zn（bpp）（tda）2（H2O）]n是目前发现的相互穿插重数最多的配位聚合物。（2）、当金属离子选取能够发生八面体配位的Ni（Ⅱ）时，获得相应的配位聚合物[Ni（bpp）（tda）（H2O）2]n的晶体结构为二维层状结构通过氢键形成的双层结构。在[Ni（bpp）（tda）（H2O）2]n中，相应的拓朴学特征为（4，4），首次从小分子晶体学角度直接观察到水分子与芳香环之间的H-O-H...π弱相互作用，这为更精确的量子力学计算提供了结构化学基础。5、以bpp作为中心配体，单纯利用配位键来构筑新型的三维配位聚合物，并获得相应的配位聚合物{[Co（bpp）2Cl2]·（CH3CH2OH）·（CH3OH）·1．5H2O}n、{[Cu（bpp）2Cl2]·2．5H2O}n和{[Cd（bpp）2Cl2]·2．5H2O}n的晶体结构。结果发现它们都是等结构的三维配位聚合物。结构中都包含有两个配位单元，利用配体bpp在空间不同的伸展方向，总体形成拓扑学特征为66的四重互穿三维金刚石型结构，整个结构约26％的孔洞体积为溶剂分子所占据。6、用2，2’-二硫联吡啶（ps-sp）替代bpp，试图利用吡啶氮原子和连接臂上的硫原子与金属离子同时配位来合成新型三维配位聚合物。当我们使用水热法合成相应的铜（I）配位聚合物时，发现2，2’-二硫联吡啶的二硫键发生断裂，并得到的一个含有Cu（I）-Cu（I）金属键的六核配合物Cu6-（ps）6。综合考虑各种因素，提出了导致这种情况是由于2，2’-二硫联吡啶的二硫键发生自由基断裂的三步机理。综合以上研究，在共计获得14个晶体结构中，包含了从小分子配位单元到一维配位聚合物链，再到二维、三维聚合物网与氢键相结合，以及直接通过配位键来构筑新型的配位聚合物，构成了一套完整的研究系列，丰富了配位聚合物的研究内容，经检索比较，部分结果是首次发现。
【Abstract】 In this dissertation, based on the coordination bond and the other intermolecular interaction such as hydrogen bonding, a series of one dimensional （1-D）, two dimensional （2-D） and three dimensional （3-D） coordination polymers have been designed in the principle of crystal engineering and synthesized by means of hydrothermal or homogeneous reactions. By comparison of some related crystal data from the Cambridge Structural Database （CSD）, some internal causes of reactions have been explored.1. In chapter 1, the factors regulating the structure of coordination polymer are concisely outlined, and the recent progress of the related to our azaaromatic ligands in the field of coordination polymer is also briefly reviewed.2. Some crystal structures of novel supramolecular aggregates have been obtained by means of the hydrogen bonding interaction between small coordination units and water molecules.（1）. A novel supramolecular aggregate, [Cu（H2bpdc）（NO3）（H2O） Cl]2 （bpdc denotes 2,2’-bipyridine-4,4’-dicarboxylic acid）, has been constructed by means of the hydrogen bonding interaction between two H2bpdc molecules, and between small coordination units and water molecules under the condition of nitric acid. In this complex, water molecule, chloride ion, and nitrate ion which possess different coordination ability can coordinate the same Cu（Ⅱ） ion. This is rare according to the data index from CSD.（2）. Two isomeric supramolecular aggregates, [Co（bpp）2（H2O）] （1,5-nds）·2H2O and [Co（bpp）2（H2O）]（2,6-nds）·2H2O, have been prepared by means of the hydrogen bonding interaction between water molecules and 1,5-nds or 2,6-nds. bpp denotes the central ligand of l,3-bis（4’-pyridyl）propane with a flexible spacer between its two pyridine rings, and 1,5-nds or 2,6-nds denotes 1,5-naphthalene or 2,6-naphthalene disulfonate dianions, respectively, which their sulfate anions have weak coordination ability. The complex [Co（bpp）2（H2O）] （1,5-nds）·2H2O is linked into 3D structure through hydrogen bond interactions, while the structure of complex is a 2D layer network. The result indicates that the big anion can balance the charge of the whole structure, and it can also affect notably the structure of network.3. Five supramolecular aggregates, {[Ag（bpp）]·0.5（1,5-nds）·H2O}n, {[Ni（bpp）2（H2O）2]·（1,5-nds）}n, {[Zn（bpp）（2,6-nds）（H2O）2]·2H2O}n, {[Co（bpy）（H2O）4]·（1,5-nds）}n and {[Co（bpy）2（H2O）4][Co（bpy） （H2O）4]·（2,6-nds）2·2H2O}n have been prepared, where bpy is 4,4’-bipyridine. Among the five crystal structure except Zn-bpp-（2,6-nds）, the coordinated water molecules act as donor of hydrogen bond and nds act as acceptor.（1）. In the coordination polymer {[Zn（bpp）（2,6-nds）（H2O）2]·2H2O}n, Zn（Ⅱ） coordinates O atoms of 2,6-naphthalene disulfonate dianions with Zn-0 bond length ca. 2.2 A. This is the first case of coordination between Zn（Ⅱ） and naphthalene disulfonate based on the index from CSD. According to our cases and the data index from CSD, for a linear coordination metal ions, a 1D sinusoidal structure can be obtained easily when the ligand is bpp with a flexible spacer. For octahedron coordination metal ions such as Ni（Ⅱ）, Co（Ⅱ） and Cd（Ⅱ）, a 1D duplex structure can be obtained easily. All these 1D structures can be further linked into 3D structures by means of hydrogen bonding interaction between their coordinated waters and naphthalene disulfonate dianions.（2）. As a control, two coordination polymers {[Co（bpy）（H2O）4]·（1,5-nds）}n and {[Co（bpy）2（H2O）4]·[Co（bpy）（H2O）4]·（2,6-nds）2·2H2O}n from a rigid ligand bpy can be obtained. Based on the two complexes and the data index from CSD, 1D linear coordination structure is still kept after the flexible ligand bpp is replaced by rigid ligand bpy. Similarly, naphthalene disulfonate dianions can act as a hydrogen bond bridging these 1D linear polymeric strands.In the structure of {[Co（bpy）2（H2O）4]·[Co（bpy）（H2O）4]·（2,6-nds）2·2H2O}n, a 2D layer structure from one coordination unit can be formed by hydrogen bond between the water molecules and sulfate, which the depth is ca. 23 A. On the both sides of the layer structure, it consists of two types of acceptors of hydrogen bond from uncoordinated N atoms of bpy and O atoms of sulfate. The 3D structure can be formed by means of this bilayer acceptors and coordinated water molecules of other 1D Co （II） coordination polymers. This novel assembly style has not been reported in previous researches.4. Two novel coordination polymers [Zn（bpp）（tda）2（H2O）]n and [Ni（bpp）（tda）（H2O）2]n have been obtained, which tda is thiophene-2,5-dicarboxylic dianions.（1）. In the structure of [Zn（bpp）（tda）2（H2O）]n, the coordination mode of Zn（II） is tetrahedral, which its one site is occupied by one water molecule. The hydrogen bonds between water molecules and carbonyl O atoms play an important role in the aspect of interpenetration. From the topological point of view, because each Zn（II） acts as a T type three-connected center, [Zn（bpp）（tda）2（H2O）]n is the first example of eightfold interpenetration of （10,3）-b （ThSi2） nets.（2）. In the structure of [Ni（bpp）（tda）（H2O）2]n, the coordination mode of Ni（Ⅱ） is a distorted octahedral geometry, which its two sites are occupied by two water molecule. The structure of [Ni（bpp）（tda）（H2O）2]n belongs to an interesting two-dimensional grid-type bilayer running parallel to （001） plane, and the bilayer is formed through intermolecular O-H...O hydrogen bonds. The topological property of [Ni（bpp）（tda）（H2O）2]n is a general （4,4） net when each Ni（Ⅱ） acts as node.In this structure, the more remarkable structural character is that the H-O-H...πinteraction between water molecule and aromatic ring is directly found. This is the first observation in the crystal of small molecule. It provides a base of structural chemistry for more precise quantum mechanics calculation.5. Three isostructural 3D coordination polymers {[Co（bpp）2Cl2]·（CH3CH2OH）·（CH3OH）·1.5H2O}n, {[Cu（bpp）2Cl2]·2.5H2O}n and {[Cd（bpp）2Cl2]·2.5H2O}n were prepared. All these structures contain two equal coordination units. The total topological property is a fourfold interpenetration of 66 diamond type, and there exist ca. 26% void volume in their cells with infilling of solvent molecules.6. Using 2,2’-dithiobipyridine （ps-sp） instead of bpp, we tried to synthesize some novel copper（I） complexes that 2,2’-dithiobipyridine can coordinate metal ion with N atoms of pyridine and S atoms of its spacer. The disulfide bond was broken during hydrothermal synthesis, and a hexanucleic cluster Cu6-（ps）6 including Cu（I）-Cu（I） metal bonds was obtained. A radical mechanism has been given to explain this phenomenon of disulfide bond cleavage.Totally, here the 14 crystal structure include 3D coordination polymer and supramolecular aggregates by hydrogen bond interactions between water molecules and small coordination unit, 1D coordination polymer strand, 2D and 3D polymer networks.