吡嗪异金属冠醚的合成、晶体结构及其性质的研究

发布时间：2018-04-27 01:04

本文选题：金属冠醚 + 晶体结构　；参考：《华侨大学》2017年硕士论文

【摘要】：金属冠醚化合物在磁学、生物医药、催化、光学等领域具有非常广泛的应用前景。本文以2-甲基吡嗪、5-甲基吡嗪-2-羧酸为原料,合成配位剂:吡嗪-2-羟肟酸(pyzha,L1)、5-甲基吡嗪-2-羟肟酸(mpyzha,L2)。采用溶液挥发法与CuII和LnIII盐配位,一共合成了九个捕捉了稀土离子的吡嗪异金属冠醚配合物,包含有三种不同的结构类型:单分子结构;二聚体;一维聚合物。通过X射线单晶衍射、红外光谱、紫外-可见吸收光谱、荧光光谱以及TGA-DTA联用等方法对它们的结构、性质进行了探讨。本文所合成的化合物如下:(1)[PrCu_5(pyzha)_5(H_2O)_5(OCH_3)(NO_3)_2](2)[TbCu_5(pyzha)_5(H_2O)_7(NO_3)]·NO_3·ClO_4](3)[YCu_5(pyzha)_5(H_2O)_6(OCH_3)(NO_3)(ClO_4)_2]·H_2O(4)[TmCu_5(pyzha)_5(H_2O)_8]·2(NO_3)·ClO_4·H_2O(5)[GdCu_5(pyzha)_5(H_2O)_8(ClO_4)_2]·NO_3(6){[ErCu_5(pyzha)_5(OCH_3)_3(NO_3)1(ClO_4)_2]·H_2O}n(7)[ErCu_5(mpyzha)_5(H_2O)_6(ClO_4)(NO_3)]·2H_2O(8)[TbCu_5(mpyzha)_5(H_2O)_4(ClO_4)(NO_3)](9)[GdCu_5(mpyzha)_5(H_2O)_5(μ-NO_3)(NO_3)]2X-射线单晶衍射试验表明:配合物(1)-(6)为单斜晶系,空间群都为P21/c。配合物(7)、(8)、(9)为三斜晶系,P-1空间群。配合物(1)、(2)、(3)、(4)、(5)、(7)、(8)结构类似,都是单分子结构的金属冠醚。配合物(9)为一个二聚体缔合物,配合物(6)为金属冠醚的一维配位聚合物。所有配合物都是以[-M-N-O-](M=metal)骨架为重复单元的15-冠-5六核异金属冠醚,中央空穴分别捕获了PrⅢ、TbⅢ、YⅢ、ErⅢ、GdⅢ、TmⅢ等稀土元素。在十五元环所组成的核心环结构中所有的原子趋于在同一平面上,其Rms介于0.1306?到0.2579?之间。五个吡嗪环分别偏向核心环平面两边或全部偏向其中一边,处于结构中心的LnⅢ离子朝平面一个方向凹陷,形成一个碗状结构。金属CuⅡ与两两相邻的吡嗪羟肟酸形成两个顶对顶的五元螯合环结构。一分子配位剂与两个CuⅡ离子配位形成两个共用一条边的五元环,十个五元环一起组成一个星形结构。cu离子的配位方式有4、5、6配位三种,其中5配位居多,稀土离子有8配位和9配位两种。配合物中都存在分子内和分子间的氢键相互作用力。配合物(9)为二聚物金属冠醚,两个平行的金属冠醚单分子之间通过两个硝酸根离子桥连,形成一个层层相叠的金属冠醚化合物。配合物(6)中一个吡嗪环上两个n原子都参与了配位,其中一个n原子与相邻金属冠醚单分子上的cu发生配位,依次相连成一个一维无限延伸的聚合物。红外图谱表明:配位剂与金属配位后官能团特征峰相比配位剂的相应峰值发生了变化,说明配体与金属发生了配位。从紫外-可见光谱可以看出:配合物在370nm左右均出现一个吸收峰,而配体在附近区域无吸收,可以归属为配位剂上的电子转移到配位金属上,即lmct荷移。荧光光谱看以看出配体l2与配体l1相比最佳发射峰发生了红移,甲基的存在增强了结构的刚性。金属冠醚配合物(1)-(9)几乎没有荧光出现,可能是因为cu2+离子的存在以及结合水分子中的高频o-h振动导致了荧光猝灭。tga-dta分析可知,吡嗪羟肟酸与金属配位后,化合物的热稳定性较有机配位剂有了较大的提高。本文所合成的化合物结构如下:
[Abstract]:Metal crown compounds have a very wide range of applications in the fields of magnetism, biomedicine, catalysis, optics and other fields. In this paper, 2- methyl pyrazine and 5- methyl pyrazine -2- carboxylic acid are used as raw materials to synthesize ligands: pyrazine -2- hydroxamic acid (pyzha, L1), 5- methyl pyrazine -2- hydroxamic acid (mpyzha, L2). The solution volatilization method and CuII and LnIII salt coordination are used in total synthesis. Nine complexes of pyrazine isometallic crown ethers that capture rare earth ions include three different structural types: single molecular structure, two polymer and one dimensional polymer. Their structure and properties are discussed by X ray single crystal diffraction, infrared spectroscopy, UV visible absorption spectra, fluorescence spectra and TGA-DTA combination. The synthetic compounds are as follows: (1) [PrCu_5 (pyzha) _5 (H_2O) _5 (OCH_3) _2] (NO_3) _2] (2) [TbCu_5 (pyzha) _5 (H_2O). 1 (ClO_4) _2] / H_2O}n (7) [ErCu_5 (mpyzha) _5 (H_2O) _6 (ClO_4) (NO_3)) 2H_2O (8) [TbCu_5 single crystal diffraction test shows that the complex (1) - (6) is monoclinic system, space group is 7, (8) and (9) is three diagonal system, space group. (1) (2), (2), (3), (4), (5), (7), (8) structure similar to all metal crown ethers of a single molecular structure. The complex (9) is a two polymer Association, and the complex (6) is a one-dimensional coordination polymer of metal crown ether. All complexes are 15- crown -5 six hetero metal crown ethers with the [-M-N-O-] (M=metal) framework as repeating units, and the central holes capture Pr III, T respectively. B III, Y III, Er III, Gd III, Tm III and other rare earth elements. In the core ring structure of the fifteen membered ring, all the atoms tend to be in the same plane, and their Rms is between 0.1306? And 0.2579?. five pyrazine rings are polarized on both sides of the core ring plane or all to one side, and the Ln III ions in the center of the structure are depressed in one direction. A bowl shaped structure is formed. Metal Cu II and 22 adjacent pyrazine hydroxamic acids form two top to top five membered chelation rings. One molecular coordination agent and two Cu II ions coordinate two shared one edge five ring, and ten five membered rings together form a 4,5,6 coordination three species, of which 5 There are 8 coordination and 9 coordination complexes of rare earth ions. There are both intramolecular and intermolecular hydrogen bond interactions in the complexes. The complexes (9) are two polymer metal crown ethers and two parallel metal crown ethers pass through two nitrate ion bridges to form a laminated metal crown compound. The complex (6) is one of the complexes (6). Two N atoms on the pyrazine ring are involved in the coordination. One of the N atoms is coordinated with the Cu of the adjacent metal crown ethers and is connected to a one-dimensional infinite extension. The infrared map shows that the peak value of the functional group after the coordination agent and metal coordination has changed as compared with the coordination agent, indicating the ligand and gold. According to the UV visible spectrum, it can be seen that the complexes have an absorption peak around 370nm, and the ligand is not absorbed in the nearby area, and can belong to the electron transfer on the coordination metal to the coordination metal, that is, the LMCT charge shift. The fluorescence spectrum shows that the ligand L2 has a red shift of the best emission peak compared with the ligand L1. The existence of the metal crown ether complex (1) - (1) - (9) has almost no fluorescence. It is possible that the thermal stability of the compound is larger than that of the organic coordination agent because of the presence of cu2+ ions and the high frequency O-H vibration in the combination of water molecules. High. The structure of the compound synthesized in this paper is as follows:

【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.4

【相似文献】