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本文利用一个新的二羧酸配体5-羧基-1-羧甲基-2氧吡啶(H2L),合成了4个异分同构的配合物,通式为[M(HL)2(H2O)]·2H2O,M=CuII(1),ZnII(2),MnII(3),CdII(4).金属氯化物与配体H2L以1:2的摩尔比在乙醇的水溶液中混合,混合物在40～50℃下搅拌回流1小时,过滤后在室温下静置一周后,得到适合X-射线单晶衍射分析的晶体,产率为40%～50%.X-射线单晶衍射分析表明配合物1～4属异质同晶体,单斜晶系,C2/c空间群.以铜的配合物为代表进行结构分析.在最小不对称单元中包含半个CuII,一个配体HL-离子,半个配位水和一个结晶水.中心金属CuII分别与4个HL-配体的2个羧基氧原子,2个羟基氧原子和1个水分子配位,形成了一个配位数为5的近四方锥构型,其中Cu原子与4个HL-配体上的氧原子构成四方锥底面,水分子则占据锥顶位置.需要注意的是另一个羧基氧,它与金属原子之间的距离为0.2765(2)nm,根据文献可认为它与CuII之间形成了较弱的配位键,因此中心Cu原子也可以称为7配位的五角双锥构型.2个HL-配体上的羧酸氧原子和配位水分子构成五角双锥底面,另2个HL-配体上的酚羟基氧原子则占据锥顶位置.HL-配体桥联两个Cu金属中心沿a轴方向形成一维链结构,链状结构通过羧酸氧原子与配位水及结晶水分子间的氢键最终连成三维结构.从拓扑角度来看,该配合物框架是新颖的两节点(6,8)-连接的拓扑网络,其Schlfli符号为(32.45.57.6)(34.412.58.64)2.在该拓扑网络中,2个6节点和4个8节点构成四边形的螺旋通道,并且相邻的通道显示不同的螺旋结构(左旋和右旋),所以整个网络结构是外消旋的,不显手性.在这些螺旋通道中贯穿着二重菱形的自穿插结构.研究了配体H2L和配合物1～4的固相荧光光谱.配合物1的中心金属原子为Cu,发生了荧光猝灭;配合物2～4的荧光发射峰类似,在254nm的激发波长下,在483,484和515nm处分别有强的荧光发射峰,较配体的最大发射峰410nm均发生红移,表明是配体与金属之间发生了电子转移,荧光的增强可能是由于配体与金属的配位使配体的刚性增加,减少了非辐射能量的损失.
In this paper, four isomers of isomorphic isomers were synthesized by using a new dicarboxylic acid ligand 5-carboxy-1-carboxymethyl-2-oxopyridine (H2L) )] 2H2O, M = CuII (1), ZnII (2), MnII (3), CdII (4) The metal chloride and the ligand H2L are mixed in a 1: 2 molar ratio in an aqueous ethanol solution, The mixture was stirred and refluxed for 1 hour at 40-50 ° C, filtered and allowed to stand for one week at room temperature to obtain a crystal suitable for X-ray single crystal diffraction analysis with a yield of 40% to 50% .X-ray single crystal diffraction analysis showed that the complex Materials 1 to 4 belong to the same isomorphic, monoclinic, C2 / c space group.The structural analysis is carried out on the basis of copper complexes, including half of CuII and one ligand of HL-ion in the smallest asymmetric unit, Half coordination water and one crystal water.The center metal CuII coordinated with two carboxyl oxygen atoms, two hydroxyl oxygen atoms and one water molecule of four HL-ligands respectively to form a coordination number of 5 Nearly quadrilateral pyramidal conformation, in which Cu atoms and four HL-ligand oxygen atoms constitute the bottom surface of the tetragon cone, water molecules occupy the cone top position. It should be noted that the other carboxyl oxygen, its metal atoms with the distance Is 0.2765 (2) nm, which can be considered according to the literature And CuII formed a weak coordination bond, so the center of the Cu atoms can also be called the seven coordination pentagonal bipyramidal configuration. Two HL-ligand carboxylic oxygen atoms and coordination water molecules form the pentagon Bipyramidal bottom, the other two HL-ligand phenolic hydroxyl oxygen atoms occupy the cone top position.HL-ligand bridge two Cu metal center along the a-axis direction to form a one-dimensional chain structure, the chain structure through the carboxylic acid Hydrogen bonds between oxygen atoms and coordination water and crystal water molecules eventually become three-dimensional structures. From a topological point of view, the complex framework is a novel two-node (6,8) -connected topology network with Schlfli The symbol is (32.45.57.6) (34.412.58.64) 2. In this topological network, two 6-node and 4 8-node form quadrilateral spiral channels, and adjacent channels show different helical structures (left-hand and right-hand ), So the whole network structure is racemic, non-significant chiral .In these spiral channels through the double diamond self-interspersed structure.The ligand fluorescence spectra of the ligand H2L and complexes 1 to 4 were studied. The central metal atom of Cu2 was Cu, which quenched by fluorescence. The fluorescence emission peaks of Cu2 ~ 4 were similar at excitation wavelength 254nm Strong fluorescence emission peaks at 83, 484 and 515 nm, respectively, were red shifted from the maximum emission peak at 410 nm, indicating that the electron transfer occurred between the ligand and the metal. Fluorescence enhancement may be due to ligand-metal coordination The ligand increases the rigidity of the ligand, reducing the loss of non-radiant energy.