由2-(4'-羧基苯基)咪唑-4,5-二羧酸构筑的过渡金属配位聚合物的合成、结构及性质

在溶剂热条件下,由2-(4′-羧基苯基)咪唑-4,5-二羧酸(H_4L,C_(12)H_8N_2O_6),合成了4个配位聚合物{M(H_3L)_2]·2H_2O}_n(M=Zn(1),Cd(2),Co(3)),Cd(H_2L)(H_2O)]_n(4)。用元素分析、红外光谱、热重分析和单晶X射线衍射对配合物进行了表征和结构分析。结构分析结果表明:1～3是异质同晶。配体失去1个质子以H_3L~-的形式通过单齿和N,O-双齿螯合的配位模式与中心金属离子配位,构成一个略有变形的八面体结构。对于配合物4来说,配体失去2个质子以H_2L~(2-)的形式分别通过单齿和N,O-双齿螯合的配位方式与Cd~(2+)配位,中心离子采取扭曲的七配位五角双锥配位模式,并且通过配体苯环上羧基氧原子的双齿桥联作用连接2个中心离子,形成四元环的双核结构;同时呈现双节点(3,6)-连接的二维拓扑网络(4.4.4)(4.4.4.4.4.4.5.6.6.6.6.6)。测定了产物的固体荧光光谱;用EtBr荧光探针法研究了配体及配合物与ct-DNA的相互作用。

Syntheses, Crystal Structures and Properties of Transition Metal Coordination Polymers Constructed by 2-(4'-Carboxyphenyl)-1H-imidazole-4,5-dicarboxylic Acid

Four transition metal coordination polymers of two series, {M(H₃L)₂]·2H₂O}_n (M=Zn (1), Cd (2), Co (3)) andCd(H₂L)(H₂O)]_n (4), have been synthesized by solvothermal reaction from 2-(4''-carboxyphenyl)-1H-imidazole-4,5-dicarboxylic acid (H₄L, C₁₂H₈N₂O₆) and characterized by IR, EA, TG. Single crystal X-ray diffraction shows that 1~3 are heterogeneous. Every ligand loses one proton in the form of H₃L^-, and coordinates with the central metal ion by the coordination mode of monodentate and N, O-double-dentate chelate to form a slightly deformed octahedral structure. In complex 4, every ligand loses two protons in the form of H₂L^2-, which coordinates with the central metal ion by the coordination mode of monodentate and N,O-double-dentate chelation. The central ion adopts a twisted seven-coordinate pentagonal double-cone coordination mode, and the two central ions are connected by the double-tooth bridging of the carboxyl oxygen atom on the ligand benzene ring to form a dinuclear structure of a four-membered ring, meanwhile they exhibit 2D structures with two-node (3,6)-connected frameworks with (4.4.4)(4.4.4.4.4.4.5.6.6.6.6.6) topology. The fluorescence spectra in the solid state and DNA binding properties of the polymers and ligand were investigated.