3,5-二(3’,5’-二羧基苯基)-1,2,4-三唑构筑的过渡金属配位聚合物的合成、结构和荧光性质

Synthesis, Structure and Fluorescence Properties of Transition Metal Coordination Polymers Constructed by 3,5-bis(3’,5’-dicarboxylphenyl)-1H-1,2,4-triazole

摘要: 以3,5-二(3’,5’-二羧基苯基)-1,2,4-三唑(H₄L)为有机配体，分别与Zn(II)和Cd(II)离子反应，通过自组装形成两个新型配位聚合物 [Zn(H₂L)(H₂O)₂•H₂O]_n(1)和[Cd(H₂L)(H₂O)₂•H₂O]_n(2)。通过单晶及粉末Ｘ射线衍射、红外光谱、元素分析和热重分析对化合物进行了表征。结果表明化合物1和2为二维层状结构，1中H₂L²⁻配体的三个羧基均采取单齿配位模式桥联Zn(II)，而2中H₂L²⁻配体有两个羧基采取双齿螯合配位，另外一个羧基单齿配位。相邻的二维层之间又通过氢键和π-π堆积作用拓展为三维超分子结构。固体荧光发射光谱表明，化合物1和2具有良好的荧光性质，其发光机理归因于配体的π→π*跃迁。此外，不同有机小分子对化合物1的荧光强度有不同程度的影响，丙酮对其有显著的淬灭作用，基于荧光淬灭机理，化合物1可以作为一种有前途的荧光探针用于检测丙酮小分子。

Abstract: Two novel coordination polymers [Zn(H₂L)(H₂O)₂•H₂O]_n (1) and [Cd(H₂L)(H₂O)₂•H₂O]_n (2) were synthesized by self-assembly of 3,5-bis(3’,5’-dicarboxylphenyl)-1H-1,2,4-triazole (H4L) ligand and metal ions Zn(II)/Cd(II). The compounds were characterized by single crystal X-ray diffraction, powder X-ray diffraction, IR, elemental analysis and thermogravimetric analysis. The results show that compounds 1 and 2 are two-dimensional layered structures. The three carboxyl groups of H₂L²⁻ lig-and in 1 are bridged zinc ions in monodentate coordination mode, while two carboxyl groups in 2 are bidentate chelating and another one is monodentate coordination. The adjacent 2D layers are extended to three-dimensional supramolecular structures by hydrogen bonding and π-π stacking interaction. The fluorescence emission spectra of solid state show that 1 and 2 have good fluorescence properties, and their luminescence mechanism is attributed to π→π* transition of ligands. In addition, different organic small molecules have different effects on the fluorescence intensity of compound 1, and acetone has a significant quenching effect on it. Based on the mechanism of fluorescence quenching, 1 can be used as a promising fluorescent probe for detecting acetone.