Coordination Polymers Supported By N,S-heterocyclic And Pyridyl-carboxylic Derivatives:Syntheses,Structures And Properties

Recently, metal-organic frameworks (MOFs) constructed from N/S or N/O ligands,(e.g. sulfhydryl imidazole, sulfhydryl triazole, sulfhydryl thiadiazole, nitrogenous carboxylic ligands), have aroused increasing interest in both academic research and applications, in view of their intriguing variety of architectures along with potentially functional materials. To date, the goal-directed design and construction of the coordination complexes with desired topologies still face with urgent challenge, partially due to organic ligands possessing effective metal coordination sites and diverse coordination modes and some other factors. Therefore, on the base of rational design of organic ligands, it is essential to continuously accumulate and explore the synthetic experience.We adopt three organic ligands in which multiple function coordinating groups are introduced, including mercapto group, triazole or thiadiazole, pyridyl group and carboxyl group. These ligands self-assemble with metal ions to give ten complexes with intriguing architectures, some of which employ favourable property. We also detailedly describe relevant influence factors to the structure and properties of complexes.The dissertation includes two parts as follows:1. Using2-(3-pyridyl)-1H-1,3,4-thiadiazole-5-thi one (3-pttH) and4-amino-3-(3-pyridyl)-1H-1,2,4-triazole-5-thione (3-apttH) as ligands to self-assemble with metal salts under hydrothermal condition, we obtained five new complexes1-5and conformed the crystal structures by single crystal X-ray diffraction. We also studied the thermostability and fluorescence properties of some complexes and discussed influence of metal ions to the structure of complexes. Complexes [Zn(3-ptt)2]n(1) and [Co(3-ptt)2]n(2) exhibit novel twofold penetrated3D structure with66-dia topology. Complex{[Ni(3-ptt)2]·CH3OH}n(3) displays ID chain structure linked by vertical planes. Complexes [Pb(3-ptt)2](4) and [Hgl2(3-aptt)2](5) are mononuclear structure. Further study shows that complexes1,4display stronger fluorescence emission than3-pttH and the luminescent intensity of1is almost thirty-fold larger than that of4.2. Using2-(3-pyridyl)-1H-1,3,4-thiadiazole-5-thione (3-pttH) as a pecursor, Sodium [2-(3-pyridyl)-1,3,4-thiadiazole-5-]-thio-acetate (3-Sptta) was acquired at room temperature. By the self-assembly of3-Sptta and metal salts, five complexes were obtained. We confirmed the crystal structures by single crystal X-ray diffraction and discussed influence of reaction temperature to the structure of complexes. The thermostability and fluorescence properties of some complexes were also investigated. Complexes{[Cu(3-ptta)2]·1/2H2O}n (6) and{[Cd(3-ptta)2]·1/2H2O}n (10) possess similar (4,4)-connected2D structure with [M2(COO)2](M=Cu,Cd) binuclear unit. Complexes [Zn(3-ptta)2(H2O)4](7),[Co(3-ptta)2(H2O)4](8) and [Cd(3-ptta)2(H2O)4]·H2O (9) are isostructural. These mononuclear structures are connected through hydrogen bonds and π…πstacking interaction to form3D supramolecular network. Further study shows that7presents stronger fluorescence emission, while9and10display serious fluorescence quenching than that of3-Sptta. And the quenching degree in10is bigger than that of9.