The Synthesis And Crystal Structure Of Coordination Polymers Based On1,2,4-Triazole Dominated By Metals

The coordination polymers (CPs) have great attentions to many chemical andbiological researchers because of their intriguing structures and properties. A numberof coordination polymers with novel structures and unique performances have beensynthesized through designing organic ligands, adding some bridging ligands andchanging reaction conditions. However, the structures and properties of CPs arehighly influenced by several factors, so it is difficult to synthesize a novel complexwith specific structures and properties. Therefore, the effects on the structure ofcoordination polymers should be further studied and discussed. In this paper, withtransition metals as center atom, eight heterometallic and two monometalliccoordination polymers were synthesized with two1,2,4-triazoles ligands throughsolvent evaporation and hydrothermal methods, which were never reported byprevious research. Their structures were determined by X-ray single diffraction,PXRD, IR and TG. Through changing metals ions and adding second metal ions in thesame system, we found that the structures and properties of coordination polymersdependent on the radius, coordination geometry and tendency of metal ions.1. The structures of two heterometallic coordination polymers of3d-3d metalions Fe(Ⅱ)-Co(Ⅱ) synthesized with4-amino-1,2,4-triazole and SCN~-ligands wereresearched. The complex1is trinuclear structure but2is five nuclear structure. Thestructures constructed by single metal and atrz and SCN-ligands mostly aremononuclear complexes, the other structures is rarely reported. So, mixed metal ionscan contracture more interesting structure.2. Three3D heterometallic coordination polymers3,4and5with same structurewere synthesized by adding3d metal ions to the reaction system of Cd(Ⅱ),4-amino-1,2,4-triazole and SCN-ligands. When the metal ion is Cd(Ⅱ), the complex is1D chain. On the basis of previous study results of our laboratory, when the Zn(Ⅱ)was doped, the complex is3D. The study result shows that the different coordination properties of3d metal ions can influence the crystallization process. In the process ofexperiment, we find that the duration of structural transforming from1D to3D differs,which is associated with the different hydration of metal.3. Two monometallic coordination polymers of Zn(Ⅱ) and Cd (Ⅱ) weresynthesized with the1,2-bis(1,2,4-triazol-4-yl)ethane (btre) and terephthalic acid (tp)ligands, their structures differ although the reactants and reaction conditions, and theconfiguration if outermost layers electron of the Zn(Ⅱ) and Cd(Ⅱ) are same. The metalions in complex6is coordinated to four ligands but in7is coordinated six ligands,which indicate the different radius of metal ions can greatly influence the structures ofthe complexes greatly. At room temperature, the two complexes have strongfluorescence emission.4. Three heterometallic complexes of Zn(Ⅱ)-Co(Ⅱ) were synthesized with the1,2-bis(1,2,4-triazol-4-yl)ethane (btre) and terephthalic acid (tp) ligands byhydrothermal method. Complex9is2D,8and10are3D. The results indicate thatreactants ratio, pH, temperature and reaction time can affect the structures ofcomplexes, the ratio of metals is major factor of impacting the structures. In addition,the catalytic property of the complexe10was studied, it can show favorable catalyticproperties on oxidation of tetrahydrofuran(THF).