Synthesis,Crystal Structures And Properties Of Iron And Cobalt Complexes Based On Bis-Triazole Ligands

Coordination polymers based on iron-series metal ions have been widely used in the researches of selective adsorption and separation,molecular sensing,etc.The ligands based on 1,2,4-triazole could be used to construct iron series metal coordination polymers,making them novel materials that could provide apparent indications for gas separation.There have been plenty studies on coordination polymers such as Cu（I）,Cu（II）,Zn（II）and Cd（II）based on ligands containing bis-1,2,4-triazole groups,however,due to the rigid coordination structure and strong reductivity of Fe²⁺,Fe²⁺and Co²⁺complexes have not been reported.In this paper,metal ion substitution strategy was adopted.Ligands containing several 1,2,4-triazole groups were selected to react with Fe²⁺and Co²⁺to construct new types of iron series metal coordination polymers.By designing the structure of the connecting groups between the 1,2,4-triazole groups,the relative positions of the 1,2,4-triazole groups can be controlled.Then we successfully adjusted the final structures of the obtained iron metal coordination polymers and studied the relationship between the structures and performance in details,which provides some examples for the research of the novel multi-functional iron series metal coordination polymers.The main works of this paper are listed below.1.We designed and synthesized four ligands containing multiple 1,2,4-triazole groups:4,4’-bis-1,2,4-triazole（L₁）,1,4-bis（4H-1,2,4-triazole-4-yl）benzene（L₂）,4,4’-bis（4H-1,2,4-triazol-4-yl）-1,1’-biphenyl（L₃）and 4,4’-（oxybis（4,1-phenylene））bis（4H-1,2,4-triazole）（L₄）.These ligands were characterized by elemental analysis,IR,¹H-NMR and single crystal diffraction（L₃）.2.Three coordination polymers were synthesized based on L₂ ligand:[Fe（L₂）（SO₄）]_∞（1）,[Fe（L₂）（SO₃）]_∞（2）and[Co（L₂）（SO₄）]_∞（3）.Their properties were fully analyzed by IR,XRD,TGA,nitrogen adsorption isotherm,electrochemical micro-SQUID.Especially the structures of compounds 1 and 2 were determined by single crystal diffraction,and we confirmed that compounds 1 and 3 have the same structure by X-ray powder diffraction.