基于联苯四羧酸的镍金属-有机骨架的合成、表征和性能研究

Synthesis,characterization and properties of Ni(Ⅱ)-based metal-organic framework with biphenyl tetra-carboxylic acid

通过水热法合成了一种新型镍金属-有机骨架化合物(Metal-organic framework,MOF){[Ni(H_(2)bptb)_(0.5)(bibp)(H_(2)O)_(2)]·H_(2)O}_(n)(I)(H 4bptb=2,4,4′,6-联苯四羧酸,bibp=4,4′-双(咪唑基)联苯)。运用红外光谱、X射线单晶衍射、热重分析和X射线粉末衍射对其进行了结构表征。X射线单晶衍射分析表明,镍离子形成六配位的扭曲八面体几何结构,构成{NiN_(2)O_(4)}单元,Ni-MOF通过H_(2)bptb^(2)-和bibp配体的键连、氢键以及π…π弱作用力形成了三维穿插结构。此外,对其磁性和电化学性质进行了探究。CV(cyclic voltammetry)测试结果表明:在300~500 mV的范围内,具有一对明显的可逆氧化还原峰,与Ni(Ⅱ)/Ni(Ⅲ)的氧化还原过程有关,而且该变化是受表面控制的。同时,χ_(m)T vsT曲线符合Curie-Weiss定律,表明其具有弱的反铁磁性。

A novel Ni(Ⅱ)-based metal-organic framework(MOF),namely,{[Ni(H_(2)bptb)_(0.5)(bibp)(H_(2)O)_(2)]·H_(2)O}n(I)(H_(4)bptb=2,4,4′,6-biphenyl tetra-carboxylic acid,bibp=4,4′-bis(imidazolyl)biphenyl)was successfully synthesized under hydrothermal conditions.The Ni-MOF was characterized by IR spectroscopy,X-ray single crystal diffraction,thermogravimetric analysis and powder X-ray diffraction.Single-crystal X-ray diffraction indicates that Ni(Ⅱ)center is six-coordinated with a distorted octahedral geometry of{NiN_(2)O_(4)}.The as-synthesized Ni-MOF is assembled into three-dimensional interpenetrating architecture through the connections of H_(2)bptb^(2)-and bibp ligands as well as hydrogen bonding interactions and π…π stacking.The properties of electrochemistry and magnetism were performed in the work.The CV experiments display a pair of quasi-reversible redox peak in 300-500 mV,which are connected with Ni(Ⅱ)/Ni(Ⅲ)of oxidation reduction process and show the redox processes are controlled by the surface.In addition,the χ_(m)T vs T curve obeys the Curie-Weiss law,demonstrating the weak antiferromagnetic interactionis.