Study On Synthesis,Structures And Properties Of Metal Organic Frameworks Materials Based On Nitrogen Heterocyclic Ligands

It is inevitable for human to face the growing problem of water environmental pollution.Due to human activities,the classification of pollutions mainly includes industrial pollution,agricultural pollution and domestic pollution.Industrial sewage,including complicated ingredients with good solubility and stability,is the dominant cause of water pollution.So the uneasy water treatment and purification are an urgent task with the faster pace of city development.Contribute to the high specific surface area,porosity,diversity structures and many active sites,Metal Organic Frameworks（MOFs）are widely applied to fluorescence sensor,catalyst,gas absorption and separation,drug delivery and optoelectronic magnetic spectrometer as a new crystalline porous solid material.Two nitrogen heterocyclic ligands BBPTZ,TIMB have been successfully prepared to self-assemble eight coordinated polymers with secondary ligands including4,4’-bipyridine,1,3,5-benzenetricarboxylic acid（H₃BTC）and p-nitrobenzoic acid（p-NBH）.In addition,ZIF-8-based hollow TiO₂ has been synthesized.According to their structural characters,study on fluorescence sensor and photocatalyst has been explored.The research content is divided into three parts:Two new 1D luminescent metal-organic frameworks with identical structure{[Mn（BBPTZ）₂（MeCN）₂]·（ClO₄）₂}n（1）,{[Zn（BBPTZ）₂（MeCN）₂]·（MeCN）₂·（ClO₄）₂}n（2）have been synthesized under solvent diffusion evaporation and characterized by elemental analyses,infrared spectroscopy,thermal analyses and single crystal X-ray diffraction.Excited by a certain wavelength light,complex 1 and 2 can exhibit another wavelength fluorescence.Two complexes show the single selectivity to Fe³⁺in acetonitrile by the quenching of strong fluorescent signal,and that can be luorescent sensors for detecting Fe³⁺with high selectivity,high sensitivity and low limit of detection.BBPTZ and TIMB paired with（H₃BTC）,（p-NBH）,under hydrothermal method to get complex 3,4,5 and 6 with 3D structures.4,4’-bipyridine in N,N-dimethyl formamide（DMF）and water under heat to bridge two 3D complex 7 and 8.X-ray single crystal diffraction,elemental analysis,infrared spectroscopy and thermal analyses are used to characterize the structures.Through solid ultraviolet diffuse absorption spectra,X-ray photoelectron spectroscopy to calculate corresponding band gap E_g between highest occupied molecular orbital and lowest unoccupied molecular orbital of these six complexes,as well as valence band value VB and conduction band CB.Complexes 4,5,6 as MOFs materials,under UV light,showed varying degrees of photocatalytic properties in degradation of methylene blue（MB）.7,8 complexes showed good performance in MB photodegradation under visible light when hydrogen peroxide introduced to the system.Reported multifunction ZIF-8,used to package a hollow nano TiO₂ to grow heterostructure TiO₂@ZIF-8 by ultrasonic method.And then TiO₂@ZIF-8 was characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray powder diffraction,infrared and Raman spectraelemental analyses,infrared spectroscopy,thermal analyses,X-ray photoelectron spectroscopy.Through solid ultraviolet diffuse absorption spectra,X-ray photoelectron spectroscopy to calculate band gap E_g between highest occupied molecular orbital and lowest unoccupied molecular orbital,as well as valence band value VB and conduction band CB.TiO₂@ZIF-8 showed better photocatalysis in hydrogen generation than traditional TiO₂ under visible light.