Synthesis And Photocatalytic Performances Of Zn-based Coordination Compound

Water is one of the most important resources,there is rich in water resources on the earth,but the water resources available for human use are only surface water and groundwater,and desalinated seawater,This small portion of potable water is an important guarantee for the survival of mankind and many living things.However,with the rapid development of social economy and industry,the contradiction between the water environment and the rapid development of the society has gradually emerged.Water shortage and water pollution are more and more influence to our life and the social economy’s development,the destruction of the ecological environment,traditional water treatment method has been gradually difficult to meet all kinds of sewage and wastewater treatment needs.In recent years,researchers have realized that the material can be expanded into the improvement and treatment of water environment,so a new method of water treatment has become a hot topic in material field,that photocatalytic degradation of organic pollutants by using a new type of functional material with special response to light,combined with the traditional water treatment process technology,they can supplement each other.Not only can make full use of solar energy to solve the problem of water environment,but also improve the use of e nergy to ease the energy crisis.According to this idea,a series of photocatalytic properties of coordination compound materials have been designed and developed,and explored the performance of catalyst under ultraviolet light degradation of organic wastewater,and discussed the effect of catalyst amount,initial p H value of dye wastewater on degradation efficiency.These results were briefly described as follows:1.Two novel coordination compounds based on zinc ions,1,10-phenanthroline（phen）and two similar azophenyl ligands,3,4-dicarboxyl-（3‘,4‘-dicarboxylazophenyl）benzene（3,4-H4dczpb）,as well as 2,3-dicarboxyl-（2‘,3‘-dicarboxylazophenyl）benzene（2,3-H4dczpb）,namely [Zn（phen）（2,3-H₂dczpb）（H₂O）]·H₂O（1）,and [Zn2（phen）4（3,4-H₂dczpb）]（3,4-H4dczpb）2·2H₂O（2）,have been synthesized under hydrothermal conditions,and a series of characterizations are carried out.Compound 1 was built up of one dimensional [Zn（phen）（2,3-H₂dczpb）（H₂O）] chains,while compound 2 was composed of zero-dimensional discrete [Zn2（phen）4（3,4-H₂dczpb）] unit and uncoordinated 3,4-H4 dczpb.The UV–Vis DRS results revealed that the Eg values of compounds 1 and 2 are 3.0 and 2.9 e V,respectively,implying that both 1 and 2 illustrate selective absorption in the ultraviolet region.The photocatalytic activities of degradation of methylene blue（MB）in compounds 1 and 2 under UV light irradiation were conducted,and the results revealed that both 1 and 2 can decompose MB efficiently.Finally,the TGA results exhibited 1 and 2 possess good thermal stability.2.Synthesis of novel Zn-based coordination compound [Zn（1,4-chdc）（bpp）]·6H₂O,and has carried on the list of some characterization experiments,by the analysis of the crystal structure,the complex 3 is a one-dimensional [Zn（1,4-chdc）（bpp）] chain composition,and two dimensional plane frame structure is formed by the hydrogen bonding between water molecules that are not coordinated.The UV-Vis diffuse reflectance analysis shows that the Eg value of complex 3 is 4.5e V,which indicates that it can be used in UV light.Thermogravimetric analysis shows that the structure of complex 3 has good thermal stability.In addition,the complex 3 can be used as a high efficient photocatalyst to produce hydroxyl radical to degrade MB dye molecules under UV irradiation.The mechanism of photocatalytic reaction in the reaction system was verified by adding isopropanol as a free radical scavenger.The effect of complex 3 on the degradation of MB dye was investigated at different p H,and the results showed that the degradation efficiency of MB were all over 90%,which indicated that the complex 3 was a kind of photocatalyst with good acid and alkali resistance.3.Two coordination polymers,[Zn（5-aip）（bpy）0.5]·H₂O（4）,and [Ni（5-aip）（bpy）0.5（H₂O）]·2H₂O（5）,constructed by 5-aminoisophthalic acid（5-H₂aip）,4,4’-bipyridine（bpy）,and corresponding ions,have been synthesized under hydrothermal conditions,and characterized by single crystal X-ray diffraction,Fourier transform infrared spectroscopy（FTIR）,CHN elemental analysis and UVe Visible diffuse reflectance spectra（UV-Vis DRS）.Both 4 and 5 were built up of two-dimensional [Zn（5-aip）（bpy）0.5] and [Ni（5-aip）（bpy）0.5（H₂O）] sheets,respectively.The UV-Vis DRS results revealed that the Eg values of 4 and 5 are 3.4 and 2.4 eV,respectively.The photocatalytic activities of degradation of methyl orange（MO）,methylene blue（MB）and MO&MB mixture over 4 and degradation of MB over 5 under UV light irradiation were investigated.The results revealed that 4 exhibited good performance to photocatalytically decompose MB,MO and MB&MO mixture,while 5 can only degrade MB efficiently.