| Water resources and other natural environmental protection issues have attracted the focus of global attention.Heavy metal ions,organic solvent molecules and organic dyes in water pollution pose a great threat to human health and ecological environment due to their high toxicity and poor biodegradability.At present,ICP-MS,AAS and HPLC are commonly used to detect metal ions in water environment.However,these methods also have shortcomings such as expensive equipments and complex operations,so it is of great significance to build an efficient,fast,green and inexpensive detection method.The traditional treatment methods of water organic dyes include chemical treatment,physical degradation,biological degradation and ect.But the most widely used one is photocatalytic degradation,which has the advantages of simple operation,high degradation rate and environmental protection.Therefore,it is extremely important to design and synthesize coordination polymers that can efficiently detect metal ions and photocatalytic degradation of organic pollutants in aqueous systems.In this paper,dicarboxylic acid isomers are used as organic carboxylic acid ligands,and 9kinds of coordination polymers are synthesized under hydrothermal/solvothermal conditions with different nitrogen-containing auxiliary ligands and transition metal ions,namely:[Zn?opda??obiyb?]n?1?,{[Zn?mpda??obiyb?]·H2O}n?2?,[Zn?ppda??obiyb?]n?3?,[Cd?opda??obiyb?]n?4?,{[Cd?mpda??obiyb?]·H2O}n?5?,[Cd?ppda??obiyb?]n?6?,{[Ni3?opda?3?mbib?4?H2O?4]·2H2O}n?7?,{[Ni?mpda??mbib?]·H2O}n?8?,{[Ni?ppda??mbib?]·H2O}n?9?,H2opda=1,2-phenylenediacetic acid,H2mpda=1,3-phenylenediacetic acid,H2ppda=1,4-phenylenediacetic acid,obiyb=1,2-bis?imidazol-1-ylmethyl?benzene,mbib=1,3-bis?1-imidazoly?benzene.The structure of the coordination polymers will be measured by X-ray,meanwhile infrared spectrum?IR?,elemental analysis,X powder diffraction?XRD?,thermogravimetric analysis?TGA?,fluorescence spectrum?FL?,ultraviolet-visible spectrum?Abs?and other methods will be used to characterize the structure and properties of the coordination polymers.1.Using H2pda as the main ligand of organic carboxylic acid,obiyb as the auxiliary ligand of imidazole,and Zn?II?as the central metal ion in d10 configuration,1-3coordination polymers were successfully synthesized by water/solvothermal method.Among them,1 and 3 are two-dimensional layered porous structures,and 2 is a unique three-dimensional porous structure interspersed with two-dimensional layers.Coordination polymers 1-3 have good water stability,excellent fluorescence sensing performance,and can efficiently and sensitively detect Fe3+and Cr2O72-in water systems with detection limits of 0.34?M,0.36?M,0.57?M,and 0.57?M,0.34?M,0.48?M.After 240 minutes of visible light irradiation,the degradation rates of methylene blue by1-3 and hydrogen peroxide were respectively 65.52%,71.2%and 54.52%.The photocatalytic activity of 2 pair of methylene blue was the best,because the coordination polymer 2 has a three-dimensional multi-void structure,a large specific surface area,and a strong adsorption force,so as to promote the catalytic degradation effectively.2.Using H2pda as the main ligand of organic carboxylic acid,obiyb as the auxiliary ligand of imidazole,and Cd?II?as the central metal ion in d10 configuration,4-6coordination polymers were successfully synthesized by water/solvothermal method.Among them,4 and 6 are two-dimensional layered porous structures,and 5 is a three-dimensional porous structure which formed by the two-dimensional surfaces of two layers interspersed with each other.Coordination polymers 4-6 have good water stability,and based on excellent fluorescence sensing performance,they can efficiently and sensitively detect Fe3+and Cr2O72-in water systems with detection limits of 0.30???0.25???0.28??and 0.19??,0.24??,0.40??.After 240 minutes of visible light irradiation,the degradation rates of methylene blue by 4-6 and hydrogen peroxide are respectively 92.12%?64.17%and 86.20%.The photocatalytic activity of 5 pair of methylene blue was the best,because the coordination polymer 5 has a three-dimensional multi-void structure,a large specific surface area,and a strong adsorption force,so as to promote the catalytic degradation effectively.3.Using H2pda as the main ligand of organic carboxylic acid,mbib as the auxiliary ligand of imidazole,and Ni?II?as the center ion of metal ion with d8 electronic structure,7-9 coordination polymers was successfully synthesized by water/solvothermal method.Among them,coordination polymer 7 is two-dimensional grid structure,8 and 9 are one-dimensional ring-containing chains.The cyclic voltammetry?CV?curves of coordination polymer 7-9 indicated that they have electrochemical activity.In particular,the oxygen evolution reaction?OER?of 8 shows a relatively low potential(10 mA·cm-2,217 mV).After 240 minutes of visible light irradiation,the degradation rates of methylene blue by 7-9 and hydrogen peroxide were respectively 92.12%?85.25%and86.20%.The photocatalytic activity of 7 pair of methylene blue was the best,because 7 is two-dimensional multi-void structure,which has a large specific surface area and a strong adsorption force,so as to promote the catalytic degradation effectively.Among the coordination polymers 1-9,7-9 have better photocatalytic activity,which are attributed to the wider light absorption range of the coordination polymers and the metal center nickle d8 electronic structure. |
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