Construction MOFs Of Based Flexible Pentacarboxylic Acid Ligand And Fluorescent Sensing Properties Application

Metal-organic frameworks materials（MOFs）,which was formed by self-assembly metal ion/clusters and organic ligand,are new crystal materials.Due to their diverse structure,high specific surface area,adjustable porosity and other excellent performance,MOFs are broadly used in gas adsorption/separation,luminescence,chemical sensing,catalysis,magnetism,drug delivery and other filed.In this paper,the novel luminescent MOFs were constructed from two aspects of ligand and metal,in which the fluorescence generated by interaction between rare elements,organic ligand and guest molecules,and the excellent fluorescence properties were used to detect pollutants in water.The main work contents are as follow:（1）In this paper,3,5-di（2’,4’-dicarboxylphenyl）benozoic acid（H₅DBA）,europium nitrate hexahydrate（Eu（NO₃）₃·6H₂O）and samarium nitrate hexahydrate（Sm（NO₃）₃·6H₂O）were selected to successfully construct a new luminescent multifunctional Eu/Sm-MOF containing Eu and Sm bimetal by hydrothermal method.The complex Eu/Sm-MOF was characterized by single crystal X-ray diffraction,Thermogravimetric（TGA）,X-ray powder diffraction（PXRD）,Infrared Radiation（IR）,Energy dispersive spectrometer（EDS）and solid fluorescence.Fluorescence analysis showed that Eu/Sm-MOF showed good structural stability and excellent luminescence properties in aqueous solution.The target molecules were specifically identified by the fluorescence quenching effect of Fe³⁺,H₂PO₄^-,and acetaldehyde toward Eu/Sm-MOF.The detection limit were Fe³⁺（0.045μM）,H₂PO₄^-（0.073μM）,and acetaldehyde（0.28 m M）.At the same time,Fe³⁺was detected in the actual water sample,and the recovery rate was between 95.06%and 104.60%.（2）A novel multifunctional luminescent Tb/Sm-MOF containing the coexistence of Tb and Sm was successfully constructed by hydrothermal method using flexible pentcarboxylic acid ligand（H₅DBA）,terbium nitrate hexahydrate（Tb（NO₃）₃·6H₂O）,samarium nitrate hexahydrate（Sm（NO₃）₃·6H₂O）.A series of characterization of the complex showed that its good stability,high phase purity and excellent fluorescence properties.Fluorescence analysis showed that Tb/Sm-MOF is an excellent sensor with fast response,high sensitivity,low detection limit and chemical stability.The detection limit is Fe³⁺（0.035μM）and H₂O₂（0.082 m M）.It can be used for the determination of Fe³⁺in actual water samples and the recovery rate is between95.20%and 104.5%.（3）Europium nitrate hexahydrate（Eu（NO₃）₃·6H₂O）,Parseodyminum（Pr（NO₃）·6H₂O）and 3,5-di（2’,4’-dicarboxylphenyl）benozoic acid（H₅DBA）was successfully synthesis the Eu/Pr-MOF with containing Eu and Pr by hydrothermal process.Through the characterization,Eu/Pr-MOF has good stability,high phase purity.The research showed that Eu/Pr-MOF has excellent sensing performance for Cr₂O₇^2-and ethyl acetate molecules in aqueous solution with detection limits of 0.041μM and 0.056 m M,respectively.As a multifunctional sensor with high sensitivity,fast response and low detection limit.It will be widely application in the detection of pollutants in water.（4）Two different complexes were synthesized by hydrothermal method by using transition metal element Zn,flexible pentacarboxylic acid ligand（H₅DBA）and different auxiliary 1,10-phenanthrene,4,4’-bipyridine.The structural are respectively([Zn₃（DBA）（OH）（1,10-phen）₂]_n（1）;{[Zn₂（HDBA）（4,4’-bipy）_1.5]·H₂O}_n（2）)。By single crystal X-ray diffraction,elemental analysis,Thermogravimetric（TGA）,X-ray powder diffraction（PXRD）,Infrared Radiation（IR）and solid fluorescence shows that two complexes have good thermal stability and high phase purity.It was found that 1 has excellent fluorescence performance and was used to efficiently detect Fe³⁺,Cr₂O₇^2-and acetone molecules with detection limits of 0.54μM,0.69μM and7.26 m M,respectively.Under stimulated physiological conditions,the quenching constant of Fe³⁺and reach 1.9×10⁴L/mol.And the fluorescence quenching mechanism of various analytes was discussed.