| In today's world,increasing pollutants in the environment pose a great threat to ecosystems.Therefore,the design and development of multifunctional detection sensors is of great importance in environmental protection.In recent years,metal-organic frameworks and their hybrid materials can be potential candidates for chemically responsive luminescent sensors because of their high sensitivity,good selectivity and fast response.First of all,we synthesized a rare earth coordination polymer[Tb(dpcp)(H2O)]n(Tb-1)by using 3-(2,4-dicarboxyphenyl)-6-carboxypyridine(H3dpcp)as the ligand,and explored the fluorescent probe behaviors and response mechanism of Tb-1 on food preservatives,folic acid,and"lean meat powder"in detail.Secondly,[Zn(Hdpcp)]n was used as the main body,and then functionalized lanthanide metal-organic frameworks composites,Tb@Zn-MOF and Eu@Zn-MOF was obtained by post-modified with luminescent lanthanide ions(Tb3+/Eu3+).The photoluminescence characteristics of the two post modified materials were further studied,meanwhile Tb@Zn-MOF and Eu@Zn-MOF as fluorescent probes for the detection of biological molecules such as food preservatives,antibiotics,"lean meat powder",alkaloids and amino acids were discussed comprehensively.The main research contents of this paper are as follows:1.A coordination polymer Tb-1 with three-dimensional structure was synthesized by self-assembly of pyridine containing polycarboxylic acid organic ligands H3dpcp and rare earth nitrates under solvothermal conditions.Fluorescence detection experiments showed that Tb-1 can be used as a multifunctional fluorescence sensor with high sensitivity,high selectivity and recyclability to identify food additives potassium sorbate,biological small molecule folic acid,"lean meat powder"albuterol,and can realize quantitative detection of the above analytes.The response mechanism in different analytes was amply studied by infrared spectroscopy,X-ray powder diffraction,UV-vis absorption spectroscopy and fluorescence lifetime.Based on the above research,Tb-1 has the potential to become a fluorescent sensor with“Turn-Off”response.2.Through the strategy of post-synthetic modification,Ln3+(Tb3+/Eu3+)ions were combined with the free carboxyl groups on[Zn(Hdpcp)]n(Zn-MOF)to obtain photoluminescent functionalized composites Tb@Zn-MOF and Eu@Zn-MOF.The structures and properties of Zn-MOF,Tb@Zn-MOF and Eu@Zn-MOF before and after modification were compared by IR,EA,PXRD and SEM.Studies have shown that Tb@Zn-MOF and Eu@Zn-MOF have the characteristic emission peaks of the corresponding lanthanide ions,and have good fluorescence stability in a certain range of p H aqueous solution.At the same time,Tb@Zn-MOF can recognize the food additive sodium dehydroacetate molecules and the veterinary broad-spectrum antibacterial agent sulfaquinoxaline molecules through fluorescence quenching response;Eu@Zn-MOF can detect food additive sodium dehydroacetate molecule,"lean meat powder"clenbuterol molecule and alkaloid cinchonidine molecule by fluorescence quenching;in addition,food additives sodium salicylate m olecules and tryptophan molecules can be detected by fluorescence enhancement.Besides,Tb@Zn-MOF and Eu@Zn-MOF were investigated as the mechanism of action in the fluorescence response process of the above different analytes.Based on the above studies,it was found that Tb@Zn-MOF and Eu@Zn-MOF can be used as multifunctional fluorescent probes for some biological molecules such as food additives,veterinary antibiotics,"lean meat powder",alkaloids,amino acids,and have the potential to be applied to the practical detection of the above analytes. |
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