Construction Of Stable MOFs And Its Specific Recognition Of Pollutants

With the rapid growth of population and the fast development of global economy,the whole ecosystem is facing serious environmental pollution.These problems have seriously affected human health and daily life.Tracing back to the source,all environmental pollution problems are caused by various pollutants.How to effectively detect and identify pollutants in the environment is one of the key technologies to solve environmental problems.Nowadays,fluorescence detection is widely used in the detection of pollutants because of its simple operation,short response time and high sensitivity.Metal-organic frameworks(MOFs)are a new type of materials that can be used for fluorescence detection of pollutants in the environment,but their stability is still an important factor limiting their application.In this work,a series of stable MOFs materials are designed and constructed,and they are used to detect pollutants in the environment,such as antibiotics,food additives etc.(1)Two water stable Al-MOFs(BUT-178 and BUT-179)were constructed by modifying ligands on CAU-4 ligands to improve their fluorescence properties,and they were used to detect tetracycline pollutants in eggs.These antibiotics can cause strong fluorescence quenching efficiency of BUT-179,the quenching efficiency is about 96%,the limit of detection is 20 n M,and the detection performance is excellent.Through the analysis of fluorescence quenching mechanism,it is found that the excellent detection effect of BUT-179 on tetracycline antibiotics is due to the synergistic effect of fluorescence resonance energy transfer(FERT),photoinduced electron transfer(PET)and internal filtration effect(IFE).Cyclic experiments show that BUT-179 can be easily recycled and reused without obvious loss of quality and performance.This work shows the good application potential of MOFs in food safety(especially in the fluorescence detection of antibiotics in food),and also provides a new idea for the construction and modification of MOFs.(2)A novel flexible Zn-MOF was constructed by regulating the proportion of ligands involved in complexation.The strong conjugation system of ligands makes it have excellent fluorescence properties.In this study,it was used for the detection and recognition of sweeteners in water system.The results show that among the five sweeteners,saccharin has excellent fluorescence quenching efficiency on the MOF,and other sweeteners do not cause obvious fluorescence changes,indicating that the constructed Zn-MOF can selectively detect saccharin in water system and is not affected by other sweeteners.The study on the fluorescence quenching mechanism under this detection system found that the reason for the selective detection of saccharin is that there are IFE effect and PET effect between saccharin molecule and Zn-MOF at the same time,while there is no such unique effect between other sweetener molecules and Zn-MOF.This work further proves that MOFs have great application prospects in food detection,and provides a reference for the design and construction of fluorescence stable MOFs.