Preparation Of Metal-organic Frameworks Ln(BTC) And MOF-5,and Their Applications In High-sensitivity Fluorescence Detection Of 2,6-pyridine Dicarboxylic Acid(DPA) And Acetone

Fluorescent metal-organic frameworks(MOFs)are one of the most promising materialsfor high-sensitivity fluorescence detection.Compared with organic dyes or inorganic quantum dots,fluorescent MOFs show high porosity,large specific surface area,as well as great possibility of structural modification and functionalization.Especially,the emitting centers in fluorescent MOFs,including metal ions or ligands,are extremely sensitive to variations in environment,which allows for high sensitivity of detection.Therefore,fluorescent MOFs have found applications in the detection of various molecules,cations,and anions.Based on the excellent properties of fluorescent MOFs,we have applied them to the detection of biomarkers 2,6-pyridine dicarboxylic acid(DPA)and volatile organic compound acetone.Bacillus anthracis is an extremely dangerous bacterium with high morbidity and mortality.It is thus of great significance to detect Bacillus anthracis or its major biomarker 2,6-pyridine dicarboxylic acid(DPA)in a rapid and sensitive way.Although MOFs have found great applications in catalysis and sensing,there are only a few fluorescent MOFs can be used in DAP detections,and the key factors determining the detection sensitivity is not clear yet.In this study,we successfully synthesized a novel nano-sized dual-emitting lanthanide MOF,namely Eu/Tb(BTC),for the high-sensitivity DPA detection.The synthesized Eu/Tb(BTC)showed a remarkable sensitivity,excellent selectivity,and a high accuracy.Through comprehensive characterizations of the microstructure,luminescence properties,and sensing performance of products with different Eu/Tb ratios,the unique capability as a sensitive fluorescent probe(limit of detection 1087 nM)for selectively detecting DPA was demonstrated.More importantly,a possible route to control the sensitivity of detection by controlling the original energy transfer efficiency between Eu3+and Tb3+ was revealed.This work not only provides an excellent nano-probe for qualitative and quantitative detection of biomarker of Bacillus anthracis,but also reveals an important rule for improving the sensitivity of sensing systems.Acetone is not only a highly volatile organic compound,but also a product of human metabolism.Therefore,the detection of acetone concentration is of great importance to food,industrial safety,and human health.Although many MOFs have been reported for the detection of acetone,most of them are qualitative,and there are relatively few MOFs for quantitative detection of acetone in the low concentration range.In this paper,we first successfully prepared MOF-5 using microwave synthesis,and then functionalized MOF-5 by post-doping Eu3+and Tb3+.Based on the excellent fluorescence performance of Eu@MOF-5 and Tb@MOF-5 and their specific response on acetone,they can be used as a fluorescent probe for the quantitative detection of acetone with a high sensitivity.Even the acetone concentration in a very low range(0-0.5 vol%),the change in fluorescence intensity(I0/I)shows a good linear function with the acetone concentration.The detection limits of these two types of fluorescence sensors are 0.028 vol%and 0.025 vol%,respectively,which are lower than the occupational exposure limit of acetone.Therefore,the prepared Eu@MOF-5 and Tb@MOF-5 have great potential for the quantitative detection of acetone in a low concentration range.