The Study On Fluorescence Sensing Of Metal Ions Based On Pillared-layered Frameworks

Metal-organic framework compounds?MOFs?have the advantages of high sensitivity,fast response and recycle in ion fluorescence recognition.It is considered as a promising class of fluorescent sensing materials.Reasonable design and synthesis of sensors with high sensitivity and rapid recognition of metal ions is one of the hot research fields of coordination chemistry and materials chemistry.Therefore,in this dissertation,the properties of fluorescence recognition of metal ions was studied by using a serials of isostructural,pillared-layered metal-organic frameworks based on nitrogen-containing dipyridine ligands with different functional groups and different flexible alkyl chains.The results reveal the influencing factors that affect the fluorescence recognition of metal ions,which lays a certain foundation for building metal ion fluorescence sensors of MOFs.The specific work is as follows:1.A comparative analysis of three isostructural,pillared-layered frameworks,namely[Zn₂?DMTDC?₂?bpe?]?PL-1,H₂DMTDC=3,4-dimethylthieno[2,3-b]thiophehe-2,5-dicarboxylic acid,bpe=1,2-di?pyridin-4-yl?ethane?[Zn₂?DMTDC?₂?dpe?]?PL-2,dpe=1,2-di?4-pyridyl?ethylene?and[Zn₂?DMTDC?₂?bpa?]?PL-3,bpa=1,2-di?pyridin-4-yl?ethyne?was studied on the sensing of metal ions.It was found that all three pillar-layer structures can be used as a sensor of Fe³⁺by fluorescence quenching.Fluorescence titration analysis revealed that the fluorescence quenching constants of the three compounds is in this order:PL-1(Ksv=1.6×10⁴ M^-1)<PL-2(Ksv=1.7×10⁴ M^-1)<PL-3(Ksv=2.5×10⁴ M^-1).This study revealed that the bipyridine ligands with different functional groups show an effect on the fluorescence recognition of metal ions.2.A new double interpenetrated,pillared-layered framework,[Zn₂?DMTDC?₂(dpp]·3DMF·0.5H₂O?PL-4,dpp=1,3-di?pyridin-4-yl?propane?,was synthesized under solvothermal conditions.,characterized by X-ray single-crystal diffraction,infrared spectroscopy and thermogravimetric analysis..The gas adsorption showed that the activated sample PL-4a wican not adsorb N₂,but adsorb CO₂.The study of fluorescence properties showed that PL-4 shows selective fluorescence quenching of Fe³⁺.In addition,the fluorescence recognition Fe³⁺performance was analyzed for two pillared-layered frameworks PL-4 and PL-1constructed by two different alkyl chain-linked bipyridyl ligands The results indicate that the fluorescence quenching constant of PL-4(Ksv=4.5×10⁴ M^-1)is larger than that of PL-1(Ksv=1.6×10⁴ M^-1),which isconstructed by an ethyl-linked bispyridine ligand.This study shows that different alkyl chains of bipyridine ligands also have an effect on the fluorescence recognition of metal ions.