Study On The Fluorescence Properties And Application Of Metal-organic Frameworks Modified By AIE Molecules

Metal-organic frameworks（MOFs）refer to polymer materials with open porous structures,which formed by metal centers and organic ligands through coordination bonds orderly assembly.Due to the wide choice of metal ions and organic ligands,it is possible to synthesize MOFs with various structures and unique optical,electrical and magnetic properties.Aggregation-induced emission（AIE）molecules refer to a class of fluorescent molecules whose fluorescence intensity is greatly enhanced in the aggregation state.In recent years,AIE molecules become a research hotspot in the filed of analytical chemistry because of its unique optical properties.In this dissertation,we use MOFs as the matrix to aggregate and assemble AIE fluorescent molecules forming into new AIE aggregates with special optical properties in a specific order and manner,thus acquired AIE molecules functionalized MOFs,and applied them to small molecule analysis and sensing.The specific work is shown as follows:Firstly,we investigated fluorescent MOFs（NU-1000）in the detection of small biological molecules.The study shows that pyridoxal phosphate（PLP）can interact with NU-1000 and led to the fluorescence quenching,which is a dynamic quenching process.Based on this fluorescent quenching,a high sensitivity and good selectivity method for pyridoxal phosphate（PLP）in aqueous solution was established.Secondly,ZIF-8 with zinc ion as the central ion was selected as the substrate to study the optical properties of the AIE molecules of HDBB.The results showed that due to the coordination HDBB molecules with Zn²⁺,the emission wavelength of ZIF-8@HDBB have a blue shift from 580 nm to 525 nm and a new excitation peak was appeared at 440nm.Moreover,the fluorescence intensity was gradually reduced with the increasing of pH within the range of pH 3.0⁹.0.Finally,PCN-700-Me₂-HDBB was built by using HDBB molecules as conjugate ligand with a sequential linker installation（SLI）process.The fluorescence properties of PCN-700-Me₂-HDBB were studied.It was found that the emission wavelength with a blue shift from 580 nm to 570 nm and stable fluorescence intensity of PCN-700-Me₂-HDBB in the range of pH 2.0¹0.0 due to the strong coordination effect between HDBB and Zr cluster,verifying the restriction of intramolecular rotations mechanism about AIE.