Synthesis And Property Investigation Of Rare Earth-doped Porous Organic Cage CC3 Composite Luminescent Materials

With the rapid development of modern industry and technology,composite luminescent materials with the advantages of high photoelectric efficiency and fast response have been widely used in the preparation of white light-emitting devices and fluorescence sensing detection.Among them,white light-emitting diodes（W-LEDs）have become a new green light source in the 21st century;the large discharge of industrial wastewater has also caused serious environmental pollution problems,especially Fe³⁺ion pollution.Therefore,in order to further practice energy-saving,environmental protection and green-friendly chemistry,it is of great significance to develop high-efficiency white light emission materials and highly selective Fe³⁺fluorescent materials.Lanthanide ions and their complexes have the luminescence characteristics of narrow emission band,high color purity and strong light absorption capacity,which makes various composite materials doped with lanthanides and their complexes with inorganic/organic materials as the carrier develop rapidly in the field of white light emission and Fe³⁺sensing detection.Among them,porous organic cages（POCs）are a kind of three-dimensional cage-type organic porous molecules with unique host-guest interaction,permanent internal cavity and accessible external cavity,good solubility and strong chemical stability,which are currently widely used in gas separation,catalysis,fluorescence sensing and other fields.The unique advantages of the porous organic cages make it an excellent carrier for doping lanthanide ions and their complexes to prepare ideal new high-efficiency white light emitting materials and highly selective Fe³⁺sensing detection materials.Based on the above reasons,in this paper,a novel lanthanide functionalized POCs material was designed and synthesized by loading Eu³⁺and itsβ-diketone complexes on CC3R porous organic cage,and its white light emission performance and Fe³⁺sensing detection performance were explored.The research work of this paper mainly focused on the following two aspects:1.The luminescent functionalized porous organic cage composite(Eu³⁺@CC3R)was designed and synthesized by introducing lanthanide metal ions(Eu³⁺)into porous organic cage（CC3R）,and its luminescent properties were systematically studied.The results showed that the fluorescence lifetime of Eu³⁺@CC3R reached 155.05μs and the fluorescence quantum efficiency was as high as 92.43%,which was due to the confinement of the CC3R cavity.Based on the RGB principle,Eu,Tb@CC3R composites were prepared by adjusting the doping ratios of different luminescent lanthanide metal ions(Eu³⁺and Tb³⁺).Under the excitation wavelength of 365 nm,when the Eu³⁺:Tb³⁺=1:5 in the composite material,the warm white light material was obtained,and the CIE chromaticity coordinate was（0.3403,0.3456）.2.Three europiumβ-diketone complexes（Eu（tta）₃·2H₂O,Eu（tfacac）₃·2H₂O,Eu（acac）₃·2H₂O）were introduced into porous organic cage（CC3R）,and three luminescent functionalized porous organic cage composites（Eu（tta）₃@CC3R,Eu（tfacac）₃@CC3R,Eu（acac）₃@CC3R）were designed and synthesized.The fluorescence properties and sensing applications of the composites were systematically studied.The results showed that the fluorescence lifetime and fluorescence quantum efficiency of the three composites were improved,and the quenching effect of nitrobenzene and Fe³⁺was good.The relationship between fluorescence intensity and low concentration of Fe³⁺conformed to the Stern-Volmer（S-V）equation.The detection limits of Eu（tta）₃@CC3R,Eu（tfacac）₃@CC3R and Eu（acac）₃@CC3R for Fe³⁺were 0.087 ppm,0.537 ppm and 0.568 ppm,respectively,which proved that the three composites had good Fe³⁺detection ability and anti-interference ability.