Synthesis Of Novel Porous Organic Polymers And Their Fluorescence Sensing Properties

In recent years,with the progress and development of society,people are committed to the development and utilization of various high-performance fluorescent materials.Porous Organic Polymers（POPs）,as a new material,has attracted the research interest of many chemical workers.Porous organic polymer is a kind of new polymer porous material with micropore or mesoporous structure,which is connected by organic units through covalent bonds.Compared with inorganic materials,POPs have the characteristics of low density,high specific surface area,adjustable pore size and high stability.Therefore,it is widely used in many fields such as catalysis,sensing,gas adsorption and storage,gas separation,energy storage and biomedicine.In this paper,two kinds of porous organic polymer are synthesized,and they have been applied to the field of fluorescence sensing.Both of them have obtained excellent properties.In the second chapter of this paper,the novel conjugated microporous organic polymer（TPA-Bp）was prepared by Schiff base reaction with 1,3,5-tri（4-aminophenyl）benzene（TPA）and 2,2’-bipyridine-5,5’-diformaldehyde（Bp）at room temperature.TPA-Bp is a kind of amorphous microporous spherical nanoparticles with high stability.The addition of Fe³⁺and Fe²⁺can quench the fluorescence of TPA-Bp.The fluorescence intensity of TPA-Bp at 331 nm was linearly related to the concentration of Fe³⁺and Fe²⁺.The detection limits of Fe³⁺and Fe²⁺were 1.02×10^-5 M and 5.37×10^-6 M respectively.The fluorescence quenching of TPA-Bp after the addition of Fe³⁺/Fe²⁺can be attributed to the absorption competition quenching（ACQ）mechanism and the energy transfer between TPA-Bp and Fe³⁺/Fe²⁺.This work demonstrates that the conjugated microporous polymers（TPA-Bp）are promising candidates as luminescent sensor for detection of Fe³⁺and Fe²⁺in practical applications.In the third chapter of this paper,an unconventional structural organic framework（named CHOF-1）combined with 1,3,5-tris（4-aminophenyl）benzene（TAPB）and 5-hydroxyisophthalaldehyde（HP）through the synergetic effect of covalent bonds and hydrogen bonds.The addition of 4-nitrophenol（4-NP）and 2,4,6-trinitrophenol（TNP）can make the fluorescence quenching and red shift of CHOF-1,respectively.The detection limits of 4-NP and TNP are 8.78×10^-6M and 1.11×10^-5 M,respectively.It has satisfactory recovery in the detection of 4-NP and TNP in practical water samples.The quenching of CHOF-1 fluorescence caused by 4-NP is due to the absorption competition quenching（ACQ）mechanism.In the structure of CHOF-1,the hydroxyl group of TNP is acidic and can form a hydrogen bond with the unreacted-NH₂ to decompose the crystal structure of CHOF-1 and the electron structure of the photophore changed,so the fluorescence spectrum of CHOF-1 is redshifted.This is a novel example of a covalent bond and hydrogen bonds combined organic framework（CHOF）.This work not only demonstrates a synthesis strategy of the first novel structural organic framework through the synergetic effect of covalent bonds and hydrogen bonds but also provides a fluorescent sensing material for the detection of 4-NP and TNP with high selectivity and sensitivity.