Application Of Metal-organic Porous Polymers In Fluorescence And Colorimetric Detection Of Water Environmental Pollutants

Recently,the influence of phosphate(PO4^3-),antibiotics and sulphur ions(S^2-)on environmental pollution has become more and more serious,therefore such environmental pollutants have received extensive attention in many aspects.And it is vital to establish new methods for the detection of pollutants in the environment.Porous polymers have been widely used in the sensing fields due to their high surface areas,tunable porosities,excellent thermal and chemical stability.In this thesis,we constructing covalent organic framework（COF）-metal organic framework（MOF）,metal nanoclusters（Au NCs）/MOFs shell composites and lanthanide coordination polymer nanosheets（Ce-CPNSs）for sensing of PO4^3-,antibiotics and S^2-.Porous polymers are introduced along with sensor detection principles,with a focus on COF,MOF,colorimetric and fluorescence sensing.The carboxy-modified fluorescent COF was firstly prepared from1,3,6,8-tetra（4-formylphenyl）pyrene（TFPPy）,p-phenylenediamine（Pa）and2,5-diaminobenzoic acid（Aba）monomers through a solvothermal method.Then COF,europium chloride and 2’-amino-[1,1’:4’,1’’-terphenyl]-3,3’’,5,5’’-tetracarboxylic acid（H4TPTC-NH2）was dissolved in N,N-dimethylformamide solution（DMF）,the surface-COOH reacts with europium(Eu³⁺)ion and ligand to integrate MOF on the COF.Moreover,COF-MOF exhibited dual emissions at 446 nm and 621 nm and show the fluorescence resonance energy transfer（FRET）process from COF to MOF.The combination of PO4^3-and europium ions can destroy the MOFs and inhibit the FRET process from the COF to MOF.As a result,the fluorescence of COF（446 nm）increased while the fluorescence of MOF（621 nm）decreased.With dual emissions and phosphate affinity,the COF-MOF based sensing strategy exhibits good performance for ratiometric fluorescence detection of phosphate.A general strategy to embed gold nanoclusters（Au NCs）into the architecture of MOFs via a biomimetic mineralization process was developed.Several Au NCs/MOFs（HKUST-1,Eu-BDC and ZIF-90）shell composites are prepared by simply mixing Au NCs,metal ions,and organic ligands in an aqueous solution.Au NCs/ZIF-90 shell composite was selected as an example to demonstrate its potential application in sensing.The composite was stable due to the protection of the shell and exhibits dual emission at460 nm and 640 nm.A novel ratiometric fluorescence probe for the detection of antibiotics in aqueous solution with good sensitivity and selectivity was developed.Moreover,the quantitative spike recoveries for the detection of antibiotics in water ranged from 94.1%to 103.4%,suggesting that the Au NCs/ZIF-90 shell composite-based sensing platform has a potential for antibiotics assay in biological samples.A colorimetric sensor for the detection of S^2-was constructed by simply mixing the cerium ions(Ce³⁺),2-ICA and tetrakis（4-aminophenyl）ethane（ETTA）in the solution to synthesize Ce-CPNSs.In the presence of H2O2,Ce-CPNSs can generate reactive oxygen species（ROS）and oxidize ETTA which causes the color change from yellow to green.When S^2-was added,S^2-are oxidized by H2O2 and inhibited the color change of Ce-CPNSs.The absorbance decreased linearly as the concentration of S^2-and the limit of detection was 0.35μM.The quantitative spike recoveries for the detection of S^2-in lake and tap water ranged from 99.2% to 102%.