Synthesis And Application Of Polymer Nanotubes And Metal Organic Framework Materials

Chemical industry can promote economic development and meet human needs,but it also brings serious environmental pollution simultanesously.The recurrence of various pollution problems and poisoning events has greatly restricted our quality of life.To identify environmental pollution,many detection methods have been used.Among them,fluorescence detection method is easy and convenient.Therefore,we synthesized a series of fluorescenct materials including porous polymer nanotubes and metal-organic frameworks,and further investigated their application in sensing of pollutants,including metal ions,toxic gas and nitroexplosives.The main content is as follows:(1)Performance of Porous Polymer Nanotubes for Fluorescence Detection of Metal Ions.We use 2,4,6-Tris-(4-bromo-phenyl)-[1,3,5]-triazine(TBT)as one monomer and 2,7-Dibromopyrene(DBP)and 1,3,6,8-tetrabromopyrene(TBP)as another monomer to synthesize two porous organic polymer nanotubes(PNT-2 and PNT-3)via Ni-catalyzed Yamamoto reaction.The fluorescence test shows that PNT-2 and PNT-3 have high fluorescence intensity,but the different second ligands lead to different luminescence colors of the two materials.PNT-2 shows blue,while PNT-3 is yellow.Further luminescent measurements indicate that both PNT-2 and PNT-3 can serve as luminescent probes for highly selective and sensitive detection of Fe3+ in ethanol solutions by luminescent quenching effect.Absorption competition quenching(ACQ)mechanism is also proposed to explain luminescent quenching behavior,i.e.,the overlap of the UV-spectra between analyte(Fe3+)and PNTs causes the absorption competition of the light source energy,and the energy absorbed by the PNTs material is greatly reduced,which leads to the instantaneous quenching of the luminescence intensity of the PNTs material.Moreover,both PNT-2 and PNT-3 still show high selectivity and sensitivity for sensing Fe3+ in 10%ethanol aqueous solutions,which means that the two porous PNTs materils are promising candidates as luminescent probes for detecting Fe3+ in practical applications.(2)The detection and adsorption of polymer nanotubes.Three PNTs materials(PNT-4,PNT-5 and PNT-6)with different benzene ring lengths were synthesized by Yamamoto coupling reaction with TBT as one of the monomers,1,4-dibromobenzene(DB),4,4’-dibromobenzene(2DB),4,4"-dibromo-p-terphenyl(3DB)as the second monomers.These three PNTs materials have good porosity.Further results indicate that the three PNTs can be used not only as a fluorescent probe for high selective and sensitive sensing of picric acid(PA)in real-time,but also as an excellent adsorbent for fast removal of PA from water.And fluorescent quenching behavior of PNTs for PA can be well explained by the previously proposed ACQ mechanism in this paper,because both of them have strong absorption in the range of 300～400 nm,and the energy absorbed by PA will reduce the energy absorbed by the PNTs material.Moreover,the saturated adsorption capacities of PNT-4,PNT-5 and PNT-6 for PA reach 260.2,200.5,and 178.8 mg/g,respectively.This adsorption phenomenon is not only related to the specific surface area of PNTs,but also related to Zeta potential.Three PNTs materials show positive potential,while the Zeta potential of PA is negative,which is helpful for PNTs to adsorb PA.In short,the bifunctional properties of these PNTs for sensing and removing PA provide a useful strategy to detect the PA pollution and further remove it in practical applications.(3)Fluorescent detection performance of MOFs material and its detection mechanism——"Absorbance caused enhancement(ACE)".IRMOF-3 was prepared by room temperature method and used as fluorescence probe to detect metal ions.The fluorescence detection research experiment shows that IRMOF-3 can recognize trivalent metal ions(M3+,Cr3+,Al3+,Ga3+,In3+)through fluorescence intensity enhanced response,while other valence metal ions(M+,M2+)basically do not cause the luminescent intensity change of IRMOF-3.By examining the relationship of absorbance and luminescent intensity of IRMOF-3 before and after adding metal ions,we propose a novel luminescence turn-on mechanism,i.e.,absorbance caused enhancement(ACE)mechanism,to reveal the luminescence turn-on phenomena of IRMOF-3 for selectively sensing M3+metal ions.That is,the absorbance of materials can be significantly improved after adding analyte(M3+),so that more energy can be absorbed from light source,and finally the more energy released in the form of light,which results in an obvious increase in fluorescence intensity.The subsequent experimental results indicate that IRMOF-3 exhibits high sensitivity and anti-interference ability in the whole process of M3+ metal ion recognition.In short,the ACE mechanism provides a possible strategy for designing of luminescence turn-on probes.(4)Gas Sensing Properties of-NH2 Modified MOFs Materials.MOFs materials(MOF-5 and MOF-5-NH2)were prepared and the effect of amino functionalization on the gas identification of MOFs materials was explored.Gas sensitivity test have shown that amino modified MOF-5-NH2 can realize the selective detection of SO2 gas through enhanced fluorescence intensity,and the fluorescence enhancement phenomenon can be observed by the naked eye,while MOF-5 has no obvious fluorescence change.In order to facilitate practical use,this paper also assembled the MOF-5-NH2 material into wet fluorescent test paper.After testing,it was found that the detection of limit of the MOFs test paper reached the ppm level.Since SO2 can be hydrolyzed to form SO32-in solution,MOF-5-NH2 can recognize SO32-among many anions,while MOF-5 material does not show any selectivity.The above experimental results show that the amino-functionalized MOF-5-NH2 can not only detect SO2,but also its derivative SO32-.