Synthesis And Fluorescent Property Of Porous Organic Materials

While the development of the chemical industry promotes the growth of GDP,it also brings serious environmental problems.In recent years,metal ion pollution events,explosion events and organic small molecule pollution events seriously harm human health,environmental safety and social security.Therefore,rapid sensing or detection of these harmful substances is attracting increasing attention since it is closely related to security,environmental and human health implications.Currently,several methods have been used to detect explosives,such as metal detection,physicochemical method,and some advanced instrument measurement techniques,etc.Generally,these techniques are expensive and not easily fielded in a small and low-power package.Alternatively,fluorescence-based detection has been proposed because it has a series of advantages over traditional detection methods.For example,it has high sensibility and selectivity,short response time,and could be used in both solution and solid phases.Therefore,fluorescent materials-based chemical sensors have attracted increasing attention due to its high sensibility and selectivity for detecting explosives.In fluorescence-based detection,one of the most important step is to find the suitable fluorescent material.Porous materials have been widely applied in gas adsorption,energy storage,catalysis,fluorescence sensing and other fields because of their low relative density,large specific surface area,adjustable pore size,diverse structure,good permeability and light weight.Metal-organic frameworks(MOFs)and covalent Organic Materials(COMs)are porous materials,and they can be use as fluorescent probe to detect metal ions,small molecules,explosives and bio-applications,etc.In this work,we synthesized a series of covalent organic polymers(COPs)and MOF materials,and studied their fluorescent property and their applications in the fluorescent sensing of metal ions,explosives,organic molecules,harmful gas and finger identification.The main work and innovation point of these thesis are as follows:(1)Color tunable porous organic polymer and its applications in fluorescent sensing:We adopt 1,3,6,8-tetrabromopyrene(TBP)and 1,3,5-tris(4-bromphenyl)benzene(TBB)as double monomers to synthesize a series of porous covalent organic polymers(COPs)using the Ni-catalyzed Yamamoto reaction.By manipulating the reactive ratios of two monomers,we successfully achieve the color tailoring of the resultant five COP samples,COP-61?COP-65.And,the fluorescent emitting color ranged from green-yellow(COP-61)to light yellow green(COP-62),yellow(COP-63),orange(COP-64),and red(COP-65).Moreover,the fluorescent emission peak of COP-65 is 815 nm,and it is the first near-infrared luminescent porous organic material.Further study indicates that these porous COPs can serve as luminescent sensors for highly sensitive and selective sensing of nitroaromatic explosives and metal ions.These materials might also find more applications in photocatalysis,organic electronics and medical imaging.(2)Effects of functional groups for the fluorescent property of COPs:A seires of functional group decorated porous covalent organic polymers(COPs)have been synthesized,and the effects of founctional groups on the fluorescent property of these materials were investigated.Results indicate that both the carboxyl(-COON)and sulfuryl chloride(-SO2CI)functional groups can significantly enhance the luminescent intensity of matrix COP-401,while other groups(i.e.,-NH2;-NO2;-OH;-CHO)cannot.Further studies show that the carboxyl and sulfuryl chloride functionalized COPs(i.e.,COP-401-COOH and COP-401-SO2Cl)as luminescent probes can high selectively and sensitively sense Fe3+ ion,while unmodif-cated maxtrix COP-401 cannot.In addition,when COP-401-SO2C1 is dissolved inchloroform,it shows an obvious luminescence changing from blue to yellow,which indicates that it is a very promising luminescent probe for selectively sensing chloroform.In short,the-COOH and-SO2Cl functional groups are two excellent modifiers for developing new luminescent porous organic polymer.(3)The.propose of "absorption competition quenching(ACQ)mechanism”:In this work,we use tetrakis(pbroMophenyl)methane(TBM)as a monomer,and 4,4'-Dibromobiphenyl(2DB),9,10-Dibromoanthracene(DA),and 1,4-dibromonaphthalene(DN)as another monomer to synthesize three porous fluorescent covalent-organic polymers(COPs)by Ni-catalyzed Yamamoto reaction respectively.Results indicate that these COPs exhibit excellent selectivity and sensitivity for detecting Fe3+ in 10 wt%ethanol aqueous solutions.By using the three COPs as representative sensors,we reveal the absorption competition quenching(ACQ)mechanism of the COPs for sensing Fe3+,i.e.,the absorption spectrum overlap between the COPs and analytes leads to a competition of absorption of the light source between the analyte and the COP material,which causes the luminescence quenching of the COPs in detecting analytes.For all cases studied here,the ACQ mechanism takes effect.It is expected that the ACQ mechanism provided here can be used as an efficient strategy to design the new luminescent sensors for applications of interest.(4)Synthesize of porous organic polymer nanotube and its fluorescent sensing study:In this study,we synthesize a fluorescent(PNT-1)through copolymerization of the monomers 1,3,5-tris-(3-bromo-phenyl)-[1,3,5]-triazine(TBT)and 2,6-dibromopyridine(2,6-DP)by Ni-catalyzed Yamamoto reaction.Results indicate that PNT-1 exhibits high luminescence intensity,stability and reusability,and it can be used as an efficient luminescent probe for sensitively and selectively sensing H2S.Furthermore,we also use UV-absorption as well as EDS and XPS spectra to further explore the luminescence quenching mechanism of PNT-1 as a luminescent probe for sensing H2S.All the results reveal that the formation of N-S bond between PNT-1 and H2S makes the electron in PNT-1 more stable and therefore leads to the luminescence quenching effect of PNT-1 for sensing H2S.Moreover,we also find that PNT-1 as a luminescent probe is still applicable for sensing H2S in vitro assay system simulated using PBS buffer solution.For practical application,we make PNT-1 into fluorescent test paper for detecting H2S?(5)Synthesisis of Zr-MOF and as fluorescence turn-on probe for sensing and fingerprint identification:We use Zr as the metal center and 1,3,6,8-Tetra(4-carboxylphenyl)pyrene(TBAPy)and Tetrakis-(4-carboxyphenyl)porphyrin(TCPP)as double linkers to synthesize a novel Zr(TBAPy)5(TCPP)material.Results indicate that Zr(TBAPy)5(TCPP)can be used as fluorescence turn-on probe to high selectively and sensitively detect H2S gas and its derivatives S2-in aqueous solutions with an extremely low concentration(?1 ppb)and fast response time(<10 seconds).Moreover,by tailoring the particle size of samples,we find that Zr(TBAPy)5(TCPP)can efficiently achieve the visualization identification of fingerprint.All the results indicate that the Zr(TBAPy)5(TCPP)is a promising multifunctional fluorescence turn-on probe.