| Diazo compound plays an important role in organic synthesis for its unique structure,in which 1,3-dipole and 1,3-diradical are two main resonance forms.The classical reaction between olefin and diazo compound as a 1,3-dipole is 1,3-dipolar cycloaddition,and the product is usually a 2-pyrazoline with five-membered ring.When diazo compound presents its 1,3-diradical properties,it can copolymerize with carbene or olefin.Besides,diazo compound can act as a precursor of a-carbonyl carbene and the research on the cyclopropanation of a-carbonyl carbene and olefin is also common.Thus,the diazo compound has attracted the interest of many chemists for its various reactivities.In this article,the author focuses on the synthesis and application of C1N2-group-contained polymers.In Chapter 1,the methods for the synthesis of diazo compounds and the diazo-compound-participated reactions were summarized.In addition,the author introduced the structure and properties of carbenes,diazo compounds and radicals.At last,the up-conversion and down-conversion fluorescent materials and their photoluminescent mechanisms were presented.In Chapter 2,the copolymerization between alkyl diazoacetate and?,?-unsaturated aldehyde,which was a one-pot,one-step and catalyst-free reaction,was presented.The product was ternary copolymer composed of alkyl diazoacetate(C1N2),?,?-unsaturated aldehyde(C2)and a-carbalkoxy carbene(C1),which was derived from alkyl diazoacetate by the release of N2.Thus,the reaction was named as the CIN2/C2/Cl copolymerization.Various diazoacetates and ?,?-unsaturated aldehydes were utilized to establish the methodology.Their products were down-/up-conversion fluorescence molecules that could significantly enhance cell imaging through the synchronized excitation of near-ultraviolet and near-infrared light and might be widely used in other optical fields.The up-conversion fluorescence was the result of a two-photon excitation process.In Chapter 3,ethyl diazoacetate(EDA)and cinnamaldehyde(CA),as representative reactants for alkyl diazoacetate and ?,?-unsaturated aldehyde respectively,were chosen to study the mechanism of the copolymerization in Chapter 2.Through MALDI-ToF-MS,MALDI-ToF/ToF-MS,ESI-MS,EPR,on-line FT-IR and DFT calculations,it concluded that the reaction of EDA and CA proceeds via a diradical mechanism.In the copolymerization,EDA was able to act as a Ndiazo,C3-diradical(-N=N-HC·)in spite that it was conventionally considered as a 1,3-dipole.In the chain propagation,it wasn't simply through the addition of EDA and CA,but the coupling of the building species Ndiazo,C3-diradical,Ndiazo,C5-diradical and Ndiazo,C8-diradical.A series of Ndiazo,C?-diradicals would be generated as intermediates.ED As were accumulated in the propagating chain of copolymer at the first time and then released N2 to generate a carbon radical in situ after a while.In the termination,the radicals would either be coupled to form the macrocycle or be terminated to form linear copolymer.In addition,the bindings between these Ndiazo,C?-diradicals were C-N bond formation processes and the multiple azo groups in the copolymer made it own unique down-/up-conversion fluorescence.In Chapter 4,on the basis of the Chapter 2 and Chapter 3,the author utilized the copolymerization of allyl diazoacetate(ADA)with acrolein(Ac)to synthesize the quaternary copolymer poly(ADA-co-Ac),with diazo group in the side chain and azo group in the backbone.Under microwave irradiation,the poly(ADA-co-Ac)was modified onto the surface of graphite oxide(GO-1),graphene oxide(GO-2)and graphite(G)through cyclopropanation,and the graphene-polymer nanocomposites were obtained.The structure of the graphene-polymer nanocomposites were characterized by FT-IR?CRM?XPS and XRD.After the modification of poly(ADA-co-Ac),GO-1 and G were exfoliated to graphene sheets,in which the heights of the graphene-polymer nanocomposites were within 10 nm in AFM images.From the SEM images,the copolymer nanoparticles could be observed directly on the surface of graphenes.In addition,fluorescence could be observed on the surface of graphene-polymer nanocomposites under fluorescence microscope.Thus,this work expanded the applications of C1N2/C2/C1 copolymerization and realized the modification of the diazo-included copolymer onto the surface of graphene under microwave irradiation at the first time.In Chapter 5,the presented contribution described the innovation in the copolymerization of EDA with cyclic monomers(s-caprolactam and 2,2-dimethyltrimethylene carbonate)under microwave irradiation,which realized the combination of ring-opening polymerization,C1 polymerization and C1N2 polymerization.Through 1H NMR,13C NMR,DSC and SEC,the structures of the copolymers were characterized,which proved the occurrence of the copolymerization.XRD results showed that the synthesized copolymers were amorphous.In Chapter 6,various kinds of 2-pyrazolines were synthesized via the 1,3-dipolar cycloaddition between diazoacetates and olefins.These 2-pyrazolines were treated as monomers to be polymerized to get poly(2-pyrazoline)s in one pot.By replacement of metal-catalysts,reaction time,reaction temperature and percentage of metal-catalyst,the reaction conditions were systematically studied.Every peak in the MALDI-ToF-MS spectra could be resolved clearly to present the corresponding structure,and they could prove the occurrence of condensation polymerization.The products were down-/up-conversion fluorescence molecules.Cell imaging experiments showed that the fluorescence was discretely and homogeneously localized in the cellular cytoplasm and the two-channel synchronized excitation of near-ultraviolet and near-infrared light could indeed increase the beneficial imaging effect of the specific down-and up-conversion fluorescence.In Chapter 7,5-cyano-3-ethoxycarbonyl-2-pyrazoline(Py-1)was synthesized via the 1,3-dipolar cycloaddition between EDA and acrylonitrile.In the X-ray single-crystal diffraction analysis,the author found that the racemic 5RS-Py-1 didn't appear as a pair in the formation of crystal,but occurred the homochiral supramolecular polymerization,in which the 5R-Py-1 or 5S-Py-1 were homopolymerized through hydrogen-bonding interactions.Each homoconfigurated polymerized main chain was a double-chain containing two strands running in opposite directions,which is somehow similar with the 3' to 5' and 5' to 3'double-helix structure of DNA and may offer a simple model in the research of formation and behavior of DNA or even life science.In addition,through the introduction of chiral groups in the side chain of Py-1,the derivative 5S-Py-3 could be obtained facilely.The 5S-Py-3s would form the homochiral supramolecular polymer through hydrogen-bonding interactions,which was similar to the crystal structure of 5R-Py-1 or 5S-Py-1.The spontaneous formation of 5S-Py-3 suggested that the homochiral supramolecular polymerization was helpful for the chiral resolution. |
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