电荷转移法化学改性 High dissolution and strong light emissio

碳纳米管的电荷转移法化学改性

5348J.Am.Chem.Soc.2001,123,5348-5349

CommunicationstotheEditor

HighDissolutionandStrongLightEmissionofCarbonNanotubesinAromaticAmineSolvents

YiSun,StephenR.Wilson,*andDavidI.Schuster

DepartmentofChemistryand

CenterforAdVancedMaterialsandNanotechnologyNewYorkUniVersity,NewYork,NewYork10003

ReceiVedDecember5,2000

Carbonnanotubes(NT)havebeenthesubjectofmuchresearchinrecentyearsbecauseoftheiruniqueelectronic,mechanical,andphysicalproperties.1,2Somesolutionpropertiesofcarbonnanotubeshavealsobeenstudied,aimedattheirchemicalmodificationandfunctionalization.3-6However,thelowsolubilityofNTinmostorganicsolventslimitstheirchemicalmanipulation,quantitativecharacterization,andwideapplication.Severalmeth-odshavebeenreportedtomakesolubilizedNT,includingattachmentoflongalkylchains3andadmixturewithpolymers.4,5Despitethoseattempts,thedissolutionofpristinecarbonnano-tubes,toourknowledge,hasnotbeenrealized.Inthispaper,wereportherethehighdissolutionofpristinesingle-walledcarbonnanotubesinaromaticamines,andthestrongfluorescenceoftheseNT-anilinesolutions.SimilarresultshavebeenobtainedwithmultiwalledNTaswell.

Purifiedsingle-walledcarbonnanotubes(SWNT)werepur-chasedfromRiceUniversity(http://cnst.rice.edu)intoluenesuspension.SWNTwerefilteredthrougha0.2µmPTFEfiltermembranetoproduceso-called“buckypaper”.2MultiwallednanotubeswerepurchasedfromNanocsInc.,NewYork(http://www.77cn.com.cn).Inatypicalexperiment,40mgofaccuratelyweighedNTwereaddedto5mLofanilineandthemixturewasheatedatrefluxfor3hinthedark.Dissolutionofcarbonnanotubesinanilinecanbeobservedbythecolorchangeofthesolutionafterrefluxforashorttime.Thus,withcontinuousheating,theoriginalcolorlessanilinesolutionfirstbecamebrownishandthenturneddarkred.Afterbeingcooledtoroomtemperature,aNTsolutionwasobtainedbyfiltrationthrougha0.2PTFEmembrane.AnSEMpictureofcarbonnanotubesdissolvedinaniline(seeFigure1)showedsimilarstructuralfeaturestothatbeforedissolution,9suggestingnodamagehad

(1)(a)Yakobson,B.I.;Smalley,R.E.Am.Sci.1997,85,324.(b)Tans,S.J.;Devoret,M.H.;Dai,H.;Thess,A.;Smalley,R.E.;Geerligs,L.J.;Dekker:C.Nature1997386,474.(c)Treacy,M.M.J.;Ebbesen,T.W.;Gibson,J.M.Nature1996,381.(d)Wong,E.W.;Sheehan,P.E.;Lieber,C.M.Science1997,277,1971.(e)Ebbesen,T.W.CarbonNanotubes:PreparationandProperties;CRCPress:BocaRaton,FL,1997.(f)Dressel-haus,M.S.;Dresselhaus,G.;Eklund,P.C.ScienceofFullerenesandCarbonNanotubes;AcademicPress:NewYork,1996.

(2)Liu,J.;Rinzler,A.G.;Dai,H.;Hafner,J.H.;Bradley,R.K.;Boul,P.J.;Lu,A.;Liverson,T.;Shelimov,K.;Huffman,C.B.;Rodriguez-Macias,F.;Shon,Y.-S.;Lee,T.R.;Colbert,D.T.;Smalley,R.E.Science1998,280,1253.

(3)Chen,J.;Hamon,M.A.;Hu,H.;Chen,Y.;Rao,A.M.;Eklund,P.C.;Haddon,R.C.Science1998,282,95.

(4)(a)Riggs,J.E.;Guo,Z.;Carroll,D.L.;Sun,Y.P.J.Am.Chem.Soc.2000,122,5879-5880.(b)Sun,Y.-P.;Guduru,R.;Lawson,G.E.;Mullins,J.E.;Guo,Z.;Quinlan,J.;Bunker,C.E.;Gord,J.R.J.Phys.Chem.B2000,104,4625.

(5)Tang,B.Z.;Xu,H.Macromolecules1999,32,2569.

(6)Baran,P.S.;Khan,A.U.;Schuster,D.I.;Wilson,S.R.FullereneSci.Technol.1999,7,921.

(7)Rao,A.M.;Eklund,P.C.;Bandow,S.;Thess,A.;Smalley,R.E.Nature1997,388,257.

(8)Yudasaka,M.;Zhang,M.;Jabs,C.;Iijima,S.Appl.Phys.A2000,71,449.

(9)SeeoriginalSEMpictureofSWNTathttp://cnst.rice.edu.

Figure1.SEMpictureofdissolvedcarbonnanotubesafterevaporationof

solvent.

Figure2.UV-visabsorptionspectraofanilinedissolvedcarbonnanotubessolution.Inset:Carbonnanotubeanilinesolutiondilutedwithacetone.

occurredtotheNT(ofcourse,SEMwouldnotrevealevidenceofchemicalreactionoftheNT).ThesolubilityofSWNTinanilineisupto8mg/mL.Thisaniline-nanotubesolutioncanbereadilydilutedwithotherorganicsolventssuchasacetone,THF,andDMF.

Figure2showstheUV-visabsorptionspectraoftheSWNT-anilinedilutedwithacetonesolution.Absorptionbetween310and400nmisverystrongwhileanewpeakat530nmsuggeststheformationofananiline-SWNTcharge-transfercomplex.Inverydilutesolution,thebroadpeakbetween310and400nmcanberesolvedintotwosharppeaksat325and375nm,respectively,whilethepeakat530nmisnolongerobserved.C60hasbeenshowntoformdonor-acceptorcomplexesintheliquidstatewhendissolvedintertiaryaminesandsubstitutedanilines.TheroomtemperaturesolubilityofC60inaniline,N-methylaniline,andN,N-dimethylanilinewasfoundtobe1.05,1.16,and3.89mg/mL,respectively.10-12ComplexationwithanilinehasalsobeenappliedtoseparateC60fromvarious

(10)Allemand,P.M.;Khemani,K.C.;Koch,A.;Wudl,F.;Holczer,K.;Donovan,A.;Gruner,G.;Thompson,J.D.J.Am.Chem.Soc.1991,113,1050.

(11)Sension,R.J.;Azarka,A.Z.;Smith,G.R.;Hochstrasser,R.M.Chem.Phys.Lett.1991,185,179.

(12)Wang,Y.J.Phys.Chem.1992,96,764-

767.

10.1021/ja0041730CCC:$20.00©2001AmericanChemicalSociety

PublishedonWeb05/11/2001

碳纳米管的电荷转移法化学改性

CommunicationstotheEditorFigure3.Emissionspectraofanilinedissolvedcarbonnanotubesindifferentsolvents:inacetone(s),intoluene(- -),andinmethanol(---).Allsampleswereexcitedat500nm.

Scheme1.ProposedReactionMechanismbetweenNTsandAromatic

Amines

endohedralcomplexes.13C60alsoshowedreactivityinthegroundstatewithvariousprimary,secondary,andtertiaryamines,attributedtoelectrontransferfromtheaminestothefullerene.14Becauseofitsstructuralsimilaritytofullerenes,NTshouldbeagoodelectronacceptor,4,7whileanilineisafairlygoodelectrondonor.Atelevatedtemperatures,NTandanilinemayformacharge-transfercomplexinitsgroundstate,asevidencedbytheappearanceofnewabsorptioninthevisibleregion(Figure2).AsintheinteractionofprimaryandsecondaryamineswithC60,14thismaybefollowedbyprotontransferfromanilinetothefullerene(seeScheme1).TheNT-anilinecomplex(oradduct)isquitestable,evenafterthreemonths,asshownbythepersistenceofthenewspectralfeatures.Incontrast,nomeasurabledissolutionofcarbonnanotubeswasobservedinnitrobenzene,anelectronacceptor.SolubilizationwasalsoobservedbetweenN,N-di-methylaniline(DMA)andNT,buttheprocessmaynotbethesameaswithaniline,sin …… 此处隐藏：8152字，全部文档内容请下载后查看。喜欢就下载吧 ……