無(wú)機(jī)物理方法核磁共振部分

無(wú)機(jī)物理方法核磁共振部分BasicTwo-DimensionalExperimentsWhymulti-dimensional?ResolutionMulti-quantumcoherencesCoherencetransferTypesofmulti-dimensionalspectra:ToCorrelateToResolveToExchange(Diffusion)From1Dto2D,3D…t2t1Ifyoulookatthesamedatamatrixinadifferentway….YoualsogetaseriesofFIDs.Ineitherdirection,youseeFIDsYoureallydon’tknowwhichis“acquisitiondimension”,Doyou?A2DSpectrumt2t1FT2FT1F2F12DFTTypical2DLineshapesResolutionTheresolutionintheseconddimensionisdeterminedthesamewayasin1DNMR.Theresolutioninthefirstdimensionisdeterminedbythelongestevolutiontimeinthefirstdimension(maximumoft1).Thetotalevolutiontimeintheindirectdimensionisequivalenttothetotalacquisitiontimeinthedetectiondimension.F1F2Acquisitionanddataprocessing:COSYpulsesequence(top)withapresaturationpulsetosuppresswatersignal.Alsoshowninthediagramarethecoherencetransferpathway(middle)andphasecyclingscheme(bottom).Presatt1t2p=+1p=0p=-1COSYpulsesequence(top)withapresaturationpulsetosuppresswatersignal.Alsoshowninthediagramarethecoherencetransferpathway(middle)andphasecyclingscheme(bottom).Presatt1t2p=+1p=0p=-1RecollectingChapter2FourbasiclineshapesAnti-phaseabsorptiveIn-phasedispersiveAnti-phasedispersiveIn-phaseabsorptiveFTRealpartFTRealpartFTRealpartFTRealpartA2DdispersivepeakA2Dabsorptivepeak+--++--++--+-++-+--+-++-AbsorptivecrosspeaksDispersivediagonalpeaksDispersivecrosspeaksAbsorptivediagonalpeaksAbsorptivecrosspeaksAbsorptivecrosspeaksDispersivediagonalpeaksABCDFE125346789101329674851012534678910AbsoluteValueDisplayThemajordrawbackofCOSY:crosspeaksnearthediagonallinemaybeobscuredbydiagonalpeaks.DQFCOSY1253467891012534678910TheAdvantagesofDQFCOSYHavingthesamephaseforboththediagonalandcrosspeaks;Becausethemagnetizationisdetectedinanti-phase,themultipletstructureisretainedwithoppositephase.Inotherwords,thetwolinesofadoubletare180°outofphasewithrespecttoeachother.Whilethiscanleadtocancellationincrowdedregionsofthespectrum,italsoallowsfortheeasyidentificationofmultiplets(basedontheirsquare,orbox,shape),andformeasuringthesizeofthescalarcouplingconstantconnectingthetwospins.AnotheradvantageoftheDQF-COSYexperimentisnotsoimmediatelyobvious.Inorderforatransitiontocreatemultiplequantumlevels,andtosurviveamultiplequantumfilter,youneedtohaveatleasttwospinsorthreespinsfora2Qor3Qtransition,respectively.Thus,singletsaredrasticallyreducedinintensityinaDQF-COSYspectrum.TheDisadvantagesofDQFCOSYTherearealsodisadvantagestotheDQF-COSYrelativetoCOSY.First,thesensitivityofDQFisaboutafactoroftwolowerthanregularCOSY.Second,MQrelaxationin1Hsisveryslow,sotheexperimentsrequirearelativelylongd1relaxationdelay.Thus,whileagoodCOSYspectrumcouldbegeneratedinabout2-4hoursofdataaccumulation,agoodDQF-COSYrequiresabout16-24hourstoallowcompleterelaxationduringd1.βαγδεTOCSYregionofamideprotonsfromresiduesLysine29and48TOCSYofBPTIatdifferentpressuresTOCSYofBPTIatdifferentpressuresCOSYFamilyCOSYCOSY-45,COSY-90R-COSY(LR-COSY)pQFCOSYPE-COSYE-COSYMQCOSYTOCSYzCOSY,zzCOSY…..3JHNα=5.9cos2Φ-1.3cosΦ+2.2

3Jαβ=9.5cos2χ1-1.6cosχ1+1.8

JCouplingMeasurementJcouplingandpeakintensityJcouplingandlinewidthJcouplingandoverlapBasicHeteronuclear2DExperimentsIntroductionHeteronuclearcorrelation(HETCOR)anditsvariants(COLOC,HMBCetc)Heteronuclearmultiple-quantumcoherence(HMQC)Heteronuclearsingle-quantumcoherence(HSQC)Introduction

Theavailabilityofother(“hetero”)nucleithanprotonformulti-dimensionalNMRspectroscopyisextremelyuseful,particularly,formacromolecules(ofsyntheticorbiologicalorigin)becausetheconnectivitybetweenprotonsandheteronuclearspinscanbeestablishedinadditiontothehomonuclearmulti-dimensionalspectra.Likehomonuclear2Dspectroscopy,thecentraltaskinheteronulcear2Dexperimentsistoselectpropercoherencepathwayssothatthedesiredinteractioncanbeelucidated.Heteronuclear2Dexperimentscanbemorediversebecause,e.g.,thedataacquisitioncanbecarriedoutonheteronuclei(C-13,N-15etc)oronprotons(inversedetection).

Heteronuclearcorrelation(HETCOR)anditsvariantsDuringt1,thecarbonsthatarecoupledtoprotonsareselectedsothatonlythosecarbonsare“visible”inthedetectionperiod.ThechoiceoftwofixeddelaysΔ1andΔ2isdeterminedbysmallestJ-couplingwewanttoobserve,i.e.,whenlong-rangecoupledcarbons(inadditiontodirectlybondedcarbons)arealsotobeobserved:Δ1=1/2Jmin,Δ2=1/3Jmin.EnhancedHeteronuclearCorrelationS(δI,δS)ωIωSCOrrelationviaLOng-rangeCoupling(COLOC)ThechoiceoftwofixeddelaysΔ1andΔ2isdeterminedbysmallestJ-couplingwewanttoobserve,i.e.,whenlong-rangecoupledcarbons(inadditiontodirectlybondedcarbons)arealsotobeobserved:Δ1=1/2Jmin,Δ2=1/3Jmin.HeteronuclearMulti-BondCorre