二维核磁共振谱原理

2D核磁共振谱COSY:HypotheticalCouplingCOSY:1H-1HCouplingCouplingnetworkscanbetracedout,asshowninthefigurebelow.Thecoloredarrowstraceoutcouplingnetworks,correspondingto:H-3—H-5—H-10—OHH-10-H-9H-3—H-16H-16—H-11COSYSpectrumofCodeineTableofCOSYcorrelationsshiftshiftAssignments6.66.77-85.75.33-55.72.73-165.74.93-9weak5.34.25-105.32.75-164.94.29-104.22.910-OH3.32.711-163.32.411-143.32.311-18'3.02.418-143.02.318-18'2.62.413-13'2.62.113-172.61.913-17'2.42.113'-172.41.913'-17'2.11.917-17'COSYSpectrumofCodeineWhatYouSeeInaNOESY...突出表现NOE效应的NOESY谱NOESY...NOESYSpectrumofCodeineThesampleis3.3mgofcodeinein.65mlCDCl3AcontourplotoftheNOESYspectrumisshownbelow.Aswithallhomonuclear2Dplots,thediagonalconsistsofintensepeaksthatmatchthenormalspectrum,asdoprojectionsontoeachaxis.Theinterestinginformationiscontainedinthecross-peaks,whichappearatthecoordinatesof2protonswhichhaveanNOEcorrelation.Forsmallmolecules,theNOEisnegative.ExchangepeakshavetheoppositesignfromNOEpeaks,makingthemeasytoidentify.Thewaterpeakat1.5ppmexchangeswiththeOHat2.9ppm,shownhereinred.Thespectrumisphasedwiththelargediagonalpeaksinverted(showninredhere),sotheNOEcross-peaksarepositive.Expansionoftheupfieldregion:8-7,127-18,18'3-5,105-11,16,18'9-10,17,17'10-1611-18,16,14,18'18-13,18'16-14,1713-14,17,17'13'-17,17'17-17'NOESYSpectrumofCodeineTableofNOEs:('indicatesthemoreupfieldofgeminalCH2protons)Inadditiontoconfirmingassignments,theNOESYspectrumallowsstereospecificassignmentsofmethyleneHs.The3cross-peaksindicatedinredontheplotbelowdistinguishbetweenthe3CH2pairs:5-18'16-1718-13NOESYSpectrumofCodeine2DC-H相关谱（C-HCOSY)2D远程C-HCOSYHeteronuclearMultipleQuantumCoherence(HMQC)andHeteronuclearMultipleBondCoherence(HMBC):2-DinverseH,Ccorrelationtechniquesthatallowforthedeterminationofcarbon(orotherheteroatom)tohydrogenconnectivity.GradientHMBC(gHMBC)improvestheacquiredspectrabysignificantlyreducingunwantedsignalartifacts.HMQCisselectivefordirectC-HcouplingHMBCwillgivelongerrangecouplings(2-4bondcoupling).HMQCandHMBCHMQC(trans-ethyl2-butenoate)HMQC–HeteronuclearMultiple-QuantumCoherenceExperimentC(9)-HC(9)-HHMQC–HeteronuclearMultiple-QuantumCoherenceExperimentHMQC(1-BondCHCorrelation)ofCodeine1H13CAssignment6.611386.512075.713335.312854.89194.266103.856123.359113.0&2.320182.640162.6&2.446132.443142.0&1.83617Thisisa2Dexperimentusedtocorrelate,orconnect,1Hand13Cpeaksforatomsseparatedbymultiplebonds(usually2or3).Thecoordinatesofeachpeakseeninthecontourplotarethe1Hand13Cchemicalshifts.Thisisextremelyusefulformakingassignmentsandmappingoutcovalentstructure.TheinformationobtainedisanextensionofthatobtainedfromanHMQCspectrum,butismorecomplicatedtoanalyze.LikeHMQC,thisisaninversedetectionexperiment,andispossibleonlyonnewermodelspectrometers.AcornNMR'snewJEOLEclipse+400isequippedtoperforminverseexperiments,andusesZ-gradientsforimprovedspectralquality.ThetimerequiredforanHMBCdependsontheamountofmaterial,butismuchgreaterthanforHMQC,andcantakefromanhourtoovernight.HMBC(Multiple-BondCHCorrelation)ofCodeinePeaksoccuratcoordinatesinthe2dimensionscorrespondingtothechemicalshiftsofacarbonandprotonsseparatedby(usually)2or3bonds.Theexperimentisoptimizedforcouplingsof~8Hz.Smallercouplingsareobserved,buttheirintensitiesarereduced.Comparetothespectrumobtainedwhentheexperimentisoptimizedfor4Hz.Theexperimentisdesignedtosuppress1-bondcorrelations,butafewareobservedinmostspectra.Inconcentratedsamplesofconjugatedsystems,4-bondcorrelationscanbeobserved.ThereisnowaytoknowhowmanybondsseparateanHandCwhenapeakisobserved,soanalysisisaprocessofattemptingtoassignallobservedpeaks,testingforconsistencyandcheckingtobesurenoneoftheassignmentswouldrequireimplausibleorimpossiblecouplings.Becauseofthelargenumberofpeaksobserved,analysisrequiresseveralexpandedplots.Inthiscase,thespectrumhasbeendividedinto4sections,eachofwhichisdiscussedbelow.HMBC(Multiple-BondCHCorrelation)ofCodeineHMBC(Multiple-BondCHCorrelation)ofCodeineThediscussionbelowusesthenumberingsystemshownatright.Thenumberswereassignedtopeaksinthe1D13Cspectrum,startingdownfield,movingupfield,andnumberingeachsequentially.ThisgeneratesauniqueidentifierforeachCarbon,evenbeforeknowinganyassignments.HMBC(Multiple-BondCHCorrelation)ofCodeineC9-HC3-HC5-H123456C9-HC3-HC5-H17HMBC(Multiple-BondCHCorrelation)ofCodeineMore1Dand2D-SepctraforCodeine1D1Hand13CNMRSpectraofCodeineC18H21NO3,MW=299.4DataacquiredonaJEOLEclipse+400spectrometer1Hspectrum:C3-HC5-HC10-HC7-HC8-HC9-HC12-H3C11-HC16-HC18-HC18-HC17-HC14-HC3-HC5-HC9-HC3-HC5-H13Cspectra18mgsample,1.3hrsacquisitiontime123456791011121314,151617181D1Hand13CNMRSpectraofCodeinePeakAssignmentsforCodeine13C(ppm)1H(ppm)1146.3q2142.23q3133.43CH5.714131.13q5128.30CH5.296127.30q7119.58CH6.578113.03CH6.66991.39CH4.891066.43CH4.181158.92CH3.351256.40CH33.841346.47CH22.59,2.401443.12CH32.441542.99q1640.82CH2.671735.85CH22.06,1.881820.46CH23.04,2.30OH2.99Bothexperimentsareusedtoidentifymultiplicity(quaternary,CH,CH2orCH3)ofpeaksina13Cspectrum.Usually,DEPTispreferredbecausemuchlesstimeisrequired.ForDEPT,1Hmagnetizationisgeneratedfirs