NMR spectroscopy explained

685 Pages·2007·13.26 MB·English

NMR SPECTROSCOPY EXPLAINED

NMR SPECTROSCOPY
EXPLAINED
Simplified Theory, Applications and
Examples for Organic Chemistry
and Structural Biology
Neil E. Jacobsen, Ph.D.
University of Arizona
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LibraryofCongressCataloging-in-PublicationData:
Jacobsen,NeilE.
NMRSpectroscopyExplained:SimplifiedTheory,ApplicationsandExamplesforOrganicChemistryand
StructuralBiology/NeilEJacobsen,Ph.D.
p.cm.
ISBN978-0-471-73096-5(cloth)
1. Nuclearmagneticresonancespectroscopy.2. Chemistry,Organic.3. Molecularbiology. I.Title.
QD96.N8J332007
543(cid:2).66--dc22
2007006911
PrintedintheUnitedStatesofAmerica
10987654321
CONTENTS
Preface xi
Acknowledgments xv
1 FundamentalsofNMRSpectroscopyinLiquids 1
1.1 IntroductiontoNMRSpectroscopy, 1
1.2 Examples:NMRSpectroscopyofOligosaccharidesandTerpenoids, 12
1.3 TypicalValuesofChemicalShiftsandCouplingConstants, 27
1.4 FundamentalConceptsofNMRSpectroscopy, 30
1
2 InterpretationofProton( H)NMRSpectra 39
2.1 Assignment, 39
2.2 EffectofB FieldStrengthontheSpectrum, 40
o
2.3 First-OrderSplittingPatterns, 45
2.4 TheUseof1H–1HCouplingConstantstoDetermineStereochemistry
andConformation, 52
2.5 SymmetryandChiralityinNMR, 54
2.6 TheOriginoftheChemicalShift, 56
2.7 JCouplingtoOtherNMR-ActiveNuclei, 61
2.8 Non-First-OrderSplittingPatterns:StrongCoupling, 63
2.9 MagneticEquivalence, 71
3 NMRHardwareandSoftware 74
3.1 SamplePreparation, 75
3.2 SampleInsertion, 77
3.3 TheDeuteriumLockFeedbackLoop, 78
vi CONTENTS
3.4 TheShimSystem, 81
3.5 TuningandMatchingtheProbe, 88
3.6 NMRDataAcquisitionandAcquisitionParameters, 90
3.7 NoiseandDynamicRange, 108
3.8 SpecialTopic:OversamplingandDigitalFiltering, 110
3.9 NMRDataProcessing—Overview, 118
3.10 TheFourierTransform, 119
3.11 DataManipulationBeforetheFourierTransform, 122
3.12 DataManipulationAftertheFourierTransform, 126
4 Carbon-13(13C)NMRSpectroscopy 135
4.1 Sensitivityof13C, 135
4.2 Splittingof13CSignals, 135
4.3 Decoupling, 138
4.4 HeteronuclearDecoupling:1HDecoupled13CSpectra, 139
4.5 DecouplingHardware, 145
4.6 DecouplingSoftware:Parameters, 149
4.7 TheNuclearOverhauserEffect(NOE), 150
4.8 HeteronuclearDecouplerModes, 152
5 NMRRelaxation—Inversion-RecoveryandtheNuclear
OverhauserEffect(NOE) 155
5.1 TheVectorModel, 155
5.2 OneSpininaMagneticField, 155
5.3 ALargePopulationofIdenticalSpins:NetMagnetization, 157
5.4 Coherence:NetMagnetizationinthex–yPlane, 161
5.5 Relaxation, 162
5.6 SummaryoftheVectorModel, 168
5.7 MolecularTumblingandNMRRelaxation, 170
5.8 Inversion-Recovery:MeasurementofT Values, 176
1
5.9 Continuous-WaveLow-PowerIrradiationofOneResonance, 181
5.10 HomonuclearDecoupling, 182
5.11 PresaturationofSolventResonance, 185
5.12 TheHomonuclearNuclearOverhauserEffect(NOE), 187
5.13 SummaryoftheNuclearOverhauserEffect, 198
6 TheSpinEchoandtheAttachedProtonTest(APT) 200
6.1 TheRotatingFrameofReference, 201
6.2 TheRadioFrequency(RF)Pulse, 203
6.3 TheEffectofRFPulses, 206
6.4 QuadratureDetection,PhaseCycling,andtheReceiverPhase, 209
CONTENTS vii
6.5 ChemicalShiftEvolution, 212
6.6 Scalar(J)CouplingEvolution, 213
6.7 ExamplesofJ-couplingandChemicalShiftEvolution, 216
6.8 TheAttachedProtonTest(APT), 220
6.9 TheSpinEcho, 226
6.10 TheHeteronuclearSpinEcho:ControllingJ-CouplingEvolution
andChemicalShiftEvolution, 232
7 CoherenceTransfer:INEPTandDEPT 238
7.1 NetMagnetization, 238
7.2 MagnetizationTransfer, 241
7.3 TheProductOperatorFormalism:Introduction, 242
7.4 SingleSpinProductOperators:ChemicalShiftEvolution, 244
7.5 Two-SpinOperators:J-couplingEvolutionandAntiphaseCoherence, 247
7.6 TheEffectofRFPulsesonProductOperators, 251
7.7 INEPTandtheTransferofMagnetizationfrom1Hto13C, 253
7.8 SelectivePopulationTransfer(SPT)asaWayofUnderstanding
INEPTCoherenceTransfer, 257
7.9 PhaseCyclinginINEPT, 263
7.10 IntermediateStatesinCoherenceTransfer, 265
7.11 Zero-andDouble-QuantumOperators, 267
7.12 SummaryofTwo-SpinOperators, 269
7.13 RefocusedINEPT:AddingSpectralEditing, 270
7.14 DEPT:DistortionlessEnhancementbyPolarizationTransfer, 276
7.15 ProductOperatorAnalysisoftheDEPTExperiment, 283
8 ShapedPulses,PulsedFieldGradients,andSpinLocks:
Selective1DNOEand1DTOCSY 289
8.1 IntroducingThreeNewPulseSequenceTools, 289
8.2 TheEffectofOff-ResonancePulsesonNetMagnetization, 291
8.3 TheExcitationProfileforRectangularPulses, 297
8.4 SelectivePulsesandShapedPulses, 299
8.5 PulsedFieldGradients, 301
8.6 CombiningShapedPulsesandPulsedFieldGradients:
“ExcitationSculpting”, 308
8.7 CoherenceOrder:UsingGradientstoSelectaCoherencePathway, 316
8.8 PracticalAspectsofPulsedFieldGradientsandShapedPulses, 319
8.9 1DTransientNOEusingDPFGSE, 321
8.10 TheSpinLock, 333
8.11 Selective1DROESYand1DTOCSY, 338
8.12 Selective1DTOCSYusingDPFGSE, 343
8.13 RFPowerLevelsforShapedPulsesandSpinLocks, 348
viii CONTENTS
9 Two-DimensionalNMRSpectroscopy:
HETCOR,COSY,andTOCSY 353
9.1 IntroductiontoTwo-DimensionalNMR, 353
9.2 HETCOR:A2DExperimentCreatedfromthe1DINEPTExperiment, 354
9.3 AGeneralOverviewof2DNMRExperiments, 364
9.4 2DCorrelationSpectroscopy(COSY), 370
9.5 UnderstandingCOSYwithProductOperators, 386
9.6 2DTOCSY(TotalCorrelationSpectroscopy), 393
9.7 DataSamplingint andthe2DSpectralWindow, 398
1
10 AdvancedNMRTheory:NOESYandDQF-COSY 408
10.1 SpinKinetics:DerivationoftheRateEquationforCross-Relaxation, 409
10.2 DynamicProcessesandChemicalExchangeinNMR, 414
10.3 2DNOESYand2DROESY, 425
10.4 ExpandingOurViewofCoherence:QuantumMechanics
andSphericalOperators, 439
10.5 Double-QuantumFilteredCOSY(DQF-COSY), 447
10.6 CoherencePathwaySelectioninNMRExperiments, 450
10.7 TheDensityMatrixRepresentationofSpinStates, 469
10.8 TheHamiltonianMatrix:StrongCouplingandIdealIsotropic
(TOCSY)Mixing, 478
11 InverseHeteronuclear2DExperiments:HSQC,HMQC,andHMBC 489
11.1 InverseExperiments:1HObservewith13CDecoupling, 490
11.2 GeneralAppearanceofInverse2DSpectra, 498
11.3 ExamplesofOne-BondInverseCorrelation(HMQCandHSQC)
Without13CDecoupling, 501
11.4 ExamplesofEdited,13C-DecoupledHSQCSpectra, 504
11.5 ExamplesofHMBCSpectra, 509
11.6 StructureDeterminationUsingHSQCandHMBC, 517
11.7 UnderstandingtheHSQCPulseSequence, 522
11.8 UnderstandingtheHMQCPulseSequence, 533
11.9 UnderstandingtheHeteronuclearMultiple-BondCorrelation
(HMBC)PulseSequence, 535
11.10 StructureDeterminationbyNMR—AnExample, 538
12 BiologicalNMRSpectroscopy 551
12.1 ApplicationsofNMRinBiology, 551
12.2 SizeLimitationsinSolution-StateNMR, 553
12.3 HardwareRequirementsforBiologicalNMR, 558
12.4 SamplePreparationandWaterSuppression, 564
12.5 1HChemicalShiftsofPeptidesandProteins, 570
CONTENTS ix
12.6 NOEInteractionsBetweenOneResidueandtheNextResiduein
theSequence, 577
12.7 Sequence-SpecificAssignmentUsingHomonuclear2DSpectra, 580
12.8 MediumandLong-RangeNOECorrelations, 586
12.9 Calculationof3DStructureUsingNMRRestraints, 590
12.10 15N-Labelingand3DNMR, 596
12.11 Three-DimensionalNMRPulseSequences:3DHSQC–TOCSY
and3DTOCSY–HSQC, 601
12.12 Triple-ResonanceNMRonDoubly-Labeled(15N,13C)Proteins, 610
12.13 NewTechniquesforProteinNMR:ResidualDipolarCouplings
andTransverseRelaxationOptimizedSpectroscopy(TROSY), 621
AppendixA:APictorialKeytoNMRSpinStates 627
AppendixB:ASurveyofTwo-DimensionalNMRExperiments 634
Index 643