NMR Spectroscopy Explained

Neil E. Jacobsen, PHD, is the NMR Facility Manager in the Department of Chemistry at the University of Arizona in Tucson, where he also teaches graduate-level NMR courses. He received his PhD in organic chemistry at the University of California-Berkeley and gained experience in protein NMR spectroscopy at the University of Washington and at Genentech, Inc.

• Preface xiAcknowledgments xv1 Fundamentalsof NMR Spectroscopy in Liquids 11.1 Introduction to NMR Spectroscopy 11.2 Examples: NMR Spectroscopy of Oligosaccharides and Terpenoids 121.3 Typical Values of Chemical Shifts and Coupling Constants 271.4 Fundamental Concepts of NMR Spectroscopy 302 Interpretation of Proton (1 H) NMR Spectra 392.1 Assignment 392.2 Effect of B o Field Strength on the Spectrum 402.3 First-Order Splitting Patterns 452.4 The Use of 1 H– 1 H Coupling Constants to Determine Stereochemistry and Conformation 522.5 Symmetry and Chirality in NMR 542.6 The Origin of the Chemical Shift 562.7 J Coupling to Other NMR-Active Nuclei 612.8 Non-First-Order Splitting Patterns: Strong Coupling 632.9 Magnetic Equivalence 713 NMR Hardware and Software 743.1 Sample Preparation 753.2 Sample Insertion 773.3 The Deuterium Lock Feedback Loop 783.4 The Shim System 813.5 Tuning and Matching the Probe 883.6 NMR Data Acquisition and Acquisition Parameters 903.7 Noise and Dynamic Range 1083.8 Special Topic: Oversampling and Digital Filtering 1103.9 NMR Data Processing—Overview 1183.10 The Fourier Transform 1193.11 Data Manipulation Before the Fourier Transform 1223.12 Data Manipulation After the Fourier Transform 1264 Carbon-13 (13 C) NMR Spectroscopy 1354.1 Sensitivity of 13 C 1354.2 Splitting of 13 C Signals 1354.3 Decoupling 1384.4 Heteronuclear Decoupling: 1 H Decoupled 13 C Spectra 1394.5 Decoupling Hardware 1454.6 Decoupling Software: Parameters 1494.7 The Nuclear Overhauser Effect (NOE) 1504.8 Heteronuclear Decoupler Modes 1525 NMR Relaxation—Inversion-Recovery and the Nuclear Overhauser Effect (NOE) 1555.1 The Vector Model 1555.2 One Spin in a Magnetic Field 1555.3 A Large Population of Identical Spins: Net Magnetization 1575.4 Coherence: Net Magnetization in the x–y Plane 1615.5 Relaxation 1625.6 Summary of the Vector Model 1685.7 Molecular Tumbling and NMR Relaxation 1705.8 Inversion-Recovery: Measurement of T 1 Values 1765.9 Continuous-Wave Low-Power Irradiation of One Resonance 1815.10 Homonuclear Decoupling 1825.11 Presaturation of Solvent Resonance 1855.12 The Homonuclear Nuclear Overhauser Effect (NOE) 1875.13 Summary of the Nuclear Overhauser Effect 1986 The Spin Echo and the Attached Proton Test (APT) 2006.1 The Rotating Frame of Reference 2016.2 The Radio Frequency (RF) Pulse 2036.3 The Effect of RF Pulses 2066.4 Quadrature Detection Phase Cycling and the Receiver Phase 2096.5 Chemical Shift Evolution 2126.6 Scalar (J) Coupling Evolution 2136.7 Examples of J-coupling and Chemical Shift Evolution 2166.8 The Attached Proton Test (APT) 2206.9 The Spin Echo 2266.10 The Heteronuclear Spin Echo: Controlling J-Coupling Evolution and Chemical Shift Evolution 2327 Coherence Transfer: INEPT and DEPT 2387.1 Net Magnetization 2387.2 Magnetization Transfer 2417.3 The Product Operator Formalism: Introduction 2427.4 Single Spin Product Operators: Chemical Shift Evolution 2447.5 Two-Spin Operators: J-coupling Evolution and Antiphase Coherence 2477.6 The Effect of RF Pulses on Product Operators 2517.7 INEPT and the Transfer of Magnetization from 1 Hto 13 C 2537.8 Selective Population Transfer (SPT) as a Way of Understanding INEPT Coherence Transfer 2577.9 Phase Cycling in INEPT 2637.10 Intermediate States in Coherence Transfer 2657.11 Zero- and Double-Quantum Operators 2677.12 Summary of Two-Spin Operators 2697.13 Refocused INEPT: Adding Spectral Editing 2707.14 DEPT: Distortionless Enhancement by Polarization Transfer 2767.15 Product Operator Analysis of the DEPT Experiment 2838 Shaped Pulses Pulsed Field Gradients and Spin Locks: Selective 1D NOE and 1D TOCSY 2898.1 Introducing Three New Pulse Sequence Tools 2898.2 The Effect of Off-Resonance Pulses on Net Magnetization 2918.3 The Excitation Profile for Rectangular Pulses 2978.4 Selective Pulses and Shaped Pulses 2998.5 Pulsed Field Gradients 3018.6 Combining Shaped Pulses and Pulsed Field Gradients: “Excitation Sculpting” 3088.7 Coherence Order: Using Gradients to Select a Coherence Pathway 3168.8 Practical Aspects of Pulsed Field Gradients and Shaped Pulses 3198.9 1D Transient NOE using DPFGSE 3218.10 The Spin Lock 3338.11 Selective 1D ROESY and 1D TOCSY 3388.12 Selective 1D TOCSY using DPFGSE 3438.13 RF Power Levels for Shaped Pulses and Spin Locks 3489 Two-Dimensional NMR Spectroscopy: HETCOR COSY and TOCSY 3539.1 Introduction to Two-Dimensional NMR 3539.2 HETCOR: A 2D Experiment Created from the 1D INEPT Experiment 3549.3 A General Overview of 2D NMR Experiments 3649.4 2D Correlation Spectroscopy (COSY) 3709.5 Understanding COSY with Product Operators 3869.6 2D TOCSY (Total Correlation Spectroscopy) 3939.7 Data Sampling in t 1 and the 2D Spectral Window 39810 Advanced NMR Theory: NOESY and DQF-COSY 40810.1 Spin Kinetics: Derivation of the Rate Equation for Cross-Relaxation 40910.2 Dynamic Processes and Chemical Exchange in NMR 41410.3 2D NOESY and 2D ROESY 42510.4 Expanding Our View of Coherence: Quantum Mechanics and Spherical Operators 43910.5 Double-Quantum Filtered COSY (DQF-COSY) 44710.6 Coherence Pathway Selection in NMR Experiments 45010.7 The Density Matrix Representation of Spin States 46910.8 The Hamiltonian Matrix: Strong Coupling and Ideal Isotropic (TOCSY) Mixing 47811 Inverse Heteronuclear 2D Experiments: HSQC HMQC and HMBC 48911.1 Inverse Experiments: 1 H Observe with 13 C Decoupling 49011.2 General Appearance of Inverse 2D Spectra 49811.3 Examples of One-Bond Inverse Correlation (HMQC and HSQC) Without 13 C Decoupling 50111.4 Examples of Edited 13 C-Decoupled HSQC Spectra 50411.5 Examples of HMBC Spectra 50911.6 Structure Determination Using HSQC and HMBC 51711.7 Understanding the HSQC Pulse Sequence 52211.8 Understanding the HMQC Pulse Sequence 53311.9 Understanding the Heteronuclear Multiple-Bond Correlation (HMBC) Pulse Sequence 53511.10 Structure Determination by NMR—An Example 53812 Biological NMR Spectroscopy 55112.1 Applications of NMR in Biology 55112.2 Size Limitations in Solution-State NMR 55312.3 Hardware Requirements for Biological NMR 55812.4 Sample Preparation and Water Suppression 56412.5 1 H Chemical Shifts of Peptides and Proteins 57012.6 NOE Interactions Between One Residue and the Next Residue in the Sequence 57712.7 Sequence-Specific Assignment Using Homonuclear 2D Spectra 58012.8 Medium and Long-Range NOE Correlations 58612.9 Calculation of 3D Structure Using NMR Restraints 59012.10 15 N-Labeling and 3D NMR 59612.11 Three-Dimensional NMR Pulse Sequences: 3D HSQC–TOCSY and 3D TOCSY–HSQC 60112.12 Triple-Resonance NMR on Doubly-Labeled (15 N 13 C) Proteins 61012.13 New Techniques for Protein NMR: Residual Dipolar Couplings and Transverse Relaxation Optimized Spectroscopy (TROSY) 621Appendix A: A Pictorial Key to NMR Spin States 627Appendix B: A Survey of Two-Dimensional NMR Experiments 634Index 643

"The uses of the many modern multiple NMW techniques are explained and demonstrated quite well." (CHOICE, September 2008)