Nuclear Magnetic Resonance: Basic Principles

Nuclear magnetic resonance spectroscopy is presently going through an explosive phase of development. This has been brought about largely on account of the advent of Fourier transform NMR spectrometers linked to powerful microcomputers which have opened up a whole new world for structural chemists and biochemists. This is exemplified by a host of publications, especially on new pulse sequences, which continue to provide new exciting modifications for recording two-dimensional NMR. Moreover, NMR is no longer confined to structural chemists but has moved firmly into the area of medicine as a powerful nondestructive body scanning technique. With this background, I felt that there was need for a text which would provide a fairly comprehensive account of the important features of 1 H- and 13C-NMR spectroscopy in one book, as well as make available an up-to-date account of recent developments of new pulse sequences, with particular reference to 2D-NMR spectroscopy. Since this book is written for students of chemistry and biochemistry as well as for biology students who have chemistry as a subsidiary, it was decided to avoid a complex mathematical treatment and to present, as far as possible without oversimplification, a qualitative account of 1 H- and 13C-NMR spectroscopy as it is today. I hope that the book satisfactorily meets these objectives.

1 Chemical Shift in 1H-NMR Spectroscopy.- 1.1. Introduction.- 1.2. Relaxation Processes.- 1.2.1. Spin—Lattice Relaxation (T1).- 1.2.2. Spin—Spin Relaxation (T2).- 1.3. Chemical Shift.- 1.3.1. Some Factors Affecting Chemical Shift.- Recommended Reading.- 2 Spin—Spin Coupling 1H-NMR Spectroscopy.- 2.1. Introduction.- 2.2. Chemical and Magnetic Equivalence of Nuclei.- 2.3. Different Spin Systems.- 2.3.1. Two Coupled Nuclei (AX, AB, A2 Systems).- 2.3.2. Three Coupled Nuclei (AX2, AMX, ABX, ABC, AB2 Systems).- 2.3.3. Four Coupled Nuclei (AX3, A2X2, AA?XX?, A2B2, AB3, AA?BB? ABCD Systems).- 2.3.4. Five Interacting Nuclei (A2X3, A2B3, AA?BB?C).- 2.4. Factors Affecting Coupling Constants.- 2.4.1. Dependence on Dihedral Angle.- 2.4.2 Dependence of Coupling Constants on Electronegativity of Substituents.- 2.4.3. Dependence of3J on H—C—C—H Valence Angles.- 2.4.4. Dependence of 3J on C—C Bond Lengths/? Bond Orders.- 2.5. Long-Range Spin—Spin Coupling.- 2.5.1. Long-Range Coupling in Unsaturated Compounds.- 2.5.2. Through-Space Coupling.- 2.5.3. Long-Range Coupling in Saturated Systems.- 2.5.4. Dipole—Dipole Interaction.- Recommended Reading.- 3 Experimental Procedures in NMR Spectroscopy.- 3.1. Pulsed Fourier Transform NMR Spectroscopy.- 3.1.1. Rotating Frame of Reference.- 3.1.2. Free Induction Decay.- 3.1.3. Setting Pulse Widths.- 3.1.4. Adjustment of Pulse Frequency.- 3.1.5. Signal Weighting.- 3.1.6. Phase Correction.- 3.1.7. Double Resonance.- 3.1.8. Off-Resonance Decoupling.- 3.2. Study of Dynamic Effects by NMR Spectroscopy.- 3.2.1. Hindered Internal Rotation.- 3.2.2. Keto-Enol Tautomerism.- 3.2.3. Inversion of Configuration.- 3.2.4. Proton Exchange Equilibria.- 3.2.5. Valence Tautomerism.- Recommended Reading.- 4 Chemical Shifts and Spin—Spin Couplings in 13C-NMR Spectroscopy.- 4.1. Chemical Shifts in 13C-NMR Spectroscopy.- 4.1.1. Factors Affecting Chemical Shifts.- 4.1.2. Additivity of Substituent Effects.- 4.1.3. Chemical Shifts of Organic Molecules.- 4.2. Couplings in 13C-NMR Spectroscopy.- 4.2.1. Carbon—Proton and Carbon—Carbon Coupling.- 4.3. High-Resolution NMR in Solids.- 4.3.1. NMR Imaging.- Recommended Reading.- 5 Special Pulse Sequences and Two-Dimensional NMR Spectroscopy.- 5.1. Spin-Echo and Polarization Transfer.- 5.1.1. Spin-Echo Measurements.- 5.1.2. Attached Proton Test by Gated Spin-Echo (GASPE) (or SEFT) Measurements.- 5.1.3. Cross-Polarization.- 5.2. Carbon—Carbon Connectivity by INADEQUATE Spectra.- 5.2.1. INADEQUATE Spectra.- 5.2.2. DANTE Spectra.- 5.3. Two-Dimensional NMR Spectroscopy.- 5.3.1. 2D J-Resolved Spectroscopy.- 5.3.2. 2D-Shift Correlated Spectroscopy.- 5.4. Chemical Shift Correlations Through Cross-Relaxation and Exchange.- 5.4.1. NOESY Spectra.- 5.4.2. Two-Dimensional Heteronuclear NOE (HOESY).- 5.4.3. Relayed NOESY.- 5.4.4. Simultaneous 2D Correlated (COSY) and 2D Nuclear Overhauser Enhancement (NOESY) Spectroscopy (COCONOSY).- 5.5. Two-Dimensional Heteronuclear Relayed Coherence Transfer (RCT) Spectroscopy.- 5.5.1. Heteronuclear Relayed Proton Correlated Spectroscopy (HERPECS).- 5.6. Double-Quantum Coherence.- 5.6.1. Carbon—Carbon Connectivity Plot (CCCP) by Double-Quantum Coherence.- 5.6.2. Two-Dimensional Double-Quantum Coherence Echo Correlated Spectroscopy (DECSY).- 5.6.3. Relayed Double-Quantum 2D-NMR Spectroscopy.- 5.6.4. X-Relayed 1H—1H Correlated Spectroscopy (X-Relayed 1H—1H COSY).- 5.6.5. Carbon-Relayed 1H—13C Correlated Spectroscopy.- Recommended Reading.- Appendix A Problems.- Appendix B Answers to Problems.