Preface xiii
1 How and Why Nuclei Relax 1
1.1 Nucleus in an External Magnetic Field 4
1.2 Spin–Lattice and Spin–Spin Nuclear Relaxation 7
1.2.1 Macroscopic Magnetization: Relaxation
Times T1 and T2 8
1.3 Molecular Motions as the Reason
for Nuclear Relaxation 11
1.3.1 Correlation Times and Activation Energies
of Molecular Motions 13
1.3.2 Isotropic and Anisotropic Molecular Motions 15
Bibliography 18
2 How to Measure NMR Relaxation
Times 19
2.1 Exponential and Non-exponential
Nuclear Relaxation 20
2.2 Measurements of Spin–Lattice
Relaxation Times 20
2.3 Measurements of Selective and Biselective
T1 Times 24
2.4 Determination of T1ρ and T2 27
2.5 Preparation of Samples for Relaxation
Experiments 28
Bibliography 29
3 Errors in Determinations
of Relaxation Times 31
3.1 Instrumental Errors 32
3.2 Incorrect Parameters for T1, T2 Measurements
and T1, T2 Calculations 33
3.3 Coupled Nuclear Relaxation 34
3.4 Chemical Exchange 37
Bibliography 42
4 NMR Relaxation by Dipole–Dipole
and Quadrupole Interactions 43
4.1 Intramolecular Dipole–Dipole Relaxation:
Homo- and Heteronuclear Dipolar Coupling and
the Spectral Density Function 44
4.2 How to Reveal the Presence of the Dipolar
Mechanism 48
4.2.1 NOE as a Test for Dipole–Dipole Nuclear
Relaxation 48
4.2.2 Evaluations of the Dipolar Contributions from
Selective and Nonselective T1 Times 52
4.3 Intermolecular Dipole–Dipole Interactions 53
4.4 Electric Field Gradients
at Quadrupolar Nuclei 53
4.5 Nuclear Quadrupole Coupling Constant
as Measure of the Electric Field Gradient 54
4.6 Quadrupole Relaxation 56
Bibliography 57
5 Relaxation by Chemical Shift
Anisotropy, Spin–Rotation
Relaxation, Scalar Relaxation
of the Second Kind
and Cross-mechanisms 59
5.1 Relaxation by Chemical Shift Anisotropy 59
5.2 Spin–Rotation Relaxation 63
5.3 Interference Mechanisms of Nuclear Relaxation 64
5.4 Scalar Relaxation of the Second Kind 65
Bibliography 67
6 Nuclear Relaxation in Molecular
Systems with Anisotropic Motions 69
6.1 Spin–Lattice Nuclear Relaxation in Ellipsoidal
Molecules: Temperature Dependences
of T1 Times 70
6.2 How to Reveal Anisotropic Molecular Motions
in Solution 74
6.3 Nuclear Relaxation in the Presence
of Correlation Time Distributions 76
Bibliography 80
7 1H T1 Relaxation Diagnostics
in Solution 81
7.1 Revealing Weak Intermolecular Interactions
by T1 Time Measurements in Solution 82
7.2 T1 Studies of Exchange in Simple Molecular
Systems 87
7.3 Structural 1H T1 Criterion 89
7.4 Partially Relaxed NMR Spectra 92
Bibliography 94
8 Internuclear Distances from 1H T1
Relaxation Measurements
in Solution 97
8.1 X−H Distances: Metal–Hydride
Bond Lengths 98
8.1.1 How to Determine Metal–Hydride Bond Lengths
by Standard 1H T1 Measurements 101
8.1.2 Metal–Hydride Bond Lengths by 1H T1sel
and 1H T1min Measurements 104
8.2 Proton–Proton Distances by Standard
1H T1 Measurements 108
8.3 H−H Distances by T1sel/T1bis Measurements 111
8.4 H...H Distances in Intermediates 115
8.5 Analyzing the Errors in 1H T1 Determinations
of Internuclear Distances 119
Bibliography 120
9 Deuterium Quadrupole Coupling
Constants from 2H T1 Relaxation
Measurements in Solution 123
9.1 How to Determine DQCC Values 123
9.2 DQCC Values from 2H T1 Measurements
in Solution (Fast Motion Regime) 126
9.3 DQCC Values via 2H T1min Measurements
in Solution 130
9.4 Errors in DQCC Determinations 132
Bibliography 136
10 Spin – Lattice 1H and 2H Relaxation
in Mobile Groups 139
10.1 1H T1 Times and H−H Distances in the Presence
of Fast Vibrations and Librations 141
10.2 1H T1 Times and H−H Distances in the Presence
of Fast Rotational Diffusion 142
10.3 The Spectral Density Function
for High-amplitude Librations 145
10.4 90◦ Jumps in a Four-fold Potential 146
10.5 Deuterium Spin – Lattice NMR Relaxation in
Mobile Molecular Fragments 148
Bibliography 154
11 Relaxation of Nuclei Other Than 1H
and 2H and Specific Relaxation
Experiments 155
11.1 Chemical Shift Anisotropies and Nuclear
Quadrupole Coupling Constants from T1 Times
of Heavy Nuclei in Solution 156
11.2 Multinuclear Relaxation Approaches to
Complexation, Association and H-bonding 159
11.3 23Na Relaxation in Solutions of Complex
Molecular Systems 162
11.4 Character of Molecular Motions from 17O and 2H
T1 Relaxation in Solution 165
11.5 Two-dimensional T1 and T1ρ NMR Experiments 166
11.6 Chemical Exchange in Complex Molecular
Systems from 15N Relaxation in Solution 168
11.7 R1/R2 Method 170
11.8 Cross-correlation Relaxation Rates
and Structures of Complex Molecular
Systems in Solution 172
11.9 Variable-field Relaxation Experiments 174
Bibliography 176
Contents xi 12 Paramagnetic NMR Relaxation 179
12.1 Theoretical Basis of Paramagnetic Relaxation
Enhancement 179
12.2 Paramagnetic Relaxation Rate Enhancements
in the Presence of Chemical Exchange 185
12.3 Structural Applications of Paramagnetic
Relaxation Rate Enhancement 187
12.4 Kinetics of Ligand Exchange via Paramagnetic
Relaxation Rate Enhancement 191
12.5 Longitudinal Electron Relaxation Time
at Paramagnetic Centers from
Variable-high-field NMR Experiments 193
Bibliography 195
Concluding Remarks 197
Index 199
请点击此处下载
收藏
