Preface ...................................................... XIII
Symbols and Abbreviations ...................................... XV
1 Fundamentals of Magnetism ..................................... 1
Jun Yamauchi
1.1 Magnetism of Materials .................................... 1
1.1.1 Historical Background ............................... 1
1.1.2 Magnetic Moment and its Energy in a Magnetic
Field ............................................... 3
1.1.3 Definitions of Magnetization and Magnetic
Susceptibility ...................................... 4
1.1.4 Diamagnetism and Paramagnetism ...................... 5
1.1.5 Classification of Magnetic Materials ................ 6
1.1.6 Important Variables, Units, and Relations ........... 7
1.2 Origins of Magnetism ...................................... 8
1.2.1 Origins of Diamagnetism ............................. 8
1.2.2 Origins of Paramagnetism ........................... 10
1.2.3 Magnetic Moments ................................... 13
1.2.4 Specific Rules for Many Electrons .................. 15
1.2.5 Magnetic Moments in General Cases .................. 17
1.2.6 Zeeman Effect ...................................... 18
1.2.7 Orbital Quenching .................................. 19
1.3 Temperature Dependence of Magnetic Susceptibility ........ 21
1.3.1 The Langevin Function of Magnetization and
the Curie Law ...................................... 21
1.3.2 The Brillouin Function of Magnetization and
the Curie Law ...................................... 22
1.3.3 The Curie-Weiss Law ................................ 24
1.3.4 Magnetic Ordered State ............................. 26
1.3.5 Magnetic Interactions .............................. 30
1.3.5.1 Exchange Interaction ....................... 30
1.3.5.2 Dipolar Interaction ........................ 31
1.3.6 Spin Hamiltonian ................................... 34
1.3.7 Van Vleck Formula for Susceptibility ............... 35
1.3.8 Some Examples of the van Vleck Formula ............. 36
1.3.8.1 The Curie Law .............................. 36
1.3.8.2 Zero-Filed Splitting Case .................. 37
1.3.8.3 Spin Cluster Case—The Dimer Model .......... 37
1.3.8.4 Multiple-spin Cluster Case—The Triangle
or Others .................................. 39
1.3.8.5 Temperature-Independent Paramagnetism ...... 39
1.3.9 Low-Dimensional Interaction Network ................ 40
1.4 Experimental Magnetic Data Acquisition ................... 43
1.4.1 Methods ............................................ 43
1.4.2 Evaluations of Magnetic Susceptibility and
Magnetic Moment References ......................... 45
2 Molecular Magnetism .......................................... 47
Jun Yamauchi
2.1 Magnetic Origins from Atoms and Molecules ................ 47
2.1.1 Historical Background .............................. 47
2.1.2 Spin States Derived from Chemical Bonds ............ 48
2.1.3 Organic Free Radicals .............................. 50
2.1.4 Coordinate Compounds ............................... 50
2.2 Characteristics of Molecular Magnetism ................... 51
2.2.1 Molecular Paramagnetism ............................ 51
2.2.2 Magnetic Properties of Organic Free Radicals ....... 52
2.3 Nitroxide as a Building Block ............................ 53
2.3.1 Stability of the N-O Bond .......................... 53
2.3.2 Structural Resonance of the N-O Bond ............... 54
2.3.3 Molecular and Magnetic Interactions between
Nitroxides ......................................... 55
2.3.4 Nitroxides as Building Block ....................... 56
2.4 Low-Dimensional Properties of Nitroxides ................. 57
2.4.1 One-Dimensional Magnetism .......................... 57
2.4.1.1 TANOL (TEMPOL) ............................. 57
2.4.1.2 F5PNN ...................................... 59
2.4.2 Interchain Interaction and Spin Long-Range
Ordering ........................................... 60
2.4.3 Two-Dimensional Magnetism .......................... 63
2.4.3.1 DANO ....................................... 63
2.4.3.2 p-NPNN ..................................... 64
2.4.4 Coordination of Nitroxide with Metal Ions .......... 65
2.4.4.1 Cu2+, Mn2+-TANOL (TEMPOL) ................... 65
2.4.4.2 Mn2+-IPNN .................................. 66
References ................................................... 68
3 Fundamentals of Electron Spin Resonance (ESR) ................ 71
Jun Yamauchi
3.1 Magnetic Resonance of Electron and Nuclear Spins ......... 71
3.1.1 Historical Background .............................. 71
3.1.2 Classification of Magnetic Resonance ............... 72
3.2 Principle of Electron Spin Resonance (ESR) ............... 72
3.2.1 Principle of ESR from Spectroscopic
Interpretation ..................................... 72
3.2.2 Principle of ESR from Resonance Interpretation ..... 74
3.2.3 Bloch Equation ..................................... 77
3.2.3.1 Solutions of the Bloch Equation ............ 77
3.2.3.2 Absorption Line Shape ...................... 78
3.2.3.3 Relaxation Times ........................... 81
3.2.4 Modified Bloch Equation ............................ 82
3.2.5 Hyperfine Interaction .............................. 84
3.2.5.1 Interaction of the Electron Spin with
Nuclear Spins .............................. 84
3.2.5.2 Hyperfine Splitting ........................ 85
3.2.5.3 Hydrogen Atom (S = 1/2 and I = 1/2) ........ 87
3.2.5.4 Spin Polarization Mechanism ................ 88
3.2.6 Fine Structure ..................................... 90
3.2.7 Dynamical Phenomena ................................ 91
3.2.7.1 Correlation Time ........................... 91
3.2.7.2 Rotational Correlation Time ................ 92
3.2.7.3 Chemical Exchange .......................... 94
3.3 Anisotropic Parameters in Crystal ........................ 94
3.3.1 g-Anisotropy ....................................... 94
3.3.2 A-Anisotropy ....................................... 96
3.3.3 D-Anisotropy ....................................... 99
3.3.4 Anisotropic Parameters from ESR Powder Pattern ..... 99
3.4 Pulsed ESR .............................................. 102
3.4.1 Fundamental Concept of FT-ESR ..................... 102
3.4.2 Electron Spin Echo (ESE) .......................... 104
3.4.2.1 Two-Pulse Method .......................... 104
3.4.2.2 Three-Pulse Method ........................ 105
3.4.2.3 Inversion Recovery Method ................. 106
3.4.2.4 Echo-Detected ESR (ED-ESR) ................ 106
3.4.2.5 Nutation Spectroscopy ..................... 107
3.4.3 ESEEM ............................................. 108
3.5 Double Resonance ........................................ 108
3.5.1 ENDOR ............................................. 108
3.5.2 TRIPLE ............................................ 110
3.5.3 ELDOR ............................................. 111
3.5.4 Pulsed Methods for Double Resonance ............... 113
3.6 ESR of Magnetic Materials ............................... 114
3.6.1 Low-Dimensional Magnetic Materials ................ 114
3.6.2 Ferromagnetic Resonance (FMR) ..................... 115
3.6.3 Antiferromagnetic Resonance (AFMR) ................ 116
3.6.4 Ferrimagnetic Resonance ........................... 118
References .................................................. 118
4 Recent Advantages in ESR Techniques Used in Nitroxide
Applications ................................................ 121
Alex I. Smirnov
4.1 Introduction ............................................ 121
4.2 Macromolecular Distance Constraints from Spin-Labeling
Magnetic Resonance Experiments .......................... 122
4.2.1 Continuous Wave ESR of Nitroxide-Nitroxide
Pairs ............................................. 123
4.2.2 Continuous Wave ESR of Nitroxide-Metal Ion
Pairs ............................................. 125
4.2.3 Time Domain Magnetic Resonance of Spin Pairs ...... 128
4.2.3.1 Nitroxide Spin Labels in Protein
Structure Determination by NMR ............ 128
4.2.3.2 Electronic Relaxation Enhancement in
Spin Pairs ................................ 130
4.2.3.3 Pulsed Double Electron-Electron
Resonance ................................. 131
4.2.3.4 ESR Double Quantum Coherence
Experiments ............................... 133
4.2.4 Distance and Angular Constraints by ESR of Spin
Pairs at High Magnetic Fields ..................... 134
4.3 Multiquantum ESR ........................................ 135
4.4 Spin-Labeling ESR of Macroscopically Aligned Lipid
Bilayers and Membrane Proteins .......................... 136
4.4.1 Mechanical Alignment of Lipid Bilayers on Planar
Surfaces .......................................... 136
4.4.2 Alignment of Discoidal Bilayered Micelles by
Magnetic Forces ................................... 138
4.4.3 Nanopore-Confmed Cylindrical Bilayers ............. 139
4.5 Spin-labeling ESR at High Magnetic Fields ............... 141
4.5.1 Spin-Labeling HF and Multifrequency ESR in
Studying Molecular Dynamics ....................... 142
4.5.1.1 Stochastic Liouville Theory of Slow
Motion ESR Spectra Simulations ............ 143
4.5.1.2 Molecular Dynamics Simulation Methods ..... 145
4.5.2 High Field ESR in Studying Nitroxide
Microenvironment .................................. 146
4.5.2.1 Probing Local Polarity and Proticity of
Membrane and Proteins ..................... 146
4.5.2.2 Site-Directed pH-Sensitive Spin-labeling:
Differentiating Local pK and Polarity
Effects by High-Field ESR ................. 150
4.6 Perspectives ............................................ 152
Acknowledgements ............................................ 154
References .................................................. 154
5 Preparations, Reactions, and Properties of Functional
Nitroxide Radicals .......................................... 161
Shin'ichi Nakatsuji
5.1 Short Historical Survey and General Preparative
Methods of NRs ......................................... 161
5.2 Early Progress toward FNRs for Organic Magnetic
Materials .............................................. 164
5.3 Organic Ferromagnets Based on NRs ...................... 165
5.4 Charge-Transfer Complexes/Radical Ion Salts Based on
NR ..................................................... 168
5.5 Donors and Acceptors Carrying NRs and the Derived CT
Complexes/Radical Salts ................................ 172
5.6 Suprampolecular Spin Systems Carrying NRs .............. 175
5.7 Photochromic Spin Systems Carrying NRs ................. 184
5.8 FNRs for Biomedicinal Applications ..................... 191
5.9 Functional Nitrones .................................... 196
5.10 Conclusion ............................................. 197
References .................................................. 198
6 Nitroxide Spin Probes for Studies of Molecular Dynamics
and Microstructure .......................................... 205
Gertz I. Likhtenshtein
6.1 Nitroxide Molecular Dynamics ........................... 205
6.1.1 Introduction ..................................... 205
6.1.2 Molecular Dynamics of Surrounding Molecules ...... 206
6.1.2.1 Microviscosity and Fluidity .............. 206
6.1.2.2 Motion of Macromoles as a Whole and
Segmental Dynamics ....................... 207
6.1.2.3 Low-Amplitude High-Frequency Motion and
Phonon Dynamics .......................... 208
6.2 The Spin Label-Spin Probe Methods ...................... 212
6.3 Spin Oximetry .......................................... 215
6.4 Determination of the Immersion Depth of Radical and
Flourescent Centers .................................... 217
6.4.1 Analysis of Power Saturation Curves in Solids
by CW ESR ........................................ 217
6.4.2 Determination of Depth of Immersion of
a Luminescent Chromophore and a Radical Using
Dynamic Exchange Interactions .................... 218
6.5 Nitroxide as Polarity Probes ........................... 220
6.6 Electrostatic Effects in Molecules in Solutions ........ 221
6.6.1 Effect of Charge on Dipolar Interactions
Between Protons and a Paramagnetic Species ....... 221
6.6.2 Impact of Charge on Spin Exchange Interactions
Between Radicals and Paramagnetic Complexes ...... 223
6.7 Spin-Triplet-Fluorescence-Photochrome Method ........... 224
6.8 Dual Fluorophore-Nitroxide as Molecular Dynamics
Probes ................................................. 227
6.9 Nitroxide Spin pH Probes ............................... 230
6.10 Nitroxides as Spin Probes for SH Groups ................ 231
References .................................................. 232
7 Nitroxide Redox Probes and Traps, Nitron Spin Traps ......... 239
Gertz I. Likhtenshtein
7.1 Nitroxide Redox Probes .................................. 239
7.1.1 Introduction ...................................... 239
7.1.2 Quantitative Characterization of Antioxidant
Status ............................................ 240
7.1.3 Antioxidant Activity .............................. 242
7.1.3.1 SOD Mimetic Activity ...................... 242
7.1.3.2 Spin Trapping by Nitroxides ............... 244
7.2 Nitron Spin Trapping .................................... 247
7.2.1 Introduction ...................................... 247
7.2.2 Chemical Structure and Reactions of Nitrones
with Radicals ..................................... 248
7.2.3 Non-Radical Reactions of Nitrones ................. 253
7.2.4 Nitric Oxide Trapping ............................. 254
7.2.5 Thermodynamics and Kinetics of Nitron Reactions ... 254
7.3 Dual Fluorophore-Nitroxides (FNRO-) as Redox Sensors
and Spin Traps .......................................... 256
7.3.1 Introduction ...................................... 256
7.3.2 Analysis of Antioxidant Status .................... 257
7.3.3 Analysis of Superoxide and Nitric Oxide by
Pyren-Nitronyl .................................... 261
7.3.3.1 Superoxide Analysis ....................... 261
7.3.3.2 Nitric Oxide Analysis ..................... 262
7.3.4 Dual Molecules as Spin Traps ...................... 263
References .............................................. 264
8 Nitroxides in Physicochemistry .............................. 269
Gertz I. Likhtenshtein
8.1 Polymers ................................................ 269
8.1.1 Introduction ...................................... 269
8.1.2 Polymerization: Nitroxides Mediated Living
Polymerization (NMLP) ............................. 269
8.1.2.1 Phenomenon of and Chemistry of Nitroxide
Mediated Living Polymerization ............ 270
8.1.2.2 Thermodynamic and Kinetics ................ 272
8.1.3 Molecular Dynamics and Microstructure of
Polymers .......................................... 274
8.1.3.1 Introduction .............................. 274
8.1.3.2 Polymers Segmental Dynamics ............... 276
8.1.3.3 Spatial and Orientational Distribution
of Nitroxides ............................. 279
8.2 Nitroxides in Photochemistry and Photophysics ........... 279
8.2.1 Fluoresence Quanching, Photoelectron Transfer
and Photoreduction ................................ 279
8.2.1.1 Duel Fluorophore-Nitroxide Compounds ...... 279
8.2.1.2 Nitroxides in Multispin Systems ........... 284
8.2.1.3 Spin Trapping in Photochemical
Reactions ................................. 285
8.3 Complexes Transition Metals with Nitroxide Ligands ...... 287
8.4 Nitroxides in Inorganic Chemistry ....................... 292
8.4.1 Langmuir-Blodgett (LB) Films on Inorganic
Substrates ........................................ 293
8.4.2 Surface Microstructure and Dynamics ............... 294
8.4.3 Nanoparticles ..................................... 295
8.4.4 Local Acidity ..................................... 296
References .................................................. 297
9 Organic Functional Materials Containing Chiral Nitroxide
Radical Units ............................................... 303
Rui Tamura
9.1 Introduction ............................................ 303
9.2 Synthesis and Structure of Chiral NRs ................... 304
9.2.1 Chiral Five-Membered Cyclic NRs ................... 304
9.2.1.1 Chiral α-NNs .............................. 304
9.2.1.2 Chiral PROXYLs ............................ 305
9.2.1.3 Chiral DOXYLs ............................. 313
9.2.2 Chiral Six-Membered Cyclic NRs .................... 314
9.2.3 Miscellaneous Examples ............................ 314
9.3 Magnetic Properties of Chiral NRs in the Solid State .... 315
9.3.1 Chiral Nitoxide-Mn2+ Complex Magnets .............. 315
9.3.2 Chiral Multispin System ........................... 316
9.4 Properties of Chiral NRs in the Liquid Crystalline
State ................................................... 318
9.4.1 DOXYL and TEMPO Liquid Crystals ................... 318
9.4.2 PROXYL Liquid Crystals ............................ 320
9.4.2.1 Phase-Transition Behavior ................. 320
9.4.2.2 Ferroelectric Properties .................. 322
9.4.2.3 Nonlinear Mesoscopical-Ferromagnetic
Interactions .............................. 323
9.5 Application of Redox Properties of NRs .................. 323
9.5.1 Oxidation Catalyst ................................ 323
9.5.1.1 Achiral Catalyst .......................... 323
9.5.1.2 Chiral Catalyst ........................... 325
9.5.2 Radical Battery ................................... 325
9.6 Conclusion .............................................. 326
References .............................................. 327
10 Spin Labeling in Biochemistry and Biophysics ............... 331
Certz I. Likhtenshtein
10.1 Proteins and Enzymes .................................. 331
10.1.1 Intramolecular Dynamics and Conformational
Transition in Enzymes .......................... 332
10.1.1.1 Introduction .......................... 332
10.1.1.2 Low-Temperature Molecular Dynamics .... 332
10.1.1.3 Protein Dynamics at Ambient
Temperature ........................... 334
10.1.2 Conformational Changes in Proteins and
Enzymes, and Mechanism of Intramolecular
Dynamics ....................................... 336
10.1.3 Structure of the Enzymes' Active Centers ....... 338
10.1.4 Site-Directed Spin-Labeling (SDSL) ............. 340
10.1.4.1 Introduction .......................... 340
10.1.4.2 Soluble Proteins ...................... 341
10.1.4.3 Rhodopsin and Bacteriorhodopsin ....... 344
10.1.4.4 Muscle Proteins ....................... 344
10.1.4.5 Membrane Proteins ..................... 345
10.2 Biomembranes .......................................... 346
10.2.1 Structure and Dynamics ......................... 347
10.2.1.1 Location of Labels, Water, and
Oxygen in Membranes ................... 347
10.2.1.2 Membrane Microstructure ............... 348
10.2.2 Membrane Dynamics .............................. 349
10.2.3 Proteins and Peptides in Membranes ............. 350
10.3 Nucleic Acids ......................................... 354
10.3.1 Introduction ................................... 354
10.3.2 DNA ............................................ 355
10.3.3 RNA ............................................ 358
10.4 Polysacchrides and Dextrins ........................... 360
10.4.1 Cotton and Cellulose ........................... 360
10.4.2 Cyclodextrins .................................. 362
References ............................................ 363
11 Biomedical and Medical Applications of Nitroxides .......... 371
Gertz I. Likhtenshtein
11.1 Cells and Tissues. Biomedical Aspects ................. 371
11.1.1 Cell Membrane Fluidity ......................... 371
11.1.2 Cells Redox Status ............................. 372
11.1.3 Nitroxides as Cell Protectors .................. 373
11.2 Nitroxides In Vivo .................................... 374
11.2.1 Introduction ................................... 374
11.2.2 Nitroxide In Vivo Biochemistry. Biomedical
Aspects ........................................ 375
11.2.2.1 Antioxidant Activity of Nitroxides .... 375
11.2.2.2 Detection of Reactive Radicals:
Spin-Trapping ......................... 376
11.2.2.3 Spin Farmokinetics In Vivo ............ 378
11.2.2.4 Spin pH Probing ....................... 380
11.2.2.5 Spin Imaging .......................... 381
11.2.2.6 Nitroxide Spin Probe Oximetry ......... 383
11.3 Medical Application of Nitroxides ..................... 385
11.3.1 Nitroxides and Nitrons as Drugs ................ 385
11.3.2 Protection in Animal Model Diseases ............ 386
11.3.3 Human Diseases. Therapeutic Aspects ............ 388
11.3.4 Nitroxides in Clinics .......................... 389
11.4 Areas Related to Future Development of Nitroxide
Applications in Biomedicine ........................... 391
References ............................................ 393
12 Conclusion ................................................. 401
Index ......................................................... 405
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