Electron Paramagnetic Resonance Vol. 20

283 Pages·2006·4.951 MB·English

Electron Paramagnetic Resonance
Volume 20

A Specialist Periodical Report
Electron Paramagnetic
Resonance
Volume 20
A Review of the Recent Literature
Editors
BC Gilbert, University of York, UK
MJ Davies, Heart Research Institute, Sydney, Australia
DM Murphy, Cardiff University, UK
Authors
A Caragheorgheopol, Romanian Academy Institute of Physical
Chemistry, Bucharest, Romania
V Chechik, University of York, UK
J-L Cle´ment, Universite´ d’Aix Marseille, Marseille, France
D Collison, The University of Manchester, UK
JB Feix, Medical College of Wisconsin, Milwaukee, US
JT Hancock, University of the West of England, Bristol, UK
SK Jackson, University of the West of England, Bristol, UK
PE James, Cardiff University, UK
CS Klug, Medical College of Wisconsin, Milwaukee, US
EJL McInnes, The University of Manchester, UK
MV Motyakin, Russian Academy of Science, Moscow, Russia
F Neese, New Universita¨t Bonn, Germany
ME Newton, University of Warwick, UK
PC Riedi, University of St Andrews, UK
S Schlick, University of Detroit Mercy, Michigan, US
P. Tordo, Universite´ d’Aix Marseille, Marseille, France
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ISBN-10:0-85404-325-X
ISBN-13:978-0-85404-325-5
ISSN1464-4622
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Preface
The topics described in Volume 20 of the EPR Specialist Periodical Report
Serieshavebeenselectedtoreflectparticularlyexcitingandtimelyexamplesof
the renaissance in the development and application of EPR spectroscopy,
including ENDOR, time-resolved and imaging techniques. We have again
aimed to reflect the widespread application of EPR in chemistry and the
cognate fields of physics, material science, biology, and medicine – and to
provide updates for specialists as well as overviews for non-experts who may
wish to learn of the scope of the technique. Authors with particular expertise
havebeeninvitedtocontributeauthoritativeandcriticalreviewswhich,whilst
concentrating on major developments in 2004 and 2005, also provide descrip-
tive and accessible accounts which are suitable for both existing and potential
practitioners.
We have intended to balance different types of article in this Volume. For
example, in some cases we have continued our coverage of developments in
relatively well-established fields for which detailed updates are appropriate –
for example, in describing recent advances in spin-trapping methodology
(especially in the design of new traps), in the study of exchange-coupled
multi-spinoligomers,theapplicationofhigh-fieldEPR(especiallytoinorganic
compounds and materials) and in biological and biomedical applications.
In other areas we have invited practicing experts to illustrate the scope for
applicationofEPRspectroscopyinneworrapidly-developingfields,andhave
accordingly chosen the use of EPR-imaging instudies of polymerdegradation
and the use of spin-labels and spin-probes for investigating a variety of
nanomaterials; a review of site-directed spin-labelling (SDSL) in biological
systemsillustratesnotonlythesubstantialactivityinthisfield,butalso,aswith
applications in nanomaterials and oligomers, shows how study and under-
standing of spin-spin interactions provides unique, subtle, and detailed infor-
mation about molecular motion and distances.
We have added two particularly novel chapters for this Volume – a timely
review of quantum chemical approaches to aid the interpretation of spin-
Hamiltonianparameters(reflecting theincreasinglyaccessibleandinformative
links which can be made between theoretical analysis and magnetic resonance
observations) and an authoritative essay on defects in diamonds (which illus-
trates the beauty of the method and theoretical analysis, as well as potential
materials-based applications).
v
vi ElectronParamag.Reson.,2007,20,v–vi
We hope that experts and potential beginners alike will value these reviews
andbestimulatedintheirresearch.Asalways,wewouldvaluefeedbackonour
choice of topics and styles, together with suggestions of possible topics for
future coverage.
Finally we thank all the authors for their care and promptness in contrib-
uting their articles, and acknowledge with gratitude the skilled cooperation of
the RSC Editorial Staff.
Bruce Gilbert
Michael Davies
Damien Murphy
Contents
Cover
Thecoverdepictsasingle-
crystalEPRstudyofa
dodecametallicCr(III)cluster
withanS=6groundstate.
ESR Imaging Beyond Phantoms: Application to Polymer Degradation 1
Shulamith Schlick and Mikhail V. Motyakin
1 Introduction and Motivation 1
1.1 Polymer Degradation 1
1.2 Polymer Stabilization by Hindered Amines 2
1.3 Motivation for ESRI Studies of Polymer Degradation 2
2 ESR Imaging and Applications to Polymer Systems 5
2.1 ESR Spectra in the Presence of Magnetic Field Gradients 5
2.2 ESR Imaging of Polymeric Systems 6
2.3 ESR Imaging of Polymers Stabilized by Hindered Amines 7
3 Experimental Details 8
3.1 Hardware for ESRI 8
3.2 Intensity Profiling from 1D ESRI 9
3.3 Line-Shape Profiling from 2D Spectral-Spatial ESRI 10
3.4 The Polymers Studied 11
4 ESR Spectra of Nitroxides Derived From Hindered Amine
Stabilizers in Heterophasic Polymers 12
5 1D and 2D Spectral-Spatial ESRI of Heterophasic Polymers
Stabilized by Hindered Amines 14
vii
viii ElectronParamag.Reson.,2007,20,vii–xii
5.1 Thermal Treatment 14
5.2 Photodegradation 18
5.3 AdvantagesofESRIComparedtoFTIRandtoDestructive
Methods of Study 23
6 Conclusions 24
Acknowledgments 25
References 25
Advances in Spin Trapping 29
J.-L. Cle´ment and P. Tordo
1 Introduction 29
2 Basic Principles 30
3 New Nitrones for Spin Trapping 30
4 Spin Trapping Studies of Superoxide Radicals 36
4.1 Use of Cyclodextrins 36
4.2 Formation of Diastereoisomer Spin Adducts 37
4.3 Kinetic Studies 38
4.4 Chemical Exchange in Alkylperoxyl and Superoxide
Radical Adducts of b-Phosphorylated Nitrones 41
5 Theoretical Calculations 43
6 Immuno Spin Trapping of Proteins 43
7 Separation and Identification of Spin Adducts 44
8 Conclusion 45
References 45
Site-Directed Spin-Labelling (SDSL) Applications in Biological Systems 50
Jimmy B. Feix and Candice S. Klug
1 Introduction 50
2 Soluble Proteins 51
3 Integral Membrane Proteins 53
4 Membrane-Associated Proteins 56
5 Fibril-Forming Proteins 62
6 Nucleic Acids 62
7 Substrates 63
8 Distance Measurements 64
9 Conclusions 67
Acknowledgements 68
References 68
ElectronParamag.Reson.,2007,20,vii–xii ix
Quantum Chemical Approaches to Spin-Hamiltonian Parameters 73
Frank Neese
1 Introduction 73
2 Theoretical Aspects 74
2.1 General Theory 74
2.2 Spin-Free Approaches 75
2.3 Two-Component Approaches 77
2.4 The Spin-Orbit Coupling Operator 78
3 Application to EPR Spin-Hamiltonian Parameters 80
3.1 g-Tensor 80
3.2 Hyperfine Couplings 82
3.3 Zero-Field Splittings 83
3.4 Quadrupole Couplings 84
3.5 Functional and Basis Set Effects 84
3.6 Environment Effects 85
4 Application Studies 86
4.1 Small Molecules 86
4.2 Organic and Biological Radicals 86
4.3 Transition Metals 87
5 Concluding Remarks 87
Acknowledgements 88
References 88
Getting an Inside View of Nanomaterials with Spin Labels and Spin
Probes 96
Victor Chechik and Agneta Caragheorgheopol
1 Introduction 96
2 Self-Assembled Supramolecular Structures 98
3 Polymers 102
4 Mesoporous Materials 107
5 Adsorption in Mesopores 112
6 Adsorption on Surfaces 115
6.1 Planar Surfaces 115
6.2 Rough Surfaces 117
7 Au Nanoparticles 119
8 Dendrimers 123
9 Conclusions 127
Acknowledgements 128
References 128