Preface Free

The topics described in the current Volume 27 of the EPR Specialist Periodical Report Series have been selected to reflect particularly exciting and timely examples of the applications and developments in EPR spectroscopy. We have again aimed to reflect the widespread applications 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 better understand the scope of the technique. We have also intended to balance the different types of articles in this volume from relatively well-established fields to the latest instrument developments, in order to demonstrate not only the diversity of research fields in which EPR is used but additionally the wealth of information that can be extracted from the advanced pulsed capabilities. This information includes not just the simple detection and quantification of a free radical or paramagnetic ion, but also the detailed insights into the structure, conformation and dynamics of the spin system on length/time scales not easily accessible by other techniques. For all these reasons, EPR has and will continue to be the most powerful technique to inform, study and interrogate paramagnetic species in almost any sample system.

In the current Volume of this SPR series, we have commissioned a diverse but exciting series of Chapters that illustrate and exemplify some of the current applications and developments of EPR. In Chapter 1, Murphy and co-workers provide an overview on the applications of EPR to examine open-shell paramagnetic species of relevance to heterogeneous, homogeneous and enzymatic catalysis, giving recent examples which best demonstrate the power of the technique to uncover complex reaction pathways. In Chapter 2, Bode and co-workers offer a timely perspective on the investigation of biomolecular binding events, by comprehensively showing the multitude of ways in which EPR can detect and quantify interactions, whilst intimately coupling structural information and binding events within the biological structural context. EPR has long been used to study membrane proteins including investigations of conformation, folding, oligomerisation and dynamics, and this theme is picked up in Chapter 3 by Pliotas, who focuses on the applications of pulsed EPR in this area, coupled with experimental consideration and supporting computational tools, including illustrative work on mechanosensitive ion channels. Nitroxides (as spin labels) and nitrones (as spin traps) have a long history in the field of EPR over many decades, so Stipa provides a comprehensive review covering their most recent applications for EPR spectroscopy in Chapter 4. Another incredibly important application area of EPR, lies in the field of quantum computing, so in Chapter 5 Tuna gives an overview of the latest advances in the design and testing of molecular electron spin systems with Quantum Information Processing (QIP) attributes, thereby highlighting the tremendous progress made in electron spin manipulations driven by pulse EPR spectroscopy. Finally, in Chapters 6 and 7, attention is focussed on the development and instrumentation aspects of EPR. In Chapter 6, Tseytlin presents the latest developments in CW rapid scan EPR, highlighting the recent practical progress that has been achieved, complemented by the important algorithms and instrument developments that enable measurement of undistorted EPR spectra with enhanced sensitivity. Volume 27 is then nicely rounded off in Chapter 7, as Neugebauer discusses the latest developments in high-frequency EPR with a special focus on experiments in frequency domain compared to traditional field domain EPR, highlighting the possibility of accessing very short relaxation times by implementing frequency rapid scans.

From these excellent series of Chapters, we hope that both the expert EPR practitioner and novice user will value these timely reviews, offering a broad perspective on the latest developments in the field. Finally, we are most indebted to all of our reporters for their excellent, prompt and efficient cooperation in the production of this Volume, and the staff at the Royal Society of Chemistry for their continued and professional editorial support.

Bela E. Bode (St Andrews), Victor Chechik (York) and Damien M. Murphy (Cardiff)