H a r r y K u r r e c k - on the O c c a s i o n o f his 65th Birthday This issue of Applied Magnetic Resonance is dedicated to Harry Kurreck on the occasion of his 65th birthday and his formal retirement from the Chemistry Departrnent of the Free University of Berlin. The collection of papers in this issue is meant a s a small tribute from some of his friends and colleagues to Harry's lasting contribution to the field of organic and bioorganic radicals and model systems for light-induced electron transfer as studied by EPR techniques.

Harry was boro on the 18th of December 1932 in Halle/Saale in Sachsen-Anhalt. He went to school in Berlin, acquired his high school diploma (Abitur) in 1953 and studied chemistry first at the Technical University (TU) and later at the Free University (FU) of Berlin. In 1960 he finished his Diploma in Chemistry and only two years later received his Dr. rer. nat. at the FU with Prof. Dr. W. Broser.

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He habilitated in Organic Chemistry in 1970 and shortly after became Professor at the Chemistry Department of the FU Berlin. In 1955, at a chemists' ball in Berlin, Harry met Babette. On bis 29th birthday they were married. With her background a s a technician in chemistry she always had an open ear for his professional problems and thus provided a supportive atmosphere for Harry's work. In 1969 their only son, Jens, was bom. Later they bought a house in Berlin Zehlendorf. I still remember the many enjoyable evenings at their home with excellent food carefully prepared by his wife, and long conversations with many scientists from all over the world who were invited to their house. Sometimes, a f t e r a few bottles of wine, all of us went down to the basement and played with his son's elect¡ trains. For many years Harry owned a sailboat and went out quite regularly with his family or with friends and colleagues on Lake Wannsee during the summer months. Once we bought hito a metal sign saying "... I'd rather be sailing" and nailed it on his door at the Institute. Fortunately, Harry took that in the right spirit - he loves to hear and tell good jokes - and invited us to join him on his boat. Harry still likes to go on long bicycle tours with Babette, and he enjoys his home and the cultural city life which offers so muela for cormoisseurs of classicaI music. To Harry's delight bis son Jens was an excellent student in high school where he developed, in addition to his love for philosophy, a strong interest in Chemistry and Biochemistry. He is currently finishing his doctoral degree in this field at the TU Berlin. Very recently, Harry's first grandson Paul was boro - a big event for the whole family. Harry took over his new role as a grandfather with great joy and is now, after years of intense work, able to spend a lot of time playing with Paul and taking care of him. Harry stayed at the FU during bis whole career, presumably because o f strong family ties, his love of the city of Berlin, the strong support of bis work by the Department and the University and - last but not least - the exeellent scientific surroundings and the close contact with his f¡ and colleagues in Berlin in Chemistry and particularly in Physics. Following the reunification of Germany the Berlin universities are now confronted with the largest financial cutbacks in their history. Fortunately, Harry's excellent researeh projects have always been supported by grants, in particular from the Deutsche Forschungsgemeinschaft (DFG) which made his group iargely independent of the budget problems o f his Department. Organic radicals have been the main interest of Harry throughout his scientific life. The method of choice to study such systems is EPR spectroscopy and he managed to get an instrument early in bis career, in the sixties, during his habilitation at the FU Berlin. He started to teach EPR, regularly offered laboratory-training courses and thus got many students interested in this field. Harry's lectures have always been very well prepared, clearly presented and included the latest scientific results. He invested a lot of bis time to tutor his students and was therefore one of the most popular professors in the Department. No wonder

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that many students - and often the best in a course - later decided to join his research group. Early in the seventies an exciting new technique, Electron-Nuclear DOuble Resonance (ENDOR), discovered in the USA by G. Feher and extended by J. Hyde and A. H. Maki to radicals in solution was installed and further developed to TRIPLE resonance in the group of Klaus Mrbius together with his coworker Martin Plato and his doctoral students Peter Dinse and Reinhard Biehl in the Physics Department of the FU Berlin. This method allowed resolution of the hyperfine structure even of very complicated radicals. Harry rapidly recognized the power of this method to overcome the serious limitations of single resonance EPR, and he managed to acquire the advanced instrumentation. This heralded a very fruitful decade in his laboratory during which many different types of radicals were studied under high resolution conditions by using not only ENDOR o f proton nuclei but extending it to carbon-13 and a variety o f other heteronuclei. During this period his highly original work on sterically crowded radicals, on organic multispin systems, on radicals in anisotropic media such as liquid crystals and micelles, and on flavin radicals in vitro and in enzymatic systems should be mentioned. Part of this work was summarized in a highly cited article in Angew. Chem. published in 1984. It formed the basis for Harry's book on ENDOR spectroscopy that appeared in 1988, now considered a standard text in the field. I vividly remember the time working with Harry and Burkhard Kirste on the many versions of the text and how Harry insisted on illustrating ir well by many examples, on including all the work done by other groups in the field in a well-balanced manner and on presenting the complicated theory "as simple as possible - but not simpler". Prompted by the crystallization o f the photosynthetic reaction center in the early eighties and the enhanced activity in the field of natural and artificial photosynthesis, Harry became interested in biomimetic model systems for light-induced electron transfer. During the last decade his group prepared a large number of novel donor-acceptor systems with various spacers through state-of-the-art synthesis. In this field the cw-EPR techniques available in his laboratory turned out to be very helpful although other spectroscopic studies, in particular time-resolved EPR and laser spectroscopy, were required to fully characterize the compounds. These were carried out together with several other collaborating groups inside and outside Germany. The work was recently reviewed in Angew. Chem. in an article written together with Martina Huber. It is certainly fair to say that Harry's group is now one of the world leaders in this field. The work briefly described above has led to over a hundred publications in scientific journals. Many of his frequently cited articles paved the way for other groups working in this field. The record clearly shows that Harry's work has contributed greatly to our understanding of a variety of organic and biological radicals, of multispin systems in solution and anisotropic media, and of biomimetic systems for photosynthetic charge separation.

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Lubitz: Harry Kurreck - on the Occasion of his 65th Birthday

Harry Kurreck's outstanding research in the field of electron magnetic resonance spectroscopy together with the synthesis of specially tailored novel organic compounds made bis group an important member o f the Sp~cial Research Unit "Energy and Charge Transfer in Molecular Aggregates" of the DFG in Berlin (SFB 337) during the last decade. His work is currently also supported by the Volkswagen-StiRung in the Priority Program "Inter- and Intramolecular Electron Transfer". In spite of his formal retirement Harry is still actively involved in all these projects and plans to continue his successful work in the next few years, a decision of great importance for bis many collaborators. During his scientific career Harry has worked together with many groups in and outside Berlin. The longest and most fruitful eollaboration is that with Klaus M/Sbius and bis coworkers from the Department of Physics of the FU Berlin which is based on a long-standing personal friendship between Harry and Klaus. Both have shared several students who profited from the interdisciplinary work early in their careers. Harry Kurreck's open-minded approach to collaborations with many other groups from physical and inorganic chemistry, biochemistry, physics and biology is indicative for his truly interdisciplinary approach to solve complex scientific problems. This philosophy has affected and inspired many of bis students and collaborators, including myself. I had the pleasure to work with Harry Kurreck for several years. He has been a great teacher, a gracious colleague and is now one of my most reliable and closest friends. I consider the early years in his laboratory as a very important stepping stone for my later scientific career. I am sure that this view is shared by many of the approximately fifty students who received their doctoral degree and the other four scientists, in addition to myself, who habilitated with him. In a recent conversation Harry told me that it was probably a mistake to dedicate a large part of his scientific life to EPR and ENDOR spectroscopy - which is indeed quite unusual for a scientist with a background in organic chemistry. I told him that I totally disagree with this view. How much poorer would our research field be without people like Harry Kurreck• Wolfgang Lubitz