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Scientific biography of Dr. Günter Engelhardt
SOLID STATE Nuclear Magnetic Resonance
ELSEVIER
Solid State Nuclear Magnetic Resonance
Scientific Biography of Dr. Giinter Engelhardt Dr. Gunter Engelhardt, a well-known member of the solid-state NMR research community, celebrated his 60th birthday on June 16, 1996. This special issue is devoted in honor of this occasion, in appreciation for his contributions to the development of NMR spectroscopy for application to zeolites and silicates, and for his contributions to the understanding of chemical shift data in terms of structure and bonding. Gunter Engelhardt was born in Chemnitz in 1936, and between 1954 and 1960 he studied chemistry at Leuna-Merseburg and Dresden, where he completed his diploma. For his doctoral research he conducted Raman and IR investigations on disiloxanes with H. Kriegsmann at the Technical University of Dresden, where he obtained his PhD in 1963. He was then appointed head of the NMR laboratory at the Zentralinstitut fur Physikalische Chemie at the Akademie der Wissenschaften of the GDR in Berlin-Adlershof. His habilitation thesis on the NMR spectroscopic study of the properties of chemical bonds in organic silicon, germanium and tin compounds was completed in 1969. His first years of research at Berlin were dominated by multinuclear NMR experiments on organic and elementorganic compounds in solution. In 1973 the group obtained a new JEOL FT NMR spectrometer, and the first experiments on this instrument were devoted to 29Si NMR of silicate solutions. Spectral assignments of chemical shifts to individual silicate anions were developed in collaboration with W. Wieker and D. Hoebbel, and these pioneering studies were recognized and cited worldwide. It was at this time that the Q” nomenclature for different building units of silicate structures was introduced, and it is now well established and applied in silicate research. By 1977 it was obvious that further progress would necessitate the development of high-resolution solid-state NMR facilities. In this time E. Lippmaa
9 (1997) ix-xi
and co-workers had just started with “C solid-state NMR spectroscopy at the Estonian Academy of Sciences in Tallin. Instantly, the Berlin and Tallin groups embarked on the first systematic high-resolution solid-state NMR study of crystalline silicon compounds. The first solid-state NMR paper of this collaboration came out as early as 1978 with 13C, 29Si, and ‘19Sn CPMAS NMR experiments on a variety of organic compounds (J. Am. Chem. Sot. 100 (1978) 1929). However, the two groups soon decided to focus their attention on inorganic silicates and zeolites. The paper published in the Journal of the American Chemical Society (Vol. 102 (1980) 4889) can be regarded as a breakthrough of 29Si NMR spectroscopy of solid silicates. I found it to be a most intriguing experience to listen to G. Engelhardt talking about the exciting story of solid-state NMR on silicates in those early days: “Every spectrum told us something new, since nothing had been done before”. Due to the technological importance of zeolites, these materials were studied systematically by solid-state NMR, addressing issues such as structure, synthesis, and modification. Due to the pioneering achievements of this joint research, Giinter Engelhardt and Endel Lippmaa were awarded the Max-Planck Research Prize in 1992. In concert with the experimental progress, a semi-empirical model has been developed with R. Radeglia in order to understand the chemical shift of 29Si and other nuclei (see for example Chem. Phys. Lett. 114 (1985) 28). The famous book, High-Resolution Solid-State NMR on Silicates and Zeolites, appeared in 1987 with D. Michel as co-author. The popularity of this book is most clearly illustrated by the large number of annual citations which is still increasing. Fig. 1. There was an experience in G. Engelhardt’s life which needs to be mentioned. Most scientists of the former German Democratic Republic, including Gunter Engelhardt, had to work under burdensome and oppressive conditions imposed by the political
G. Englehardt/Solid
x
State Nuclear Magnetic Resonance 9 (1997) ix-xi
120 L!! .$ 100 s b $
60
z 2
40
60
20
Fig. 1. Annual number of citations of the monograph, High-Resolution Solid-State NMR of Silicates and Zeolites (John Wiley & Sons, Chichester, 1987) written by G. Engelhardt and D. Michel; source: Science Citation Index.
system. These difficulties are veiled by such successful records as the one of G. Engelhardt. It is difficult for someone who did not live under these hampering restrictions to fully understand how frustrating this situation must have been. His freedom to exchange views was permitted by the political system only with others in one part of the world, a restriction which was shared with many colleagues. Many invitations for visits to the western world had to be turned down because the authorities did not allow for such contacts since 1965. It is possible for one to imagine how the initiator of a flourishing research area must feel when it becomes clear that many scientists in the whole world are interested in the work, and are starting projects on related issues, but he is neither allowed to attend conferences nor visit other laboratories for the opportunity of discussion. Perhaps a grotesque illustration of the discrepancy between the reputation of a renowned researcher and the humiliating disregard by the authorities was that Engelhardt was forced to ask the publisher in London to send blank paper for the manuscript of his book. Another frustration must have been the cumbersome procedures necessary for getting permission to publish in western, particularly American, journals. These reasons led to an important decision in his life. In January, 1987, Gunter Engelhardt took a big step between different worlds and moved to western Germany. He soon found a new home and joined the Faculty of Chemistry at the University of Konstanz, where he was affiliated with the group of J. Felsche
in solid-state chemistry. He now was able to add new scientific activities to his schedule, such as a stay of two months at the University of Cambridge in 1987 (with J. Klinowski) and another visit for two months as a visiting professor at the UniversitC Pierre et Marie Curie at Paris in 1990 (with J. Fraissard). His stay in Konstanz lasted from 1987 to 1992. Engelhardt’s work concentrated on sodalites and sodium silicates and new developments on the methodology of NMR of quadrupolar nuclei. While much of the work in this research area at that time focused on extracting accurate electric field gradient tensor values from the NMR spectra, Engelhardt’s primary goal lay one step beyond: what do the parameters teach us about structure and bonding in the solid state? In 1992 he became head of the solid-state NMR laboratory of the Institute of Chemical Technology (J. Weitkamp) at the University of Stuttgart. A new solid-state NMR spectrometer (Bruker MSL400) was installed in this laboratory, and a double-rotation (DOR) probe came with this instrument. Once again he had the ideal samples for this new technique already waiting on the shelf. The very first sample examined with this DOR probe was calcium tungstate aluminate sodalite. These early 27A1 DOR NMR spectra with seven resolved lines were particularly convincing illustrations of the power of this technique. (Solid State NMR 1 (1992) 127). Engelhardt’s current research interests are the development and application of MAS NMR spectroscopy on the structural characterization of inorganic materials (zeolites, minerals, glasses, mesoporous M41S-type phases), the location of cations in zeolites, the study of host-guest interactions and dynamics of guest molecules in microporous solids, the NMR spectroscopic characteristics of quadrupole nuclei (technique, analysis and interpretation), and the investigation of paramagnetic centers in zeolites. Certainly, the paramagnetic shift effects observed recently in Na-implanted sodalites will continue to engage his curiosity and his energy in future years. Beyond research, G. Engelhardt is an effective scientific writer as well as instructor. To date, he is author of roughly 200 scientific papers including review articles and a book which is widely regarded as the classical standard monograph of 29Si NMR spectroscopy of silicates and zeolites. As a teacher,
G. Englehardt/
Solid State Nuclear Magnetic Resonance 9 (1997) ix-xi
he knows how to balance perfectly the conflicting needs of providing efficient guidance to scientific working and thinking, while leaving enough space for developing intellectual independence. I had the pleasure to work with him, and would like to acknowledge here the wonderful time I had in both Konstanz and Stuttgart. There is perhaps one characteristic goal that Gilinter Engelhardt persistently pursued. He strove to stay close to his scientific endeavors, for example by refusing offers which would have meant a larger administrative role for him.
xi
Nevertheless, he continues to provide service to his scientific community, as a member of the editorial board of this journal, and as a sought-after referee for many international journals and funding organizations, to name just a few. We wish Giinter Engelhardt continued happiness and success in his work and private life. Undoubtedly, he and his ideas will remain in high demand for his students, colleagues and friends.
Hubert Koller
ELSEVIER
Solid State Nuclear Magnetic Resonance
Scientific Biography of Dr. Giinter Engelhardt Dr. Gunter Engelhardt, a well-known member of the solid-state NMR research community, celebrated his 60th birthday on June 16, 1996. This special issue is devoted in honor of this occasion, in appreciation for his contributions to the development of NMR spectroscopy for application to zeolites and silicates, and for his contributions to the understanding of chemical shift data in terms of structure and bonding. Gunter Engelhardt was born in Chemnitz in 1936, and between 1954 and 1960 he studied chemistry at Leuna-Merseburg and Dresden, where he completed his diploma. For his doctoral research he conducted Raman and IR investigations on disiloxanes with H. Kriegsmann at the Technical University of Dresden, where he obtained his PhD in 1963. He was then appointed head of the NMR laboratory at the Zentralinstitut fur Physikalische Chemie at the Akademie der Wissenschaften of the GDR in Berlin-Adlershof. His habilitation thesis on the NMR spectroscopic study of the properties of chemical bonds in organic silicon, germanium and tin compounds was completed in 1969. His first years of research at Berlin were dominated by multinuclear NMR experiments on organic and elementorganic compounds in solution. In 1973 the group obtained a new JEOL FT NMR spectrometer, and the first experiments on this instrument were devoted to 29Si NMR of silicate solutions. Spectral assignments of chemical shifts to individual silicate anions were developed in collaboration with W. Wieker and D. Hoebbel, and these pioneering studies were recognized and cited worldwide. It was at this time that the Q” nomenclature for different building units of silicate structures was introduced, and it is now well established and applied in silicate research. By 1977 it was obvious that further progress would necessitate the development of high-resolution solid-state NMR facilities. In this time E. Lippmaa
9 (1997) ix-xi
and co-workers had just started with “C solid-state NMR spectroscopy at the Estonian Academy of Sciences in Tallin. Instantly, the Berlin and Tallin groups embarked on the first systematic high-resolution solid-state NMR study of crystalline silicon compounds. The first solid-state NMR paper of this collaboration came out as early as 1978 with 13C, 29Si, and ‘19Sn CPMAS NMR experiments on a variety of organic compounds (J. Am. Chem. Sot. 100 (1978) 1929). However, the two groups soon decided to focus their attention on inorganic silicates and zeolites. The paper published in the Journal of the American Chemical Society (Vol. 102 (1980) 4889) can be regarded as a breakthrough of 29Si NMR spectroscopy of solid silicates. I found it to be a most intriguing experience to listen to G. Engelhardt talking about the exciting story of solid-state NMR on silicates in those early days: “Every spectrum told us something new, since nothing had been done before”. Due to the technological importance of zeolites, these materials were studied systematically by solid-state NMR, addressing issues such as structure, synthesis, and modification. Due to the pioneering achievements of this joint research, Giinter Engelhardt and Endel Lippmaa were awarded the Max-Planck Research Prize in 1992. In concert with the experimental progress, a semi-empirical model has been developed with R. Radeglia in order to understand the chemical shift of 29Si and other nuclei (see for example Chem. Phys. Lett. 114 (1985) 28). The famous book, High-Resolution Solid-State NMR on Silicates and Zeolites, appeared in 1987 with D. Michel as co-author. The popularity of this book is most clearly illustrated by the large number of annual citations which is still increasing. Fig. 1. There was an experience in G. Engelhardt’s life which needs to be mentioned. Most scientists of the former German Democratic Republic, including Gunter Engelhardt, had to work under burdensome and oppressive conditions imposed by the political
G. Englehardt/Solid
x
State Nuclear Magnetic Resonance 9 (1997) ix-xi
120 L!! .$ 100 s b $
60
z 2
40
60
20
Fig. 1. Annual number of citations of the monograph, High-Resolution Solid-State NMR of Silicates and Zeolites (John Wiley & Sons, Chichester, 1987) written by G. Engelhardt and D. Michel; source: Science Citation Index.
system. These difficulties are veiled by such successful records as the one of G. Engelhardt. It is difficult for someone who did not live under these hampering restrictions to fully understand how frustrating this situation must have been. His freedom to exchange views was permitted by the political system only with others in one part of the world, a restriction which was shared with many colleagues. Many invitations for visits to the western world had to be turned down because the authorities did not allow for such contacts since 1965. It is possible for one to imagine how the initiator of a flourishing research area must feel when it becomes clear that many scientists in the whole world are interested in the work, and are starting projects on related issues, but he is neither allowed to attend conferences nor visit other laboratories for the opportunity of discussion. Perhaps a grotesque illustration of the discrepancy between the reputation of a renowned researcher and the humiliating disregard by the authorities was that Engelhardt was forced to ask the publisher in London to send blank paper for the manuscript of his book. Another frustration must have been the cumbersome procedures necessary for getting permission to publish in western, particularly American, journals. These reasons led to an important decision in his life. In January, 1987, Gunter Engelhardt took a big step between different worlds and moved to western Germany. He soon found a new home and joined the Faculty of Chemistry at the University of Konstanz, where he was affiliated with the group of J. Felsche
in solid-state chemistry. He now was able to add new scientific activities to his schedule, such as a stay of two months at the University of Cambridge in 1987 (with J. Klinowski) and another visit for two months as a visiting professor at the UniversitC Pierre et Marie Curie at Paris in 1990 (with J. Fraissard). His stay in Konstanz lasted from 1987 to 1992. Engelhardt’s work concentrated on sodalites and sodium silicates and new developments on the methodology of NMR of quadrupolar nuclei. While much of the work in this research area at that time focused on extracting accurate electric field gradient tensor values from the NMR spectra, Engelhardt’s primary goal lay one step beyond: what do the parameters teach us about structure and bonding in the solid state? In 1992 he became head of the solid-state NMR laboratory of the Institute of Chemical Technology (J. Weitkamp) at the University of Stuttgart. A new solid-state NMR spectrometer (Bruker MSL400) was installed in this laboratory, and a double-rotation (DOR) probe came with this instrument. Once again he had the ideal samples for this new technique already waiting on the shelf. The very first sample examined with this DOR probe was calcium tungstate aluminate sodalite. These early 27A1 DOR NMR spectra with seven resolved lines were particularly convincing illustrations of the power of this technique. (Solid State NMR 1 (1992) 127). Engelhardt’s current research interests are the development and application of MAS NMR spectroscopy on the structural characterization of inorganic materials (zeolites, minerals, glasses, mesoporous M41S-type phases), the location of cations in zeolites, the study of host-guest interactions and dynamics of guest molecules in microporous solids, the NMR spectroscopic characteristics of quadrupole nuclei (technique, analysis and interpretation), and the investigation of paramagnetic centers in zeolites. Certainly, the paramagnetic shift effects observed recently in Na-implanted sodalites will continue to engage his curiosity and his energy in future years. Beyond research, G. Engelhardt is an effective scientific writer as well as instructor. To date, he is author of roughly 200 scientific papers including review articles and a book which is widely regarded as the classical standard monograph of 29Si NMR spectroscopy of silicates and zeolites. As a teacher,
G. Englehardt/
Solid State Nuclear Magnetic Resonance 9 (1997) ix-xi
he knows how to balance perfectly the conflicting needs of providing efficient guidance to scientific working and thinking, while leaving enough space for developing intellectual independence. I had the pleasure to work with him, and would like to acknowledge here the wonderful time I had in both Konstanz and Stuttgart. There is perhaps one characteristic goal that Gilinter Engelhardt persistently pursued. He strove to stay close to his scientific endeavors, for example by refusing offers which would have meant a larger administrative role for him.
xi
Nevertheless, he continues to provide service to his scientific community, as a member of the editorial board of this journal, and as a sought-after referee for many international journals and funding organizations, to name just a few. We wish Giinter Engelhardt continued happiness and success in his work and private life. Undoubtedly, he and his ideas will remain in high demand for his students, colleagues and friends.
Hubert Koller