SPECIAL ISSUE PREFACE pubs.acs.org/JPCA
Autobiography of Pavel Hobza
I
was born in Prerov, Czechoslovakia, on October 21, 1946, i.e., one and half years after the end of World War II. The country slowly recovered from 6 years of Nazi occupation and sought the way back to democracy and the prosperity of interwar Czechoslovakia. The short postwar period of democratic development was broken up by the communist coup in 1948 and the country, along with my generation, fell to a long period of the communist regime. The communist dictatorship strongly affected the lives of all citizens, including my own. From time to time I think about how different my private and scientific life would have been if democratic forces had not failed in our country in February of 1948. I had a happy childhood, first in a small town near Olomouc. When my one year older brother and myself had to start elementary school, we moved to Olomouc, a beautiful and magical town full of baroque fountains and monuments. My life-long interest in chemistry might already have been awakened in my childhood, for both my loving parents worked in a pharmacy where I very much liked to visit and later help them. Because of the communist repression and persecutions, the first half of the 1950s was the worst period of our postwar history. Communists, inspired by Stalinist procedures liquidated all their “enemies” and spread fear among the whole society. The omnipresence of secret police made people too scared to freely pronounce their opinions and convictions. Despite this situation, the atmosphere in our family was open and critical, and my parents were never afraid to speak out in a straightforward and honest way about the situation of the country. My own experiences of the Stalinist regime helped me to realize that there is very little difference between fascism and communism. This child’s insight prevented me from entering the communist party in adulthood, despite the many advantages that come from this. Like most young people of high school age, I had many interests. At that time I also started to be interested in, and even fascinated by, the world of atoms, molecules, and their interactions. I read several popular books on the topic and decided to devote myself to the study of this branch of chemistry. My interests in chemistry were strongly supported by my father, who was a pharmacist and had a degree in chemistry, and also by the very encouraging atmosphere at my high school, where we had an excellent and very enthusiastic chemistry teacher. I successfully participated in several chemical olympiades. After the Abitur, I started to study at the most prestigious (at that time) Faculty of Technical and Nuclear Physics at the Czech Technical University in Prague. In 1964 the political atmosphere in Czechoslovakia started to change and became a little more open to criticism. We, as Prague university students, enjoyed participating in political discussions and were fascinated by the idea of political plurality, free speech, and freedom of the press. In 1967 the so-called “Strahovske Udalosti” (Strahov events) took place, and are now believed to have been one of the triggers of the Prague Spring. We who participated in events understood them as a protest march against unsuitable living conditions at our dormitories. Nevertheless, the communists interpreted it as a protest against the communist regime in our country, and strong police r 2011 American Chemical Society
repression followed. However, our protest initiated a series of political discussions and other activities. The famous Prague Spring started in January 1968 with the appointment of Alexandr Dubcek as the secretary general of the communist party, which was the highest political position. The eight months that followed were the most exciting time of my life. Like the majority of Czech people, I also started to believe that we were constructing a new society between socialism and capitalism. But as we soon learned, we had all been naive. On August 18th I left the country for a short visit to my relatives in Vienna. My uncle woke me up on August 21st with the news that Soviet tanks were occupying Prague and the entire country. I, as well as others in our country, first believed that this was only a misunderstanding that would soon be settled and our country would continue its independent way. Unfortunately, we all were wrong. On the occasion of the first anniversary of the Soviet occupation (on August 21, 1969), a huge demonstration took place. In the evening the tanks entered downtown Prague, and the demonstration changed into a street war. Even now I remember the moments very vividly when we fled the army and found refuge in a cellar. This encounter with such a brutal political and military power was a life-long traumatizing experience, not only for me, but for a whole generation. Although in the following years there were no executions, as in the 1950s, the regime put a lot of pressure on its citizens and forced them to collaborate and give up their hopes. In this atmosphere it was not easy to retain one’s own dignity and integrity. It was my work and affection for chemistry that partly enabled me to forget and survive the desperate political and social situation in our country. During the first few years of my studies, I found out that the type of chemistry I wanted to study was not given at my university. Our professors were flexible and cooperative and recommended that I go to the Czechoslovak Academy of Sciences and visit Rudolf Zahradník, who was a cofounder (with Jaroslav Koutecky ) of the renowned Prague school of quantum chemistry, which included such prominent ízek, Josef Paldus, and Josef Michl. The first scientists as Jirí C meeting with Rudolf was one of the key moments of my professional career. Soon I started my Diplom (master) year and later my Ph.D. research with Rudolf. As a subject of my Ph.D. thesis, he proposed weak intermolecular interactions, which we now term noncovalent interactions. The subject was original and completely new, literally terra nova. This was such a strong and promising subject that I have stayed with it up to the present time. At the time when I was completing my Ph.D. thesis (1973), I was fervently confronted with the political reality of our country. I remember very well the moment when the secretary of the communist party denounced me: “There is no place at the Academy of Sciences for such elements like you!” I was very lucky to be allowed to finish my Ph.D., but there was no position Special Issue: Pavel Hobza Festschrift Published: October 13, 2011 11115
dx.doi.org/10.1021/jp208265u | J. Phys. Chem. A 2011, 115, 11115–11118
The Journal of Physical Chemistry A in science for “politically unreliable” people like me. The situation was really difficult, and it was not clear at all whether I would find any place in science. Finally I obtained a position at the Institute of Hygiene and Epidemiology in Prague, where I stayed for 12 years. Since I was the only quantum chemist among about 1000 employees, I was given relative freedom to do my scientific work, but I was not allowed to travel abroad and to have any students. Despite this, together with my Ph.D. mentor, Rudolf Zahradník, who was also partially employed there, we were able to make important progress toward the understanding of noncovalent interactions. We published several dozen publications on this subject and also two books issued by Elsevier (Amsterdam), Academia (Prague), and Mir (Moscow). Our most fruitful cooperation over these 15 years culminated in 1987 in the publication of a review article in Chemical Reviews entitled, “Intermolecular Interactions between Medium-Sized Systems. Nonempirical and Empirical Calculations of Interaction Energies: Successes and Failures”. With the publication of this review we were lucky, since it appeared at the proper time at the end of the 1980s when the role of intermolecular interactions in science were finally fully recognized—which was also partially due to our efforts. In 1979 I received a postdoc offer in the laboratory of Camille Sandorfy at the Universite de Montreal. At that time in Czechoslovakia, the regime slowly started to loosen the stifling grips it had since the Prague Spring. Even though I did not expect to be endorsed by the Czechoslovak authorities to go to Canada, finally, and to my big surprise, I was given permission to go. However, I was only allowed to go to Canada by myself, without my wife, whom I had married six years before, and without my son and daughter. In later years opportunities arose for a few shorter stays at Montreal. Camille was in a position to support excellent working conditions, but in addition he turned out to be a genuine gentleman, and it was a great pleasure to work with him. In his laboratory I was first confronted with the paradigm involved in DNA bases and base pairs; this subject became one of the key issues in my scientific career. Our last project concerned calculations on different DNA base pairs in vacuo, and in 1987 we published the paper, “Nonempirical Calculations on All the 29 Possible DNA Base Pairs” in the Journal of the American Chemical Society. This paper seems to be regarded as quite seminal since, first, we found out that there exist base-pairs other than Watson Crick ones, which are comparably stable, and, second, we recognized the crucial importance of dispersion energy. The total stabilization energy of DNA base pairs (at that time very large complexes) was constructed as the sum of the Hartree Fock and dispersion energies, providing the basis for the recent (and very successful) development in computational chemistry of including the dispersion energy in DFT theory. In 1986 I received an offer from the Institute of Organic Chemistry and Biochemistry of the Czechoslovak Academy of Sciences to work on a newly installed workstation, which was, at that time the most powerful computer in Czechoslovakia. I embraced this offer also because, for the first time in my professional career, I had the possibility to work at a top scientific institute, which it was at that time and is at present. At the end of the 1980s, initiated by Perestroika in the Soviet Union, our communist regime started to become unstable and collapsed, as did others in Middle and Eastern Europe. However, the regime’s decline was also accompanied by a deterioration of civil rights and freedom, since the collapsing regime often reacted mindlessly and desperately against civil disobedience, protests,
SPECIAL ISSUE PREFACE
and demonstrations. Events culminated in the so-called Velvet Revolution, on Friday November 17, 1989. November 17th is an important day in our history since on that day in 1939 the Nazis brutally smashed a student demonstration. On the same day in 1989, students peacefully protested against the communist power and, like in 1939, the police brutally reacted. In the following week, a series of protest demonstrations took place. Although at first I was scared that the demonstrations would be dispersed by tanks like in 1969 (and in fact there were lots of rumors announcing the arrival of the army), I, along with most people in our country could not forego the opportunity to openly and loudly express our feelings about an oppressive regime that beats innocent students. On the last day of the Velvet Revolution, about 1 million people protested in Prague, and the communist regime collapsed. After the Velvet Revolution, the Academy of Sciences, as well as the whole of science in our country, changed. Rudolf Zahradník, my Ph.D. advisor, became the Director of the Heyrovsky Institute of Physical Chemistry and later the President of the Academy of Sciences of the Czech Republic. Rudolf invited me to his Institute, and in 1992 I moved from the Institute of Organic Chemistry to the Heyrovsky Institute and started to build an independent group. I was now allowed to teach and also did my habilitation at the Charles University. For the first time I had a group of students. The group grew and we focused on the theory of noncovalent interactions and its applications in the biodisciplines. By the middle of the 1980s I had started a very fruitful cooperation with two distinguished professors in Germany: Paul von Rague Schleyer and Edward W. Schlag. With Paul we studied different types of noncovalent bonds. One of the main projects in Ed’s laboratory was the benzene dimer, and I participated in this. Ed recognized the predictive strength of quantum chemical calculations and purchased a CONVEX computer, which was at that time one of the fastest computers. Since I was the only theoretician in his group, I had excellent working conditions. In 1993 we published a paper entitled “New Structure for the Most Stable Isomer of the Benzene Dimer: A Quantum Chemical Study” in the Journal of Physical Chemistry, where we proved the existence of the parallel-displaced structure. It turned out to be even more stable than the T-shape structure, which was believed to be the global minimum. This finding is still valid. Careful theoretical investigation of the T-shaped structure resulted in a surprising finding. The T-shaped structure was believed to be stabilized by the C H 3 3 3 π hydrogen bond, which should result in an elongation of the C H bond and a red-shift of the relevant stretching frequency. To our surprise, the opposite effect was found. At that time, no textbook referred to any H-bond as having a blue-shift. It took us more than 2 years to publish, again in the Journal of Physical Chemistry, the paper entitled “AntiHydrogen Bond in the Benzene Dimer and Other Carbon Proton Donor Complexes”. We recalculated all the results with a variety of computer codes on different computers, we used different basis sets and passed from the harmonic to the anharmonic approximation, and still observed this blue shift in all investigated complexes. This gave us the confidence that the predicted blue shift was not an artifact of our computational methods but a physical reality. However, it was not immediately broadly accepted. The turning point appeared with the experimental verification of the blue shift in the fluorobenzene 3 3 3 chloroform complex. Bernd Brutschy from Frankfurt agreed to perform an IR gas phase experiment on this complex. I still remember a call from him asking about the magnitude of the blue 11116
dx.doi.org/10.1021/jp208265u |J. Phys. Chem. A 2011, 115, 11115–11118
The Journal of Physical Chemistry A shift. I told him that our theoretical prediction is 12 cm 1 and he replied their experimentally observed shift was 14 cm 1. This was really a full conquest. Since then, improper blue shifting hydrogen bonding, as we (with Zdenek Havlas) called this type of hydrogen bonding in our Chemical Reviews paper (“Blue-Shifting Hydrogen Bonds”, Chem. Rev. 2000, 100, 4253), started its independent life. Finally, the IUPAC changed the definition of the H-bond, and according to this new definition, which has just appeared recently, H-bonding can be accompanied by red, blue, or no change of X H stretching frequency upon complexation. I fully realize that a part of this success is due to Bernd and I am grateful to him. My stay at Technische Universit€at M€unchen culminated in 1991 with a oneyear visiting-professor fellowship granted to me by the Deutsche Forschungsgemeinschaft. I spent one, scientifically fruitful and personally happy, year in Garching, this time with my family. While doing research in Schlag’s laboratory in Garching, I became a good friend with Klaus M€uller-Dethlefs, the inventor (together with Ed Schlag) of ZEKE spectroscopy. The ZEKE experiments provide accurate characteristics of noncovalent complexes, and it was quite natural to combine ZEKE experiments with high-level calculations. We published several papers and in 2000 a review article in Chemical Reviews: “Non-covalent Interactions: A Challenge for Experiment and Theory”. In this paper we used, probably for the first time, the dedicated name “noncovalent interactions” for interactions that were, up to then, called by different names such as van der Waals interactions, intermolecular interactions, nonchemical interactions, or weak interactions. I believe that it was a good decision to strongly push the term noncovalent interactions, and this name is now widely acknowledged and used more and more in the literature. This 2000 Chemical Reviews article is also important because here we looked consistently at noncovalent interactions from the viewpoint of both experiment and theory. Since the “proof of the pudding is the eating”, the Royal Society of Chemistry asked us to write a book, and voila, a few years later, with German and Czech efficiency, and surprisingly for both of us, we finished it in time, and “Noncovalent Interactions: Theory and Experiment” was published in 2009. Klaus and I happen to share similar views, not only on noncovalent interactions, but on some of the more general problems of our world, and I appreciate my friendship with him very much. In 2003, the Czech Scientific Council introduced the concept of Research Centers. This brought the opportunity of considerably higher financial support and allowed one to create larger research units. Together with my younger colleagues, Pavel Jungwirth and Petr Nachtigall we prepared the “Center for Complex Molecular Systems and Biomolecules” and won funding in a very strong competition. This was a big success, and our working conditions improved dramatically. Despite this success, our situation at the Heyrovsky Institute became worse, and it was not possible for me and my entire group to stay at the Institute anymore. Fortunately, the Director of the Institute of Organic Chemistry and Biochemistry (IOCB), my previous student, Zdenek Havlas, made us a very generous offer. The whole group of almost 20 scientists and students moved to the IOCB at the beginning of 2004, and since then we are all enjoying the friendly atmosphere at the Institute. I do hope that the Institute is also profiting from our presence and that the very high reputation of the Institute is also partially due to us. Zdenek helped us in this difficult time and this cannot be forgotten. The organization of the Institute changed in 2006, and, besides Junior and Senior Research Teams, two Distinguish
SPECIAL ISSUE PREFACE
Chairs were also created. The first belongs to Antonin Holy, probably the most famous and successful Czech scientist, who invented the most efficient antiviral drugs for the treatment of AIDS and hepatitis B. I was very fortunate that the Institute offered me the second Distinguish Chair position, and I happily accepted this offer. In 2007, I received the very prestigious and generous “Praemium Academiae” from the Academy of Sciences of the Czech Republic. A year later I was awarded with the highest eska Hlava”. The prize for science in our country, the “C combined resources from the Center, the Distinguished Chair, and the Praemium Academiae granted me highly above-standard conditions for scientific work, and I am most grateful for it. The group has grown, and presently it comprises 15 members. I have been very lucky to work with outstanding students, postdocs, and senior co-workers. The present team includes several previous students and co-workers from other laboratories. We all focus on theory and application of noncovalent interactions and the strongest point, from the point of view of theory, involves the development of new methods for calculating noncovalent interactions. All these methods generally contain empirical parameters. Parametrization and/or verification of these newly developed methods critically depends on the availability of highquality reference data. Our S22 data set, based on CCSD(T) stabilization energies, was introduced in 2006 and become the most popular noncovalent binding energy and geometry database. It has been and still is extensively used in the literature. For highly accurate calculations of complexes with up to 100 atoms, we introduced the SCS-MI-CCSD and MP2.5 methods, which provide stabilization energies within a few percent of the benchmark data. The computational time is shorter by 1 or 2 orders of magnitude compared to the benchmark calculations. For extended complexes with several thousands of atoms, we suggested a modification of the PM6 semiempirical QM method, and our version, called PM6-DH2X gives surprisingly accurate stabilization energies for various types of noncovalent complexes. The method is much faster than any other QM method, and it is only slightly more time-demanding than the empirical force field methods that have been used exclusively up to now in the field of extended complexes. This method represents an important base for our recent activity in novel applications of our noncovalent interaction project, namely, in silico drug design. This work brings me joy and pleasure. Practically all drugs interact with proteins via noncovalent interactions. Optimization of drug activity basically means maximizing the binding free energy of a protein drug complex, and for this we utilize our long-term experience in calculation and understanding of noncovalent interactions. Currently we are working on more than a dozen projects on various protein-inhibitor systems, and the first inhibitors have already been synthesized on the basis of our theoretical predictions. Since 1972, I have been happily married to Pavla, who has been my constant support in all peripetias of my life, and her presence, help, and advice have always been of vital importance to me. Our first son, Pavel, was born two years after our marriage. He fell in love with philosophy and is now an assistant professor at the Palacky University in Olomouc, the city I grew up in. Our daughter was born five years later. She finished social sciences at the University of Olomouc. We have three grandsons, Pavel, Dan, and Antonín. (I take delight that not only my son but also my first grandson is named Pavel.) Since grandparents are not expected to bring up and educate their grandchildren, they can just have a good time with them, which brings a new (and for me 11117
dx.doi.org/10.1021/jp208265u |J. Phys. Chem. A 2011, 115, 11115–11118
The Journal of Physical Chemistry A
SPECIAL ISSUE PREFACE
surprising) dimension to my life. I am very grateful to be an important part of my grandsons’ experience as they grow up, a privilege that my father unfortunately could not enjoy. Last, but not least, I am very much indebted to my colleagues Dana Nachtigallova, Petr Nachtigall, Jirí Vondrasek, Ota Bludsky , and Pavel Jungwirth for their effort in assembling this issue and, of course, to all who have contributed to this special issue of the Journal of Physical Chemistry. Pavel Hobza Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic
11118
dx.doi.org/10.1021/jp208265u |J. Phys. Chem. A 2011, 115, 11115–11118
