9.00 A.M. We bicycle down the scenic streets to the Bodensee where the sessions is going to be held in the Inselhalle. The meeting begins in front of a packed audience in the Inselhalle. The region is known for apples and these grace the tables outside. Students and scholars from all nationalities are seen, eager to open their minds. Gerhard Ertl (Chemistry, 2007) begins his talk. Ertl received the Nobel Prize for his pioneering studies of reactions on surfaces.
Ertl emphasizes the role of catalysis in modern chemistry and traces the history of early studies on catalysis and kinetics, including Ostwald’s understanding that catalysis is intimately related to kinetics. The next slides talk about the Haber-Bosch process including the nature of the catalysis and the steps involved; essentially dissociation of nitrogen and hydrogen into monoatomic entities followed by combination. The reaction is complicated by the fact that the catalyst exposes different crystal planes with differing reactivities.
Later slides talked about carbon monoxide dissociation on metal surfaces and the reaction of oxygen on platinum surfaces. Carbon monoxide can poison the surface of the catalyst so that oxygen can no longer bind. This is especially prominent at low temperatures (that’s part of the explanation for your car exhaust stalling in the cold)
Ertl also mentioned the oscillation in the production of carbon dioxide through catalysis as the concentration of oxygen is varied. Interestingly this oscillation is similar to the oscillation in prey-predator populations which is often described by the Lotka-Volterra equations. The equations explain for instance why a fur-trading company called the Hudson Trading Company saw periodic and inverse relationships between the quantities of Lynx and Hare fur supplied to it. The oscillation also bears a relationship to the famous Belousov-Zhabotinsky reaction, a beautiful and fascinating color-change reaction which I had experimented with during college days. This reaction when performed in 2D on a Petri dish can display spiral waves. Similar spiral waves in carbon-monoxide oxidation on Pt were illustrated. (As an aside, for an excellent introduction to chaos theory and non-linear dynamics in chemistry, I would recommend Stephen Scott’s “Chemical Chaos”)
Ertl concluded by demonstrating turbulence resulting from chemical waves. At this point, he said, we have progressed from atoms to complexity, requiring a different kind of understanding.
9:33 A.M. Richard Ernst won the Nobel prize in 1991 for revolutionizing NMR spectroscopy and especially for the development of Fourier Transform NMR spectroscopy. But today he is talking about passions and activities beyond science. Ernst mentioned several scientists who were seriously interested in the arts, music, writing and poetry. Einstein’s violin, Djerassi’s poetry, Feynman’s drumming, Gell-Mann’s bird-watching, Eigen’s piano are only some examples of the myriad interests that scientists sustain while doing high-quality science. Ernst’s talk is pictorial and appealing to a very general audience.
Ernst’s own interests extend to Tibetan art and Buddhist philosophy, and he is illustrating this interest through several paintings and illustrating. He talks about Buddhist istadevatas or ‘enlightened beings’ that have been displayed on many beautiful paintings. Some key tenets of Buddhist philosophy including the eightfold way are briefly discussed. Ernst also talks about painting technology during the ancient era and mentioned the use of infrared and Raman spectroscopic techniques to analyze the paintings (“Unfortunately NMR is useless in these cases”). Ernst himself has tried his hand at a little bit of painting in the old tradition, using primitive, colored chemicals. His enthusiasm has led him to install a Raman spectrometer in his bedroom that provides instruction during sleepless nights. Raman spectroscopy reveals the use of several rather simple chemicals in the paintings, including malachite green, carbon black, cinnabar and vegetable dyes.
Ernst concludes with a brief mention of a science teaching programs for Tibetan monks that he and others have initiated in India (“Science meets Dharma”). The conclusion is that extra-curricular activities form an essential ‘second leg’ of your life and are necessary if you want to avoid becoming a ‘one-sided nerd’!
10:14 A.M. Ryoji Noyori won the Nobel Prize in 2001 for his development of an asymmetric version of a reaction that organic chemistry students study in their first or second semester; catalytic hydrogenation of alkenes. Noyori invented valuable catalysts based on binapthol and ruthenium to bring about highly efficient and stereospecific hydrogenation of organic compounds. He won the prize long with co-recipients William Knowles who studied similar reactions, and Barry Sharpless who discovered asymmetric epoxidation. Digressing a little, for what it’s worth, Barry Sharpless is one of the most entertaining speakers I have come across. Others may find his meandering exasperating but when I heard him talk I relished the multidimensional perspectives he had, displaying click chemistry on one slide and the space shuttle on the next one.
But coming back to Noyori; in this talk, Noyori is talking about the centrality of chemistry in human life (for a great illustrated perspective on the central nature of chemistry, I would recommend Ronald Breslow’s “Chemistry: The Central Science”). He mentions the key role that chemistry plays in pharmaceutical research. A slide shows a structure of atorvastatin (lipitor) bound to HMG-coA reductase. The binding of the drug is dictated in part by its electrostatic potential, a feature that is presented differentially to the protein for different stereoisomers for the drug.
The next slides illustrate the importance of chirality in medicine and biology; the usual suspects were displayed, including limonene and thalidomide. R and S limonene smell like oranges and lemons. The value of single-enantiomer drugs cannot be overemphasized. Noyori’s own asymmetric hydrogenation is used in the manufacture of many important drugs, including carbapenem antibiotics as well as the isoquinoline antibiotic levofloxacin. Japan’s Takasago which produces most of the world’s supply of menthol also uses the reaction in menthol manufacture.
After a brief overview of drug development and the attrition rates typically seen, Noyori further showed interesting statistics on non-responders to drugs for specific diseases. As is well known, cancer drugs top the list in the number of patients who don’t respond or who stop responding to treatment.
Getting to his own research, Noyori talks about the synthesis of compounds for brain imaging using PET that he and he his colleagues have worked on. He concludes by a message to young researchers that emphasized the importance of chemical research as well as its public awareness in the twentieth century.
11:15 A.M. F. Sherwood Rowland shared the 1995 prize with Mario Molina and Paul Crutzen. Their work, which met with considerable corporate and political opposition, delineated the role of chlorofluorocarbons in causing the destruction of the ozone layer. The work led the way to further studies of human manipulation of climate and encouraged awareness of global warming.
Rowland begins by citing the opinion of the Supreme Court in 2007 that emphasized the connection between atmospheric CO2 and rise in global temperatures. This is followed by a slide with the famous curve obtained by Charles David Keeling from 1957 onwards that meticulously detailed the rise in CO2. The slide is followed by a basic discussion of greenhouse and gases and necessary requirements for a molecule to act as a greenhouse gas (it should have three atoms and it should have a reasonably long lifetime in the atmosphere). Rowland further talks about radiative forcings including the albedo effect mediated by clouds, snow and ice. A discussion of ice core measurements yielding the earth’s record of CO2 and temperature changes follows.
Rowland’s talk was followed by that of his fellow Nobel laureate Paul Crutzen who reiterated several of Rowland’s points. In recent years Crutzen has also become known for his proposal for climate geoengineering in which he has suggested infusing the atmosphere with sulfate aerosols. These aerosols would lead to cloud formation and reduce solar heating. The proposal is widely debated so I am looking forward to hearing something about it.
Crutzen starts by noting the tremendous increase in human and cattle population, industrial output, water and energy usage and urbanization that has taken place over the last three centuries. The problem of water usage is especially acute and never readily appreciated; it takes 12,000 liters of water to produce a liter of coffee for instance. Nitrogen fixation has also been tremendously accelerated with the invention of the Haber-Bosch process. All these developments, while raising our standard of living, have also put significant strain on our biosphere and atmosphere.
Crutzen then talks about the measures we need to adopt for mitigating global warming, including decreasing CO2 concentrations by 60%. One slide does talk about injecting sulfate aerosols in the stratosphere by using balloons and airplanes. This is where Crutzen’s discussion of geoengineering begins. Crutzen talks about the history of ideas about geoengineering which go back to the 1970s. Such models have had some success; for instance James Hansen of the Goddard Institute somewhat famously predicted that the eruption of Mount Pinatubo in 1991 would lead to a slight reduction in global temperatures, a prediction that was validated. Geoengineering models start with a fixed aerosol and greenhouse forcing in a General Circulation Model. CO2 is then injected into the atmosphere, followed by the hypothetical introduction of 1 Tg of sulfate aerosols. The computer simulations clearly show the reduction of average surface temperature induced by sulfate, although Crutzen himself is careful to emphasize that the model is simplistic. Neither does he fail to mention that any such geoengineering schemes should not neglect other efforts to reduce CO2 concentrations.
12:26 P.M. The last talk is by Hartmut Michel from the Max Planck Institut for Biophysical Chemistry in Frankfurt. Michel along with Robert Huber and Johann Deisenhofer received the prize in 1988 for his discovery of the structure of an extremely important protein; the photosynthetic reaction center. This was the first determination of the structure of any protein involved in this fundamental life process. The story itself is interesting since Huber was not involved from the very beginning but was asked to collaborate by Michel after Michel obtained crystals of the protein. In today’s talk Michel is going to talk about cytochrome c oxidase.
Michel started by elaborating the importance and features of membrane proteins, including their importance as drug targets. He then moved on to enumerate a brief history of Cytochrome c oxidase. Crystal structure determination of membrane proteins is still a tricky art. There are two operative mechanisms operative in the protein; the K pathway and the D pathway. It’s the D pathway involving proton transfer that really concerned Michel. Three amino acids in the active site impede protein transport and this lack of access must be relieved for efficient transfer. The important question seems to be; what are the proton-accepting amino acids for the charge compensation involved in the counter transport of an electron for every proton that is pumped? Electrostatic calculations do not show readily visible charge acceptors in the active site and possible acceptors seem to be in a neutral state in the oxidized form of the protein. A plausible model involving a glutamate still needs to be validated. A related question is what exactly is in the active site. One postulated possibility based on size is peroxide, a species you don’t commonly find in actives sites. Yet it seems to provide the best fit for the electron density. A mechanism has been proposed for how the peroxide would react with the iron and copper centers in the active site. Work still needs to be done.
| » Ashutosh Jogalekar studied chemistry and is currently a postdoctoral fellow. |  |
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