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YOSHIMURA PI-ELECTRON and the pi-electron materials that carry obtained in quantity. As a result, the MATERIALS PROJECT: NEW them. The Yoshimura Pi-Electron materials science of carbon is active HORIZON OF PI-ELECTRON Materials Project will do this.
again. Single crystals of inorganic mateMATERIALS
The Yoshimura Pi-Electron Mate- rials that have a pi-electron system based
rials Project will assemble international on boron, nitrogen, or oxygen moleProject Director: Susumu Yoshimura teams of chemists, physicists, materials cules have recently been synthesized.
scientists, and biochemists to attack Scanning tunneling microscope obserThe plants, animals, and minerals the secrets of pi electrons and pi-electron vations have recently revealed that the of nature contain two kinds of elec- materials. These researchers will dis- reconstructed surface of a silicon sintrons, sigma electrons and pi electrons. cover ways to make new pi-electron gle crystal contains pi-electron-like The sigma electrons hold nature materials. What they learn about why defect states. These new pi-electron together. They provide the strength pi electrons are so light and fast may materials prompt research on the solid that holds trees up and keeps mountains lead to new high-speed electronic state physics and on the controlof their high. The pi electrons make nature devices. What they learn about super- electronic behaviors. work. They give us the bright greens polarizability may lead to new non- The Yoshimura Pi-Electron Mateand reds. They catch the light needed linear (red light in, blue light out) optical rials Project will view the large space for photosynthesis.
devices, which are essential for com- occupied by the freely moving pi elecOrganic chemistry has a long his- puters based on light. Their study of trons as domains of electron motion tory of making new compounds that the biocompatibility of pi-electron and materials transformation. The hold pi electrons. But the pi electrons materials may lead to new materials for project will exploit and elucidate unique in these compounds can only move in use in medicine.
physical, chemical, and biochemical small areas; they cannot wander freely By focusing the attention of phenomena that result from these very far without running into walls. researchers from a wide range of back- domains. For this, the project will One compound of nature is different. grounds on pi-electron materials, the develop synthetic methods and proIn graphite, the pi electrons can wan- Yoshimura Pi-Electron Materials cesses for new organic and inorganic der far and wide. Recently, scientists Project hopes to generate a wide range materials with extended pi-electron have learned to make graphites that of new knowledge, new materials, and systems and with high crystallinity. It are large single crystals. They have also new devices.
will elucidate the mechanisms of superfound pi electrons in inorganic mate- “Pi electrons” are mobile electrons polarization, high electron mobility, rials, for example, on the surface of whose cloud extends normal to the bond and nonlinear phenomena (Ref 67). silicon that is used in transistors and in axis between atoms. Since the delocal. The project may propose new eleccompounds of boron or nitrogen. ized pi electrons can move about tronic devices based on unique fea
The pi electrons in large single crys- throughout a crystal or molecule with- tures of pi electrons. Other work will tals of graphite are light and fast. They out distorting it, pi-electron materials focus on biological or biochemical can be faster than the electrons in the have many peculiar characteristics, such activities of pi electrons and reactions gallium arsenide high electron mobil- as extremely high electron mobility and in two dimensions that take place in ity transistors (HEMTs) that are being superpolarization. The pi-electron cloud graphite intercalation compounds developed for the newest generation of is also a fundamental reaction field for (Ref 68). The project will study selective supercomputers. Under the right con- organic and biological materials. Exam- and/or anomalous reactions in which ditions, they may become supercon- ples are photo-charge-transfer reaction the pi-electron domains participate. This ducting. When placed in electric fields, and photosynthesis. Little is known, work may shed light on mechanisms of pi electrons move to and fro over long however, about the roles of pi elec- biocompatibility and proliferation on distances, a phenomenon called trons in solid surface state or quantum carbonaceous materials in relation to “superpolarizability."
effects in two-dimensional conductors. electronic structures of the pi-electron Up until now, our knowledge of pi Low-dimensional graphites, which systems. electrons has come indirectly from are typical organic pi-electron mate- This project hopes to establish a research not aimed at pi electrons them- rials, have been made in the forms of materials science based on pi electrons selves. For example, pi electrons are fibers and sheets that have physical by reexamining and enriching our important for photosynthesis so research properties almost identical to those of knowledge on optical, electronic, on photosynthesis has taught us some- single crystals. Superaromatic carbon magnetic, chemical, and biochemical thing about pi electrons. Little research clusters such as Coo and Co can now be properties of pi-electron materials. has focused directly on pi electrons
ligands. These ligands will make cer- substances and no wastes is crucially CATALYSIS PROJECT:
tain that the metal ion cuts only the significant. In contrast to enzymatic FROM READY-MADE TO desired bonds and joins only the desired reaction, which efficiently gives chiral TAILOR-MADE CATALYSTS molecules in the desired way, much as substances, synthetic reaction remains
a woodworker's jig hold the wood pieces far from perfect. Project Director: Ryoji Noyori
so that precisely the desired joint can Recently, synthetic chemists are
be made quickly, efficiently, and with meeting this challenge by developing The perfect chemical reaction pro- little waste. These metal-ligand catalysts highly selective reactions catalyzed by duces only the desired product and no are called “molecular catalysts.” organometallic complexes, and the wastes. It starts with economical raw The Noyori Molecular Catalysis chemist's dream of achieving perfect materials and wastes little energy. It Project will focus mainly on reactions reaction is now being converted into allows the chemist to construct exactly that can make either left-handed or reality. Particularly, homogeneous the molecule desired in the shape right-handed molecules. Many reactions asymmetric catalysis using chiral metal desired.
used for making drugs do this. Getting complexes provides a promising way Until recently, perfect chemical rid of the undesired molecule can be and powerful tool to produce chiral reactions were found almost only in very expensive. Researchers in the substances, complementary to biological nature. The chemical reactions devel- project will design metal-ligand catalysts
project will design metal-ligand catalysts transformations, structural modification oped by man are still far from perfect. that cause the reaction to make only of naturally occurring chiral substances, Many consume large amounts of energy one of the two molecules.
classical resolution methods, etc. and produce hazardous wastes that Researchers will also design and study Asymmetric catalysis is capable of endanger the environment. Removing molecular catalysts for making polymers. multiplying chirality, and the efficiency reaction wastes from pharmaceuticals Many polymers come in left-handed of the chiral multiplication, defined as is very expensive.
and right-handed helices. By themselves, (major enantiomer-minor enantiomer The reactions of nature are brought the left-handed helices may have spe- (in mole)]/chiral source (catalyst) in about by catalysts called enzymes. These cial electrical or optical properties.
cial electrical or optical properties. mole, can be increased to infinite catalysts speed reactions by reducing However, if the right-handed helices depending on catalyst designing. The the barriers to the reactions. They also are also present, they cancel out the selection of central metals and molecdirect the reactions along exactly the special effects. Polymers that are purely ular designing of chiral ligands are right pathways. They have long been left-handed or purely right-handed may particularly significant to attain perthe envy of chemists. Indeed, many provide new electronic or optical devices. fect reaction. Such a molecular catalyst chemists are trying to adapt the reac- The Noyori Molecular Catalysis consisting of reactive metal center and tions of nature to make the chemicals Project will also research molecular auxiliaries (chiral source) not only needed for our modern everyday lives. catalysts for making polymers in which promotes reactions of associated sub
The Noyori Molecular Catalysis all the chains are the same length. Strates but also controls the stereoProject, however, is taking a different Currently, most reactions for making chemical outcome in an absolute sense. approach. Rather than try to improve polymers make the chains in many dif- To our knowledge, the first cataon nature, which is already close to ferent lengths. If the chains are all the lytic asymmetric reaction of prochiral perfect, researchers in this project will same length, the polymer may have compounds promoted by homogeneous design and study molecules that special properties, much as a paint- transition metal complexes was reported approach perfection in catalyzing brush with bristles of the same length in 1966. Ever since this discovery specreactions that nature cannot perform. spreads paint better than a brush hav- tacular progress has been made in this The researchers will start with metal ing bristles of varying lengths.
field, and with synthetic chiral metal atoms or ions. Metals can catalyze many Intrinsic properties and functional- complex catalysts optical yields over reactions. However, a metal ion by itself ities in materials are strongly influ- 80%, or even close to 100%, are freis somewhat like a naked bit on a enced not only by their molecular and/ quently obtained. In certain cases, the woodworker's tool. It cuts quickly but oratomiccomposition but also by their
or atomic composition but also by their efficiency of artificial complexes rivals is very hard to control. It often cuts purity. Particularly, chirality plays an that of natural enzymes and we can wrong and wastes the wood. The important role in science and technol- produce large amounts of chiral comresearchers of the Noyori Molecular ogies related to molecular electronics pounds having natural and unnatural Catalysis Project will mount these metal and optics. The perfect chemical reac- configurations with the use of only a ions in special organic "jigs” called tion producing only the desired very small amount of a chiral source. Some of them are applied to commer- cause the larvae to attach to the sand OKAYAMA CELL-SWITCHING cial production of chiral products of and begin growing. Other species are PROJECT:UNDERSTANDING extremely high enantiomeric purity. unaffected by the same odors.
THE "MASTER SWITCH” The Noyori Molecular Catalysis Once a larva touches the right place CONTROLLING CELL Project will focus mainly on perfectly and receives the signal to stop and grow, GROWTH AND controlled reactions leading to only what happens inside the larva? Are DIFFERENTIATION desired small or large molecules. For there internal chemical messengers? this purpose we will design new, well- Or is there some kind of electrical sig. Project Director: Hiroto Okayama defined organometallic complexes as nal such as occurs in nerves? Little is molecular catalysts. The concept for known and research has tended to be Cells in higher life forms such as “molecular catalysis” will generate a scattered among disciplines and target yeasts, plants, and animals grow and new type of chiral materials having species.
divide in a four-step cycle. They divide, potent biological functions and unique The Fusetani Biofouling Project will then grow some, then make a copy of physical properties.
gather international teams of marine their genes, grow some more, then divide Our basic principle, “molecular biologists, organic chemists, biochem- again. This simple cycle is crucially catalysis,” relies on “four-dimensionalists, and electrophysiologists to research important. Evolution has left it almost chemistry,” in which high efficiency is how these marine larvae know when to untouched. Genes controlling growth only attainable through a combination stop, attach, and grow. They will pay
stop, attach, and grow. They will pay in human cells also work when they are of both an ideal three-dimensional specialattention to barnacles, mussels, put into yeasts. structure (x,y,z) and appropriate kinetics and bryozoans.
Among the four steps, the growth (1). This chemical methodology will The biggest challenge for the right after division (called G1) is a most certainly contribute to industrial pro- Fusetani Biofouling Project will be to critical time. Will the cell divide? Will duction and molecular science and learn how to test chemical signals and it produce sperm and egg cells? Will it industry in the emerging generation. settling in the laboratory. Once this is change form such as into a muscle cell
achieved the researchers will be able to or into a blood vessel cell? Or will it FUSETANI BIOFOULING proceed rapidly to learn what kinds of lose control and become cancer? The PROJECT
chemical signals trigger settling and cell's fate is determined by events that
transformation of the larvae. They will occur during G1. Project Director: Nobuhiro Fusetani be able to decipher the changes that The Okayama Cell-Switching Proj
occur inside the larvae after they receive ect will use an amazing array ofrecently A barnacle larva hatches from its the chemical signal and how the signal developed tools to unravel the secrets egg and embarks on its search for a is transmitted inside the larvae. of G1 and how genes control it. place to settle and grow into an adult. Even before the Fusetani Biofoul- One tool is a specially designed gene Carried by ocean currents, it floats and ing Project develops the tests for the library. This is not a library of books swims, bumping into plants, fish, and chemical signals, the researchers will but a library containing DNA cloned rocks until, maybe days later, it touches be isolating and characterizing possi- from cells, for example, human muscle the right place. In minutes, the larva ble signal chemicals. They will also be cells. There are millions of volumes in bonds tightly to its new home and begins researching the basic physiology of the a gene library. There may be many making its shell and growing. This larvae to learn what pathways are duplicates and some may be missing settling process is repeated by count- there for the signals to follow.
pages or chapters. This library, howless sea animals: sponges, corals, mus- From this research we may learn ever, is not a mere collection of cloned sels, barnacles, and tunicates.
better ways for controlling these marine genes. It consists of genes engineered How does a larva know what surface organisms and thus help solve prob
organisms and thus help solve prob- so as to work in a wide variety of cells is right and what surfaces are not? There lems that have plagued man for mil- from human to yeast. The Okayama must be some kind of chemical signal. lennia, such as barnacle growth on ships, Cell-Switching Project will search these Scientists have learned, for example, and more recent problems such as beach libraries for genes that control G1. that if ocean sand contains certain odors erosion, the fouling of underwater One search will be done with fission (chemicals) that result from other adults pipes by clams, and the disruption of yeast mutants that have defects in G1. of the same species, these odors will coral reefs. We may also learn better Using such a mutant, the researchers
ways to cultivate clams, mussels, and can find the human gene that fixes the other marine organisms for food. defect. They can then decode the gene, that is, find out the structure of the G1 until it receives the next growth away from the stated objectives of the protein that is made from it. From the stimulus or a stimulus for differentia- project. Basic scientific objectives are protein's structure they can get clues to tion. When differentiation stimuli are served as well as societal needs and its role in G1.
received, the cell stays in G1 but changes objectives, with a focus on the distant A different search will be done with form into such specialized cells as muscle, future. a special kind of rat-kidney cell. These nerve, or kidney. Thus, the cell's fate is Within the Japanese scientific and cells become cancerous if they are determined by events that occur during technical community, ERATO is given exposed to growth factors. If the growth G1. The switch mechanism controlling wide publicity and has earned great factors are taken away, the cancer stops cell growth and differentiation is respect over its first decade of operaand the cells return to normal. In other ubiquitous among all eukaryotes and tion. The nation's best young scientists words, the cancer can be turned on and seems to be evolutionally well conserved. are attracted to work on ERATO projoff. Scientists have made several mutants This project will use one of the most ects, even though they have a limited of this rat-kidney cell and know that sophisticated gene cloning techniques 5-year lifetime (see Tables 1 and 2). there are switches in G1. The Okayama presently available, which we devel- Younger scientists are employed for Cell-Switching Project will search the oped, to unravel the secret of the “master the bulk of the research, and their human gene library for genes that cor- switch.” The technique is expression experience prepares them well for rect the defects in the mutants. From cloning using heterologous hosts, which greater responsibilities in the future. these genes, the researchers hope to allows us to use fission yeast mutants as Even with the 5-year cutoff, mid-career learn about switches that turn on can- hosts for isolation of mammalian genes. scientists are not reluctant to accept cer in humans and, perhaps, clues as to Using yeast mutants with defects in such a limited 5-year appointment how to turn it off.
G1, we can clone mammalian genes because they are confident that the Proliferation is a unique attribute that complement the defect. In paral- experience and the contacts developed of living organisms. Multicellular organ- lel, we will isolate extragenic suppressors during the ERATO adventure will isms proliferate through the process of known Gi mutants of fission yeast ensure them a satisfactory follow-on called development, which involves and use them to generate mutants that appointment. concerted replication and/or differen- would in turn serve as hosts for isola- Assessing the overall success of tiation of each cell composing the organ
tion of their mammalian counterparts. ERATO is hardly necessary. A brief isms. However, cell differentiation is Repeating these steps, we hope to iso- glance at the project reports above is not unique to multicellular organisms, late most of the genes comprising the enough to convince all but the most as yeast undergoes sexual differentia- “master switch” of mammalian and yeast skeptical of the value of ERATO's tion and forms spores when it encounters cells.
technical achievements to date. In poor nutrition, thereby surviving hostile Unraveling the mechanism control- addition, the opportunity for younger environments.
ling cell growth and differentiation will and mid-career scientists to devote Eukaryotic cells replicate in a four- provide a clue to understanding the 5 years of their career to innovative, step cycle called the cell cycle. Most molecular mechanism of malignant team-type, project research is of great cells in organisms are in a G1 phase, transformation and cell aging. We also value in their professional development. and they can stay there for quite a long hope to find a basis for the next gener- Many of the projects involve crossperiod of time. When a cell receives ation of biotechnology, which would disciplinary research teams and some growth stimuli, its enter the S phase, in allow us to manipulate the develop- involve international teams, thereby which DNA synthesis occurs and its ment of organisms.
presenting a broadening of scope for genetic information is duplicated. After
most younger scientists. DNA is synthesized, the cell proceeds CONCLUSIONS
As Japanese scientists struggle to to the G2 phase, in which the timing of
find the meaning and value of their role mitosis is determined, based on nutri- The ERATO program is certainly in global scientific leadership, ERATO's tion, cell organelle synthesis, and the unique in several aspects. Although international component, while not completion of DNA synthesis. Finally, clearly aimed at increasing Japan's large, contributes significantly to the in mitosis, the cell divides into two technology base in wide areas of sci- international interaction, in both sciidentical cells. After division, the cell ence, project managers are given encour- ence and technology, that seems desmay enter another cell cycle or stay in agement to follow their scientific and tined to grow in the next few years. technological intuition, even if it leads Some data on this latter point are given
in Table 3.
5. M. Sano and T. Kunitaki, J. Vac.
Sci. Tech. B9, 1137 (1991). Other arti1. E. Goto, “Josephson junction pair cles submitted to Langmuir and Ultracircuit,” in Proc. First Riken Sympo- microscopy. sium, 48 (1983).
6. H. Shimawaki et al., J. Appl. Phys. 2. H. Takahashi, editor, Parametron 69, 7939 (1991). Computer (Iwanami, Tokyo, 1968).
7. K Motoya and J. Nishizawa, Topics 3. Quantum Magneto Flux Logic Proj- in Millimeter-Wave Technology, ect Publication List, ERATO Symposia volume 2, chapter 1 (Academic Press, (JRDC, November 1991).
New York, 1988).
4. E. Goto, Y. Woad, and K. F. Loe, 8. Y. Horiike et al., J. Vac. Sci. Technol editors, Advances in Quantum Flux
Flux A8, 1844 (1990). Parametron Computer Design (to be published by World Scientific). 9. T. Meguro et al., Appl. Phys. Lett.
56, 1552 (1990)