FEATURE KANAGAWA UNIVERSITY Magazine Associate Professor Izumi Iwakura Laser Chemistry and Physical Organic Chemistry Professor Tadashi Sugawara PROUD Physical Organic Chemistry Professor Kinya Hibino BLUE High-energy cosmic ray research on the Tibetan English Plateau version 01 2016/11 Distinguished Professor Daisuke Uemura Compound Hunter Assistant Professor Sachi Yamaguchi Mathematical Biology Professor Nobuhiro Kihara Organic Chemistry, Bioorganic Chemistry Professor Susumu Izumi Molecular biology, Insect physiology and biochemistry ESSAY : SCIENCE INSIGHTS Professor Emeritus Wasuke Mori Magnetic chemistry, Functional materials chemistry, Complex chemistry 2 CONTENTS p.04-19 FEATURE p.04-06 p.12-13 p.18-19 Unobservable bond Chemical approach to A life mechanism breaking and bond the strategies of life hidden within reforming steps during Distinguished Professor the silkworm, chemical reactions Daisuke Uemura glimpsed through molecular biology Associate Professor Compound Hunter Izumi Iwakura Professor Department of Chemistry, Susumu Izumi Faculty of Engineering p.14-15 Department of Laser Chemistry Biological Science, Faculty of Science and Physical Organic The mysterious sexuality Chemistry Molecular biology, of the marine organism Insect physiology and that confounded Darwin. biochemistry p.07-09 We are challenging this mystery with a p.20-23 One more theory bringing mathematical model. us closer to the mystery ESSAY : SCIENCE INSIGHTS Assistant Professor of the origin of life Sachi Yamaguchi Measuring novelty The rich behavior of the Department of Information “membrane”, clarified Systems Creation Professor Emeritus Faculty of Engineering through “artificial cells” Wasuke Mori Mathematical Biology Department of Chemistry, Professor Faculty of Science Tadashi Sugawara Magnetic chemistry, Department of Chemistry, p.16-17 Functional materials Faculty of Science chemistry, Physical Organic Chemistry Chemical reconstruction Complex chemistry of the underlying molecular concept in p.10-11 organisms We are looking into Professor space from here Nobuhiro Kihara Department of Chemistry, Professor Faculty of Science Kinya Hibino Organic Chemistry, Department of Physics, Bioorganic Chemistry Faculty of Engineering High-energy cosmic ray research on the Tibetan Plateau PROUD BLUE 3 PROUD BLUE ISSUE: Kanagawa University published “PROUD BLUE” in Japanese as a public relations magazine focused on our research and researchers. The title is associated with the school color, and the first issue was published in February, 2015 and the third issue in February, 2016. This English version was based on the above Japanese versions of the first and third issues. 4 FEATURE Unobservable bond breaking and bond reforming steps during chemical reactions 2H2+O2→2H2O: This is one of the most well-known chemical reactions in science textbooks. Indeed, even if you are not a scientist, you have most likely seen this chemical reaction at some point. It describes the oxidation of hydrogen, where hydrogen reacts in the presence of oxygen to produce water. The arrow symbol in this familiar chemical reaction indicates an unknown reaction mechanism, as it has so far been impossible to determine when and how the bond breaking between the hydrogen atoms and oxygen atoms, and the bond formation between the hydrogen and oxygen atoms occur during the reaction. Dr. Izumi Iwakura is a chemist who explores such unobserved reaction mechanisms using ultrashort pulse lasers. A five-femtosecond strobe that Associate Professor reveals the reaction process In the last 100 years, many hypotheses have at- Izumi Iwakura tempted to explain the unobserved reaction Department of Chemistry, mechanism of the Claisen Rearrangement, a Faculty of Engineering reaction originally reported by the German sci- entist, Rainer Ludwig Claisen in 1912. During Laser Chemistry the Claisen rearrangement of allyl vinyl ether (CH2CHCH2OCHCH2), the carbon-oxygen bond and Physical Organic is broken upon heating, and a new carbon-car- Chemistry bon bond is formed. Three hypotheses exist to explain the unobserved reaction mechanism and the transition state of the reaction: i) The C–O bond is broken first and then the C–C bond is formed; ii) C–C bond formation occurs first; and iii) Bond breaking and bond formation occur simultaneously. Although one can specu- late, it was considered impossible to actually observe the transition state and the structural changes taking place in this transformation. Indeed, these steps are exactly what Iwakura is attempting to visualize, which leads to the question, how exactly can she visualize this? The actual visualization of chemical reaction processes began with the pump-probe mea- surement study in 1949. The time resolution of this study was limited by a flash pulse duration of microseconds (10−6s), while in the last 50 years, the visualization of chemical reaction processes has now approached the femtosec- ond (10−15s) scale. Using a high-speed imaging camera, workers have visualized the “milk crown,” i.e., the crown-shaped structure formed when a drop of milk impacts on a thin layer of milk or any other liquid. They wondered if a chemical reaction process could be visualized using a strobe, just as a high-speed imaging camera can capture an instant snapshot that cannot be observed by PROUD BLUE 5 the naked eye. Thus, a strobe with a short flash these steps during a thermal reaction. time is required to visualize the bond breaking Chemical reactions can be generally divided and bond reforming steps during a chemical into two main groups, namely thermal reactions reaction. More specifically, the required flash and photoreactions. A thermal reaction is trig- time of the strobe would be shorter than the gered when the molecular vibrations are ex- duration of molecular vibrations. This led to cited by heat, while a photoreaction is triggered Iwakura developing the five-femtosecond pulse when the electrons are excited by light. Indeed, laser for such a purpose. thermal reactions will likely be familiar to Izumi Iwakura many. In terms of photoreactions, perhaps one The third type of chemical Izumi Iwakura graduated from the of the most well-known of these is damage to reaction that creates Department of Chemistry, Faculty DNA caused by ultraviolet irradiation, which of Science and Technology, Keio University in March 2001 and com- an observable condition can result in the formation of skin cancers. pleted her doctoral studies (science) In 2002, Takayoshi Kobayashi (a specially ap- One of the main reasons for difficulties in visu- in the same institution in September pointed professor by The University of Electro- alizing the movement of atoms in molecules is 2005. Following positions such as the Japan Society for the Promotion Communications), with whom Iwakura had a disorganized molecular vibration. The move- of Science Research Fellowship fateful encounter later on, developed a visi- ment of atoms in a disorganized manner is like and PRESTO, and the Japan ble-five-femtosecond pulse laser that allowed a large party where everyone is talking at once, Science and Technology Agency full-time researcher, she joined for the real-time spectroscopy of molecular vi- and it is difficult to hear anyone in particular. the Department of Material & Life brations. Kobayashi conducted a study to visu- Eventually, the noise takes over and the situa- Chemistry, Faculty of Engineering, alize the bond breaking and bond reforming tion cannot be understood. Kanagawa University in 2012. She later became an associate profes- steps during a photoreaction. This was followed Thus, to control the situation, Iwakura success- sor in the Department of Chemistry by Iwakura’s attempt to apply it to visualize fully developed a novel type of reaction, called at the same faculty in 2014. 6 as reactions induced by coherent molecular vi- Transition state spectroscopy of the Claisen Rearrangement bration (RCMV). This third type of chemical re- action excites the molecular vibration instantly using a five-femtosecond pulse laser. In a typical thermal reaction, molecules move ) in a disorganized manner. However, in the −1 RCMV triggered by irradiation using a five-fem- tosecond pulse laser, all molecules vibrate in 1500 unison to trigger the thermal reaction. Upon ir- radiating with a flash time of five femtoseconds, which is shorter than the molecular vibrational 1000 period, the atomic positions are measured as if in strobe light photographs, and the changes in molecular structure (i.e. when and how bond (cm frequency vibrational Molecular 500 1500 2500 breaking and bond reforming occur) during a Reaction time (fs) reaction can be visualized as instantaneous Changes in molecular vibration molecular vibrational frequencies. accompanying the thermal This was the moment when Iwakura finally vi- calculations to simulate reaction mechanisms, Claisen Rearrangement were visualized using a five-fem- sualized this key transformation that had been and based on the results, she developed the tosecond pulse laser. The shrouded in mystery for over 100 years. novel reaction. This led to Iwakura’s desire to resulting spectrum indicated observe actual chemical reaction processes. when and how bond breaking From observing molecules to and bond reforming occurred. During her studies, she met Takayoshi creating molecules Kobayashi, who was teaching at the University Iwakura’s obsession with chemical reaction of Tokyo, and learned that she could indeed vi- Step-wise reaction mechanisms began in the synthetic organic