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Young researchers' glittering success with decorated molecular rings

  • Read in Japanese
  • 2015/04/28
  • WPI-ITbM
  • JST-ERATO Itami Project
  • Graduate School of Science
  • Ms. Natsumi Kubota (a graduate student)
  • Designated Associate Prof. Yasutomo Segawa
  • Prof. Kenichiro Itami

Prof. Kenichiro Itami, Designated Associate Prof. Yasutomo Segawa, and Ms. Natsumi Kubota (a graduate student) at the Institute of Transformative Bio-Molecules (WPI-ITbM), JST-ERATO Itami Molecular Nanocarbon Project, and Graduate School of Science at Nagoya University, have developed a way to modify a site on a carbon nanoring. This modification is expected to transfer a nanoring to carbon nanotube efficiently and functionalize the nanoring or carbon nanotube through the site.
This research was published in the Journal of the American Chemical Society on January 13, 2015.→ Nagoya University Press Release

Young researchers have challenged an infinite number of possibilities in molecules, finding further interests in their surprising research results.

"Nothing will start without molecules."

Prof. Kenichiro Itami at the Graduate School of Science is the director of the Institute of Transformative Bio-Molecules (WPI-ITbM) and a project leader of the JST-ERATO Itami Molecular Nanocarbon Project. In his laboratory, he welcomes several students as his research team members.


Prof. Itami, who challenges an infinite number of possibilities with molecules, now has 64 members with expertise synthetic chemistry in the interdisciplinary fields of nanocarbon, catalysis and reaction, and animals and plants science. Prof. Itami mentions the value of cooperative relationship while chatting about “what the molecule is doing?” Since the age of 28, when he started his academic career, he has developed an interdisciplinary base in research. “After I moved to Nagoya University,” said Prof. Itami, “I could do various things, especially due to a lot of cooperative work.”


The interdisciplinary atmosphere in Prof. Itami’s laboratory also triggers discussion between students from different research backgrounds and concepts. With such motivation, students are learning from one another and achieving important research results.


Ms. Natsumi Kubota, a master’s course student at the Graduate School of Science at Nagoya University, is one of them, and successfully led the modification of a site on a cycloparaphenylene (CPP) that forms a ring connecting para-position in benzene. This shows that CPPs possibly make a new formulation of molecular nanocarbon, resulting in the world’s leading research group taking another key step in synthetic chemistry.


*******


A carbon nanotube is made only of carbons. Because of its good electric and thermal conductivity, it is used as a material for batteries, alternative rare metals, and semiconductors, and it is further expected to expand utility value.


“This is the molecule that can become the seed for a carbon nanotube; it is rather interesting.”

Yasutomo Segawa, a designated associate professor at the Graduate School of Science at Nagoya University and a group leader of the JST-ERATO Itami Molecular Nanocarbon Project, expects a new development in cycloparaphenylenes (CPPs)—a minimum organic molecular unit of the lateral structure of a carbon nanotube (Figure 1).



Figure 1. A carbon nanotube and a cycloparaphenylene (CPP)—a minimum organic molecular unit of the lateral structure of a carbon nanotube (Figure: by courtesy of Designated Associate Prof. Segawa)



Since 2008, CPPs have been synthesized, and man-made CPP-rings formed with 5 to 18 connected benzene rings have been produced so far. (Jasti et al. J. Am .Chem. Soc. (2008) 130: 17646-7; Takaba et al. Angew. Chem. Int. Ed. (2009) 48: 6112-6)

Designated Associate Prof. Segawa and his colleagues used the CPPs as a seed to successfully build a carbon nanotube with various diameters (Figure 2). (Omachi et al. Nature Chemistry (2013) 5: 572-6)



Figure 2. CPPs with various diameters that can be a seed to build a carbon nanotube (Figure: Omachi et al. Nature Chemistry (2013) 5: 572-6. Copyright © 2013, Rights Managed by Nature Publishing Group)



“We expect to create two connected CPPs for the next challenge.”

“That is a necessity,” adds Designated Associate Prof. Segawa. The ring of CPPs is constantly distorted; that is, it is an unfavorable state for the molecules to remain its shape. If some external factor, such as heat, electrons, or light act against CPPs, the connection bonds between benzene rings will be cut. Thus, because this will morph the ring into a straight chain of benzene rings, researchers all over the world have been trying to create a new unit that increases the strength of carbon rings.


Therefore, Designated Associate Prof. Segawa and his co-workers have been attempting to attach functional moieties on a CPP by an aromatic electrophilic substitution reaction, as is generally known. Although mono- to poly-substituted products were obtained, they were mixed; therefore it was difficult to separate various substitution products. The research group also tried to synthesize a functionalized CPP starting from raw materials that included a functional moiety. Still, this caused an efficiency problem that is difficult to undo, especially when replacing the moiety.


Designated Associate Prof. Segawa proposed that CPPs may have been functionalized directly (Figure 3) and Ms. Natsumi Kubota, who was then in the senior year at the School of Science at Nagoya University, took up the challenge to make a functionalized CPP.



Figure 3. A schematic image for the direct attachment of functional moieties on a CPP (Figure: by courtesy of Designated Associate Prof. Segawa)



First, Ms. Kubota learned how to make a [9]CPP consisting of nine benzene rings. Because she could produce only a small amount at a time in a test tube, she took further responsibility as part of her research and kept performing experiments as the “factory manager,” a name coined by her colleagues in the laboratory.


After a while, Ms. Kubota could finally produce the [9]CPP with high yield.

Designated Associate Prof. Segawa and Ms. Kubota conceived that simple aromatic compounds such as benzene have a complex forming reaction with chromium; therefore, for the next challenge, they applied the same method for [9]CPP.



[9]CPP that glows green and Ms. Kubota @ laboratory



A [9]CPP connects nine benzene rings at para-position, and 36 of all carbon–hydrogen bonds show the same reactivity. Expectedly, all nine benzene rings could have made complex forms with chromium.


“I was amazed when the resulting structure was characterized by mass spectrum.”

Surprisingly, Ms. Kubota obtained mono-substituted products by complexation, identified by mass spectrum (Figure 4). According to the simulation study calculated from the molecular structure, in the CPP chromium complex, chromium suppresses the entire reactivity and inhibits the reaction of the second chromium atom. Therefore, she addressed mono-substituted CPPs to synthesize.



Figure 4. Mono-substituted CPP obtained by complexation (Figure: by courtesy of Designated Associate Prof. Segawa)



Besides support from her professors, Ms. Kubota had a fruitful discussion with student colleagues regarding interdisciplinary research fields in the laboratory. Learning knowledge and skills from one another, Ms. Kubota found out the best parameters for a one-pot synthesis, the method in adding base, the electrophile reaction, and so on, which is truly an original synthetic method (Figure 5).



Figure 5. A synthetic method of mono-functionalized CPP — a one-pot synthesis is possible. (Figure: by courtesy of Designated Associate Prof. Segawa)



“I made what nobody has ever created. I now have them in my very hands.”

The synthetic procedure is to add base and then electrophile on the CPP chromium complex.

Removing chromium from the CPP, the CPP can finally be synthesized with accessible substituents such as silicon, boron, and ester. Ms. Kubota continued experiments to increase the yield of her modified CPP until the article was written and ready to submit.


*******


“Research is interesting as we come to results that we could not have even supposed.”

The interesting point of research is to have both on- and off-target results. “Off-target results are rather interesting because these results will expand the possibilities of what we have never thought before,” adds Designated Associate Prof. Segawa.


All are the result of great efforts achieved by Ms. Kubota as factory manager in the laboratory. At the end of 2014, Prof. Itami awarded a “never-give-up” prize to Ms. Kubota.


Young researchers are enthusiastic about their role.

—This is the attractiveness of the world’s leading laboratory.

(Ayako Umemura)


Researchers featured in this article

Dr. Kenichiro ItamiProfessor, Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University

Dr. Itami graduated from the Department of Synthetic Chemistry, School of Engineering, Kyoto University in 1994 and achieved a doctorate degree in engineering at Kyoto University in 1998. Then, he worked as an assistant at the Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University. Dr. Itami moved to the Research Center for Materials Science (RCMS), Nagoya University, in 2005 to work as an assistant professor and became a researcher in the area of structure control and function for Precursory Research for Embryonic Science and Technology, Japan Science Technology Agency (JST). He became an associate professor at RCMS, Nagoya University, in 2007 and then a professor in the Department of Chemistry, Graduate School of Science at Nagoya University, in 2008. In addition, since 2013, Dr. Itami is a director of the Institute of Transformative Bio-Molecules (WPI-ITbM) and a project leader of the JST-ERATO Itami Molecular Nanocarbon Project.

Prof. Itami has received many awards during his career:

Fellow of the Royal Society of Chemistry, UK (2012);
Mukaiyama award (2013);
Novartis Chemistry Lectureship Award (2013);
The JSPS Prize (2014);
Arthur C. Cope Scholar Award (2015); and many more.


***

Dr. Itami’s contribution to research captivates the attention of worldwide researchers. When he was only 40 years old, he became the director of WPI-ITbM and the project leader of the JST-ERATO Itami Project, supporting several young researchers.
During the interview, I was very impressed not only by observing his way of thinking as a leading researcher in synthetic chemistry, but also by his great communication skills. I certainly expect further research achievements from his laboratories (by AU)



Dr. Yasumoto SegawaDesignated Associate Professor, JST-ERATO Itami Molecular Nanocarbon Project

Dr. Segawa graduated from the Department of Chemistry and Biotechnology, School of Engineering, the University of Tokyo in 2005. During his doctorate course, Dr. Segawa studied abroad at the California Institute of Technology. He obtained his doctorate degree in engineering from the University of Tokyo in 2009, then moved to the Research Center for Materials Science (RCMS), Nagoya University in 2009, to work as an assistant professor. He had the opportunity to research at the University of Toronto. Since 2013, Dr. Segawa has worked as a group leader of the JST-ERATO Itami Molecular Nanocarbon Project and a designated associate professor at the Graduate School of Science, Nagoya University.

Designated Associate Prof. Segawa has received many awards during his career:

The 7th Wakashachi Young Scientists’ Award (2013);
PCCP Prize (Physical Chemistry, Chemical Physics Prize) (2013);
Young Scholar Lectures of 93rd CSJ (the Chemical Society of Japan) annual meeting (2013);
The 2nd Japan Association for Chemical Innovation (JACI) Research Encouragement Award of New Chemical Technology (2013);
Akasaki Award (2014); and many more.


***

Even as a young researcher, Dr. Segawa mentors other young researchers and students in the laboratory. I was inspired by his attitude toward his research.
Experiments do not always progress as we expect; however, in such cases, it is rather a chance to expand another possibility. By picking up a chance to link study results, I’m looking forward to Dr. Segawa’s further achievements (by AU)



Ms. Natsumi Kubotaat that time: Master’s Student, Graduate School of Science, Nagoya University

During her undergraduate course at the Department of Chemistry at the School of Science, Nagoya University, Ms. Kubota studied abroad at Memorial University in Canada in 2012. She then graduated from Nagoya University in 2013. She completed her master’s degree at the Department of Chemistry, Graduate School of Science, Nagoya University in 2015.

Ms. Kubota has received an award thus far during her career:

International Student Research Experience Program in Chemistry Award (2012)


***

“I was doing my best when I was in school,” said Ms. Kubota. Her persistence for her research, which made Prof. Itami say, “I am beyond proud of her,” is possibly her acquired skill since she was a child.
In addition, she had fruitful discussions and learned together with her colleagues in the laboratory; this experience influenced and will influence her further toward greater successes. Impressed by her efforts in the laboratory, I expect her to achieve much in the future (by AU)


Links

Natsumi Kubota,Yasutomo Segawa, and Kenichiro Itami.

η6 ‑Cycloparaphenylene Transition Metal Complexes: Synthesis, Structure, Photophysical Properties, and Application to the Selective Monofunctionalization of Cycloparaphenylenes.

J. Am. Chem. Soc. 137: 1356 (2015).
(First published on January 12, 2015; doi: 10.1021/ja512271p)

Ramesh Jasti, Joydeep Bhattacharjee, Jeffrey B. Neaton,and Carolyn R. Bertozzi.

Synthesis, Characterization, and Theory of [9]-, [12]-, and [18]Cycloparaphenylene: Carbon Nanohoop Structures.

J. Am. Chem. Soc. 130: 17646 (2008).
(First published on December 4, 2008; doi: 10.1021/ja807126u)

Hiroko Takaba, Haruka Omachi, Yosuke Yamamoto, Jean Bouffard, and Kenichiro Itami.

Selective Synthesis of [12]Cycloparaphenylene.

Angew. Chem. Int. Ed. 48: 6112 (2009).
(First published on July 8, 2009; doi: 10.1002/anie.200902617)

  • Link to related article3 (from a search-result)

    http://www.nature.com/nchem/journal/v5/n7/full/nchem.1655.html

    Haruka Omachi, Takuya Nakayama, Eri Takahashi, Yasutomo Segawa, and Kenichiro Itami.

    Initiation of carbon nanotube growth by well-definedcarbon nanorings.

    Nature Chemistry 5: 572 (2013).
    (First published on May 26, 2013; doi:10.1038/nchem.1655)

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