Columns that reveal the world
- Getting up close and personal with the researchers -

The Faculty of Science and College of Science and Engineering is a faculty that pursues academic studies from the complementary perspectives of engineering and science. The research we conduct is scientific research, which is positioned as "basic research." Basic research is not aimed at immediately realizing special applications or uses, but is research that pursues the mechanisms of the natural world and the essence and principles of things. Understanding these things can support major developments in the applied field.

For example, let's think about "color." We are surrounded by a wealth of "colors." One of the most familiar colors in nature is the green of grass and leaves. So why do we perceive grass and leaves as green? The true identity of green is mainly chlorophyll. Photosynthesis is an essential function for plants to live, and chlorophyll contained in leaves plays a central role in this process. Chlorophyll absorbs "light with a specific energy" from the components of light contained in sunlight. Our eyes capture the light that is not absorbed by the leaves and is reflected, and we perceive it as "green." At this time, the color of the light absorbed by the plants and the color of the light reflected and captured by our eyes are complementary colors. In other words, we see the "opposite color" of the light that plants absorbed to live.

So why do leaves change color with the change of seasons? From autumn to winter, the cold breaks down proteins that contain chlorophyll, and as the chlorophyll breaks down, it no longer absorbs the light that it had been absorbing efficiently. On the other hand, in addition to chlorophyll, leaves also contain a color body called carotenoid, which our eyes perceive as "yellow". The yellow color of carotenoids is usually hidden by the green color of chlorophyll, so the leaves appear green, but as the decomposition of chlorophyll progresses, the presence of carotenoids, which were previously inconspicuous but are resistant to the cold, comes to the fore and they appear yellow. Some plants turn red in autumn, and this is said to be because a pigment called anthocyanin is produced inside the leaves in autumn. The leaves appear to be dyed red because they are absorbed by anthocyanin. If we understand this principle, the color of the leaves in autumn may be used as a means to understand information such as proteins contained in trees.

In this way, there is a reason or meaning behind every phenomenon on Earth. Finding the answers to these "whys" and "hows" through dialogue with nature and linking this to the development of the next material, for example, is "basic research."

By interacting with nature, we can unravel the "whys" and "hows" of the world... but what is the use of that? Some may wonder. It is true that the results of basic research do not often lead to immediate practical application. However, if we can discover new principles, we can see the possibility of solving the problems facing modern society and dramatically changing people's lives.

Recently, the term "rare metals" has become more common in the news and newspapers. Rare metals have a wide range of applications in functional materials, such as increasing the strength of alloys themselves, as additives to rust-resistant building materials, and as raw materials for light-emitting diodes, batteries, permanent magnets, and electronic components. They are an indispensable group of elements in modern society. Even though rare metals have such a wide range of applications, it is thought that we have only just scratched the surface of their potential.

Some elements of rare metals (rare earths) are called "rare earths." My research group has developed a material that induces a "special phenomenon" by combining a metal ion called "praseodymium," a rare earth, with stearic acid, a type of soap molecule, and has been the first in the world to succeed in elucidating the mechanism behind this phenomenon. The phenomenon is "polarized luminescence woven by molecules."

As you all know, light has wave properties. The light from the sun or a light bulb contains waves that vibrate in all directions, up and down and left and right, relative to the direction of travel. In contrast, light that vibrates in only one direction is called "polarized light." Just as it is easier to handle long rods if you bundle them together in the same direction, you can imagine that polarized light is much easier to control than normal light, which contains vibrations in different directions. Color LCD displays are also devices that use this polarized light. Current LCD displays use filters to create polarized light and control the light from the backlight. Therefore, to manufacture LCD displays, a backlight that emits light and a filter that creates polarized light were required. In contrast, the "polarized light-emitting film" that we created can emit light itself and polarize it, making it much easier to make displays than before. In addition, the polarized light-emitting film can emit two polarized lights at the same time, so in the future it may be possible to "project multiple images simultaneously on one screen." In this way, our basic research is attracting a great deal of attention not only from within Japan but also from overseas.

Students in my lab are often asked in job interviews, "What is the use of your research?" When asked, I instruct them to answer, "The distinctive feature of our lab is that we do not conduct research aimed at immediate use, but research that can only be done at a university, which pursues eternal truths. This research is also connected to the principles of designing new materials." In fact, I have a secret ambition. That is, "Through all my research until I retire, I will find a 'principle' that will be included in textbooks around the world."

It was more than 15 years ago that I came up with the idea for my research into the expression of polarized luminescence by forming a film of soap molecules and praseodymium. I came up with this new idea while searching for a topic, hoping to take on a research theme that no one had yet tackled. At the time, I had no idea how it could be applied. However, after I published a paper on it in 2007, experts from a variety of fields suggested possible applications from their own perspectives. One after another, ideas that I would never have thought of came up, such as applications to next-generation displays, anti-prying features in bank ATMs, and security inks to prevent counterfeiting of bank notes.

The discoveries of new materials and new mechanisms lead to possibilities that even the researchers themselves had never anticipated...this is the true joy of basic scientific research.

The new molecule announced in January 2014 is not only a simple molecule that emits beautiful light, but also has a helical structure. Ten years ago, the need arose for a "rare earth molecule that would glow strongly in solution," and after much effort in molecular design, the helical structure was finally achieved. Water and other solutions are also collections of molecules. The problem was that the rare earth molecules would stop emitting light when the molecules swayed back and forth. However, by creating a molecule with a helical structure, it was possible to overcome this problem and create a new luminous molecule.

One of the reasons why Japan has produced so many Nobel Prize winners is the Japanese people's passion and tenacity in basic research. Taking time to concentrate on research... this research culture, which is also related to the "craftsmanship" of the craftsmen, has been passed down through the generations. The fact that many high-quality research results have been produced in-house, such as blue light-emitting diodes, lithium-ion batteries, and carbon nanotubes, is proof that such a research culture has been cultivated in companies as well. We must pass on this Japanese research culture to the next generation.

Nowadays, young people are turning away from science, which has become a problem, but I believe that there is no distinction between "science" and "humanities" in the human mind. This is because I was once a humanities student myself. Originally a fan of classical literature, I was aiming to enter College of Literature as a high school student, but I could not forget the fascination with science that I discovered through my summer vacation independent research project, and so I enrolled in the Faculty of Science and College of Science and Engineering Aoyama Gakuin University. This was the trigger that led me to pursue a career as a chemist.

When deciding on your future career path, I think it's a waste to base your decision on "subjects," such as "I'm not good at science" or "I'm good at math." Instead, I want students to value their curiosity and desire to "know" things they don't understand.

The principle that you discover may completely change the world thereafter... just imagining that makes you feel excited, doesn't it?

(Published in 2014)