| Mar 27, 2023 |
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(Nanowerk News) Near-infrared light, whose wavelength is longer than visible light, is invisible and can pass through many substances. Organic materials that efficiently absorb near-infrared light are essential for technological innovations that utilize near-infrared light, such as the dyes in the infrared blocking filters of smartphone cameras and security inks. These and many more technical applications make developing new dyes that can absorb longer wavelengths of near-infrared light desirable.
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| Illustration of properties and electronic structure of a near-infrared absorbing dye in an intermediate state between closed- and open-shell states. (Image: Takeshi Maeda, Osaka Metropolitan University)
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Previously, near-infrared absorbing organic materials were treated as closed-shell molecules without unpaired electrons. However, a joint research group led by Associate Professor Takeshi Maeda, Assistant Professor Daisuke Sakamaki, and Professor Hideki Fujiwara from Osaka Metropolitan University discovered that near-infrared absorbing oxocarbon-based dyes have an intermediate state between closed-shell and open-shell electronic configurations. They also found that as the wavelengths of near-infrared light absorbed increase, so does the contribution of open-shell forms in the dye.
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The research has been published in Chemical Science (“Unveiling a new aspect of oxocarbons: open-shell character of 4- and 5-membered oxocarbon derivatives showing near-infrared absorption”).
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“We have clarified the proper electronic structure of near-infrared absorbing oxocarbon-based dyes that are regarded as pure closed-shell molecules. We hope that this will lead to advances in the molecular design, properties, functions, and applications of near-infrared absorbing dyes and to the development of new near-infrared absorbing organic materials that be used in society,” Professor Maeda concluded.
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An Osaka Metropolitan University joint research group has discovered that near-infrared absorbing dyes, which had previously been considered to have closed-shell electronic structures, have an intermediate electronic structure, between closed- and open-shell structures. They also found that as the wavelength of near-infrared light that can be absorbed becomes longer the contribution of open-shell forms increases within the dye. These newly discovered characteristics are expected to be utilized to develop new near-infrared absorbing dyes that can absorb longer wavelength near-infrared light.
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