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Published on: November 21, 2017
Control of the electronic and optical properties of aminoxyl radicals via boron complexation
Takuma Kuroda1, Peiyuan Yang2, Marika Nakamura2
1Department of Material Science, Graduate School of Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan. agou@sci.u-hyogo.ac.jp.
Abstract:
Stable radicals have attracted increasing attention in recent years because of their unique electronic and optical characteristics. Aminoxyl radicals are one of the most widely studied stable radicals to date, but their applications in opto-functional materials have yet to be explored in detail. Our group previously reported the boron complexes of aminoxyl radicals exhibit near-infrared (NIR) absorption. In this work, an aminoxyl radical without boron-complexation was synthesized to elucidate the effects of boron coordination on the properties of the aminoxyl radicals. The results of electron spin resonance spectroscopy, ultraviolet-visible-NIR absorption measurements, and density functional theory calculations indicated that boron complexation facilitated spin delocalization over the radical π-frameworks. Furthermore, a π-extended aminoxyl radical-boron complex exhibited a significant wavelength-shift to longer wavelengths in the NIR-II absorption region, thereby reflecting its larger π-conjugated radical skeleton.
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