Planarized Phenyldithienylboranes: Effects of the Bridging Moieties and π-Extension on the Photophysical Properties and Lewis Acidity |
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Authors: | Mika Sakai Masayoshi Mori Dr. Masato Hirai Dr. Naoki Ando Prof. Dr. Shigehiro Yamaguchi |
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Affiliation: | 1. Department of Chemistry, Graduate School of Science, Research Center for Materials Science (RCMS), and, Integrated Research Consortium on Chemical Sciences (IRCCS), Nagoya University Furo, Chikusa, Nagoya, 464-8602 Japan;2. Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University Furo, Chikusa, Nagoya, 464-8601 Japan |
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Abstract: | Two kinds of planarized phenyldithienylboranes, which contain (CH3)2C- or CH2-bridging moieties, were synthesized. The difference of the bridging moieties affects their packing structures and photophysical properties. In particular, the (CH3)2C-bridged derivative exhibits a large Stokes shift, unusual for such planarized compounds, that results from a large structural relaxation in the excited state. A series of π-extended derivatives was synthesized, among which a p-(diphenylamino)phenyl-substituted derivative shows large solvatochromism in the fluorescence spectra, while maintaining high quantum yields even in polar solvents. The Lewis acidity of the phenyldithienylborane derivatives was also assessed by titration with pyridine. The Lewis acidity of the boron center is affected not only by the difference in the steric bulk of the bridging moieties, but also by the electronic effect of the substituents introduced at remote positions relative to the boron atom. These results demonstrate the characteristic features of planarized phenyldithienylboranes as building blocks for boron-based π-electron materials. |
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Keywords: | boron fluorescence Lewis acidity thiophene π-electron materials |
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