meso‐Hydroxysubporphyrins: A Cyclic Trimeric Assembly and a Stable meso‐Oxy Radical |
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| Authors: | Daiki Shimizu Juwon Oh Prof Dr Ko Furukawa Prof Dr Dongho Kim Prof Dr Atsuhiro Osuka |
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| Institution: | 1. Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo‐ku, Kyoto 606‐8502 (Japan);2. Spectroscopy Laboratory for Functional π‐Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120‐749 (Korea);3. Centre for Instrumental Analysis, Niigata University, Nishi‐ku, Niigata, 950‐2181 (Japan) |
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| Abstract: | Treatment of meso‐chlorosubporphyrin with potassium hydroxide in DMSO followed by aqueous work up and recrystallization gave a cyclic trimer consisting of meso‐hydroxysubporphyrin units linked between the central boron atoms and meso‐hydroxy groups. Solutions of this trimer are nonfluorescent, but become fluorescent when exposed to acid or base, since hydrolytic cleavage of the axial B? O bonds generates the meso‐hydroxysubporphyrin monomer or its oxyanion. Ring cleavage of the trimer was also effected by reaction with phenylmagnesium bromide to produce meso‐hydroxy‐B‐phenyl subporphyrin, which can be quantitatively oxidized with PbO2 to furnish a subporphyrin meso‐oxy radical as a remarkably stable species as a result of spin delocalization over almost the entire molecule. |
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| Keywords: | boron porphyrinoids radicals self‐assembly subporphyrin |
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