title: meso-Hydroxysubporphyrins: A Cyclic Trimeric Assembly and a Stable meso-Oxy Radical.
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.
authors: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan).
authors: Daiki
authors: D
authors: Shimizu
authors: Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749 (Korea).
authors: Juwon
authors: J
authors: Oh
authors: Centre for Instrumental Analysis, Niigata University, Nishi-ku, Niigata, 950-2181 (Japan). kou-f@chem.sc.niigata-u.ac.jp.
authors: Ko
authors: K
authors: Furukawa
authors: Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749 (Korea). dongho@yonsei.ac.kr.
authors: Dongho
authors: D
authors: Kim
authors: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan). osuka@kuchem.kyoto-u.ac.jp.
authors: Atsuhiro
authors: A
authors: Osuka
mesh_terms: D001895:Boron / Q000737:chemistry; D018360:Crystallography, X-Ray; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007854:Lead / Q000737:chemistry; D008968:Molecular Conformation; D010087:Oxides / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005609:Free Radicals; D006878:Hydroxides; D010087:Oxides; D011166:Porphyrins; D017680:Potassium Compounds; D007854:Lead; C047365:lead oxide; D001895:Boron; C029943:potassium hydroxide; D004121:Dimethyl Sulfoxide
keywords: boron; porphyrinoids; radicals; self-assembly; subporphyrin