Directly Diphenylborane-Fused Porphyrins

Keisuke Fujimoto; Juwon Oh; Hideki Yorimitsu; Dongho Kim; Atsuhiro Osuka

doi:10.1002/anie.201511981

Directly Diphenylborane-Fused Porphyrins

Angew Chem Int Ed Engl. 2016 Feb 24;55(9):3196-9. doi: 10.1002/anie.201511981. Epub 2016 Jan 28.

Authors

Keisuke Fujimoto¹, Juwon Oh², Hideki Yorimitsu³, Dongho Kim⁴, Atsuhiro Osuka⁵

Affiliations

¹ Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
² Spectroscopy Laboratory of Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 120-749, Korea.
³ Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan. yori@kuchem.kyoto-u.ac.jp.
⁴ Spectroscopy Laboratory of Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 120-749, Korea. dongho@yonsei.ac.kr.
⁵ Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan. osuka@kuchem.kyoto-u.ac.jp.

PMID: 26821874
DOI: 10.1002/anie.201511981

Abstract

Mono- and bis(diphenylborane)-fused porphyrins were synthesized from the corresponding β-(2-trimethylsilylphenyl)-substituted porphyrins through the sequence of Si-B exchange reaction, intramolecular bora-Friedel-Crafts reaction, and ring-closing Si-B exchange reaction. Effective electronic interactions of the empty p-orbital of the boron atom with the porphyrin π-circuit lead to red-shifted absorption spectra and substantially decreased LUMO energy levels. Pyridine adds at the boron center to cause disruption of the electronic interaction of the boron atom with large association constants (1.9-17×10(4) m(-1)) depending on the central metal at the porphyrin. The Zn(II) complex behaved as a hetero-dinuclear Lewis acid, exhibiting regioselective binding of pyridines at the boron or the zinc center.

Keywords: Lewis acidity; boron; porphyrin; structural constraint; π-extension.

Publication types

Research Support, Non-U.S. Gov't