Photocatalytic Oxygenation Reactions with a Cobalt Porphyrin Complex Using Water as an Oxygen Source and Dioxygen as an Oxidant

Young Hyun Hong, Ji Won Han, Jieun Jung, Tatsuo Nakagawa, Yong Min Lee, Wonwoo Nam, Shunichi Fukuzumi

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34 Scopus citations

Abstract

Photocatalytic oxygenation of hexamethylbenzene occurs under visible-light irradiation of an O2-saturated acetonitrile solution containing a cobalt porphyrin complex CoII(TPP) (TPP2- = tetraphenylporphyrin dianion), water, and triflic acid (HOTf) via a one-photon-two-electron process, affording pentamethylbenzyl alcohol and hydrogen peroxide as products with a turnover number of >6000; in this reaction, H2O and O2 were used as an oxygen source and a two-electron oxidant, respectively. The photocatalytic mechanism was clarified by means of electron paramagnetic resonance, time-resolved fluorescence, and transient absorption measurements as well as 18O-labeling experiments with H218O and 18O2. To the best of our knowledge, we report the first example of efficient photocatalytic oxygenation of an organic substrate by a metal complex using H2O as an oxygen source and O2 as a two-electron oxidant.

Original languageEnglish
Pages (from-to)9155-9159
Number of pages5
JournalJournal of the American Chemical Society
Volume141
Issue number23
DOIs
StatePublished - 12 Jun 2019

Bibliographical note

Funding Information:
This work was supported by the NRF of Korea through CRI (NRF-2012R1A3A2048842 to W.N.) and the Basic Science Research Program (2017R1D1A1B03029982 to Y.-M.L. and 2017R1D1A1B03032615 to S.F.) and by MEXT (Grant-in-Aid 16H02268 to S.F.). We appreciate Dr. Muniyandi Sankar-alingam for help with EPR measurements.

Publisher Copyright:
© 2019 American Chemical Society.

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