Dehydrogenation vs oxygenation in photosensitized oxidation of 9-substituted 10-methyl-9,10-dihydroacridine in the presence of scandium ion

Shunichi Fukuzumi, Shunsuke Fujita, Tomoyoshi Suenobu, Hiroshi Imahori, Yasuyuki Araki, Osamu Ito

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7 Citations (Scopus)

Abstract

Photooxidation of 9-substituted 10-methyl-9,10-dihydroacridine (AcrHR) with oxygen occurs efficiently in the presence of 9,10-dicyanoanthracene (DCA) and scandium triflate [Sc(OTf)3] under visible light irradiation in oxygen-saturated acetonitrile (MeCN) to yield the 9-substituted 10-methylacridinium ion (AcrR+) and H2O2 or the 10-methylacridinium ion (AcrH+) and the oxygenated products of R such as ROOH, depending on the type of substitutent R. No DCA-photosensitized oxidation of AcrHR occurs in the absence of Sc3+ under otherwise the same experimental conditions. The observed selectivities for the C(9)-H vs C(9)-C bond cleavage of AcrHR in the DCA-photosensitized oxidation of AcrHR in the presence of Sc(OTf)3 agree with those for the cleavage of radical cations of AcrHR (AcrHR.+) depending on the type of substituent R. Such product selectivities, being consistent with the electron-transfer oxidation of AcrHR, combined with quantum yield determination, the 1O2 phosphorescence decay dynamics, and the detection of radical ion intermediates in the laser-flash photolysis experiments reveal the electron-transfer radical chain mechanism for the DCA-photosensitized oxidation of AcrHR initiated by photoinduced electron transfer from AcrHR to the singlet excited state of DCA.

Original languageEnglish
Pages (from-to)1465-1472
Number of pages8
JournalJournal of Physical Chemistry A
Volume106
Issue number7
DOIs
Publication statusPublished - 2002 Feb 21

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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