TY - JOUR
T1 - Dehydrogenation vs oxygenation in photosensitized oxidation of 9-substituted 10-methyl-9,10-dihydroacridine in the presence of scandium ion
AU - Fukuzumi, Shunichi
AU - Fujita, Shunsuke
AU - Suenobu, Tomoyoshi
AU - Imahori, Hiroshi
AU - Araki, Yasuyuki
AU - Ito, Osamu
PY - 2002/2/21
Y1 - 2002/2/21
N2 - 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.
AB - 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.
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U2 - 10.1021/jp0128729
DO - 10.1021/jp0128729
M3 - Article
AN - SCOPUS:0037149138
VL - 106
SP - 1465
EP - 1472
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 7
ER -