Excited-state dynamics of highly strained 1,2,3-tri-tert-butylanthraquinone undergoing valence isomerization

Nakayama, Toshihiro; Amijima, Yutaka; Ushida, Kiminori; Hamanoue, Kumao

doi:10.1016/0009-2614(96)00690-2

Cited by 6 publications

(1 citation statement)

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“…Formation of these reduced compounds upon 366 nm steady-state photolysis, however, was followed by photochemical dehydrohalogenation yielding α-haloanthraquinones (or anthraquinone) with one less halogen atom than the original anthraquinones and thus the final product was 9,10-dihydroxyanthracene, whereas no such photochemical dehydrohalogenation was observed for β-halo-9,10-dihydroxyanthracenes. (3) Formation of a hemi-Dewar-type isomer upon photolysis of 1,2-di- tert -butyl-3-trimethylsilylanthraquinone or 1,2,3-tri- tert -butylanthraquinone reported by Miki et al could be ascribed to valence isomerization in the lowest excited singlet state . (4) The decay channels for the lowest excited singlet state of naphthoylnaphthvalene (NNV) were found to be intersystem crossing to the lowest excited triplet state ( 3 NNV*) and valence isomerization yielding ground-state naphthoylnaphthalene (NN) via an intermediate (probably a zwitterionic species) .…”

Section: Introductionmentioning

confidence: 99%

Photophysics and Photochemistry of Planar Alkylanthraquinones (the 1-Methyl and 1,4-Dimethyl Compounds) Studied by Subpicosecond and Nanosecond Laser Photolysis as Well as Steady-State Photolysis

et al. 1999

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By means of subpicosecond and nanosecond laser photolysis of the title compounds (MAQ and DMAQ), it is concluded that both the lowest excited singlet and triplet states undergo intramolecular hydrogen-atom transfer and the corresponding excited biradicals thus generated yield 9-hydroxy-1,10-anthraquinone-1-methide from MAQ and 9-hydroxy-4-methyl-1,10-anthraquinone-1-methide from DMAQ. Although these methides are stable at 77 K, they revert to the original anthraquinones at a higher temperature than 77 K. In ethanol and EPA (diethyl ether-isopentane-ethanol in 5:5:2 volume ratio) at room temperature, furthermore, 313 or 366 nm steady-state photolysis reveals that 1-methyl-9,10-dihydroxyanthracene (MAQH 2 ) is formed from MAQ irrespective of the excitation wavelength but 1,4-dimethyl-9,10-dihydroxyanthracene (DMAQH 2 ) is formed from DMAQ only upon 313 nm excitation. Undoubtedly, the lowest excited triplet state of MAQ abstracts a hydrogen atom from ethanol generating the semiquinone radical followed by formation of MAQH 2 . In contrast, not the lowest excited triplet state but the third excited singlet or triplet state of DMAQ may abstract a hydrogen atom from ethanol yielding DMAQH 2 finally.

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Section: Introductionmentioning

confidence: 99%