Phosphorescence of Large Polycyclic Aromatic Ketones

Phosphorescence measurements were performed for 6H-benzo[cd]-pyren-6-one (l), 2-nitro-benzo[hi]chrysen- 13-one (2), 2-bromo-di-benzo[a, de]anthracen- 13-one (3), and 7H-benzo[hi]chrysen-7-one (4) in an ethanol-ether-toluene mixed solution and the character of their lowest excited triplet (T 1 ) stat...

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Bibliographic Details
Published in:Polycyclic aromatic compounds 2001-12, Vol.19 (1-4), p.199-208
Main Authors: Ohshima, S., Uchida, A., Oonishi, I., Fujisawa, S.
Format: Article
Language:English
Subjects:
emission
phosphorescence
polarized
polycyclic aromatic ketones
transition moment
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Summary:Phosphorescence measurements were performed for 6H-benzo[cd]-pyren-6-one (l), 2-nitro-benzo[hi]chrysen- 13-one (2), 2-bromo-di-benzo[a, de]anthracen- 13-one (3), and 7H-benzo[hi]chrysen-7-one (4) in an ethanol-ether-toluene mixed solution and the character of their lowest excited triplet (T 1 ) states were investigated. The phos horescence of the compounds appears at about 5,200 - 6,000 cm −1 to the red of their fluorescence, indicating that the T, states have ππ * character. On the other hand, the short phosphorescence lifetimes, 10 - 60 ms, suggest nπ * transitions. Such a duality of the T 1 state seems to be characteristic of large polycyclic aromatic ketones. The polarized emission study revealed that the duality is ascribed to strong mixing of ππ * and nπ * natures.
ISSN:1040-6638
1563-5333
DOI:10.1080/10406630008034733