P. Wagner, H. Frerking
Nov 1, 1995
Citations
0
Influential Citations
8
Citations
Journal
Canadian Journal of Chemistry
Abstract
The triplet state behavior of nine α,ω-dibenzoylalkanes indicates the occurrence of a rapid quenching interaction between the two carbonyl groups. This quenching is fastest (k = 3 × 107 s−1) in dibenzoylbutane, is slightly slower (~107 s−1) in dibenzoylethane, dibenzoylpentane, and 2,2-dibenzoylpropane, but is absent in 1,3-dibenzoylpropane. It also occurs in several "mixed" 1,4-diaroylbutanes incorporating p-ethylbenzoyl or p-methoxybenzoyl chromophores This internal self-quenching is interpreted as the intramolecular counterpart of the well-known bimolecular self-quenching of aryl ketones, although no exact mechanism can be proposed. Such internal quenching does not occur as rapidly, if at all, in three "turned around" diketones: δ-(p-acetylphenyl)valerophenone, δ-(p-acetylphenoxy)valerophenone, and γ-(p-acetylphenoxy)butyrophenone. This fact, together with the varying rates of internal self-quenching in the dibenzoylalkanes, indicates the necessity for a very specific and close orientation of the two c...