The lowest triplet of these xanthones has been studied by phosphorescence spectroscopy. In 1:1 ether:ethanol, xanthone and its dimethyl derivatives have lowest triplets which contain considerable 3(π,π*) character with some 3(n,π*) character as assessed from phosphorescence lifetimes. The spectral positions and phosphorescence lifetimes are determined in part by both positional and inductive effects of the substituent. The phosphorescence of the dihaloxanthones exhibits additional spectral changes which can be attributed to an internal "heavy atom" effect which we attribute to a greater participation of the 3(π,π*) component of a "mixed" triplet state.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry