The lowest triplet states of anthraquinone and chloroanthraquinones: The 1hyphen;chloro, 2hyphen;chloro, 1,5hyphen;dichloro, and 1,8hyphen;dichloro compounds

摘要

From the measurements of phosphorescence spectra and tripletndash;triplet absorptions of the title compounds, it has been proposed that the lowest triplet states (T1) of the agr;hyphen;chloro compounds are of mixednpgr;ast;ndash;pgr;pgr;ast; or pgr;pgr;ast; character, while thenpgr;ast; triplet states are the lowest ones for anthraquinone and 2hyphen;chloroanthraquinone (the bgr;hyphen;chloro compound). Compared with anthraquinone and the bgr;hyphen;chloro compound, much shorter lifetimes of theT1states and small phosphorescence quantum yields were obtained for the agr;hyphen;chloro compounds. These results have been interpreted in terms of the modification of the geometrical molecular structure by the interaction of the carbonyl group with chlorine atom(s) at the agr; position(s), causing theT1states to be of pgr;pgr;ast; character with short lifetimes.