Photochemical hole burning and its quantum yields of quinizarin and 1,4-substituted anthraquinone derivatives in glass matrices

Photochemical hole burning (PHB) properties of 1,4-dihydroxyanthraquinone and its 1,4-substituted anthraquinone derivatives are investigated in organic glasses such as ethanol: methanol and PMMA. We changed the shape of the active groups (OH-,NH₂-etc.) and also the strength of their hydrogen bonding systematically to gain insight into the burning reaction mechanism in quinizarin and its relatives. Present results indicate that conformational changes of two OH-groups, not a single one, are involved in the hole burning reaction. The relation of electron donating power of the functional groups and of their number and position in the anthraquinone skeleton to the burning ability of the molecules is also discussed on the basis of our observation of S₁←S₀ (0-0) absorption bands.