Reversible binding of oxygen to aromatic compounds.

Many polycyclic aromatic hydrocarbons are able to trap singlet oxygen (1)O(2). Some of the endoperoxides, thus obtained, exhibit the exceptional feature of releasing oxygen, frequently in the excited singlet state, under heating or UV irradiation. In this Account, we provide a short summary of the present knowledge on these endoperoxides: preparation and thermal and photolytic decomposition, with a special emphasis on the structural requirements to favor cycloreversion. The profitable use of this property in the development of highly reversible photochromic systems and of specific sources or traps of (1)O(2) in aqueous media is also described.