Reversible binding of oxygen to aromatic compounds

Many polycyclic aromatic hydrocarbons are able to trap singlet oxygen O-1(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 O-1(2) in aqueous media is also described.