Aromatic Endoperoxides^†

Abstract

The fundamental aspects of aromatic endoperoxide chemistry are reviewed including their synthesis and reactions. The discussion will focus on factors that will both enhance and prevent the formation of aromatic endoperoxides and on structural features that will provide control over their ability to release singlet oxygen. This approach recognizes the dual use of aromatic hydrocarbons as both precursors of endoperoxides and as valuable materials for incorporation in electronic and photonic devices. Improvement of the existing methods and development of new methods for the synthesis of endoperoxides is necessary as a result of the demand to improve existing and to create new applications for these valuable materials. On the contrary, prevention of endoperoxide formation is crucial to inhibit irreversible oxidative degradation of aromatic hydrocarbons and to extend their lifetimes as useful organic semiconductors.

Unsymmetrical Anthracene Platforms as Singlet Oxygen Batteries: Effects of Substituents on Photooxygenation and Endoperoxide Thermolysis

“…Based on experimental and theoretical data, different mechanisms have been suggested for the endoperoxide formation depending on the anthracene structure and the reaction conditions (gas phase versus solvent) [9a] . For instance, a stepwise addition involving zwitterionic intermediates has been suggested for the reaction of singlet oxygen with 9,10‐diaryl‐anthracene while a radical pathway was ruled out based on control experiments [8j] .…”

Singlet Oxygen's Potential Role as aNonoxidativeFacilitator of Disulfide S–S Bond Rotation†

“…Our computations predict that energies lie on the side of 6 instead of the reactants 5 and 1 O 2 , which is consistent with persulfoxides that are sufficiently long lived to be trapped bimolecularly and play a role in converting 1 O 2 to 3 O 2 (52–54). Unlike some acene endoperoxides (55–62), 1 O 2 “on–off” is likely accompanied by substantial physical quenching to 3 O 2 in regeneration of the disulfane. Indeed, charge‐transfer quenching of 1 O 2 with disulfides can involve an exciplex MeSS(··· 1 O 2 )Me that physically quenches 1 O 2 to 3 O 2 due to sulfur's low‐lying d ‐orbitals (36).…”