Supramolecular carriers of singlet oxygen: Photosensitized formation and thermal decomposition of endoperoxides in the presence of cyclodextrins

Water-soluble 2,7-disulfonato-9,10-diphenylanthracene (2,7-dsDPA) and 2,6-disulfonato-9,10-diphenylanthracene (2,6-dsDPA) react with singlet oxygen O2(1Δg) produced by photosensitized reaction and form thermostable endoperoxides. The thermal decomposition of endoperoxides at higher temperatures (60–150 °C) leads to the production of O2(1Δg). 2,7-dsDPA, 2,6-dsDPA and corresponding endoperoxides 2,7-dsDPAO2, 2,6-dsDPAO2 form 1:1 host–guest complexes with native cyclodextrins (CDs) and 2-hydroxypropylated cyclodextrins (hpCDs). The binding constants (102–104 M−1) depend on the cavity size and the functionalization of the primary face of CDs. The thermal stabilities of both endoperoxides in host–guest complexes with CDs and hpCDs are highly increased.