Furan-Containing Singlet Oxygen-Responsive Conjugated Polymers

This paper describes conjugated polymers with 2,5-diarylfuran moieties as nonconjugated pendants that respond to singlet oxygen (¹O₂) by fluorescence quenching. By oxidizing the diarylfurans to more electron-poor moieties such as enol esters, singlet oxygen causes poly­(fluorene-co-phenylene) conjugated backbones to donate excited electrons to the oxidized pendants, resulting in quenching of up to 93% of the initial fluorescence of the polymer, while an analogous furan-substituted poly­(phenylene–ethynylene) showed no quenching upon furan–¹O₂ reaction. All furan derivatives reacted rapidly with ¹O₂ (k = 10⁷–10⁸ M^–1 s^–1), with more electron-poor furans reacting more slowly, but yielding more efficient fluorescence quenching, than less electron-poor furans.