Reversibly photoswitchable dual-color (blue ↔ green) phosphorescence from β-cyclodextrin inclusion complex materials

•3-Formyl-2,3′-biimidazo[1,2-a]pyridin-2′-ones.•A new class of phosphorescent β-cyclodextrin inclusion complexes was obtained.•The reversible dual-color switching behavior in the response to light stimuli.•The dynamic photofunctional material.

We report herein two new supramolecular materials based on β-cyclodextrin inclusion complex samples with partially included organic radicals, which emit blue phosphorescence (excitation at 365 nm), and exhibit higher phosphorescent quantum yields (9.5 and 20.3%). However, purely organic radicals emit green phosphorescence, and possess low quantum yields (1.8 and 3.3%). One inclusion complex material exhibits the reversible dual-color (blue ↔ green) switching behavior in the response to ultraviolet and visible light stimuli, respectively: upon excitation with ultraviolet light (365 nm), it emits blue phosphorescence with quantum yield of 9.5%; however, it emits green phosphorescence and possesses higher quantum yield of 29.0%, upon irradiation by visible light (425 nm). The reversibly photoswitchable behavior is probably ascribed to the light-driven guest molecular conformation conversions in the β-cyclodextrin cavities. This light-responsive dual-color phosphorescent supramolecule is unique in terms of molecular conformation conversions.

Graphical abstractA novel supramolecular material based on β-cyclodextrin inclusion complexes exhibits the reversible dual-color phosphorescent switching behavior in the response to light stimuli. Figure optionsDownload full-size imageDownload as PowerPoint slide