Controlled reversible single-molecule white-light emission from keto-enol interconversion of β-diketone dyes

New pyrene-based beta-diketone dyes were synthesized. Pure beta-diketone ketonic and enolic form dyes were prepared, where ketonic form dyes were obtained under basic solvent condition, and enolic form dyes were obtained by recrystallization. High-quality, green-light emitting single crystals of an enolic form dye were prepared. X-ray single crystal diffraction results reveal intramolecular H-bond-connected, bent-shaped pi-system structure of an enolic form dye. pi-Stacking-driven supramolecular polymer single crystals were formed from an enolic dye. Exceptional single-molecule single component white-light emission was achieved from a beta-diketone ketonic form dye. Ketonic white-light emission and enolic green-light emission could be reversibly interconverted. White-light emission of ketonic dye solution shows a transient state light-emitting color change upon excitation by pulse light.