Modulation of a fluorescence switch based on a photochromic diarylethene and a rhodamine B dye

Abstract A new fluorescence switch based on a photochromic diarylethene and a rhodamine B dye was designed and constructed successfully. With carefully selected components, the absorption band of the ring-closed photochromic diarylethene well overlapped with the emission band of the rhodamine B. The fluorescence emission intensity of rhodamine B is easily modulated with the photoisomerization of diarylethene by controlling the exposure time both in solution and in a solid medium. The photoswitchable system displayed high fluorescence quenching efficiency (>90%) and remarkable fatigue resistance in both solution and a solid medium. In a poly(methyl methacrylate) film, it can be repeated at least 20 cycles without observable change in emission intensity. A 99% fluorescence quenching efficiency can be achieved with an effective fluorescence change from bright wine red to the dark grey.