Spiropyran-modified silicon quantum dots with reversibly switchable photoluminescence

Spiropyran-modified silicon quantum dots (Si QDs) were successfully fabricated through covalently linking the aminated Si QDs and spiropyrans. In comparison with Si QDs, the fluorescence emission peaks of the Si QDs in the spiropyran-modified Si QDs always locate at 525 nm irrespective of the excitation wavelengths. The spiropyran-modified Si QDs showed reversible photoluminescence. Blue-green fluorescence of the spiropyran-modified Si QDs could be gradually switched off, and red fluorescence could be gradually switched on with UV irradiation. The process could be reversible with visible light irradiation. The reversibly switchable photoluminescence of the spiropyran-modified Si QDs using UV and visible light irradiation could also be multiply repeated with good stability. Therefore, the spiropyran-modified Si QDs could be a promising candidate in many potential application areas such as photo-switch, data storage, and biolabeling and bioimaging.