Construction of reversible fluorescent switching systems with CdSe quantum dots and photochromic diarylethenes

A series of light controlled and reversible fluorescent switching systems have been constructed with CdSe quantum dots (CdSe-QDs) and three photochromic diarylethene molecules with different functional groups. The CdSe-QDs acted as energy donor, and the diarylethene molecules served as reversible photoactive energy ac-ceptors. The results showed that all of the diarylethenes could modulate the fluorescence of CdSe-QDs efficiently by the irradiation of UV/vis lights. It is worth mentioning that the quenching efficiency of each fluorescence switch was greater than 50% for the three systems. In addition, the switching properties, fluorescence modu-lation efficiency, and fatigue resistance of the three systems were studied systematically. The modulation effi-ciency of the three switches was 76.9%, 89.5%, and 59.0% respectively. It is obvious that the diarylethene with a formyl group has the maximum fluorescence modulation efficiency, and the symmetrical diarylethene with a phenyl group at the end has the best resistance to fatigue.