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 acceptors. 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 modulation efficiency, and fatigue resistance of the three systems were studied systematically. The modulation efficiency 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.