Caging and photo-triggered uncaging of singlet oxygen by excited state engineering of electron donor–acceptor-linked molecular sensors
Devika Sasikumar, Yuta Takano, Hanjun Zhao, Reiko Kohara, Morihiko Hamada, Yasuhiro Kobori, Vasudevanpillai Biju
Abstract
Abstract Singlet oxygen ( 1 O 2 ), one of the most sought-after species in oxidative chemical reactions and photodynamic cancer therapy, is activated and neutralized in the atmosphere and living cells. It is essential to see "when" and "where" 1 O 2 is produced and delivered to understand and utilize it. There is an increasing demand for molecular sensor tools to capture, store, and supply 1 O 2 , controlled by light and engineered singlet and triplet states, indicating the 1 O 2 -capturing-releasing state. Here, we demonstrate the outstanding potential of an aminocoumarin-methylanthracene-based electron donor–acceptor molecule ( 1 ). Spectroscopic measurements confirm the formation of an endoperoxide ( 1-O 2 ) which is not strongly fluorescent and remarkably different from previously reported 1 O 2 sensor molecules. Moreover, the photoexcitation on the dye in 1-O 2 triggers fluorescence enhancement by the oxidative rearrangement and a competing 1 O 2 release. The unique ability of 1 will pave the way for the spatially and temporally controlled utilization of 1 O 2 in various areas such as chemical reactions and phototherapies.