A Highly Efficient Chemiluminescence Probe for the Detection of Singlet Oxygen in Living Cells

Singlet oxygen is among the reactive oxygen species (ROS) with the shortest life‐times in aqueous media because of its extremely high reactivity. Therefore, designing sensors for detection of 1 O 2 is perhaps one of the most challenging tasks in the field of molecular probes. Herein, we report a highly selective and sensitive chemiluminescence probe ( SOCL‐CPP ) for the detection of 1 O 2 in living cells. The probe reacts with 1 O 2 to form a dioxetane that spontaneously decomposes under physiological conditions through a chemiexcitation pathway to emit green light with extraordinary intensity. SOCL‐CPP demonstrated promising ability to detect and image intracellular 1 O 2 produced by a photosensitizer in HeLa cells during photodynamic therapy (PDT) mode of action. Our findings make SOCL‐CPP the most effective known chemiluminescence probe for the detection of 1 O 2 . We anticipate that our chemiluminescence probe for 1 O 2 imaging would be useful in PDT‐related applications and for monitoring 1 O 2 endogenously generated by cells in response to different stimuli.