Fluorescence response of compound 1 (5 μM) to various reactive oxygen species (ROS). Data shown are for 100 μM of all ROS reagents. Bar graph from left to right are for 0, 30, 60, 90, and 120 min data points. Hydrogen peroxide (H2O2), tert-butyl hydroperoxide (TBHP), and hypochlorite (OCl−) were diluted from 30%, 70% and 13% aqueous solutions, respectively. Superoxide (O2−) was added as solid KO2. Hydroxyl radical (·OH) and tert-butoxy radical (t-BuO·) were generated by reaction of 1 mM Fe2+ with 100 μM H2O2 or 100 μM TBHP, respectively. Spectra were acquired in 0.1M phosphate buffer, pH 7.4, and all data were obtained after incubation with the appropriate ROS ar room temperature. Emission intensity was collected at 475 nm (λex= 400 nm).