Selectivity of a) CLSS-1 and b) CLSS-2 with reactive oxygen, nitrogen, and sulfur species. Conditions: 50 μM probe, 33 equiv of RSONS, incubated 1 h at 37 °C. The reported intensities are background corrected, represent the integrated luminescence (λem = 425 nm), and are the average of at least 3 replicates. Error bars represent ± SE.