Fig. 5. Selectivity of 2 μM CuCLT and CuQLT toward RNOS and other biological analytes in aqueous buffer (37 °C, 100 mM KCl, 50 mM PIPES, pH 7.0). For each sample, the fluorescence emission was recorded in triplicate before and 20 min after addition of excess analyte (1500 equiv. NO, 500 equiv. all other). The measurements for OH^– were conducted in 10 mM aq. NaOH. The integrated fluorescence response was normalized in each case to the initial fluorescence of the metal-bound complexes. In all cases, excitation was provided at 540 nm and the emission intensity was integrated between 550 and 700 nm.