Figure 3.
Fluorescence titration of FeIII-HOPO-fluo and FeIII-HOPO-PhO-fluo with phosphate (Pi): (a) fluorescence spectra of FeIII-HOPO-fluo with phosphate. (b) Increase in emission intensity. Experimental conditions: [FeIII-HOPO-PhO-fluo] and [FeIII-HOPO-fluo] = 10 μM in wet ethanol. pH = 7. λexcitation = 456 nm, excitation and emission slit widths = 5 nm, voltage = 600 V. T = 25 °C. F = integrated fluorescence intensity from 500 to 650 nm in the presence of anions, Fo = integrated fluorescence intensity in the absence of anions. Fluorescence spectra were obtained 5 min after mixing to ensure that thermodynamic equilibrium was reached. The pH of all solutions was adjusted to 7 carefully by addition of either HCl or NaOH, as necessary.