Fig. 4. (a) LSV curves of 0.50 mM 1 in 0.10 M pH 2.0–7.0 phosphate buffers. (b) Plot of potential measured at j = 0.45 mA cm^–2versus pH. (c) DPV curves of 0.50 mM 1 in 0.10 M pH 2.52–4.45 phosphate buffers. (d) Plots of the first and second oxidation peak potentials versus pH from 2.52 to 4.45. Conditions: GC working electrode, scan rate 100 mV s^–1, and 20 °C.