). The controlled-potential electrolysis was performed at room temperature in an OTTLE cell (path length: 1.0 mm) using a Pt mesh working electrode (Supporting Information, Figure ). A coiled platinum counter electrode and an Ag/AgNO3 reference electrode was also used in the UV-Vis spectral measurements, as with the cyclic voltammetry measurements. To prevent contamination by moisture, samples were prepared in a glove box completely filled with N2 gas. For the electro generation of O2 •-, a DMF solution containing 0.1 mol dm -3 TPAP as a supporting electrolyte was saturated with O2 by air-bubbling the gas for ca. 2-3 min, and the gas was passed over the solutions during the electrochemical and electrolytic spectrometric measurements to maintain the concentration of O2 at a constant level. The equilibrium concentration of O2 was calculated as 4.8 × 10 -3 mol dm -3 .