| Popis: |
Disproportionation of lutetium diphthalocyanine, Pc 2 Lu, is shown to occur inside the film when a Pc 2 Lu electrode is cycled in contact with an acidic aqueous electrolyte. The voltammetric peak around 0.4 V (vs. SCE) is a two-electron peak and corresponds to the blue/orange transition HPc 2 Lu - 2 ρ − = Pc 2 Lu + + H + . Charge compensation is obtained by a flow of protons between the film and the solution. However, green Pc 2 Lu is observed by spectroscopy during the translation, which means that the disproportionation reaction 2 Pc 2 Lu + H + = HPc 2 Lu + Pc 2 Lu + is not total. The conditional disproportionation constant is estimated independently by spectroscopy and voltammetry. On a virgin electrode, disproportionation does not occur by a simple contact with the acidic solution: the first voltammetric scan, necessarily positive, is a one-electron step, Pc 2 Lu - e − → Pc 2 Lu + . Penetration of the anion of the electrolyte into the film produces charge compensation. |
