Direct Redox Potential Measurement of Naphthoquinone Derivative Monolayer at the Air-Water Interface

Abstract

Direct redox potential measurement of HNQ (2-hexadecylthio-1, 4-naphtoquinone) monolayer at the air-water interface was tried by two electrode arrangements. One method was well known horizontal touching method (HT method) in which an electrode directly contacts on the monolayer. The other one was vertical contact method (VC method) in which an electrode vertically contacts on the monolayer at the air-water interface. By the VC method, HNQ monolayer shows two redox peaks at 256 mV and 40mV vs. SCE. The 256 mV peak is assigned the HNQ molecule redox peak and 40 mV one that is not shown in HT method exhibits the lateral electron transfer in the HNQ monolayer. The VC method can detect the lateral electron transfer in the monolayer at the air-water interface.