Electron transfer of phenalenyl derivative molecules adsorbed at the graphite electrode/aqueous solution interface

The phenalenyl derivative molecules, diphenyl derivatives of 1,2-bis-(phenalen-1-ylidene) ethene (Ph2-BPLE) and tetra t-butyl derivatives of s-indacenodiphenalene (TTB-IDPL), casted on a highly oriented pyrolytic graphite (HOPG) electrode, were characterized by using cyclic voltammetry (CV) in aqueous electrolyte solution. Stable and adsorption type redox peaks at the double-layer region of a HOPG basal plane electrode revealed that the redox peaks originated from the molecules. It was found that the peak area of the CV curve, the amount of redox-active adsorbates, apparently increased after anodic potential scans up to +1.4 V vs. RHE without any additional redox-active molecules in the liquid phase. Quantitative analyses indicated that it was due to potential-induced dispersion of the phenalenyl derivative molecules on the electrode, and effective electron transfer occurred only from the molecule directly attached to the electrode surface.