Transmembrane Rectified Electron Transfer through π-Conjugated Electroactive Langmuir–Blodgett Monolayers on Gold Electrodes

Novel amphiphiles with π-conjugated electroactive groups, 1-methyl-4-[2-[4-[2-(4-pyridyl)vinyl]phenyl]vinyl]pyridinium perchlorate (1), and 1-methyl-4-[2-[4-[2-(4-quinolyl)vinyl]phenyl]vinyl]quinolinium perchlorate (2), were designed and synthesized. Both compounds formed expanded monolayers at air–water interfaces. The monolayers transferred on gold disk electrodes at 25 mN m−1 by the Langmuir–Blodgett technique (horizontal lifting method) show one electron reduction/oxidation couple: Epa = −0.86 V, Epc = −1.08 V vs. SCE for 1/Au and Epa = −0.78 V, and Epc = −0.84 V vs. SCE for 2/Au. Rectified transmembrane electron transfer through the LB monolayers of 1 and 2 on gold electrodes to [Fe(CN)6]3− in aqueous solutions has been proved by cyclic voltammetry and potential-step chronocoulometry.