A.c. impedance studies of the mechanism of electron transfer across TCNQ modified Au/thiol/lipid bilayer

Au supported octadecanethiol/phosphatidylcholine (Au/ODT/PC) bilayers modified with 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) were studied by a.c. impedance. Three kinds of Au/ODT/PC bilayer were prepared: (i) unmodified bilayer (UMB), (ii) bilayer with only the PC monolayer containing TCNQ (ODT/PC-TCNQ) and (iii) bilayer with both the ODT and PC monolayers containing TCNQ (ODT-TCNQ/PC-TCNQ). The Faraday resistances of UMB, ODT/PC-TCNQ and ODT-TCNQ/PC-TCNQ in 1 mmol/l Fe(CN)63−/4−+0.1 mol/l KCl solution were 3.9×107, 5.1×106 and 2.2×105 Ωcm2, respectively. The embedded TCNQ molecules were believed acting as electron mediators and electron transfer by hopping between TCNQ molecules was proposed as the mechanism of electron transfer across ODT-TCNQ/PC-TCNQ.