Characterization of electroactive Langmuir-Blodgett monolayers of (ferrocenylmethyl)dimethyloctadecylammonium sulfate at gold and air/water interfaces

Abstract

Organized monolayer films of (ferrocenylmethyl)dimethyloctadecylammonium hexafluorophosphate on aqueous 0.1 M Na2S04 surfaces were transferred via the Langmuir-Blodgett (L-B) technique to hydrophilic Au electrodes. These transfers resulted in the "heads down" orientation of the polar electroactive head group on the electrode. The cyclic voltammetry of electrodes coated with single L-B monolayers was examined with increasing transfer pressure, irt. The fraction of transferred electroactive sites which react faradaically with the electrode on the cyclic voltammetric time scale is consistently less than unity and passes through a maximum. It is postulated that this is due to dissolution from the Au/electrolyte interface which is maximized as a result of the competition of two factors: low film cohesiveness at low irt and intermolecular electrostatic repulsion at high ,. Detailed study of the surfactant behavior at the air/water interface is presented as it is thought that the structure of the monolayer on the electrode is influenced to a large degree by the film state at the air/water interface.

Electrochemical Characterization of Redox Polymer Langmuir−Blodgett Films Containing Ferrocene Derivatives

“…Facci 10 and Majda [11][12][13] have studied the electrochemical behaviors of LB monolayers of (ferrocenylmethyl)dimethyloctadecylammonium hexafluorophosphate and N-octadecylferrocenecarboxamide, respectively. The electrochemical characterization of self-assembled monolayers of ferrocene-terminated alkanethiols on gold was carried out by Chidsey et al 15,16 The bilayers of ferrocene LB monolayers and a selfassembled monolayer have been reported by Guo et al [17][18][19] These redox amphiphiles described above are low molecular-weight compounds.…”

Adsorption and micellization influence the electrochemistry of redox surfactants derived from ferrocene

“…An in situ ellipsometric study of the potential-dependent adsorption of sodium dodecyl sulfate on Pt electrodes has been carried out.16 Several groups are pursuing studies of the self-assembly of monolayers of amphiphilic molecules containing redox groups at electrode surfaces.9,17 -23 Also, the use of Langmuir-Blodgett techniques to prepare electrodes coated with organized molecular assemblies recently has been investigated. [22][23][24][25][26][27][28][29][30][31][32][33][34] As part of an ongoing investigation into the influence of molecular and supermolecular structure on the redox behavior of molecules at surfaces, we report here on the use of electrochemical and quartz crystal microbalance (QCM) techniques to elucidate the influence of adsorption and micellization on the redox behavior of a series of ferrocene-based redox surfactants having different alkyl chain lengths. A preliminary report of this work has already appeared in which the behavior of the dodecyl derivative was described.36 Experimental Section (Ferrocenylmethyl)heptyldimethylammonium bromide (C7Br) was prepared by stirring an equimolar mixture of ((dimethylamino)methyl)ferrocene (Aldrich) with 1-bromoheptane (Aldrich) (11) Hubbard, A. T.; Stickney, J. L.; Soriega, .…”

Preparation and characterization of redox cellulose Langmuir–Blodgett films containing a ferrocene derivative

“…Molecular assembled films containing electrochemically active functional groups have been widely used in studies from the viewpoint of the fundamental electron‐transfer property and in applications such as photosynthesis systems, electrocatalysis, biosensors, and electrochemical devices 1–4. In particular, ferrocene has been studied well as an electrochemically active group because ferrocene is known to exchange electrons very quickly between the ferrocene moiety and electrode surface and behave as a reversible compound 5. Currently, miniaturized and highly designed devices are of great interest for the development of electronic devices.…”