Effect of external magnetic fields on electron transfer and ion pairing dynamics at ferrocenyl alkane thiol SAM/solution interfaces

Abstract

The redox behaviour of ferrocene alkane thiol self assembled monolayer modified electrodes in contact with aqueous perchlorate solutions both in the absence of and in the presence of an external magnetic field is examined using both electrochemical and gravimetric techniques The redox switching process involves an ET reaction involving the ferrocene/ferricinium redox transition coupled with an ion pairing step involving perchlorate ion. The voltammetric response recorded in the latter medium is irreversibly effected by the imposition of a static magnetic field of magnitude 0.5 T applied in a direction parallel to the electrode surface. The magnetic field dependence of the redox behaviour is attributed to structural changes in the monolayer arising from double layer effects involving changes in the spatial distribution of perchlorate counterions at the monolayer/solution interface, brought about by local convective stirring arising from the B field generated magnetohydrodynamic Lorenz body force.