Redox induced orientational changes in a series of short chain ferrocenyl alkyl thiols self-assembled on gold(111) electrodes

A series of short chain alkyl thiols (n = 3-10) with a ferrocene terminal g roup were allowed to form organised monolayers at gold(111) surfaces. The r edox activity of the monolayers was monitored using cyclic voltammetry and subtractively normalised interfacial Fourier transform infrared spectroscop y (SNIFTIRS). The in situ infrared spectra show that the oxidation of the f errocene groups in the monolayers studied is accompanied by a rotation of t he ferrocene groups towards a position where the plane of the cyclopentadie nyl rings moves to a position normal to the surface of the electrode. Furth ermore, electrochemical and spectroscopic data indicate that monolayers wit h longer alkyl chains are more ordered than the shorter analogues. A trend was observed in which the rate of adsorption and the surface coverage vary between the length of the alkyl chains. (C) 2001 Elsevier Science B.V. All rights reserved.