Binding of fullerene C-60 to gold surface functionalized by self-assembled monolayers of 8-amino-1-octane thiol: a structure elucidation

Abstract

The formation of self-assembled chemisorbed monolayers (SAM) of 8-amino-1-undecane thiol functionalized with fullerene C-60 on gold, has been studied by contact angle measurements, Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). A two-step procedure was followed consisting of the chemisorption of amine-terminated organosulfur compounds, followed by their reaction with fullerenes at the solid-liquid interface. Covalent binding of fullerenes to these attachment layers was accessed by FTIR-ATR and XPS. ATR showed several major features in the C60 skeleton ring vibration region along with all the characteristic features of the aminothiol. With increase in carbon to sulfur ratio, appearance of a C1s shake-up satellite peak due to the characteristic pi-pi* transition of the C-60 backbone and a low binding energy N1s feature confirmed the -NH2 binding at the 6,6 double bond of the C60 cage. Possible explanations for these experimental findings are discussed. (C) 2003 Elsevier Inc. All rights reserved.