Nanostructured films of in situ deprotected thioacetyl-functionalized C60-fullerenes on a gold surface

Abstract

A series of thioacetyl-functionalized fullerene-C₆₀ derivatives were synthesized using the Prato reaction of fullerene-C₆₀ with six different 4-(S-acetylthioalkyl)benzaldehydes. The structures of the synthesized compounds were characterized by FT-IR, ¹H NMR and ESI-MS techniques. The LUMO–HOMO band gaps, derived from DFT B3LYP/6-31G* calculations, for the azomethine ylides corresponding to each 4-(S-acetylthioalkyl)benzaldehyde and fullerene-C₆₀ were correlated with the efficiency of the Prato reaction. The compounds were deposited onto gold electrodes via self-assembly following an in situ deprotection procedure which transformed the thioacetyl-functionalized compounds into their thiolated derivatives. The redox properties of the C₆₀ derivatives in solution were characterized using Voltammetry. The LUMO–HOMO band gaps obtained from the electrochemical data were compared with the density functional theory (DFT) values for the optimized structures. The thioacetyl-functionalized C₆₀ derivatives were employed for the catalytic reduction of halogenated hydrocarbons. Following deprotection, they were also employed for the modification of gold substrates. The solvent dependent barrier properties of the thiolated fullerene films were investigated using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The topography of the C₆₀ derivative modified electrode was investigated using X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM), which confirmed stable modification of the Au support with a three dimensional (3D) film of worm-like fullerene aggregates.