Gold-organic thin films from the reductive grafting of diazonium gold(III) salts

• Reductive grafting of diazonium gold
• Gold-organic thin film
• Perfluorinated organic film
• Blockage of gold-organic film

Perfluorinated organic film C8F17-4-C6H4- was successfully grafted on in situ reduced gold by reductive grafting from the diazonium tetrachloroaurate(III) salt [C8F17-4-C6H4N ≡ N]AuCl4. The highly irreversible broad reduction peak of 1.0 mM [C8F17-4-C6H4N ≡ N]AuCl4 occurs at − 0.08 V vs. Ag/AgCl in 0.1 M [Bu4N]PF6/CH3CN at a glassy carbon working electrode. The surface morphology and evidence of the gold-organic film formation was investigated by attenuated total reflectance-infrared spectroscopy (ATR-IR), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM). ATR-IR spectrum shows the νC-F stretching frequencies of the perfluorinated film at 1089 and 1230 cm− 1 and the absence of the diazonium peak at 2305 cm− 1. OM, SEM, and AFM images show clusters or islands and isolated sub-micron deposits protruding less than one micron above the surface. EDS measurements showed the presence of gold in the thin film. Ferrocene/ferrocenium and [Fe(CN)6]3 −/4- electron-transfer experiments, sonication in organic solvents and water, and open circuit potential (OCP) experiments showed the efficient grafting and robustness of the grafted film.

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