Generation of gold thread from Au(III) and triethylamine

Gold threads were spontaneously generated at room temperature from a combined solution of aqueous HAuCl4 and triethylamine. Initially, some reduced gold nanoparticles were self-organized into one-dimensional (1D) nanowires, which then developed into three-dimensional (3D) microscale threads of gold. After aging, the self-organized gold thread grew spontaneously, accompanied by the generation of new buds to start new branches. TEM images show that the gold thread is composed of elastic materials; in which, colloidal gold nanoparticles reduced by triethylamine serve as the bricks, whereas elastic substances formed during the reaction serve as the mortar, which holds together the gold particles. The results of IR and 1H NMR spectroscopy demonstrate that the elastic materials consist mainly of alkane-like substances. Examination of the 1H NMR spectrum of triethylamine under the conditions of the reaction shows evidence of the occurrence of oxidative N dealkylation. The observed isotope effect demonstrates the existence of O-D cleavage resulting from the degradation of carbinolamine, which is the reported oxidation route of amines. Triethylamine acts here not only acts as a stabilizer and a reducing agent, but also as a precursor to build the alkane-like material upon which the gold thread is formed.