Nonaqueous gold colloids. Investigations of deposition and film growth on organically modified substrates and trapping of molecular gold clusters with an alkyl amine
F. Tian et Kj. Klabunde, Nonaqueous gold colloids. Investigations of deposition and film growth on organically modified substrates and trapping of molecular gold clusters with an alkyl amine, NEW J CHEM, 22(11), 1998, pp. 1275-1283
Gold-acetone colloidal solutions were prepared by a metal vapor codepositio
n procedure (solvated metal atom dispersion) and from these solutions gold
films were prepared by allowing adsorption/deposition on (sulfanylpropyl)tr
imethoxysilane- (aminopropyl)trimethoxysilane or (isobutyl)trimethoxysilane
-modified substrates. The mechanism of gold film formation was studied by A
FM and TEM. At short contact times, self-assembly of colloidal gold particl
es onto the functionalized substrate surfaces took place and both individua
l particles and aggregates appeared. As contact time increased, a dynamic e
quilibrium was evident on the thiol- and amine-modified substrates and resu
lted in the development of more stable, close-packed layers. At still longe
r contact times, a smooth film was formed on the surface. Besides film grow
th studies, the gold colloid particle growth in acetone was investigated. B
y adding dodecylamine, particle growth was stunted and very small (2-3 nm)
individual crystallites coated by the amine were obtained. These materials
were molecular in nature in the sense that they could be precipitated and r
edissolved many times without change. TEM data showed that the particles we
re spatially separated and the interparticle spacing was dependent on the a
mount of dodecylamine. The FT-IR data indicated that a significant amount o
f amine (N-H bond) and acetone (C=O bond) were adsorbed on the gold particl
e surfaces.