Au(III)-PAMAM interaction and formation of Au-PAMAM nanocomposites in ethyl acetate

The interaction of tetrachloroauric anion (AuCl4-) and hydrophobic poly(amidoamine) dendrimers (PAMAM) with terminal methyl ester groups was investigated in ethyl acetate by UV-vis and IR spectroscopies. Three possible types of interaction are suggested: (a) ion pair formation between AuCl4- and protonated tertiary amine of PAMAM, (b) chelation of Au(IH) by one (or two) tertiary amine(s) and two terminal methyl ester groups, and (c) chelation of Au(III) by two tertiary amines and two adjacent amide groups of the dendrimer. Au-PAMAM nanocomposites were synthesized by reducing the AuCl4--PAMAM complex with dimethylamine borane. The structure of the nanocomposites is supposed to be of exterior or mixed type. These Au-PAMAM nanocomposites exhibit a weak surface plasmon band in the range of 480 to 500 nm. (C) 2001 Academic Press.