Synthesis and characterization of gold-nanoparticle-cored dendrimers stabilized by metal-carbon bonds

Synthesis and characterization of gold-nanoparticle-cored dendrimers (NCDs), in which the dendrons are attached to the gold core through gold-carbon bonds, are described. Synthesis of these materials involved the simultaneous reduction of HAuCl(4) and a Fréchet-type dendron with a diazonium group at the focal point, all in an organic solvent such as toluene. These materials possess a nanometer-sized gold core surrounded by a shell of polyaryl ether dendrons, which are connected radially to the core. The NCDs were characterized by TEM, thermogravimetric analysis (TGA), and IR, UV, and NMR spectroscopic techniques. Average particle diameter of the NCDs ranged from 4.7 to 5.5 nm for the different generations. All NCDs exhibit the characteristic plasmon absorption of gold nanoparticles at 520 nm. Average numbers of dendrons per NCD in AuG(n) were calculated using results from TGA and TEM studies. Multiple layering of the dendrons is proposed as a possible reason for the high dendron/NCD value.