The authors describe a strategy for the synthesis of 'nanocrystal mols.', in which discrete nos. of Au nanocrystals are organized into spatially defined structures based on Watson-Crick base-pairing interactions. The authors attach single-stranded DNA oligonucleotides of defined length and sequence to individual nanocrystals, and these assemble into dimers and trimers on addn. of a complementary single-stranded DNA template. The authors anticipate that this approach should allow the construction of more complex two- and three-dimensional assemblies. [on SciFinder (R)]