Heterosupramolecular chemistry: Recognition initiated and inhibited silvernanocrystal aggregation by pseudorotaxane assembly

Near size-monodisperse silver nanocrystals stabilized by chemisorption of a mixture of an alkane thiol (85%) and an alkane thiol incorporating a diben zo-24-crown-8 moiety (15%) have been prepared. Using dynamic light scatteri ng and nuclear magnetic resonance, it is shown that addition of bis-dibcnzy lammonium dication initiates aggregation of the silver nanocrystal dispersi on by pseudorotaxane assembly. It is also shown that addition of excess dib enzylammonium cation or dibenzo-24-crown-8 inhibits further aggregation. Th is novel demonstration of controlled nanocrystal aggregation points the way toward the programmed assembly of complex nanocrystal architectures in sol ution.