Origin of chains of Au-PbS nano-dumbbells in space.

Self-assembled, one-dimensional (1D) nanomaterials are amenable building blocks for bottom-up nanofabrication processes. A current shortcoming in the self-assembly of 1D nanomaterials in solution phase is the need for specific linkers or templates under very precise conditions to achieve a handful of systems. Here we report on the origin of a novel self-assembly of 1D dumbbells consisting of Au tipped PbS nanorods into stable chains in solution without any linkers or templates. A realistic multi-particle model suggests that the mesophase comprises 1D dumbbells arrayed in chains formed by anisotropic van der Waals type interactions. We demonstrate an alternative recognition mechanism for directing the assembly of the 1D dumbbells, based on effective interaction between the neighboring dumbbells consisting of Au tips with complementary crystallographic facets that guides the entire assembly in space.