Truncated tetrahedral nanocrystals can self-assemble into one-, two- and three-dimensional superstructures. dose electron diffraction on ten different crystalline pharmaceutical. This study provides information about the packing of non-spherical nanocrystals into complex superstructures, and may enhance the potential of self-assembled nanocrystal metamaterials in practical applications. Our packing models showed that formation of the nanocrystal superstructures is dominated by the selective facet-to-facet contact induced by the anisotropic patchiness of the tetrahedra. Using techniques in real and reciprocal spaces, we successfully characterized the superstructures from their nanocrystal translational orderings down to the atomic-orientation alignments of individual quantum dots. Here we report the packing of truncated tetrahedral quantum dot nanocrystals into three distinct superstructures-one-dimensional chiral tetrahelices, two-dimensional quasicrystal-approximant superlattices and three-dimensional cluster-based body-centred-cubic single supercrystals-by controlling the assembly conditions. The packing of spherical nanocrystals, which frequently adopt dense, face-centred-cubic or hexagonal-close-packed arrangements at thermodynamic equilibrium, has been much more widely studied than that of non-spherical, polyhedral nanocrystals, despite the fact that the latter have intriguing anisotropic properties resulting from the shapes of the building blocks.sup.11-13. 3 Examples of (a) & (b) the similar diffraction patterns with the same zone axis obtained for the materials belonging to different space groups while sharing the same crystal system (c) & (d) similar diffraction patterns with the different zone axes obtained for the materials belonging to different space groups and crystal systems and (e) & (f) apparently different diffraction patterns. Abstract : The assembly of uniform nanocrystal building blocks into well ordered superstructures is a fundamental strategy for the generation of meso- and macroscale metamaterials with emergent nanoscopic functionalities.sup.1-10.
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