Discrete Supracrystalline Heterostructures from Integrative Assembly of Nanocrystals and Porous Organic Cages

Although self-assembly across multiple length scales has been well recognized and intensively investigated in natural biological system, the design of artificial heterostructures enabled by integrative self-assembly is still in its infancy. Here we report a strategy toward the growth of discrete supracrystalline heterostructures from inorganic nanocrystals and porous organic cages (CC3-R), which in principle relies on the host-guest interactions between alkyl chains coated on nanocrystals and the cavity of cage molecules. Density functional theory calculation indicates that an attractive energy of ∼-2 k_BT is present between an alkyl chain and the cavity of a CC3-R molecule, which is responsible for the assembly of nanocrystal superlattices on the CC3-R octahedral crystals. Of particular interest is that, determined by the shape of the nanocrystals, two distinct assembly modes can be controlled at the mesoscale level, which eventually produce either a core/shell or heterodimer supracrystalline structure. Our results highlight opportunities for the development of such a noncovalent integrative self-assembly not limited to a particular length scale and that could be generally applicable for flexible integration of supramolecular systems.