Cuboctahedral Sb2O3 Mesocrystals Organized from Octahedral Building Blocks: More than Self-Similarity

Assembly of nanoparticle building blocks over multiple length scales into hierarchically ordered structures plays an essential role in the nonclassical crystallization pathway. Although random particle aggregates are constantly observed in crystallization experiments, mesocrystals with well shaped morphology and ordered hierarchical structure have been seldomly reported. Here, we describe the successful production of remarkable cuboctahedral Sb2O3 mesocrystals with hierarchical three-dimensional superstructures through a simple solution route. This is the first example of well-defined polyhedral mesocrystals with a cuboctahedral external morphology differing from the octahedral morphology of the building subunits. Electrostatic interactions between cetyltrimethylammonium cations (CTA(+)) and tartrate anions and hydrophobic interactions between the cetyltrimethylammonium bromide tails were supposed to be the driving force for the aggregation-based growth process. This novel mesocrystal formation breaks through the classical crystallization pattern and opens up a new pathway to construct mesoscale-transformed mesocrystals with hierarchical superstructures.