Unprecedented self-assembly of precise molecular particles

Abstract

Atomic self-assembly in pure metals and metal alloys can lead into various conventional (cubic, hexagonal closepacked (hcp), and icosahedron) and non-conventional (Frank–Kasper and quasicrystal [1]) structures. The nonconventional crystalline structures often lead to unexpected physical properties. For example, the A15 (A3B type) Frank– Kasper phase of Nb3Sn, Nb3Zr and Nb3Ti are found to be superconducting. Metallic quasicrystals are hard and have low-friction, low-thermal conductivity, and special electronic properties. Beyond the atomic self-assembly, computer simulations have predicted many complex self-assembled structures, such as Frank–Kasper phases and quasicrystals, as a function of shape, size, and interaction for nanoparticles (Fig. 1) [2]. However, it has been challenging to experimentally achieve these structures from both hard (colloidal particles and mixtures) and soft (hierarchically self-assembled surfactants, dendrimers, and micellar block copolymers) nanoparticles. This is because precise shape, size, and interaction for colloidal nanoparticles are still difficult to control. In a recent report by Huang et al. [3], this grand challenge has been conquered by precise synthesis of rigid giant tetrahedra from molecular nanoparticles i.e. polyhedral oligomeric silsesquioxane (POSS), by using two orthogonal ‘click’ chemistry techniques, namely, the azide-alkyne [3 + 2] cycloaddition reaction and the thiol-ene reaction. In this clever way, different numbers of Nanoparticle self-assembly