Self-assembled inorganic chiral superstructures

Controlled assembly of inorganic nanoparticles with different compositions, sizes and shapes into higher-order structures of collective functionalities is a central pursued objective in chemistry, physics, materials science and nanotechnology. The emerging chiral superstructures, which break spatial symmetries at the nanoscale, have attracted particular attention, owing to their unique chiroptical properties and potential applications in optics, catalysis, biology and so on. Various bottom-up strategies have been developed to build inorganic chiral superstructures based on the intrinsic configurational preference of the building blocks, external fields or chiral templates. Self-assembled inorganic chiral superstructures have demonstrated significant superior optical activity from the strong electric/magnetic coupling between the building blocks, as compared with the organic counterparts. In this Review, we discuss recent progress in preparing self-assembled inorganic chiral superstructures, with an emphasis on the driving forces that enable symmetry breaking during the assembly process. The chiroptical properties and applications are highlighted and a forward-looking trajectory of where research efforts should be focused is discussed. The chiral arrangement of inorganic nanoparticles brings new properties and functionalities that are distinct compared with the individual building blocks. This Review discusses the recent progress in the preparation, properties and emerging applications of self-assembled inorganic chiral superstructures. Key points The self-assembled inorganic chiral superstructures show similar motifs to their organic counterparts. Chirality can be transmitted from individual chiral nanoparticles to their assemblies. Chiral external fields can induce the chiral assembly of inorganic nanoparticles. Chiral templates are an efficient route to fabricating inorganic chiral assemblies. Inorganic chiral assemblies show distinct chiroptical properties, owing to the chiral arrangement of the individual nanoparticles. A variety of applications are enabled by inorganic chiral assemblies.