Hypermolecule: Chemically Synthesized Three-dimensional Macroscopic Molecular Moiré Superlattices

Recently, moiré superlattices in two-dimensional (2D) systems have attracted significant attention owing to their tunable optical, electronic and quantum properties. Nevertheless, the studies of moiré systems were mostly limited to 2D systems, which make scalability and reproducibility an important issue. Here, we report evidence for the formation of moleculebased macroscopic three-dimensional (3D) moiré superlattice superstructure. We define the isolated 3D assembly as a hypermolecule that has no known natural or synthetic molecular analogue. The time-dependent evolution of the 2D moiré assemblies was investigated using transmission electron microscopy, UV-visible spectroscopy and photoluminescence studies, revealing the hierarchical progression of twist-stacked 2D moiré superlattices towards the growth of macroscopic moiré systems. In addition, X-ray diffraction characterization methods were pursued to elucidate the structural characteristics of the resulting 3D assemblies and establish the correlation between the 2D and 3D superlattices. The macroscopic moiré superlattices – in addition to the 2D structures – exhibited chiroptical behavior, which was further investigated using circularly polarized luminescence study. These observations provide essential insights, and an open platform for further developments in pursuing deeper mechanism underlying their formation at the molecular level and their application potential.