Shuai Wang

The formation of random tiling within a two-dimensional molecular network of the asymmetric p-terphenyl-2',3,3″,5,5″-pentacarboxylic acid (TPPC) at the heptanoic acid/highly oriented pyrolytic graphite interface was investigated using scanning tunneling microscopy and density functional theory calculations. Assemblies of TPPC formed a random tiling network with molecular cavities composed of five distinct molecular cavities. Upon introduction of coronene (COR) and pyridine derivatives (Bispy and BD), the modulation of the self-assembly process was further investigated. The structure of the TPPC/COR coassembly shows obvious concentration dependence. At low concentrations, COR molecules entered the star-shaped cavities of the TPPC network preferentially. As the concentration increased, COR occupied all cavities within the TPPC network. The introduction of pyridine derivatives (Bispy and BD) with varying backbones can completely remodel the original TPPC architecture and induce a complete structural transformation to form long-range ordered TPPC/Bispy or TPPC/BD coassembly structures. This study realizes the molecular reprogramming of hydrogen-bond networks and the controllable transition from random tiling to ordered architectures, providing a robust strategy for the precise fabrication of two-dimensional supramolecular nanostructures.

In this research, the self-assembly behaviors of two different symmetry carboxylic acid derivatives (H₃BTE and H₄BTE) regulated by solvent and guest molecule (coronene, COR) were explored at the liquid/solid interface by scanning tunneling microscopy, and the formation mechanism was investigated by density functional theory. In 1-phenyloctane, only H₃BTE molecules dissolved with extremely low concentration and self-assembled into a honeycomb structure and a new strip structure, while H₄BTE could not. In 1-heptanoic acid, H₃BTE and H₄BTE were easily dissolved, in which H₃BTE formed a regular row structure and H₄BTE formed a tetragonal structure, respectively. The host-guest interaction was investigated by introducing the COR molecules into their self-assembly structures, and due to the different symmetry, H₃BTE and H₄BTE displayed different accommodation behavior.