Formation of Coronene Clusters in Concentration and Temperature Controlled Two-Dimensional Porous Network

In this research, with the assistance of scanning tunneling microscopy (STM), we observed the two-dimensional (2D) self-assembly transition of a star-shaped oligofluorene derivative (StOF) from disordered structure to honeycomb network by adjusting StOF concentration in solution. By introducing guest molecules coronene (COR), we for the first time achieved novel triangle-shaped COR trimers on liquid/highly oriented pyrolytic graphite (HOPG) interface in both honeycomb network and the disordered structure. In thermal tests, the COR/StOF-disorder system underwent a structural conformation to form well-ordered ladder structures, while the COR/StOF-honeycomb system remained the perfect hexagonal network with COR trimers included in the cavities. Density functional theory (DFT) calculations have been employed to investigate the forming mechanism of the molecular nanoarrays. These studies are expected to enhance controlling on 2D self-assembly and provide a facial approach toward constructing on-surface molecular clusters.