Molecular Multistate Systems Formed in Two-Dimensional Porous Networks on Ag(111)

Abstract

Host-guest interactions in porous supramolecular structures have been studied on surfaces using scanning tunneling microscopy, with anticipation of biochemical and sensor applications, but limited to cases of van der Waals interactions and hydrogen bonds. Here, we studied the intermolecular structures of 4,4 ''-dibromo-p-terphenyl molecules self-caged in porous supramolecular structures with halogen bonds on Ag(111). The caged molecules hopped among six different configurations at higher than 50 K, showing a propeller-like pattern. At 30 K, they stayed at one of six states that were stabilized with Br center dot center dot center dot Br halogen bonds and Br center dot center dot center dot H hydrogen bonds with energy gains of 225, 197, and 163 meV, as revealed by our density functional theory calculations. The self-caged structure provides a model system to simulate multistate supramolecular memories.