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•••Br halogen bonds and Br•••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.

Dissymmetric On-Surface Dehalogenation Reaction Steered by Preformed Self-Assembled Structure

“…Each rod in the STM image corresponds to a single DBTP molecule, with a measured length of 1.53 ± 0.05 nm, which is in accordance with the value from a previous report (1.52 nm) . In addition, the shape of the rod matches well with that of the DBTP molecule observed in the previous report . Two obvious protrusions at terminals of rod are ascribed to Br atoms, indicating that the C–Br bond is present.…”

“…34 In addition, the shape of the rod matches well with that of the DBTP molecule observed in the previous report. 35 Two obvious protrusions at terminals of rod are ascribed to Br atoms, indicating that the C−Br bond is present. We first discuss the molecular alignments in the rectangular selfassembled phase.…”

On-Surface Synthesis of Two-Dimensional Covalent Organic Structures versus Halogen-Bonded Self-Assembly: Competing Formation of Organic Nanoarchitectures

“…Molecules with peripheral halogen atoms are promising organic building blocks to engineer different types of two-dimensional porous carbon-nanoarchitectures. The molecular halogen atoms (X) can stabilize highly ordered organic nanoarchitectures through the formation of intermolecular halogen bonds. − Halogen-bonded self-assembled nanoarchitectures have been successfully created using molecules with bromine − and iodine substituents . In addition, these building blocks can also be used to engineer covalent nanoarchitectures taking advantage of on-surface polymerization.…”

On‐Surface Synthesis of Adenine Oligomers via Ullmann Reaction

“…The energetically most favorable structural models in gas phase are superimposed on the corresponding STM images (Figures c and f), respectively, where good agreements in both dimension and morphology are achieved. From the DFT‐optimized models, it can be seen that the adenine moieties in Phase 1 interact with each other via double NH⋅⋅⋅N hydrogen bonds forming adenine ribbon structure and the dibromophenyl groups gather together via Br⋅⋅⋅Br halogen interaction and CH⋅⋅⋅Br hydrogen bonds . In the case of Phase 2, the opposite two adenine moieties interact via double NH⋅⋅⋅N hydrogen bonds forming a head‐to‐head arrangement, and the dibromophenyl groups gather together via Br⋅⋅⋅Br halogen interaction and CH⋅⋅⋅Br hydrogen bonds at the same time .…”