Two-dimensional self-assemblies of four partially fluorinated molecules, 1,4-bis(2,6-difluoropyridin-4-yl)benzene, 4,4'-bis(2,6-difluoropyridin-4-yl)-1,1'-biphenyl, 4,4'-bis(2,6-difluoropyridin-4-yl)-1,1':4',1″-terphenyl and 4,4'-bis(2,6-difluoropyridin-3-yl)-1,1'-biphenyl, involving weak intermolecular C. H⋯F and C. H⋯N hydrogen bonds were systematically investigated on Au(111) with low-temperature scanning tunneling microscopy. The inter-molecular connecting modes and binding sites were closely related to the backbones of the building blocks, . i.e., the molecule length determines its binding sites with neighboring molecules in the assemblies while the attaching positions of the N and F atoms dictate its approaching and docking angles. The experimental results demonstrate that multiple weak hydrogen bonds such as C. H⋯F and C. H⋯N can be efficiently applied to tune the molecular orientations and the self-assembly structures accordingly.
- Fluorinated pyridyl molecules
- Grouped hydrogen bonds
- Molecular design
- Molecular self-assembly
- Scanning tunneling microscopy