PAPER: Pinning-down molecules in their self-assemblies with multiple weak hydrogen bonds of C-H…F and C-H…N

  1. Peking Univ, Coll Chem & Mol Engn, BNLMS, Beijing 100871, Peoples R China
  2. Aarhus Univ, Danish Chinese Ctr Self Assembly & Funct Mol Nano, Dept Chem, DK-8000 Aarhus, Denmark
  3. Univ Sci & Technol China, Sch Chem & Mat Sci, Dept Chem Phys, Hefei 230026, Peoples R China
  4. Natl Univ Singapore, Dept Chem, Singapore 117543, Singapore
  5. SPURc, 1 CREATE Way # 15-01 CREATE Tower, Singapore 138602, Singapore
Abstract

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. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

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