Characterize and Mediate Assembly of Triptycenes on Au(111) Surface.

Herein, we report the assembly behavior of triptycenes with aldehyde (Trip- 1 ) and amino (Trip- 2 ) groups on pristine and iodine-passivated Au(111) surfaces by a combination of scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and density functional theory (DFT) calculation. On Au(111) surface, Trip- 1 forms long trimer chains and two-dimensional islands via aldehyde-aldehyde hydrogen bonding in one dimension and π-π stacking of adjacent benzene rings in the other dimension. In contrast, Trip- 2 lies as individuals or in disorderly stacked islands. Trip- 2 and Trip- 1 can be mixed in an arbitrary ratio. And Trip- 2 molecules disrupt the ordered self-assembly structure of Trip- 1 due to the formation of stronger aldehyde-amino hydrogen bonding. DFT, XPS, and Raman spectra confirm the conformational difference of Trip- 1 and - 2 , as well as the aldehyde-amino hydrogen bonding formation in Trip- 1 and Trip- 2 mixture. On the iodine-passivated Au(111) surface, Trip- 1 forms single-molecule chains and a hexagonal closely packed structure due to iodine interlayer mediation. Trip- 2 molecules disrupt the hexagonal closely packed structure of Trip- 1 .