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

Liu, Peizhen; Zheng, Zichan; Wang, Hongchao; Wang, Peichao; Hu, Zhixin; Gao, Hong-Ying · ACS Nano · 2024

basic_science · Level V

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Abstract

Herein, we report the assembly behavior of triptycenes with aldehyde (Trip-<b>1</b>) and amino (Trip-<b>2</b>) 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-<b>1</b> 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-<b>2</b> lies as individuals or in disorderly stacked islands. Trip-<b>2</b> and Trip-<b>1</b> can be mixed in an arbitrary ratio. And Trip-<b>2</b> molecules disrupt the ordered self-assembly structure of Trip-<b>1</b> due to the formation of stronger aldehyde-amino hydrogen bonding. DFT, XPS, and Raman spectra confirm the conformational difference of Trip-<b>1</b> and -<b>2</b>, as well as the aldehyde-amino hydrogen bonding formation in Trip-<b>1</b> and Trip-<b>2</b> mixture. On the iodine-passivated Au(111) surface, Trip-<b>1</b> forms single-molecule chains and a hexagonal closely packed structure due to iodine interlayer mediation. Trip-<b>2</b> molecules disrupt the hexagonal closely packed structure of Trip-<b>1</b>.