J. Phys. Chem. Lett. 16, 3034−3038 (2025)

Phase Separation of Binary Triptycenes by an Iodine Interlayer Film on a Ag(111) Surface

Peizhen Liu¹, Peichao Wang¹, Zichan Zheng², Hongchao Wang¹, Zhixin Hu^2,* and Hong-Ying Gao^1,*

1 School of Chemical Engineering and Technology, Haihe Laboratory of Sustainable Chemical Transformations, Tianjin Key Laboratory of Applied Catalysis and Engineering, Tianjin University, Tianjin 300350, China.

2 Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin 300350, China.

* zhixin.hu@tju.edu.cn, gaohongying@tju.edu.cn

Abstract

We report the self-assembly behaviors of two triptycenes (Trip-1 and Trip-2) on metal surfaces without and with an iodine passivation interlayer by combining scanning tunneling microscopy (STM) and density functional theory (DFT) studies. On the Ag(111) surface, Trip-1 molecules form islands through intermolecular aldehyde−aldehyde hydrogen bonding and π−π stacking of benzene rings. In contrast, Trip-2 molecules lie flat and dispersed on the surface. The introduction of Trip-2 molecules can break the ordered assembly of Trip-1. Trip-1 and Trip-2 molecules will be mixed in a disorderly manner. On the iodine-passivated Ag(111) surface, Trip-1 molecules form islands of long chains by intermolecular aldehyde−aldehyde hydrogen bonding. Trip-1 and Trip-2 molecules will automatically be separated, forming a self-assembled binary monolayer. These results show that the interface can adjust the mixture and separation of two structurally analogous triptycenes.