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Surface Adatom Mediated Structural Transformation in Bromoarene Monolayers: Precursor Phases in Surface Ullmann
Qitang Fan1,2, Liming Liu3, Jingya Dai1
1National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology , University of Science and Technology of China , Hefei , Anhui 230029 , P. R. China.
ACS Nano
|February 20, 2018
Summary
Researchers observed structural transformations in supramolecular systems, converting halogen-bonded networks to coordination networks using metal adatoms. This provides insights into molecular storage and surface reactions.
Area of Science:
- Materials Science
- Surface Chemistry
- Supramolecular Chemistry
Background:
- Supramolecular systems offer potential for molecular storage devices.
- External stimuli can trigger structural transformations in these systems.
Purpose of the Study:
- To investigate the structural transformation of 4,4''-dibromo-m-terphenyl (DMTP) networks on metal surfaces.
- To understand the role of adatoms in mediating these transformations and their implications for surface reactions.
Main Methods:
- Ultrahigh vacuum scanning tunneling microscopy (UHV-STM)
- X-ray photoemission spectroscopy (XPS)
- Density functional theory (DFT) calculations
Main Results:
- Observed transformation from DMTP halogen-bonded networks to DMTP-metal (Cu/Ag) coordination networks on Cu(111) and Ag(111) surfaces at low temperatures.
- Halogen-bonded networks stabilized by Br···Br bonds; coordination networks stabilized by C-Br···Metal bonds.
- DMTP-Ag coordination network showed C-Br bond scission upon annealing to 333 K, indicating an intermediate for Ullmann reactions.
Conclusions:
- Surface adatoms mediate structural transformations in DMTP networks.
- The observed transformations are relevant for developing molecular storage and understanding surface-mediated reactions like the Ullmann reaction.
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