Work

Atomic-scale visualization of reaction intermediates in surface-confined Ullmann coupling

Year: 2025

Type: article

Abstract: Surface-confined Ullmann coupling is crucial for fabricating covalent nanostructures, while its reaction pathway requires deeper mechanistic understanding. Using scanning tunneling microscopy and density functional theory, we identify a variety of reaction intermediates and their assembly structures of dibromopyrene molecules on a silver substrate over a wide temperature range of 100–600 K, particularly covering the underexplored low-temperature regime. Through stepwise annealing, we track the complete reaction pathway from sequential dehalogenation to organometallic intermediates, followed by preferential C–C bonded dimer formation by controlling the molecular coverage. These findings provide practical guidelines for manipulating reaction intermediates and steering final products, advancing the controlled fabrication of high-quality carbon-based molecular electronic devices.

Source: Applied Surface Science

DOI: 10.1016/j.apsusc.2025.165161