Intramolecular coupling of terminal alkynes by atom manipulation

TL;DR

This paper demonstrates an intramolecular Glaser-like coupling of terminal alkynes on a surface, triggered by atom manipulation using voltage pulses, with detailed structural and theoretical analysis.

Contribution

It introduces a novel atom manipulation method to perform intramolecular coupling of alkynes, providing new insights into reaction pathways on surfaces.

Findings

Successful intramolecular coupling triggered by voltage pulses

Identification of reaction intermediates and pathways

Structural elucidation with microscopy and DFT calculations

Abstract

Glaser-like coupling of terminal alkynes by thermal activation is extensively used in on-surface chemistry. Here we demonstrate an intramolecular version of this reaction performed by atom manipulation. We used voltage pulses from the tip to trigger a Glaser-like coupling between terminal alkyne carbons within a custom synthesized precursor molecule adsorbed on bilayer NaCl on Cu(111). Different conformations of the precursor molecule and the product were characterized by molecular structure elucidation with atomic force microscopy and orbital density mapping with scanning tunneling microscopy, accompanied by density functional theory calculations. We revealed partially dehydrogenated intermediates providing insight into the reaction pathway.