Hydrogen bond

Conductance

Self-assembled monolayer

Mathematics

Molecule

Biochemistry

Density functional theory

Sulfur

Monolayer

Combinatorics

Nanotechnology

Organic chemistry

Chemical physics

Dithiol

Computational chemistry

Chemistry

Materials science

Nature Chemistry

Gold–thiol contacts are ubiquitous across the physical and biological sciences in connecting organic molecules to surfaces. When thiols bind to gold in self-assembled monolayers (SAMs) the fate of the hydrogen remains a subject of profound debate—with implications for our understanding of their physical properties, spectroscopic features and formation mechanism(s). Exploiting measurements of the transmission through a molecular junction, which is highly sensitive to the nature of the molecule–electrode contact, we demonstrate here that the nature of the gold–sulfur bond in SAMs can be probed via single-molecule conductance measurements. Critically, we find that SAM measurements of dithiol-terminated molecular junctions yield a significantly lower conductance than solution measurements of the same molecule. Through numerous control experiments, conductance noise analysis and transport calculations based on density functional theory, we show that the gold–sulfur bond in SAMs prepared from the solution depositio...

Non-chemisorbed gold–sulfur binding prevails in self-assembled monolayers