Conductance of a single molecule anchored by an isocyanide substituent to gold electrodes

TL;DR

This study compares how different anchoring groups (isocyanide, thiol, cyanide) affect the electrical conductance and bond strength of single-molecule junctions with gold electrodes, revealing that Au-CN bonds are stronger than Au-Au bonds.

Contribution

It provides experimental measurements of conductance and bond strength for single-molecule junctions with different anchoring groups, highlighting the robustness of the Au-CN bond.

Findings

Au/1,4-diisocyanobenzene/Au conductance is comparable to thiol-based junctions.

Au/1,4-dicyanobenzene/Au junctions lack well-defined conductance.

Au-CN bonds are stronger than Au-Au bonds based on stretching length data.

Abstract

The effect of anchoring group on the electrical conductance of a single molecule bridging two Au electrodes was studied using di-substituted (isocyanide (CN-), thiol (S-) or cyanide (NC-)) benzene. The conductance of a single Au/1,4-diisocyanobenzene/Au junction anchored by isocyanide via a C atom (junction with the Au-CN bond) was $3 \times 10 ^{-3} G_{0}$ ($2e^{2}/h$). The value was comparable to $4 \times 10 ^{-3} G_{0}$ of a single Au/1,4-benzenedithiol/Au junction with the Au-S bond. The Au/1,4-dicyanobenzene/Au molecular junction with the Au-NC bond did not show well-defined conductance values. The metal-molecule bond strength was estimated by the distance over which the molecular junction was stretched before breakdown. The stretched length of the molecular junction with the Au-CN bond was comparable to that of the Au junction, indicating that the Au-CN bond was stronger than the Au-Au bond.