Influence of chemical structure on the stability and the conductance of porphyrin single-molecule junctions

TL;DR

This study investigates how chemical modifications in porphyrin molecules affect their stability and conductance in single-molecule junctions, revealing that specific groups enhance stability and conductance variability.

Contribution

It demonstrates that adding thiol and pyridine groups to porphyrins increases junction stability and conductance spread, highlighting different bridging geometries compared to rod-like molecules.

Findings

Thiol and pyridine groups improve junction stability.

Multiple bridging geometries lead to conductance variability.

Porphyrins form stable junctions without anchoring groups.

Abstract

Porphyrin molecules can form stable single molecule junctions without anchoring groups. Adding thiol end groups and pyridine axial groups yields more stable junctions with an increased spread in low-bias conductance. This is a result of different bridging geometries during breaking, the stability of which is demonstrated in time-dependent conductance measurements. This is in strong contrast with rod like molecules which show one preferential binding geometry.