Beyond Simple Structure-Function Relationships: Interplay Between Cis/Trans Isomerization and Geometrically Constrained Metal/Molecule Coupling Efficiency in Single-Molecule Junctions

TL;DR

This study reveals that complex interplay of cis/trans isomerization and metal/molecule coupling significantly influences quantum transport in stilbene derivatives, challenging simple structure-function assumptions in molecular electronics.

Contribution

It introduces a nuanced, multidimensional approach to understanding structure-property relationships in single-molecule electronics, supported by experimental and computational data.

Findings

Multiple structural factors affect quantum transport unexpectedly.

Clarifies contradictions in previous charge-transport reports.

Highlights need for refined models in molecular electronics.

Abstract

Structure-function relationships constitute an important tool to investigate the fundamental principles of molecular electronics. Most commonly, this involves identifying a potentially important molecular structural element, followed by designing and synthesizing a set of related organic molecules, and finally interpretation of their experimental and/or computational quantum transport properties in the light of this structural element. Though this has been extremely powerful in many instances, we demonstrate here the common need for more nuanced relationships even for relatively simple structures, using both experimental and computational results for a series of stilbene derivatives as a case study. In particular, we show that the presence of multiple competing and subtle structural factors can combine in unexpected ways to control quantum transport in these molecules. Our results clarify the reasons for previous widely varying and often contradictory reports on charge-transport in stilbene derivatives, and highlight the need for refined multidimensional structure-property relationships in single molecule electronics.