Beyond Simple Structure–Function Relationships: The Interplay of Geometry, Electronic Structure, and Molecule/Electrode Coupling in Single-Molecule Junctions

Structure-function relationships constitute animportant tool to investigate the fundamental principles ofmolecular electronics. Most commonly, this involves identifying apotentially important molecular structural element, followed bydesigning and synthesizing a set of related organic molecules, andfinally interpretation of their experimental and/or computationalquantum transport properties in the light of this structural element.Though this has been extremely powerful in many instances, wedemonstrate here the common need for more nuanced relation-ships even for relatively simple structures, using both experimentaland computational results for a series of stilbene derivatives as acase study. In particular, we show that the presence of multiplecompeting and subtle structural factors can combine in unexpectedways to control quantum transport in these molecules. Our results clarify the reasons for previous widely varying and oftencontradictory reports on charge transport in stilbene derivatives and highlight the need for refined multidimensional structure-property relationships in single-molecule electronics.