Simultaneously Tuning the Conductance of Multiple Embedded Circuits in Bis-Terpyridine-Based Single Molecule Breadboard Junctions

Assembling and prototyping multiple circuits on a common breadboard scaffold is critical for developing functional single molecule electronic devices. However, at present, controlling and combining the electronic properties of multiple circuits within a single-molecule junction remains an unresolved challenge. Here, we describe the molecular conductance distributions for five single terminal circuits each within three constitutional isomers of a bis-terpyridine-based molecular breadboard junction through a rigorous computational framework which accounts for molecular conformational flexibility and the relative electrode accessibility (REA) of anchoring groups. The isomers, termed TPo, TPm, and TPp, differ in the relative placement of the linking nitrogen (N) atoms at ortho, meta, and para positions, respectively, of the peripheral pyridyl rings. We demonstrate that quantum interference effects (QIE) and REA of the anchoring N atoms can be exploited to alter the relative conductance of the five single terminal circuits within the molecular breadboards by ~ 4–32 times. We introduce a phase-plot-analysis to highlight the interdependence of QIE- and REA-induced changes in the conductance states of the basis circuits across breadboard pairs. Our studies predict that REA should not impact the QIE-induced boost in circuit conductance for TPp relative to that in TPm. In contrast, REA suppresses the QIE boost for circuit conductance in TPo relative to that in TPm. Our results showcase the possibility of accessing the combined effect of QIE and REA within an experimental break-junction setup to develop diverse molecular electronic breadboards with multiple embedded circuits and distinct electronic properties.