Hemilabile Ligands as Mechanosensitive Electrode Contacts for Molecular Electronics

Abstract

Single‐molecule junctions that are sensitive to compression or elongation are an emerging class of nanoelectromechanical systems (NEMS). Although the molecule–electrode interface can be engineered to impart such functionality, most studies to date rely on poorly defined interactions. We focused on this issue by synthesizing molecular wires designed to have chemically defined hemilabile contacts based on (methylthio)thiophene moieties. We measured their conductance as a function of junction size and observed conductance changes of up to two orders of magnitude as junctions were compressed and stretched. Localised interactions between weakly coordinating thienyl sulfurs and the electrodes are responsible for the observed effect and allow reversible monodentate⇄bidentate contact transitions as the junction is modulated in size. We observed an up to ≈100‐fold sensitivity boost of the (methylthio)thiophene‐terminated molecular wire compared with its non‐hemilabile (methylthio)benzene counterpart and demonstrate a previously unexplored application of hemilabile ligands to molecular electronics.

Tetrathiafulvalenes as anchors for building highly conductive and mechanically tunable molecular junctions

“…Additionally, the orientation of the molecule might change during the piezo ramp. Previously, several mechanically controlled switches have been demonstrated in molecular systems with multiple binding sites 3 , 55 – 57 . Our findings reported here provide a new design for mechanical molecular switches building on strongly coupled systems.…”

Mechanical Fixation by Porphyrin Connection: Synthesis and Transport Studies of a Bicyclic Dimer

“…While fundamental transport–property correlations corroborated the single-molecule nature of the junction and first electronic functions like rectifying or switching were successfully implemented, we became recently interested in mechanosensitive molecular junctions. First, single-molecule junctions with mechanosensitive transport features − or redox properties were reported. The variation of the single-molecule transport features was either due to a mechanically triggered alteration of the spin state or the manipulation of the spatial conformation of two neighboring π-systems in close proximity.…”