Turning the Tap : Conformational Control of Quantum Interference to Modulate Single-Molecule Conductance

Jiang, F. and Trupp, D.I. and Algethami, N. and Zheng, H. and He, W. and Alqorashi, A. and Zhu, C. and Tang, C. and Li, R. and Liu, J. and Sadeghi, H. and Shi, J. and Davidson, R. and Korb, M. and Sobolev, A.N. and Naher, M. and Sangtarash, S. and Low, P.J. and Hong, W. and Lambert, C.J. (2019) Turning the Tap : Conformational Control of Quantum Interference to Modulate Single-Molecule Conductance. Angewandte Chemie - International Edition, 58 (52). pp. 18987-18993. ISSN 1433-7851

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Abstract

Together with the more intuitive and commonly recognized conductance mechanisms of charge-hopping and tunneling, quantum-interference (QI) phenomena have been identified as important factors affecting charge transport through molecules. Consequently, establishing simple and flexible molecular-design strategies to understand, control, and exploit QI in molecular junctions poses an exciting challenge. Here we demonstrate that destructive quantum interference (DQI) in meta-substituted phenylene ethylene-type oligomers (m-OPE) can be tuned by changing the position and conformation of methoxy (OMe) substituents at the central phenylene ring. These substituents play the role of molecular-scale taps, which can be switched on or off to control the current flow through a molecule. Our experimental results conclusively verify recently postulated magic-ratio and orbital-product rules, and highlight a novel chemical design strategy for tuning and gating DQI features to create single-molecule devices with desirable electronic functions.