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Understanding the Role of Parallel Pathways via In‐Situ Switching of Quantum Interference in Molecular Tunneling Junctions
Author(s) -
Soni Saurabh,
Ye Gang,
Zheng Jueting,
Zhang Yanxi,
Asyuda Andika,
Zharnikov Michael,
Hong Wenjing,
Chiechi Ryan C.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202005047
Subject(s) - molecular switch , quantum tunnelling , conjugated system , conductance , break junction , intramolecular force , chemistry , interference (communication) , molecule , quantum , protonation , chemical physics , molecular wire , nanotechnology , optoelectronics , materials science , physics , condensed matter physics , stereochemistry , quantum mechanics , channel (broadcasting) , computer science , ion , computer network , organic chemistry , polymer
This study describes the modulation of tunneling probabilities in molecular junctions by switching one of two parallel intramolecular pathways. A linearly conjugated molecular wire provides a rigid framework that allows a second, cross‐conjugated pathway to be effectively switched on and off by protonation, affecting the total conductance of the junction. This approach works because a traversing electron interacts with the entire quantum‐mechanical circuit simultaneously; Kirchhoff's rules do not apply. We confirm this concept by comparing the conductances of a series of compounds with single or parallel pathways in large‐area junctions using EGaIn contacts and single‐molecule break junctions using gold contacts. We affect switching selectively in one of two parallel pathways by converting a cross‐conjugated carbonyl carbon into a trivalent carbocation, which replaces destructive quantum interference with a symmetrical resonance, causing an increase in transmission in the bias window.