Understanding the Role of Parallel Pathways via In-Situ Switching of Quantum Interference in Molecular Tunneling Junctions

Saurabh Soni, Gang Ye, Jueting Zheng, Yanxi Zhang, Andika Asyuda, Michael Zharnikov, Wenjing Hong (Corresponding author), Ryan C. Chiechi (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)14308-14312
Number of pages5
JournalAngewandte Chemie - International Edition
Volume59
Issue number34
Early online date29 May 2020
DOIs
Publication statusPublished - 17 Aug 2020

Keywords

  • EGaIn
  • molecular electronics
  • quantum interference
  • self-assembled monolayers
  • STM-BJ

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