title: Regulating a benzodifuran single molecule redox switch via electrochemical gating and optimization of molecule/electrode coupling.
abstract: We report a novel strategy for the regulation of charge transport through single molecule junctions via the combination of external stimuli of electrode potential, internal modulation of molecular structures, and optimization of anchoring groups. We have designed redox-active benzodifuran (BDF) compounds as functional electronic units to fabricate metal-molecule-metal (m-M-m) junction devices by scanning tunneling microscopy (STM) and mechanically controllable break junctions (MCBJ). The conductance of thiol-terminated BDF can be tuned by changing the electrode potentials showing clearly an off/on/off single molecule redox switching effect. To optimize the response, a BDF molecule tailored with carbodithioate (-CS2(-)) anchoring groups was synthesized. Our studies show that replacement of thiol by carbodithioate not only enhances the junction conductance but also substantially improves the switching effect by enhancing the on/off ratio from 2.5 to 8.
authors.affiliation: Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States.
authors.forename: Zhihai
authors.initials: Z
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Songjie
authors.initials: S
authors.lastname: Chen
authors.forename: Toni
authors.initials: T
authors.lastname: Froehlich
authors.forename: Chenyi
authors.initials: C
authors.lastname: Yi
authors.forename: Christian
authors.initials: C
authors.lastname: Schönenberger
authors.forename: Michel
authors.initials: M
authors.lastname: Calame
authors.forename: Silvio
authors.initials: S
authors.lastname: Decurtins
authors.forename: Shi-Xia
authors.initials: SX
authors.lastname: Liu
authors.forename: Eric
authors.initials: E
authors.lastname: Borguet