title: Conformation-driven quantum interference effects mediated by through-space conjugation in self-assembled monolayers.
abstract: Tunnelling currents through tunnelling junctions comprising molecules with cross-conjugation are markedly lower than for their linearly conjugated analogues. This effect has been shown experimentally and theoretically to arise from destructive quantum interference, which is understood to be an intrinsic, electronic property of molecules. Here we show experimental evidence of conformation-driven interference effects by examining through-space conjugation in which π-conjugated fragments are arranged face-on or edge-on in sufficiently close proximity to interact through space. Observing these effects in the latter requires trapping molecules in a non-equilibrium conformation closely resembling the X-ray crystal structure, which we accomplish using self-assembled monolayers to construct bottom-up, large-area tunnelling junctions. In contrast, interference effects are completely absent in zero-bias simulations on the equilibrium, gas-phase conformation, establishing through-space conjugation as both of fundamental interest and as a potential tool for tuning tunnelling charge-transport in large-area, solid-state molecular-electronic devices.
authors.affiliation: Stratingh Institute for Chemistry &Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands.
authors.forename: Marco
authors.initials: M
authors.lastname: Carlotti
authors.affiliation: Stratingh Institute for Chemistry &Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands.
authors.forename: Andrii
authors.initials: A
authors.lastname: Kovalchuk
authors.affiliation: Applied Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 253, Heidelberg 69120, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Wächter
authors.affiliation: Stratingh Institute for Chemistry &Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands.
authors.forename: Xinkai
authors.initials: X
authors.lastname: Qiu
authors.affiliation: Applied Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 253, Heidelberg 69120, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Zharnikov
authors.affiliation: Stratingh Institute for Chemistry &Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Chiechi