title: Charge Tunneling along Short Oligoglycine Chains.
abstract: This work examines charge transport (CT) through self-assembled monolayers (SAMs) of oligoglycines having an N-terminal cysteine group that anchors the molecule to a gold substrate, and demonstrate that CT is rapid (relative to SAMs of n-alkanethiolates). Comparisons of rates of charge transport-using junctions with the structure Au(TS)/SAM//Ga2O3/EGaIn (across these SAMs of oligoglycines, and across SAMs of a number of structurally and electronically related molecules) established that rates of charge tunneling along SAMs of oligoglycines are comparable to that along SAMs of oligophenyl groups (of comparable length). The mechanism of tunneling in oligoglycines is compatible with superexchange, and involves interactions among high-energy occupied orbitals in multiple, consecutive amide bonds, which may by separated by one to three methylene groups. This mechanistic conclusion is supported by density functional theory (DFT).
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA 02138 (USA).
authors.forename: Mostafa
authors.initials: M
authors.lastname: Baghbanzadeh
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA 02138 (USA).
authors.forename: Carleen M
authors.initials: CM
authors.lastname: Bowers
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA 02138 (USA).
authors.forename: Dmitrij
authors.initials: D
authors.lastname: Rappoport
authors.affiliation: Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow (Poland).
authors.forename: Tomasz
authors.initials: T
authors.lastname: Żaba
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA 02138 (USA).|Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC/CIBER-BBN), Cerdanyola del Vallès, 08193, Barcelona (Spain).
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gonidec
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA 02138 (USA).
authors.forename: Mohammad H
authors.initials: MH
authors.lastname: Al-Sayah
authors.affiliation: Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow (Poland).
authors.forename: Piotr
authors.initials: P
authors.lastname: Cyganik
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA 02138 (USA). aspuru@chemistry.harvard.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Aspuru-Guzik
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA 02138 (USA). gwhitesides@gmwgroup.harvard.edu.|Kavli Institute for Bionano Science and Technology, Harvard University, 29 Oxford Street, Cambridge, MA 02138 (USA). gwhitesides@gmwgroup.harvard.edu.|Wyss Institute of Biologically Inspired Engineering, Harvard University, 60 Oxford St. Cambridge, MA 02138 (USA). gwhitesides@gmwgroup.harvard.edu.
authors.forename: George M
authors.initials: GM
authors.lastname: Whitesides
keywords: biological conduction; density functional theory; oligopeptides; organic electronics; superexchange tunneling