title: Molecular rectification in a metal-insulator-metal junction based on self-assembled monolayers.
abstract: An electrical junction formed by mechanical contact between two self-assembled monolayers (SAMs)--a SAM formed from an dialkyl disulfide with a covalently linked tetracyanoquinodimethane group that is supported by silver (or gold) and a SAM formed from an alkanethiolate SAM that is supported by mercury-rectifies current. The precursor to the SAM on silver (or gold) was bis(20-(2-((2,5-cyclohexadiene-1,4-diylidene)dimalonitrile))decyl)) disulfide and that for the SAM on mercury was HS(CH(2))(n-1)CH(3) (n = 14, 16, 18). The electrical properties of the junctions were characterized by current-voltage measurements. The ratio of the conductivity of the junction in the forward bias (Hg cathodic) to that in the reverse bias (Hg anodic), at a potential of 1 V, was 9 +/- 2 when the SAM on mercury was derived from HS(CH(2))(15)CH(3). The ratio of the conductivity in the forward bias to that in the reverse bias increased with decreasing chain length of the alkanethiol used to form the SAM on mercury. These results demonstrate that a single redox center asymmetrically placed in a metal-insulator-metal junction can cause the rectification of current and indicate that a fixed dipole in the insulating region of a metal-insulator-metal junction is not required for rectification.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Chabinyc
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Chen
authors.forename: R Erik
authors.initials: RE
authors.lastname: Holmlin
authors.forename: Heiko
authors.initials: H
authors.lastname: Jacobs
authors.forename: Hjalti
authors.initials: H
authors.lastname: Skulason
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Frisbie
authors.forename: Vladimiro
authors.initials: V
authors.lastname: Mujica
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ratner
authors.forename: Maria Anita
authors.initials: MA
authors.lastname: Rampi
authors.forename: George M
authors.initials: GM
authors.lastname: Whitesides
mesh_terms: D004220:Disulfides / Q000737:chemistry*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods*; D006046:Gold / Q000737:chemistry; D008628:Mercury / Q000737:chemistry*; D009570:Nitriles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D004220:Disulfides; D009570:Nitriles; C013703:tetracyanoquinodimethane; D012834:Silver; D006046:Gold; D008628:Mercury