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Nonlinear and Nonsymmetric Single-Molecule Electronic Properties Towards Molecular Information Processing. Top Curr Chem (Cham) 2017; 375:79. [DOI: 10.1007/s41061-017-0167-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 08/23/2017] [Indexed: 10/18/2022]
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2
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Fletcher MC, Alexson DM, Moore MM, Prokes S, Glembocki O, Vivoni A, McCoy R, Mishra S, Tandon P, Hosten CM. Tip enhanced Raman spectroscopy, DFT and PED calculations of 4″-trimethylsilylethylsulfanyl-4,4′-di(phenyleneethynylene)benzene thiol adsorbed on silver. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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3
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Leopold MC, Doan TT, Mullaney MJ, Loftus AF, Kidd CM. Electrochemical characterization of self-assembled monolayers on gold substrates derived from thermal decomposition of monolayer-protected cluster films. J APPL ELECTROCHEM 2015. [DOI: 10.1007/s10800-015-0880-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Inelastic electron tunneling through degenerate and nondegenerate ground state polymeric junctions. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2015.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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5
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Shayeganfar F. Columnar organization of stack-assembled trimesic acid on graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:435305. [PMID: 25299971 DOI: 10.1088/0953-8984/26/43/435305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The stack-assembly of trimesic acid molecules into a highly organized columnar structure and their adsorption on graphene has been investigated by a DFT-based ab initio calculation method. Trimesic acid (TMA, benzene-1,3,5-tricarboxylic acid) constitutes an interesting building block for intermolecular hydrogen-bonding architecture by creating a strong net dipole moment which favors a symmetric π-stacking of molecular wire. Both the single orientation (syn) and alternating orientation (anti) of two- and three-unit TMA configurations are optimized, and determine that anti or AB pattern TMA wire is energetically more favorable than the syn case. Meanwhile, a decreasing band gap during the formation of the molecular wire proves the presence of delocalized π-electrons over the entire stack-assembly. The adsorption energy for a columnar TMA stack on graphene was found to be roughly less than of a single TMA adsorbed on graphene. The relative contribution of hydrogen bonding to column packing energy showed to be comparative and reasonable, with the energy of a conventional hydrogen bond. The magnitude of the band gap opening appears strongly correlated with the breaking of the symmetry of π-states of graphene by the TMA columnar patterning on the surface. Our results suggest that a stack-assembled molecular could be used to tune and control the electronic properties of graphene.
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Affiliation(s)
- F Shayeganfar
- Engineering Physics Department and Regroupement québécois sur les matériaux de pointe (RQMP), Polytechnique Montréal, Montréal, Québec H3C 3A7, Canada
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Cui B, Gu JY, Chen T, Yan HJ, Wang D, Wan LJ. Solution effect on diazonium-modified Au(111): reactions and structures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2955-2960. [PMID: 23410068 DOI: 10.1021/la400185e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Surface modifications of a Au(111) electrode with 4-bromobenzenediazonium tetrafluoroborate (BBD) in acetonitrile (ACN) and 0.1 M HClO4 have been characterized by scanning tunneling microscopy (STM). In ACN, STM results reveal the formation of disordered thin organic films. The involvement of the radical as an intermediate is evidenced by the negative effect of radical scavengers on organic thin film formation. In contrast, the 4,4'-dibromobiphenyl monolayer is observed when the aqueous solution is used as a medium to carry out the grafting experiment. The biphenyl compound is considered to be generated by a radical-radical coupling reaction.
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Affiliation(s)
- Bo Cui
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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7
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Synthesis, characterization of conjugated oligo-phenylene-ethynylenes and their supramolecular interaction with β-cyclodextrin for salicylaldehyde detection. Talanta 2012; 100:229-38. [PMID: 23141331 DOI: 10.1016/j.talanta.2012.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 08/07/2012] [Accepted: 08/09/2012] [Indexed: 11/21/2022]
Abstract
Four new conjugated oligo-phenylene-ethynylenes derivatives, N-methyl-4-(4-acetylthiophenylethynyl)-1,8-naphthalimide (1), thioacetic acid S-[4-(4-aminophenyl-ethynyl)phenyl]ester (2), 4-methylthiophenylethynylbenzenamine (3), N-methyl-4-(4-methyl-thiophenyl-ethynyl)-1,8-naphthalimide (4), were synthesized by Sonogashira and Eglinton cross-coupling reactions. The structures of the four compounds were confirmed by (1)HNMR, (13)CNMR, MS and IR and their spectral characteristics were studied by ultraviolet and visible (UV) spectroscopy as well as fluorescence spectroscopy in different medium. It was found that the fluorescence properties of compounds 2 and 3 were notably improved in aqueous solutions in the presence of β-cyclodextrin (β-CD). Spectral analysis supported the suppositions that the fluorescence intensity enhancement was due to the formation of inclusion complex with β-CD. The supramolecular interaction was investigated in detail and the reaction mechanism was provided. A salicylaldehyde determination method in aqueous medium was established based on the supramolecular complex of compound 3. Under the optimum conditions, the supramolecular complex exhibited a dynamic fluorescence response range for salicylaldehyde from 0.6 to 240×10(-6) molL(-1), with a detection limit of 1×10(-8) molL(-1).
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Fletcher M, Alexson DM, Prokes S, Glembocki O, Vivoni A, Hosten C. Surface-enhanced Raman scattering of a Ag/oligo(phenyleneethynylene)/Ag sandwich. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 78:706-711. [PMID: 21190893 DOI: 10.1016/j.saa.2010.11.053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 11/01/2010] [Accepted: 11/30/2010] [Indexed: 05/30/2023]
Abstract
α,ω-Dithiols are a useful class of compounds in molecular electronics because of their ability to easily adsorb to two metal surfaces, producing a molecular junction. We have prepared Ag nanosphere/oligo(phenyleneethynylene)/Ag sol (AgNS/OPE/Ag sol) and Ag nanowire/oligo(phenyleneethynylene)/Ag sol (AgNW/OPE/Ag sol) sandwiches to simulate the architecture of a molecular electronic device. This was achieved by self-assembly of OPE on the silver nanosurface, deprotection of the terminal sulfur, and deposition of Ag sol atop the monolayer. These sandwiches were then characterized by surface-enhanced Raman scattering (SERS) spectroscopy. The resulting spectra were compared to the bulk spectrum of the dimer and to the Ag nanosurface/OPE SERS spectra. The intensities of the SERS spectra in both systems exhibit a strong dependence on Ag deposition time and the results are also suggestive of intense interparticle coupling of the electromagnetic fields in both the AgNW/OPE/Ag and the AgNS/OPE/Ag systems. Three previously unobserved bands (1219, 1234, 2037 cm(-1)) arose in the SER spectra of the sandwiches and their presence is attributed to the strong enhancement of the electromagnetic field which is predicted from the COSMOL computational package. The 544 cm(-1) disulfide bond which is observed in the spectrum of solid OPE but is absent in the AgNS/OPE/Ag and AgNW/OPE/Ag spectra is indicative of chemisorption of OPE to the nanoparticles through oxidative dissociation of the disulfide bond.
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Affiliation(s)
- Melissa Fletcher
- Department of Chemistry, Howard University, Washington, DC 20059, United States
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9
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Khor SM, Liu G, Fairman C, Iyengar SG, Gooding JJ. The importance of interfacial design for the sensitivity of a label-free electrochemical immuno-biosensor for small organic molecules. Biosens Bioelectron 2011; 26:2038-44. [DOI: 10.1016/j.bios.2010.08.082] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/27/2010] [Accepted: 08/31/2010] [Indexed: 11/29/2022]
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10
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Kullapere M, Kozlova J, Matisen L, Sammelselg V, Menezes HA, Maia G, Schiffrin DJ, Tammeveski K. Electrochemical properties of aryl-modified gold electrodes. J Electroanal Chem (Lausanne) 2010. [DOI: 10.1016/j.jelechem.2009.12.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Tian Y, Ye S, Ran Q, Xian Y, Xu J, Peng R, Jin L. Generation of surface-confined catechol terminated SAMs via electrochemically triggered Michael addition: characterization, electrochemistry and complex with Ni(ii) and Cu(ii) cations. Phys Chem Chem Phys 2010; 12:13287-95. [DOI: 10.1039/c001205j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Lehr J, Williamson BE, Flavel BS, Downard AJ. Reaction of gold substrates with diazonium salts in acidic solution at open-circuit potential. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:13503-9. [PMID: 19697925 DOI: 10.1021/la902002n] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The reaction of gold substrates with p-nitrobenzene diazonium tetrafluoroborate (NBD) in 0.1 M H(2)SO(4) at open-circuit potential (OCP) is demonstrated to proceed by electron transfer from gold to the NBD cation. Electrochemical, atomic force microscopy, and X-ray photoelectron spectroscopy analyses reveal the formation of multilayer films with the same composition as electrografted films. The film growth characteristics (surface concentration and film thickness vs time) also follow those observed during electrografting, consistent with electron transfer from the substrate to the diazonium cation. The OCP of the gold substrate increases during the period of film growth ( approximately 60 min) and then decreases to close to its initial value. The increase corresponds to accumulation of positive charge as electrons are transferred to NBD; the discharge process is tentatively attributed to slow oxidation of adventitious impurities in the reaction solution. Films formed at OCP or by electrografting from aqueous acid solution are markedly less stable to sonication in acetonitrile than are those electrografted from acetonitrile. Increased amounts of physisorbed material in films prepared in aqueous media or bonding of aryl groups to different gold sites in the two media are tentatively proposed to account for the different stabilities.
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Affiliation(s)
- Joshua Lehr
- Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
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13
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Döring K, Taher D, Walfort B, Lutz M, Spek AL, van Klink GP, van Koten G, Lang H. Linear homobimetallic 4-thioacetyl-substituted NCN pincer palladium(II) and platinum(II) complexes with N-bidentate connecting units (NCN=[C6H2(CH2NMe2)2-2,6-R-4]−). Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.01.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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14
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Lang H, Rößler K, Taher D, Holze R, Walfort B. Thiol end-capped titanium–copper complexes: Synthesis, solid state structure and electrochemical behavior. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2007.03.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Kranz C, Kueng A, Mizaikoff B. Scanning Micro‐ and Nanoprobes for Electrochemical Imaging. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/9783527616701.ch7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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16
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Weibel N, Błaszczyk A, von Hänisch C, Mayor M, Pobelov I, Wandlowski T, Chen F, Tao N. Redox-Active Catechol-Functionalized Molecular Rods: Suitable Protection Groups and Single-Molecule Transport Investigations. European J Org Chem 2008. [DOI: 10.1002/ejoc.200700810] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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17
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The unique properties observed for the unsymmetrical macrocyclic compounds with the highly distorted structure. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.06.059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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18
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Kula M, Jiang J, Lu W, Luo Y. Effects of hydrogen bonding on current-voltage characteristics of molecular junctions. J Chem Phys 2006; 125:194703. [PMID: 17129146 DOI: 10.1063/1.2364494] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a first-principles study of hydrogen bonding effect on current-voltage characteristics of molecular junctions. Three model charge-transfer molecules, 2'-amino-4,4'-di(ethynylphenyl)-1-benzenethiolate (DEPBT-D), 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate (DEPBT-A), and 2'-amino-4,4'-di(ethynylphenyl)-5'-nitro-1-benzenethiolate (DEPBT-DA), have been examined and compared with the corresponding hydrogen bonded complexes formed with different water molecules. Large differences in current-voltage characteristics are observed for DEPBT-D and DEPBT-A molecules with or without hydrogen bonded waters, while relatively small differences are found for DEPBT-DA. It is predicted that the presence of water clusters can drastically reduce the conductivities of the charge-transfer molecules. The underlying microscopic mechanism has been discussed.
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Affiliation(s)
- Mathias Kula
- Theoretical Chemistry, Royal Institute of Technology, AlbaNova, S-106 91 Stockholm, Sweden
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Liu G, Gooding JJ. An interface comprising molecular wires and poly(ethylene glycol) spacer units self-assembled on carbon electrodes for studies of protein electrochemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:7421-30. [PMID: 16893248 DOI: 10.1021/la0607510] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The characterization and application of a modified electrode interface for protein electrochemistry is reported. This generic interface is composed of a mixed monolayer of oligo(phenylethynylene) molecular wires (MWs) and poly(ethylene glycol) (PEG) deposited on glassy carbon electrodes by reductive adsorption of the respective aryl diazonium salts. Electrochemistry and scanning electron microscopy demonstrate that the PEG component exhibits a distinct decrease in nonspecific adsorption of blood serum and the proteins bovine serum albumin (BSA) and horseradish peroxidase (HRP) relative to a bare glassy carbon electrode. The ability of the MWs to facilitate efficient electron transfer through the PEG layer to the underlying electrode was demonstrated by covalently attaching ferrocenemethylamine to the end of the MWs. The calculated rate constant for this system was 229 +/- 30 s(-1). Covalent attachment of HRP to the MWs allowed direct electron transfer to the redox protein with almost ideal electrochemistry, indicating a specific interaction between the MW and HRP, with a rate constant of 13.4 +/- 2.3 s(-1). This rate constant is more rapid than previously reported for HRP shown to still be catalytically active. Retained catalytic activity of HRP was demonstrated by the enzyme responding to the addition of hydrogen peroxide. Similarly, by attaching myoglobin to the end of the MWs, a rate constant for this protein of 2 s(-1) was measured. The rigidity of the MWs, as well as it being longer than the PEG diluent, means this generic interface can be employed to investigate the electrochemistry of a wide range of redox proteins.
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Affiliation(s)
- Guozhen Liu
- School of Chemistry, The University of New South Wales, Sydney 2052, Australia
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20
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Ye Y, Chen L, Liu X, Krull UJ. DNA and microfluidics: Building molecular electronics systems. Anal Chim Acta 2006; 568:138-45. [PMID: 17761254 DOI: 10.1016/j.aca.2005.11.080] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2005] [Revised: 11/15/2005] [Accepted: 11/15/2005] [Indexed: 11/24/2022]
Abstract
The development of molecular electronics using DNA molecules as the building blocks and using microfluidics to build nanowire arrays is reviewed. Applications of DNA conductivity to build sensors and nanowire arrays, and DNA conjugation with other nanostructures, offers an exciting opportunity to build extremely small analytical devices that are suitable for single-molecule detection and also target screening.
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Affiliation(s)
- Yun Ye
- Chemical Sensors Group, Department of Chemical and Physical Sciences, University of Toronto at Mississauga, 3359 Mississauga Road North, Mississauga, Ont, Canada L5L 1C6
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Maddox JB, Harbola U, Liu N, Silien C, Ho W, Bazan GC, Mukamel S. Simulation of Single Molecule Inelastic Electron Tunneling Signals in Paraphenylene−Vinylene Oligomers and Distyrylbenzene[2.2]paracyclophanes. J Phys Chem A 2006; 110:6329-38. [PMID: 16686469 DOI: 10.1021/jp061590b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inelastic resonances in the electron tunneling spectra of several conjugated molecules are simulated using the nonequilibrium Greens function formalism. The vibrational modes that strongly couple to the electronic current are different from the infrared and Raman active modes. Spatially resolved inelastic electron tunneling (IET) intensities are predicted. The simulated IET intensities for a large distyrylbenzene paracyclophane molecule are in qualitative agreement with recent experimental results.
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Affiliation(s)
- Jeremy B Maddox
- Department of Chemistry, University of California, Irvine, California 92697, USA
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22
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23
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Anariba F, Steach JK, McCreery RL. Strong Effects of Molecular Structure on Electron Transport in Carbon/Molecule/Copper Electronic Junctions. J Phys Chem B 2005; 109:11163-72. [PMID: 16852362 DOI: 10.1021/jp051093f] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Carbon/molecule/copper molecular electronic junctions were fabricated by metal deposition of copper onto films of various thicknesses of fluorene (FL), biphenyl (BP), and nitrobiphenyl (NBP) covalently bonded to flat, graphitic carbon. A "crossed-wire" junction configuration provided high device yield and good junction reproducibility. Current/voltage characteristics were investigated for 69 junctions with various molecular structures and thicknesses and at several temperatures. The current/voltage curves for all cases studied were nearly symmetric, scan rate independent, repeatable at least thousands of cycles and exhibited negligible hysteresis. Junction conductance was strongly dependent on the dihedral angle between phenyl rings and on the nature of the molecule/copper "contact". Junctions made with NBP showed a decrease in conductivity of a factor of 1300 when the molecular layer thickness increased from 1.6 to 4.5 nm. The slope of ln(i) vs layer thickness for both BP and NBP was weakly dependent on applied voltage and ranged from 0.16 to 0.24 A(-1). These attenuation factors are similar to those observed for similar molecular layers on modified electrodes used to study electrochemical kinetics. All junctions studied showed weak temperature dependence in the range of approximately 325 to 214 K, implying activation barriers in the range of 0.06 to 0.15 eV. The carbon/molecule/copper junction structure provides a robust, reproducible platform for investigations of the dependence of electron transport in molecular junctions on both molecular structure and temperature. Furthermore, the results indicate that junction conductance is a strong function of molecular structure, rather than some artifact resulting from junction fabrication.
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Affiliation(s)
- Franklin Anariba
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
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Lydon DP, Porrès L, Beeby A, Marder TB, Low PJ. A simple “palladium-free” synthesis of phenyleneethynylene-based molecular materials revisited. NEW J CHEM 2005. [DOI: 10.1039/b502950c] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Wu CG, Chang SS. Nanoscale Measurements of Conducting Domains and Current−Voltage Characteristics of Chemically Deposited Polyaniline Films. J Phys Chem B 2004; 109:825-32. [PMID: 16866448 DOI: 10.1021/jp046259b] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spatial variations in electric conductivity and evolutions of band structures of polyaniline (PANI) films have been studied by use of a so-called current-sensing atomic force microscope (CS-AFM) or atomic force microscope current image tunneling spectroscopy (AFM-CITS). PANI films were deposited chemically onto indium-tin oxide- (ITO-) glass substrates, and their thickness and doping levels were controlled by polymerization and acid-doping conditions. The conducting uniformity of the PANI films depends on their doping level and thickness. Conducting domains were observed in fully doped PANI film, even when the bias voltage was reduced to as small as 30 mV. High current flowing regions gradually disappeared when conducting PANI films were partially dedoped. The point-contact current-voltage (I-V) characteristics of conducting tip-polymer/ITO systems were investigated on PANI films with different thickness and degree of doping. Various types of I-V curves representing metallic, semiconducting, and insulating states were obtained depending on the aggregation of polymer chains and doping level of the polymer film. The band gap energies (estimated from the I-V or dI/dV-V curves) of emeraldine base (EB) (undoped polyaniline) films are all higher than 3.8 eV, and a wide distribution of the band gap energies (0-1.1 eV and 0.75-1.8 eV for fully and partially doped PANI thin films, respectively) was found in a single polymer film.
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Affiliation(s)
- Chun-Guey Wu
- Department of Chemistry, National Central University, Chung-Li, Taiwan 32054, Republic of China.
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Fan FRF, Yao Y, Cai L, Cheng L, Tour JM, Bard AJ. Structure-Dependent Charge Transport and Storage in Self-Assembled Monolayers of Compounds of Interest in Molecular Electronics: Effects of Tip Material, Headgroup, and Surface Concentration. J Am Chem Soc 2004; 126:4035-42. [PMID: 15038757 DOI: 10.1021/ja0359815] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The electrical properties of self-assembled monolayers (SAMs) on a gold surface have been explored to address the relation between the conductance of a molecule and its electronic structure. We probe interfacial electron transfer processes, particularly those involving electroactive groups, of SAMs of thiolates on Au by using shear force-based scanning probe microscopy (SPM) combined with current-voltage (i-V) and current-distance (i-d) measurements. Peak-shaped i-V curves were obtained for the nitro- and amino-based SAMs studied here. Peak-shaped cathodic i-V curves for nitro-based SAMs were observed at negative potentials in both forward and reverse scans and were used to define the threshold tip bias, V(TH), for electric conduction. For a SAM of 2',5'-dinitro-4,4'-bis(phenylethynyl)-1-benzenethiolate, VII, V(TH) was nearly independent of the tip material [Ir, Pt, Ir-Pt (20-80%), Pd, Ni, Au, Ag, In]. For all of the SAMs studied, the current decreased exponentially with increasing distance, d, between tip and substrate. The exponential attenuation factors (beta values) were lower for the nitro-based SAMs studied here, as compared with alkylthiol-based SAMs. Both V(TH) and beta of the nitro-based SAMs also depended strongly on the molecular headgroup on the end benzene ring addressed by the tip. Finally, we confirmed the "memory" effect observed for nitro-based SAMs. For mixed SAMs of VII and hexadecanethiol, I, the fraction of the charge collected in the negative tip bias region that can be read out at a positive tip bias on reverse scan (up to 38%) depended on the film composition and decreased with an increasing fraction of I, suggesting that lateral electron hopping among molecules of VII occurs in the vicinity of the tip.
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Affiliation(s)
- Fu-Ren F Fan
- Department of Chemistry and Biochemistry and Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712-0165, USA
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de Boer B, Frank MM, Chabal YJ, Jiang W, Garfunkel E, Bao Z. Metallic contact formation for molecular electronics: interactions between vapor-deposited metals and self-assembled monolayers of conjugated mono- and dithiols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:1539-1542. [PMID: 15801409 DOI: 10.1021/la0356349] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present grazing-incidence Fourier transform infrared and AFM data of Au, Al, and Ti vapor-deposited onto self-assembled monolayers (SAMs) of conjugated mono- and dithiols. SAMs of 4,4'''-dimercapto-p-quaterphenyl, 4,4"-dimercapto-p-terphenyl, and 4,4'-dimercapto-p-biphenyl have reactive thiols at the SAM/vacuum interface that interact with vapor-deposited Au or Al atoms, preventing metal penetration. Conjugated monothiols lack such metal blocking groups, and metals (Au, Al) can penetrate into their SAMs. Vapor deposition of Ti onto conjugated mono- and dithiol SAMs and onto hexadecanethiol SAMs destroys the monolayers.
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Cacelli I, Campanile S, Denti G, Ferretti A, Sommovigo M. [(NH3)5Ru(1,2,4,5-tetrazine)]2+: Synthesis and Experimental and Theoretical Study of Its Solvatochromism in the Visible Spectral Region. Inorg Chem 2004; 43:1379-87. [PMID: 14966973 DOI: 10.1021/ic034786o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The title compound has been first synthesized and fully characterized as both tetraphenylborate and perchlorate salt. Its 300-900 nm absorption spectrum, recorded in nitromethane, water, and dimethyl sulfoxide, reveals the peculiar existence of two distinct bands whose intensities depend on the solvent donor number. This feature can be attributed to two separate metal-to-ligand charge-transfer transitions, in agreement with the theoretical predictions obtained by extensive configuration interaction calculations, which take into account the solvent effects. The calculation of the potential energy curves of the ground and excited states along the Ru-tetrazine coordinate allows the interpretation of the relative intensities of the observed bands, as well as the interpretation of their line-shape profiles.
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Affiliation(s)
- Ivo Cacelli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, Pisa, Italy
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Walzer K, Marx E, Greenham NC, Less RJ, Raithby PR, Stokbro K. Scanning Tunneling Microscopy of Self-Assembled Phenylene Ethynylene Oligomers on Au(111) Substrates. J Am Chem Soc 2004; 126:1229-34. [PMID: 14746495 DOI: 10.1021/ja036771v] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, we report the self-assembly, electrical characterization, and surface modification of dithiolated phenylene-ethynylene oligomer monolayers on a Au(111) surface. The self-assembly was accomplished by thiol bonding the molecules from solution to a Au(111) surface. We have confirmed the formation of self-assembled monolayers by scanning tunneling microscopy (STM) and optical ellipsometry, and have studied the kinetics of film growth. We suggest that self-assembled phenylene ethynylene oligomers on Au(111) surfaces grow as thiols rather than as thiolates. Using low-temperature STM, we collected local current-voltage spectra showing negative differential resistance at 6 K.
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Affiliation(s)
- Karsten Walzer
- Mikroelektronik Centret (MIC), Technical University of Denmark, Bldg. 345 East, DK-2800 Lyngby, Denmark.
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30
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Lee HJ, Park SM. Electrochemistry of Conductive Polymers. 30. Nanoscale Measurements of Doping Distributions and Current−Voltage Characteristics of Electrochemically Deposited Polypyrrole Films. J Phys Chem B 2004. [DOI: 10.1021/jp035766a] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hyo Joong Lee
- Department of Chemistry and Center for Integrated Molecular Systems, Pohang University of Science and Technology, Pohang, Gyeongbuk 790-784, Korea (Republic of Korea)
| | - Su-Moon Park
- Department of Chemistry and Center for Integrated Molecular Systems, Pohang University of Science and Technology, Pohang, Gyeongbuk 790-784, Korea (Republic of Korea)
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Stewart MP, Maya F, Kosynkin DV, Dirk SM, Stapleton JJ, McGuiness CL, Allara DL, Tour JM. Direct Covalent Grafting of Conjugated Molecules onto Si, GaAs, and Pd Surfaces from Aryldiazonium Salts. J Am Chem Soc 2003; 126:370-8. [PMID: 14709104 DOI: 10.1021/ja0383120] [Citation(s) in RCA: 290] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using aryldiazonium salts that are air-stable and easily synthesized, we describe here a one-step, room-temperature route to direct covalent bonds between pi-conjugated organic molecules on three material surfaces: Si, GaAs, and Pd. The Si can be in the form of single crystal Si including heavily doped p-type Si, intrinsic Si, heavily doped n-type Si, on Si(111) and Si(100), and on n-type polycrystalline Si. The formation of the aryl-metal or aryl-semiconductor bond attachments was confirmed by corroborating evidence from ellipsometry, reflectance FTIR, XPS, cyclic voltammetry, and AFM analyses of the surface-grafted monolayers. A data-encompassing explanation for the mechanism suggests a diazonium activation by reduction at the open circuit potential, with aryl radical secondary products bonding to the surface. The synthetic details are included for preparing the surface-grafted monolayers and the precursor diazonium salts. This spontaneous diazonium activation reaction offers an attractive route to highly passivating, robust monolayers and multilayers on many surfaces that allow for strong bonds between carbon and surface atoms with molecular species that are near perpendicular to the surface.
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Affiliation(s)
- Michael P Stewart
- Departments of Chemistry and Mechanical Engineering and Materials Science, and Center for Nanoscale Science and Technology, MS-222, Rice University, Houston, Texas 77005, USA
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33
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Basch H, Ratner MA. Binding at molecule/gold transport interfaces. I. Geometry and bonding. J Chem Phys 2003. [DOI: 10.1063/1.1613941] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Tunneling conductivity of one- and two-component alkanethiol bilayers in Hg–Hg junctions. J Electroanal Chem (Lausanne) 2003. [DOI: 10.1016/s0022-0728(02)01265-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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35
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Warner MG, Hutchison JE. Linear assemblies of nanoparticles electrostatically organized on DNA scaffolds. NATURE MATERIALS 2003; 2:272-7. [PMID: 12690402 DOI: 10.1038/nmat853] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2002] [Accepted: 01/11/2003] [Indexed: 05/22/2023]
Abstract
A significant challenge faced in the use of nanoscale building blocks is developing parallel methods for interconnecting and patterning assemblies of the individual components. Molecular or polymeric scaffolds hold promise as a means of preparing closely spaced, specifically arranged nanoscale assemblies. Here we show how a biopolymer, DNA, can be used as a scaffold for the assembly of extended, close-packed, ligand-stabilized metal nanoparticle structures, including several desirable architectures (such as lines, ribbons, and branches). Electrostatic binding of ligand-stabilized nanoparticles to the DNA backbone results in extended linear chain-like structures, ribbon-like structures composed of parallel nanoparticle chains, and branched structures. High-resolution transmission electron microscopy shows that the particles are evenly spaced, separated only by the 15 A imposed by the intervening ligand shell. These studies demonstrate that biomolecular nanolithography (the arrangement of nanoscale building blocks on biomolecular scaffolds) is a viable approach to interconnecting individual devices into extended, closely spaced assemblies.
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Affiliation(s)
- Marvin G Warner
- Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, Oregon 97403, USA
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Stuhr-Hansen N, Christensen JB, Harrit N, Bjørnholm T. Novel synthesis of protected thiol end-capped stilbenes and oligo(phenylenevinylene)s (OPVs). J Org Chem 2003; 68:1275-82. [PMID: 12585865 DOI: 10.1021/jo0263770] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The first general procedures for preparation of thiol end-capped stilbenes and oligo(phenylenevinylene)s (OPVs) with tert-butyl- and acetyl-protected thiol termini have been developed. These reactions proceed via Br/Li exchange, McMurry, and Wittig-type reactions. The thiol functionality is protected against strong basic and acidic reaction conditions as a t-Bu sulfide. As a key point in the method, reprotection of the thiol group is accomplished by means of acetyl chloride and boron tribromide. The novel strategy forms the basis for stepwise introduction of 4-mercaptostyryl units in OPVs. The new mono-, di-, and trimercapto OPVs have potential applications as one, two, and three terminal molecular devices in gold nanoparticle clusters, self-assembled monolayers, and optoelectronic devices.
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Affiliation(s)
- Nicolai Stuhr-Hansen
- Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
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Zhou CZ, Liu T, Xu JM, Chen ZK. Synthesis, Characterization, and Physical Properties of Monodisperse Oligo(p-phenyleneethynylene)s. Macromolecules 2003. [DOI: 10.1021/ma021656a] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chuan-Zhen Zhou
- Institute of Materials Research and Engineering (IMRE), 3 Research Link, Singapore 117602, Republic of Singapore
| | - Tianxi Liu
- Institute of Materials Research and Engineering (IMRE), 3 Research Link, Singapore 117602, Republic of Singapore
| | - Jing-Mei Xu
- Institute of Materials Research and Engineering (IMRE), 3 Research Link, Singapore 117602, Republic of Singapore
| | - Zhi-Kuan Chen
- Institute of Materials Research and Engineering (IMRE), 3 Research Link, Singapore 117602, Republic of Singapore
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De Nicola A, Ringenbach C, Ziessel R. Stepwise construction of novel zig-zag shaped thiophene-based back-to-back terpyridine ligands with acetylenic tethers. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(02)02386-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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39
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Fan FRF, Yang J, Cai L, Price DW, Dirk SM, Kosynkin DV, Yao Y, Rawlett AM, Tour JM, Bard AJ. Charge transport through self-assembled monolayers of compounds of interest in molecular electronics. J Am Chem Soc 2002; 124:5550-60. [PMID: 11996598 DOI: 10.1021/ja017706t] [Citation(s) in RCA: 296] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The electrical properties of self-assembled monolayers (SAMs) on metal surfaces have been explored for a series of molecules to address the relation between the behavior of a molecule and its structure. We probed interfacial electron transfer processes, particularly those involving unoccupied states, of SAMs of thiolates or arylates on Au by using shear force-based scanning probe microscopy (SPM) combined with current-voltage (i-V) and current-distance (i-d) measurements. The i-V curves of hexadecanethiol in the low bias regime were symmetric around 0 V and the current increased exponentially with V at high bias voltage. Different than hexadecanethiol, reversible peak-shaped i-V characteristics were obtained for most of the nitro-based oligo(phenylene ethynylene) SAMs studied here, indicating that part of the conduction mechanism of these junctions involved resonance tunneling. These reversible peaked i-V curves, often described as a negative differential resistance (NDR) effect of the junction, can be used to define a threshold tip bias, V(TH), for resonant conduction. We also found that for all of the SAMs studied here, the current decreased with increasing distance, d, between tip and substrate. The attenuation factor beta of hexadecanethiol was high, ranging from 1.3 to 1.4 A(-1), and was nearly independent of the tip bias. The beta-values for nitro-based molecules were low and depended strongly on the tip bias, ranging from 0.15 A(-1) for tetranitro oligo(phenylene ethynylene) thiol, VII, to 0.50 A(-1) for dinitro oligo(phenylene) thiol, VI, at a -3.0 V tip bias. Both the V(TH) and beta values of these nitro-based SAMs were also strongly dependent on the structures of the molecules, e.g. the number of electroactive substituent groups on the central benzene, the molecular wire backbone, the anchoring linkage, and the headgroup. We also observed charge storage on nitro-based molecules. For a SAM of the dintro compound, V, approximately 25% of charge collected in the negative scan is stored in the molecules and can be collected at positive voltages. A possible mechanism involving lateral electron hopping is proposed to explain this phenomenon.
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Affiliation(s)
- Fu-Ren F Fan
- Department of Chemistry and Biochemistry and Center for Nano-and Molecular Science and Technology, The University of Texas at Austin, 78712, USA
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Cornil J, Karzazi Y, Brédas JL. Negative differential resistance in phenylene ethynylene oligomers. J Am Chem Soc 2002; 124:3516-7. [PMID: 11929235 DOI: 10.1021/ja017475q] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The origin of the sharp peak profile (i.e., negative differential resistance, NDR) observed in the I/V curves of three-ring phenylene ethynylene oligomers is a topic of major current interest. Here, quantum-chemical calculations are performed to analyze the evolution of the one-electron structure of an unsubstituted three-ring oligomer under the influence of a static electric field (which models the driving voltage applied in the experiments). The results indicate that the rotation of the central ring of the oligomer induces resonant tunneling processes over a limited voltage range. This can thus be responsible for the NDR signature observed experimentally.
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Affiliation(s)
- J Cornil
- Laboratory for Chemistry of Novel Materials, Center for Research on Molecular Electronics and Photonics, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium
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