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Nanofabrication Techniques in Large-Area Molecular Electronic Devices. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10176064] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The societal impact of the electronics industry is enormous—not to mention how this industry impinges on the global economy. The foreseen limits of the current technology—technical, economic, and sustainability issues—open the door to the search for successor technologies. In this context, molecular electronics has emerged as a promising candidate that, at least in the short-term, will not likely replace our silicon-based electronics, but improve its performance through a nascent hybrid technology. Such technology will take advantage of both the small dimensions of the molecules and new functionalities resulting from the quantum effects that govern the properties at the molecular scale. An optimization of interface engineering and integration of molecules to form densely integrated individually addressable arrays of molecules are two crucial aspects in the molecular electronics field. These challenges should be met to establish the bridge between organic functional materials and hard electronics required for the incorporation of such hybrid technology in the market. In this review, the most advanced methods for fabricating large-area molecular electronic devices are presented, highlighting their advantages and limitations. Special emphasis is focused on bottom-up methodologies for the fabrication of well-ordered and tightly-packed monolayers onto the bottom electrode, followed by a description of the top-contact deposition methods so far used.
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2
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Yang WC, Busson B, Hore DK. Determining nonlinear optical coefficients of metals by multiple angle of incidence heterodyne-detected sum-frequency generation spectroscopy. J Chem Phys 2020; 152:084708. [DOI: 10.1063/1.5133673] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Wei-Chen Yang
- Department of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6, Canada
| | - Bertrand Busson
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
| | - Dennis K. Hore
- Department of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6, Canada
- Department of Computer Science, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
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3
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Herrer L, González-Orive A, Marqués-González S, Martín S, Nichols RJ, Serrano JL, Low PJ, Cea P. Electrically transmissive alkyne-anchored monolayers on gold. NANOSCALE 2019; 11:7976-7985. [PMID: 30968913 DOI: 10.1039/c8nr10464f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Well-ordered, tightly-packed (surface coverage 0.97 × 10-9 mol cm-2) monolayer films of 1,4-bis((4-ethynylphenyl)ethynyl)benzene (1) on gold are prepared via a simple self-assembly process, taking advantage of the ready formation of alkynyl C-Au σ-bonds. Electrochemical measurements using [Ru(NH3)6]3+, [Fe(CN)6]3-, and ferrocenylmethanol [Fe(η5-C5H4CH2OH)(η5-C5H5)] redox probes indicate that the alkynyl C-Au contacted monolayer of 1 presents a relatively low barrier for electron transfer. This contrasts with monolayer films on gold of other oligo(phenylene ethynylene) derivatives of comparable length and surface coverage, but with different contacting groups. Additionally, a low voltage transition (Vtrans = 0.51 V) from direct tunneling (rectangular barrier) to field emission (triangular barrier) is observed. This low transition voltage points to a low tunneling barrier, which is consistent with the facile electron transport observed through the C-Au contacted self-assembled monolayer of 1.
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Affiliation(s)
- Lucía Herrer
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain.
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4
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Herrer IL, Ismael AK, Milán DC, Vezzoli A, Martín S, González-Orive A, Grace I, Lambert C, Serrano JL, Nichols RJ, Cea P. Unconventional Single-Molecule Conductance Behavior for a New Heterocyclic Anchoring Group: Pyrazolyl. J Phys Chem Lett 2018; 9:5364-5372. [PMID: 30160491 DOI: 10.1021/acs.jpclett.8b02051] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Electrical conductance across a molecular junction is strongly determined by the anchoring group of the molecule. Here we highlight the unusual behavior of 1,4-bis(1H-pyrazol-4-ylethynyl)benzene that exhibits unconventional junction current versus junction-stretching distance curves, which are peak-shaped and feature two conducting states of 2.3 × 10-4 G0 and 3.4 × 10-4 G0. A combination of theory and experiments is used to understand the conductance of single-molecule junctions featuring this new anchoring group, i.e., pyrazolyl. These results demonstrate that the pyrazolyl moiety changes its protonation state and contact binding during junction evolution and that it also binds in either end-on or facial geometries with gold contacts. The pyrazolyl moiety holds general interest as a contacting group, because this linkage leads to a strong double anchoring of the molecule to the gold electrode, resulting in enhanced conductance values.
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Affiliation(s)
- I Lucia Herrer
- Departamento de Química Física, Facultad de Ciencias , Universidad de Zaragoza , 50009 Zaragoza , Spain
- Instituto de Nanociencia de Aragón (INA) and Laboratorio de Microscopias Avanzadas (LMA), edificio i+d Campus Río Ebro , Universidad de Zaragoza , C/Mariano Esquillor, s/n , 50018 Zaragoza , Spain
| | - Ali K Ismael
- Department of Physics , University of Lancaster , Lancaster LA1 4YB , United Kingdom
- Department of Physics, College of Education for Pure Science , Tikrit University , Tikrit , Iraq
| | - David C Milán
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , United Kingdom
| | - Andrea Vezzoli
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , United Kingdom
| | - Santiago Martín
- Departamento de Química Física, Facultad de Ciencias , Universidad de Zaragoza , 50009 Zaragoza , Spain
- Instituto de Ciencias de Materiales de Aragón (ICMA) , Universidad de Zaragoza-CSIC , 50009 Zaragoza , Spain
| | - Alejandro González-Orive
- Technical and Macromolecular Chemistry , University of Paderborn , Warburger Straße 100 , 33098 Paderborn , Germany
| | - Iain Grace
- Department of Physics , University of Lancaster , Lancaster LA1 4YB , United Kingdom
| | - Colin Lambert
- Department of Physics , University of Lancaster , Lancaster LA1 4YB , United Kingdom
| | - José L Serrano
- Departamento de Química Física, Facultad de Ciencias , Universidad de Zaragoza , 50009 Zaragoza , Spain
- Instituto de Nanociencia de Aragón (INA) and Laboratorio de Microscopias Avanzadas (LMA), edificio i+d Campus Río Ebro , Universidad de Zaragoza , C/Mariano Esquillor, s/n , 50018 Zaragoza , Spain
| | - Richard J Nichols
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , United Kingdom
| | - Pilar Cea
- Departamento de Química Física, Facultad de Ciencias , Universidad de Zaragoza , 50009 Zaragoza , Spain
- Instituto de Nanociencia de Aragón (INA) and Laboratorio de Microscopias Avanzadas (LMA), edificio i+d Campus Río Ebro , Universidad de Zaragoza , C/Mariano Esquillor, s/n , 50018 Zaragoza , Spain
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5
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Lassoued K, Seydou M, Raouafi F, Larbi F, Lang P, Diawara B. DFT study of the adsorption and dissociation of 5-hydroxy-3-butanedithiol-1,4-naphthaquinone (Jug-C4-thiol) on Au(111) surface. ADSORPTION 2018. [DOI: 10.1007/s10450-018-9932-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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6
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Zhang S, Geng Y, Fan Y, Duan W, Deng K, Zhao D, Zeng Q. Two-dimensional (2D) self-assembly of oligo(phenylene-ethynylene) molecules and their triangular platinum(ii) diimine complexes studied using STM. Phys Chem Chem Phys 2017; 19:31284-31289. [DOI: 10.1039/c7cp06154d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The self-assembly of a series of cyclic oligo(phenylene-ethynylene) (OPE) molecules and their triangular Pt(ii) diimine complexes were studied using scanning tunneling microscope (STM).
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Affiliation(s)
- Siqi Zhang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology
- CAS Center for Excellence in Nanoscience
- National Center for Nanoscience and Technology (NCNST)
- Beijing 100190
- P. R. China
| | - Yanfang Geng
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology
- CAS Center for Excellence in Nanoscience
- National Center for Nanoscience and Technology (NCNST)
- Beijing 100190
- P. R. China
| | - Yuanpeng Fan
- Beijing National Laboratory for Molecular Sciences
- Center for Soft Matter Science and Engineering
- Key Lab of Polymer Chemistry & Physics of the Ministry of Education
- College of Chemistry
- Peking University
| | - Wubiao Duan
- Department of Chemistry
- School of Science
- Beijing Jiaotong University
- Beijing
- P. R. China
| | - Ke Deng
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology
- CAS Center for Excellence in Nanoscience
- National Center for Nanoscience and Technology (NCNST)
- Beijing 100190
- P. R. China
| | - Dahui Zhao
- Beijing National Laboratory for Molecular Sciences
- Center for Soft Matter Science and Engineering
- Key Lab of Polymer Chemistry & Physics of the Ministry of Education
- College of Chemistry
- Peking University
| | - Qingdao Zeng
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology
- CAS Center for Excellence in Nanoscience
- National Center for Nanoscience and Technology (NCNST)
- Beijing 100190
- P. R. China
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7
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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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8
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Osorio HM, Martín S, López MC, Marqués-González S, Higgins SJ, Nichols RJ, Low PJ, Cea P. Electrical characterization of single molecule and Langmuir-Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1145-57. [PMID: 26171291 PMCID: PMC4464395 DOI: 10.3762/bjnano.6.116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/13/2015] [Indexed: 05/27/2023]
Abstract
Monolayer Langmuir-Blodgett (LB) films of 1,4-bis(pyridin-4-ylethynyl)benzene (1) together with the "STM touch-to-contact" method have been used to study the nature of metal-monolayer-metal junctions in which the pyridyl group provides the contact at both molecule-surface interfaces. Surface pressure vs area per molecule isotherms and Brewster angle microscopy images indicate that 1 forms true monolayers at the air-water interface. LB films of 1 were fabricated by deposition of the Langmuir films onto solid supports resulting in monolayers with surface coverage of 0.98 × 10(-9) mol·cm(-2). The morphology of the LB films that incorporate compound 1 was studied using atomic force microscopy (AFM). AFM images indicate the formation of homogeneous, monomolecular films at a surface pressure of transference of 16 mN·m(-1). The UV-vis spectra of the Langmuir and LB films reveal that 1 forms two dimensional J-aggregates. Scanning tunneling microscopy (STM), in particular the "STM touch-to-contact" method, was used to determine the electrical properties of LB films of 1. From these STM studies symmetrical I-V curves were obtained. A junction conductance of 5.17 × 10(-5) G 0 results from the analysis of the pseudolinear (ohmic) region of the I-V curves. This value is higher than that of the conductance values of LB films of phenylene-ethynylene derivatives contacted by amines, thiols, carboxylate, trimethylsilylethynyl or acetylide groups. In addition, the single molecule I-V curve of 1 determined using the I(s) method is in good agreement with the I-V curve obtained for the LB film, and both curves fit well with the Simmons model. Together, these results not only indicate that the mechanism of transport through these metal-molecule-metal junctions is non-resonant tunneling, but that lateral interactions between molecules within the LB film do not strongly influence the molecule conductance. The results presented here complement earlier studies of single molecule conductance of 1 using STM-BJ methods, and support the growing evidence that the pyridyl group is an efficient and effective anchoring group in sandwiched metal-monolayer-metal junctions prepared under a number of different conditions.
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Affiliation(s)
- Henrry Marcelo Osorio
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto de Nanociencia de Aragón (INA), Edificio I+D, Campus Rio Ebro, Universidad de Zaragoza, C/Mariano Esquillor s/n, 50017 Zaragoza, Spain
- Laboratorio de Microscopias Avanzadas (LMA) C/Mariano Esquilor s/n, Campus Rio Ebro, 50018 Zaragoza, Spain
| | - Santiago Martín
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - María Carmen López
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto de Nanociencia de Aragón (INA), Edificio I+D, Campus Rio Ebro, Universidad de Zaragoza, C/Mariano Esquillor s/n, 50017 Zaragoza, Spain
| | | | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Paul J Low
- Department of Chemistry, University of Durham, Durham DH1 3LE, United Kingdom
- School of Chemistry and Biochemistry, University of Western Australia, Crawley 6009, WA, Australia
| | - Pilar Cea
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto de Nanociencia de Aragón (INA), Edificio I+D, Campus Rio Ebro, Universidad de Zaragoza, C/Mariano Esquillor s/n, 50017 Zaragoza, Spain
- Laboratorio de Microscopias Avanzadas (LMA) C/Mariano Esquilor s/n, Campus Rio Ebro, 50018 Zaragoza, Spain
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9
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Roy S, Covert PA, FitzGerald WR, Hore DK. Biomolecular Structure at Solid–Liquid Interfaces As Revealed by Nonlinear Optical Spectroscopy. Chem Rev 2014; 114:8388-415. [DOI: 10.1021/cr400418b] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Sandra Roy
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
| | - Paul A. Covert
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
| | - William R. FitzGerald
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
| | - Dennis K. Hore
- Department
of Chemistry, University of Victoria, Victoria, British Columbia, V8W 3V6 Canada
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10
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Oda H, Onda K, Nakagawa M. Photochemical Grafting Reactions of a Benzophenone-Containing Alkanethiol Monolayer on Au with Deuterated Polystyrene. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2013. [DOI: 10.1246/bcsj.20130137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Hirokazu Oda
- Polymer·Hybrid Materials Research Center, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University
| | - Ken Onda
- Interactive Research Center of Science, Tokyo Institute of Technology
- JST-PRESTO
| | - Masaru Nakagawa
- Polymer·Hybrid Materials Research Center, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University
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11
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Affiliation(s)
- Bala Krishna Pathem
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
| | - Shelley A. Claridge
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
| | - Yue Bing Zheng
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
| | - Paul S. Weiss
- California NanoSystems Institute,
- Department of Chemistry and Biochemistry, and
- Department of Materials Science and Engineering, University of California, Los Angeles, California 90095;
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12
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Ballesteros LM, Martín S, Cortés J, Marqués-González S, Higgins SJ, Nichols RJ, Low PJ, Cea P. Controlling the Structural and Electrical Properties of Diacid Oligo(Phenylene Ethynylene) Langmuir-Blodgett Films. Chemistry 2013; 19:5352-63. [DOI: 10.1002/chem.201203261] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 12/23/2012] [Indexed: 11/10/2022]
Affiliation(s)
- Luz Marina Ballesteros
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza 50009, Spain
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13
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Canepa M, Maidecchi G, Toccafondi C, Cavalleri O, Prato M, Chaudhari V, Esaulov VA. Spectroscopic ellipsometry of self assembled monolayers: interface effects. The case of phenyl selenide SAMs on gold. Phys Chem Chem Phys 2013; 15:11559-65. [DOI: 10.1039/c3cp51304a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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14
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Humbert C, Pluchery O, Lacaze E, Tadjeddine A, Busson B. A multiscale description of molecular adsorption on gold nanoparticles by nonlinear optical spectroscopy. Phys Chem Chem Phys 2011; 14:280-9. [PMID: 22083521 DOI: 10.1039/c1cp21091b] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Nonlinear optical Sum and Difference-Frequency spectroscopies are used to probe and model the surface of thiophenol-functionalised gold nanoparticles grafted on a Si(100) substrate through two different silanization procedures. By scanning the [980-1100 cm(-1)] infrared spectral range with the CLIO Free Electron Laser, ring deformation vibrations of adsorbed thiophenol are investigated. Quantitative data analysis addresses three levels of organization: microscopic, nanoscopic and molecular. Grafting with p-aminophenyl-trimethoxysilane shows an increase of around 40% in surface density of nanoparticles (N(s)) as compared to 3-aminopropyl-triethoxysilane. The relative amplitudes of the resonant and nonresonant contributions to the SFG and DFG spectra are discussed in terms of N(s), Fresnel reflectivity factors and local amplification of the nonlinear signals by coupling to the surface plasmon of the particles. They are shown to quantitatively scale with N(s), as measured by atomic force microscopy. Vibration mode assignment is performed through a critical analysis of literature data on IR and Raman spectroscopies coupled to DFT calculations, for which a methodology specific to molecules adsorbed on gold atoms is discussed.
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Affiliation(s)
- C Humbert
- Univ Paris-Sud, Laboratoire de Chimie Physique, CNRS, Bâtiment 201 Porte 2, 91405 Orsay, France.
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15
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Jena KC, Hung KK, Schwantje TR, Hore DK. Methyl groups at dielectric and metal surfaces studied by sum-frequency generation in co- and counter-propagating configurations. J Chem Phys 2011; 135:044704. [DOI: 10.1063/1.3614498] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Nakayama H, Kimura S. Suppression of HOMO–LUMO Transition in a Twist Form of Oligo(phenyleneethynylene) Clamped by a Right-Handed Helical Peptide. J Phys Chem A 2011; 115:8960-8. [DOI: 10.1021/jp200997c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hidenori Nakayama
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Shunsaku Kimura
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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17
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Bisio F, Prato M, Barborini E, Canepa M. Interaction of alkanethiols with nanoporous cluster-assembled Au films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:8371-8376. [PMID: 21627142 DOI: 10.1021/la200425z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This article presents a study of the interaction of octadecanethiol molecules (C(18)) with nanoporous cluster-assembled gold films under a liquid environment based on a combined spectroscopic ellipsometry and X-ray photoelectron spectroscopy investigation. By comparing the optical response, following the deposition of C(18), of cluster-assembled films with varying degrees of porosity with that of flat surfaces and by resolving the corresponding features of the molecule-Au bond, we have been able to define the conditions that either favor molecular in-depth diffusion into the pores or promote the formation of a molecular self-assembled monolayer (SAM) restricted to the film surface. In the presence of abundant open pores, C(18) molecules strongly diffuse within the film interior and bind to the pore walls, whereas in the presence of porous films with less abundant open pores we have observed that the molecules tend to remain confined to the surface region, adopting a SAM-like configuration.
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Affiliation(s)
- F Bisio
- CNR-SPIN, C. so Perrone 24, I-16152 Genova, Italy.
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18
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Moore AM, Yeganeh S, Yao Y, Claridge SA, Tour JM, Ratner MA, Weiss PS. Polarizabilities of adsorbed and assembled molecules: measuring the conductance through buried contacts. ACS NANO 2010; 4:7630-6. [PMID: 21077677 PMCID: PMC3010874 DOI: 10.1021/nn102371z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2010] [Accepted: 11/03/2010] [Indexed: 05/22/2023]
Abstract
We have measured the polarizabilities of four families of molecules adsorbed to Au{111} surfaces, with structures ranging from fully saturated to fully conjugated, including single-molecule switches. Measured polarizabilities increase with increasing length and conjugation in the adsorbed molecules and are consistent with theoretical calculations. For single-molecule switches, the polarizability reflects the difference in substrate-molecule electronic coupling in the ON and OFF conductance states. Calculations suggest that the switch between the two conductance states is correlated with an oxidation state change in a nitro functional group in the switch molecules.
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Affiliation(s)
- Amanda M. Moore
- Departments of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sina Yeganeh
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Yuxing Yao
- Department of Chemistry and Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, United States
| | - Shelley A. Claridge
- California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - James M. Tour
- Department of Chemistry and Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, United States
- Address correspondence to , ,
| | - Mark A. Ratner
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
- Address correspondence to , ,
| | - Paul S. Weiss
- Departments of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
- Address correspondence to , ,
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19
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Yoon HP, Maitani MM, Cabarcos OM, Cai L, Mayer TS, Allara DL. Crossed-nanowire molecular junctions: a new multispectroscopy platform for conduction--structure correlations. NANO LETTERS 2010; 10:2897-2902. [PMID: 20698602 DOI: 10.1021/nl100982q] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report a crossed-nanowire molecular junction array platform that enables direct measurement of current-voltage-temperature characteristics simultaneously with inelastic electron tunneling and Raman vibrational spectra on the same junction. Measurements on dithiol-terminated oligo(phenylene-ethynylene) junctions show both spectroscopies interrogate the gap-confined molecules to reveal distinct molecular features. This versatile platform allows investigation of advanced phenomena such as molecular switching and cooperative effects with the flexible ability to scale both the junction geometries and array sizes.
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Affiliation(s)
- Heayoung P Yoon
- Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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20
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Hamoudi H, Prato M, Dablemont C, Cavalleri O, Canepa M, Esaulov VA. Self-assembly of 1,4-benzenedimethanethiol self-assembled monolayers on gold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:7242-7247. [PMID: 20199099 DOI: 10.1021/la904317b] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A study of the self-assembly of 1,4-benzenedimethanethiol (BDMT; HS-CH(2)-(C(6)H(4))-CH(2)-SH) monolayers on gold is presented. Self-assembled monolayers (SAMs) are characterized by reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE) measurements. The ensemble of measurements consistently shows that well-organized BDMT SAMs, with "standing-up" molecules, can be obtained on high quality gold films with incubation in n-hexane provided that N(2)-degassed solutions are used and all preparation steps are performed at 60 degrees C in the absence of ambient light. SE data indicate that the optical interface properties of the BDMT-Au system are different from those of simple alkanethiol SAMs. A possible mechanism for the formation of the "standing-up" phase from the lying-down phase via a hydrogen exchange reaction involving chemisorbed lying-down and free dithiol molecules is discussed.
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21
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Selective detection of the antigenic polar heads of model lipid membranes supported on metals from their vibrational nonlinear optical response. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.02.061] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Chen X, Yeganeh S, Qin L, Li S, Xue C, Braunschweig AB, Schatz GC, Ratner MA, Mirkin CA. Chemical fabrication of heterometallic nanogaps for molecular transport junctions. NANO LETTERS 2009; 9:3974-9. [PMID: 19908887 PMCID: PMC3241532 DOI: 10.1021/nl9018726] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We report a simple and reproducible method for fabricating heterometallic nanogaps, which are made of two different metal nanorods separated by a nanometer-sized gap. The method is based upon on-wire lithography, which is a chemically enabled technique used to synthesize a wide variety of nanowire-based structures (e.g., nanogaps and disk arrays). This method can be used to fabricate pairs of metallic electrodes, which exhibit distinct work functions and are separated by gaps as small as 2 nm. Furthermore, we demonstrate that a symmetric thiol-terminated molecule can be assembled into such heterometallic nanogaps to form molecular transport junctions (MTJs) that exhibit molecular diode behavior. Theoretical calculations demonstrate that the coupling strength between gold and sulfur (Au-S) is 2.5 times stronger than that of Pt-S. In addition, the structures form Raman hot spots in the gap, allowing the spectroscopic characterization of the molecules that make up the MTJs.
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Affiliation(s)
- Xiaodong Chen
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798
| | - Sina Yeganeh
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
| | - Lidong Qin
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
| | - Shuzhou Li
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
| | - Can Xue
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798
| | - Adam B. Braunschweig
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
| | - George C. Schatz
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
- Corresponding authors (CAM) (MAR) (GCS)
| | - Mark A. Ratner
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
- Corresponding authors (CAM) (MAR) (GCS)
| | - Chad A. Mirkin
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
- Corresponding authors (CAM) (MAR) (GCS)
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23
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Malicki M, Guan Z, Ha SD, Heimel G, Barlow S, Rumi M, Kahn A, Marder SR. Preparation and characterization of 4'-donor substituted stilbene-4-thiolate monolayers and their influence on the work function of gold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:7967-7975. [PMID: 19419192 DOI: 10.1021/la9004104] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Self-assembled monolayers of E-stilbene-4-thiolate (SAM1), E-4'-(ethoxy)stilbene-4-thiolate (SAM2), and E-4'-(dimethylamino)stilbene-4-thiolate (SAM3) on Au(111) have been obtained from reaction of ethanol solutions of the corresponding S-acetyl derivatives with gold substrates. A combination of X-ray photoelectron spectroscopy, ellipsometry, and infrared reflection absorption spectroscopy indicates that the monolayers are dense (ca. 3.3 x 10(14) molecules/cm(2)) and that the long molecular axes of the thiolates are approximately perpendicular to the surface. Ultraviolet photoelectron spectroscopy shows that formation of these monolayers decreases the work function of pristine Au by 0.9-1.3 eV, in part due to a bond dipole of ca. 4.4 D/molecule formed upon adsorption and partly due to the molecular dipole moment arising from the 4'-pi-donor substituents. However, the extent of the work function variation between SAM1, 2, and 3 is smaller than anticipated from purely electrostatic considerations.
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Affiliation(s)
- Michał Malicki
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
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24
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Bertin PA, Georganopoulou D, Liang T, Eckermann AL, Wunder M, Ahrens MJ, Blackburn GF, Meade TJ. Electroactive self-assembled monolayers on gold via bipodal dithiazepane anchoring groups. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:9096-9101. [PMID: 18627193 DOI: 10.1021/la801165b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Novel dithiazepane-functionalized ferrocenyl-phenylethynyl oligomers 1 and 2 have been synthesized. Self-assembled monolayers (SAMs) of these ferrocene derivatives have been studied by X-ray photoelectron spectroscopy, ellipsometry, and cyclic voltammetry. It has been shown by XPS that monolayers of the dithiazepane-anchored molecules on gold electrodes contain gold-thiolate species. Cyclic voltammetry of the SAMs were characteristic of stable electroactive monolayers even for single-component SAMs of 1 and 2, with the more ideal responses recorded for the two-component SAMs diluted with undecanethiol. The small variation in peak splittings at progressively higher scan rates in these SAMs makes dithiazepane-bridged redox species promising candidates for further studies on molecular wires with bipodal anchoring.
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25
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Villares A, Martín S, Giner I, Díaz J, Lydon DP, Low PJ, Cea P. The use of scanning polarization force microscopy to study the miscibility of a molecular wire candidate and an insulating fatty acid in mixed films. SOFT MATTER 2008; 4:1508-1514. [PMID: 32907118 DOI: 10.1039/b716798a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Mixed films containing a conjugated "molecular wire" candidate and an "insulating" fatty acid have been prepared by the Langmuir-Blodgett technique. Specifically, this paper reports the fabrication of mixed films as well as miscibility studies of 4-[4-(4-hexyloxyphenylethynyl)phenylethynyl]benzoic acid (HBPEB) and docosanoic (or behenic) acid (BA). Surface pressure vs. area per molecule isotherms were recorded, with excess area and excess Gibbs energy of mixing calculated. Surface potential-area per molecule isotherms were also recorded for mixtures over the whole range of mole fractions, with negative deviations from the additivity rule revealing orientational changes induced in the HBPEB molecules. The Langmuir films were transferred onto solid supports and characterized by SPM techniques, with atomic force microscopy (AFM) revealing that well-ordered, defect-free films are obtained. The use of scanning polarization force microscopy (SPFM), which provides non-contact imaging based on differences in surface charge distribution, i.e., surface potential, provides complimentary information regarding distribution of the components within the mixed films. From the comprehensive miscibility study performed, which includes thermodynamic and imaging methods, it can be concluded that the wire-like molecule and the fatty acid are miscible over the 0-0.1 and 0.8-1 ranges of HBPEB mole fraction while phase separation occurs for HBPEB mole fractions over the 0.1-0.8 range.
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Affiliation(s)
- Ana Villares
- Department of Organic and Physical Chemistry, University of Zaragoza, 50009 Zaragoza, Spain.
| | - Santiago Martín
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, UKL69 7ZD
| | - Ignacio Giner
- Department of Organic and Physical Chemistry, University of Zaragoza, 50009 Zaragoza, Spain.
| | - Jordi Díaz
- Laboratory of Electrochemistry and Materials (LCTEM), Department of Physical Chemistry, University of Barcelona, Martí I Franquès 1 and Scientific-technical Services (Nanometric Techniques) of the University of Barcelona, Solé I Sabaris, 1, 08028 Barcelona, Spain
| | - Donocadh P Lydon
- Department of Chemistry, University of Durham, Durham, UKDH1 3LE
| | - Paul J Low
- Department of Chemistry, University of Durham, Durham, UKDH1 3LE
| | - Pilar Cea
- Department of Organic and Physical Chemistry, University of Zaragoza, 50009 Zaragoza, Spain. and Institute of Nanoscience of Aragón (INA), 50009 Zaragoza, Spain
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26
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Wang J, Lee SH, Chen Z. Quantifying the Ordering of Adsorbed Proteins In Situ. J Phys Chem B 2008; 112:2281-90. [DOI: 10.1021/jp077556u] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jie Wang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Sang-Ho Lee
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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27
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Watkins N, Zangmeister C, Chan C, Zhao W, Ciszek J, Tour J, Kahn A, van Zee R. Electron spectra of a self-assembled monolayer on gold: Inverse photoemission and two-photon photoemission spectroscopy. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.08.070] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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28
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Tour JM. Transition to Organic Materials Science. Passive, Active, and Hybrid Nanotechnologies. J Org Chem 2007; 72:7477-96. [PMID: 17628105 DOI: 10.1021/jo070543s] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article covers the author's transition from small molecule organic synthesis into polymeric materials and nanotechnology which led to receipt of the Arthur C. Cope Scholar Award in 2007. This includes his start in organometallic reaction development, synthesis of precisely controlled oligomers, conjugated polymers, planar conjugated polymers, and his work on fullerenes. Also mentioned are the people of influence in his life during that formative period. The meaning of nanotechnology is explained in light of bottom-up vs top-down construction and then more specifically related to the passive, active, and hybrid sides of nanotechnology research. These three areas are explained using examples from the author's laboratory: from the passive side, functionalization of carbon nanotubes and their use in composites; from the active side, molecular electronics and nanocars; and finally, the hybrid side, complementing silicon with molecules.
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Affiliation(s)
- James M Tour
- Department of Chemistry, The R. E. Smalley Institute for Nanoscale Science and Technology, Rice University, MS 222, 6100 Main Street, Houston, Texas 77005, USA.
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29
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Villares A, Lydon DP, Porrès L, Beeby A, Low PJ, Cea P, Royo FM. Preparation of Ordered Films Containing a Phenylene Ethynylene Oligomer by the Langmuir−Blodgett Technique. J Phys Chem B 2007; 111:7201-9. [PMID: 17552562 DOI: 10.1021/jp072052h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper reports the fabrication and characterization of Langmuir and Langmuir-Blodgett (LB) films incorporating an oligo(phenylene-ethynylene) (OPE) derivative, namely, 4-[4-(4-hexyloxyphenylethynyl)-phenylethynyl]-benzoic acid (HBPEB). Conditions appropriate for deposition of monolayers of HBPEB at the air-water interface have been established and the resulting Langmuir films characterized by a combination of surface pressure and surface potential versus area per molecule isotherms, Brewster angle microscopy, and ultraviolet reflection spectroscopy. The Langmuir films are readily transferred onto solid substrates, and one-layer LB films transferred at several surface pressures onto mica substrates have been analyzed by means of atomic force microscopy, from which it can be concluded that 14 mN/m is an optimum surface pressure of transference, giving well-ordered homogeneous films without three-dimensional defects and a low surface roughness. The optical and emissive properties of the LB films have been determined with significant blue-shifted absorption spectra indicating formation of two-dimensional H aggregates and a Stokes shift illustrating the effects of the solid-like environment on the molecular chromophore.
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Affiliation(s)
- Ana Villares
- Departamento de Química OrgAnica-Química Física, Area de Química Física, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain
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30
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Newton MD, Smalley JF. Interfacial bridge-mediated electron transfer: mechanistic analysis based on electrochemical kinetics and theoretical modelling. Phys Chem Chem Phys 2007; 9:555-72. [PMID: 17242737 DOI: 10.1039/b611448b] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Understanding the physical and chemical factors that control the kinetics of interfacial electron-transfer (ET) reactions is important for a large number of technological applications. The present article describes electrochemical kinetic studies of these factors, in which standard interfacial ET rate constants (k(0)(l)) have been measured for ET between substrate Au electrodes and various redox couples attached to the electrode surfaces by variable lengths (l) of oligomethylene (OM), oligophenylenevinylene (OPV) and oligophenyleneethynylene (OPE) bridges, which were constituents of mixed self-assembled monolayers (SAMs). The k(0)(l) measurements employed the indirect laser-induced temperature jump (ILIT) technique, which permits the measurement of interfacial ET rates that are orders of magnitude faster than those measurable by conventional techniques using the macroelectrodes that are the most convenient substrates for the mixed SAMs. The robustness of the measured rate constants (k(0)(l)), together with the Arrhenius activation energies (E(a)(l)) and preexponential factors (A(l)), is demonstrated by their invariance with respect to several experimental system parameters (including the chemical nature and length of the diluent component of the mixed SAM). Analysis of the kinetic results demonstrates that all of the observed interfacial ET processes proceed through a common type of transition state (predominantly associated with solvent reorganization around the redox moiety) and that the actual ET step involves direct electronic tunnelling between the Au electrode and the redox moiety. However, for the full range of l investigated, a global exponential decay of A(l) is not found for any of the three types of bridges. Possible reasons for this behavior, including the role of rate determining steps associated with adiabatic mechanisms within or beyond the transition state theory framework, are discussed, and comparisons with related conductance measurements are presented.
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Affiliation(s)
- Marshall D Newton
- Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973, USA.
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31
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Krapchetov DA, Ma H, Jen AKY, Fischer DA, Loo YL. High-sensitivity transmission IR spectroscopy for the chemical identification and structural analysis of conjugated molecules on gallium arsenide surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:9491-4. [PMID: 17073469 DOI: 10.1021/la0623984] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We demonstrate the use of high-sensitivity, off-normal transmission IR spectroscopy with s-polarized light to probe the chemical identity and orientation of quaterphenyldithiol (QPDT) molecular assemblies on GaAs as a function of ammonium hydroxide (NH4OH) concentration. NH4OH is added to the assembly solution to convert the thioacetyl groups on the QPDT precursor to thiolates. When assembled at high NH4OH concentrations, the acetyl groups are completely removed, and QPDT is disordered on GaAs. Assembly at low NH4OH concentrations, however, results in QPDT assemblies that are preferentially upright. The molecular orientation is further quantified with near-edge X-ray absorption fine structure spectroscopy.
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Affiliation(s)
- Dmitry A Krapchetov
- Chemical Engineering Department and Center for Nano- and Molecular Science and Technology, University of Texas at Austin, Austin, Texas 78712, USA
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32
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Long DP, Lazorcik JL, Mantooth BA, Moore MH, Ratner MA, Troisi A, Yao Y, Ciszek JW, Tour JM, Shashidhar R. Effects of hydration on molecular junction transport. NATURE MATERIALS 2006; 5:901-8. [PMID: 17041584 DOI: 10.1038/nmat1754] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Accepted: 09/01/2006] [Indexed: 05/09/2023]
Abstract
The study of charge transport through increasingly complex small molecules will benefit from a detailed understanding of how contaminants from the environment affect molecular conduction. This should provide a clearer picture of the electronic characteristics of molecules by eliminating interference from adsorbed species. Here we use magnetically assembled microsphere junctions incorporating thiol monolayers to provide insight into changing electron transport characteristics resulting from exposure to air. Using this technique, current-voltage analysis and inelastic electron tunnelling spectroscopy (IETS) demonstrate that the primary interaction affecting molecular conduction is rapid hydration at the gold-sulphur contacts. We use IETS to present evidence for changing mechanisms of charge transport as a result of this interaction. The detrimental effects on molecular conduction discussed here are important for understanding electron transport through gold-thiol molecular junctions once exposed to atmospheric conditions.
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Affiliation(s)
- David P Long
- Research and Development Center, Science Applications International Corporation (SAIC), 9460 Innovation Drive, Manassas, Virginia 20110, USA.
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33
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Lee SH, Wang J, Krimm S, Chen Z. Irreducible representation and projection operator application to understanding nonlinear optical phenomena: hyper-Raman, sum frequency generation, and four-wave mixing spectroscopy. J Phys Chem A 2006; 110:7035-44. [PMID: 16737251 DOI: 10.1021/jp057200n] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Symmetry plays an essential role in understanding optical activities of a molecule in infrared and Raman vibrational spectroscopy as well as in nonlinear optical vibrational spectroscopy. Each vibrational mode belongs to an irreducible representation of the underlying symmetry group. In this paper, using the alpha-helical polypeptide symmetry as an example, we calculate all the third rank nonzero hyper-Raman tensors as well as the infrared and Raman tensors by applying the projection operators to each irreducible species. We demonstrate that the projection operator method provides selection rules for the infrared, Raman, and hyper-Raman vibrational transitions and also other nonlinear optical spectroscopy such as sum frequency generation and the four-, five-, and six-wave mixing coherent vibrational transitions. Specific expressions for all nonzero elements of the corresponding nonlinear susceptibility tensors in a laboratory-fixed coordinate frame are also deduced.
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Affiliation(s)
- Sang-Ho Lee
- Department of Chemistry and Biophysics Research Division, The University of Michigan, Ann Arbor, 48109, USA
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Keszthelyi T, Paszti Z, Rigó T, Hakkel O, Telegdi J, Guczi L. Investigation of Solid Surfaces Modified by Langmuir−Blodgett Monolayers Using Sum-Frequency Vibrational Spectroscopy and X-ray Photoelectron Spectroscopy. J Phys Chem B 2006; 110:8701-14. [PMID: 16640426 DOI: 10.1021/jp057180p] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Langmuir-Blodgett (LB) monomolecular layers of alkylhydroxamic acids and alkylphosphonic acids on copper and iron substrates have been studied by X-ray photoelectron spectroscopy (XPS) and sum-frequency vibrational spectroscopy. According to the XPS results, the structures of the hydroxamic acid and phosphonic acid Langmuir-Blodgett films are very similar: the thickness of the layer of the hydrocarbon tails is typically 1.9-2.1 nm, while the layer of headgroups is about 0.3-0.35 nm thick. The tilt angle of the carbon chains is estimated to be 20-30 degrees with respect to the sample surface normal, and the molecules are connected to the substrate via their headgroups. Analysis of the P 2p and N 1s lines indicates the presence of deprotonated headgroups. The substrate Cu 2p line includes a component which can be assigned to Cu(2+) ions in a thin Cu(OH)(2) layer. The deposition of LB layers led to significant decrease of the hydroxide-related signal, which indicates that binding of the headgroups to the surface is accompanied by the elimination of water molecules. The sum-frequency spectra also clearly indicate that well-ordered monolayers can be formed by the Langmuir-Blodgett technique. Since the non-resonant background from the metal substrates renders the analysis of the spectra more difficult, model system samples on glass were prepared. It was found that the alkyl chains of the adsorbed acids predominantly adopt the all-trans conformation and form an ordered structure. Upper limits for the mean tilt angle of the terminal methyl groups are approximately 10-20 degrees.
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Affiliation(s)
- Tamas Keszthelyi
- Institute of Surface Chemistry and Catalysis, Chemical Research Centre, P.O. Box 17, H-1525 Budapest, Hungary.
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Stapleton JJ, Daniel TA, Uppili S, Cabarcos OM, Naciri J, Shashidhar R, Allara DL. Self-assembly, characterization, and chemical stability of isocyanide-bound molecular wire monolayers on gold and palladium surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:11061-70. [PMID: 16285772 DOI: 10.1021/la051094z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Self-assembled monolayers (SAMs) of the isocyano derivative of 4,4'-di(phenylene-ethynylene)benzene (1), a member of the "OPE" family of "molecular wires" of current interest in molecular electronics, have been prepared on smooth, {111} textured films of Au and Pd. For assembly in oxygen-free environments with freshly deposited metal surfaces, infrared reflection spectroscopy (IRS) indicates the molecules assume a tilted structure with average tilt angles of 18-24 degrees from the surface normal. The combination of IRS, X-ray photoelectron spectroscopy, and density functional theory calculations all support a single sigma-type bond of the -NC group to the Au surface and a sigma/pi-type of bond to the Pd surface. Both SAMs show significant chemical instability when exposed to typical ambient conditions. In the case of the Au SAM, even a few hours storage in air results in significant oxidation of the -NC moieties to -NCO (isocyanate) with an accompanying decrease in surface chemical bonding, as evidenced by a significant increase in instability toward dissolution in solvent. In the case of the Pd SAM, similar air exposure does not result in incorporation of oxygen or loss of solvent resistance but rather results in a chemically altered interface which is attributed to polymerization of the -NC moieties to quasi-2D poly(imine) structures. Conductance probe atomic force microscope measurements show the conductance of the degraded Pd SAMs can diminish by approximately 2 orders of magnitude, an indication that the SAM-Pd electrical contact has severely degraded. These results underscore the importance of careful control of the assembly procedures for aromatic isocyanide SAMs, particularly for applications in molecular electronics where the molecule-electrode junction is critical to the operational characteristics of the device.
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Affiliation(s)
- Joshua J Stapleton
- Department of Chemistry and The Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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36
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Wang J, Chen X, Clarke ML, Chen Z. Detection of chiral sum frequency generation vibrational spectra of proteins and peptides at interfaces in situ. Proc Natl Acad Sci U S A 2005; 102:4978-83. [PMID: 15793004 PMCID: PMC555967 DOI: 10.1073/pnas.0501206102] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Indexed: 11/18/2022] Open
Abstract
In this work, we demonstrate the feasibility to collect off-electronic resonance chiral sum frequency generation (SFG) vibrational spectra from interfacial proteins and peptides at the solid/liquid interface in situ. It is difficult to directly detect a chiral SFG vibrational spectrum from interfacial fibrinogen molecules. By adopting an interference enhancement method, such a chiral SFG vibrational spectrum can be deduced from interference spectra between the normal achiral spectrum and the chiral spectrum. We found that the chiral SFG vibrational spectrum of interfacial fibrinogen was mainly contributed by the beta-sheet structure. For a beta-sheet peptide tachyplesin I, which may be quite ordered at the solid/liquid interface, chiral SFG vibrational spectra can be collected directly. We believe that these chiral signals are mainly contributed by electric dipole contributions, which can dominate the chiroptical responses of uniaxial systems. For the first time, to our knowledge, this work indicates that the off-electronic resonance SFG technique is sensitive enough to collect chiral SFG vibrational spectra of interfacial proteins and peptides, providing more structural information to elucidate interfacial protein and peptide structures.
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Affiliation(s)
- Jie Wang
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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