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Li T, Bandari VK, Schmidt OG. Molecular Electronics: Creating and Bridging Molecular Junctions and Promoting Its Commercialization. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209088. [PMID: 36512432 DOI: 10.1002/adma.202209088] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 11/28/2022] [Indexed: 06/02/2023]
Abstract
Molecular electronics is driven by the dream of expanding Moore's law to the molecular level for next-generation electronics through incorporating individual or ensemble molecules into electronic circuits. For nearly 50 years, numerous efforts have been made to explore the intrinsic properties of molecules and develop diverse fascinating molecular electronic devices with the desired functionalities. The flourishing of molecular electronics is inseparable from the development of various elegant methodologies for creating nanogap electrodes and bridging the nanogap with molecules. This review first focuses on the techniques for making lateral and vertical nanogap electrodes by breaking, narrowing, and fixed modes, and highlights their capabilities, applications, merits, and shortcomings. After summarizing the approaches of growing single molecules or molecular layers on the electrodes, the methods of constructing a complete molecular circuit are comprehensively grouped into three categories: 1) directly bridging one-molecule-electrode component with another electrode, 2) physically bridging two-molecule-electrode components, and 3) chemically bridging two-molecule-electrode components. Finally, the current state of molecular circuit integration and commercialization is discussed and perspectives are provided, hoping to encourage the community to accelerate the realization of fully scalable molecular electronics for a new era of integrated microsystems and applications.
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Affiliation(s)
- Tianming Li
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
| | - Vineeth Kumar Bandari
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
| | - Oliver G Schmidt
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
- Nanophysics, Dresden University of Technology, 01069, Dresden, Germany
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2
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Azzam W, Subaihi A, Rohwerder M, Zharnikov M, Bashir A. Polymorphism and Building-Block-Resolved STM Imaging of Self-Assembled Monolayers of 4-Fluorobenzenemethanethiol on Au(111). Chemphyschem 2022; 23:e202200347. [PMID: 35856831 DOI: 10.1002/cphc.202200347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/17/2022] [Indexed: 11/06/2022]
Abstract
Self-assembled monolayers (SAMs) of 4-fluorobenzenemethanethiol (p-FBMT) on Au(111), prepared by immersion procedure (1 mM ethanolic solution; 60 °C; 18 h), were characterized by scanning tunneling microscopy (STM). The data suggest the formation of highly ordered monolayer with a commensurate structure, described by the 2 3 × 13 R 13 ∘ unit cell. The STM appearance of this cell occurs, however, in two different forms, with either well-localized individual spots or splitting of these spots in two components. These components are assigned to the tunneling through the entire molecule or sulfur docking group only. The respective spots correspond then to the terminal fluorine atom and sulfur docking group, manifesting, thus, building-block-resolving STM imaging. The accessibility of the docking group for direct tunneling is most likely related to a specific molecular organization for one of the two possible internal structures of the unit cell. The above results represent a showcase for potential of STM for imaging of upright-arranged and densely packed molecular assemblies, such as SAMs.
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Affiliation(s)
- Waleed Azzam
- Department of Chemistry, Tafila Technical University, P.O. Box 179, Tafila, 66110, Jordan.,Department of Chemistry, University College in Al-Qunfudah, Umm Al-Qura University, 1109, Makkah, Al-Mukarramah, Saudi Arabia
| | - Abdu Subaihi
- Department of Chemistry, University College in Al-Qunfudah, Umm Al-Qura University, 1109, Makkah, Al-Mukarramah, Saudi Arabia
| | - Michael Rohwerder
- Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, 40237, Düsseldorf, Germany
| | - Michael Zharnikov
- Applied Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 253, 69120, Heidelberg, Germany
| | - Asif Bashir
- Thyssenkrupp Bilstein GmbH, Herner Str. 299, 44809, Bochum, Germany
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3
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Ahmad SN, Zaharim WN, Sulaiman S, Hasan Baseri DF, Mohd Rosli NA, Ang LS, Yahaya NZ, Watanabe I. Density Functional Theory Studies of the Electronic Structure and Muon Hyperfine Interaction in [Au 25(SR) 18] 0 and [Au 25(SeR) 18] 0 Nanoclusters. ACS OMEGA 2020; 5:33253-33261. [PMID: 33403287 PMCID: PMC7774246 DOI: 10.1021/acsomega.0c04937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
Density functional theory computational investigation was performed to study the electronic structures, muon sites, and the associated hyperfine interactions in [Au25(SR)18]0 and [Au25(SeR)18]0 where R is phenylethane. The calculated electronic structures show inhomogeneous spin density distribution and are also affected by different ligands. The two most stable muon sites near Au atoms in the thiolated system are MAu11 and MAu6. When the thiolate ligands were replaced by selenolate ligands, the lowest energy positions of muons moved to MAu6 and MAu5. Muons prefer to stop inside the Au12 icosahedral shell, away from the central Au and the staple motifs region. Muonium states at phenyl ring and S/Se atoms in the ligand were found to be stable and the Fermi contact fields are much larger as compared to the field experienced by muons near Au atoms.
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Affiliation(s)
- Siti N. Ahmad
- Computational
Chemistry and Physics Laboratory, School of Distance Education, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia
| | - Wan N. Zaharim
- Computational
Chemistry and Physics Laboratory, School of Distance Education, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia
- USM-RIKEN
Interdisciplinary Collaboration for Advance Sciences, Universiti Sains Malaysia, Pulau
Pinang 11800, Malaysia
| | - Shukri Sulaiman
- Computational
Chemistry and Physics Laboratory, School of Distance Education, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia
- USM-RIKEN
Interdisciplinary Collaboration for Advance Sciences, Universiti Sains Malaysia, Pulau
Pinang 11800, Malaysia
- Physics
Section, School of Distance Education, Universiti
Sains Malaysia, Pulau Pinang 11800, Malaysia
| | - Dang F. Hasan Baseri
- Computational
Chemistry and Physics Laboratory, School of Distance Education, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia
| | - Nur A. Mohd Rosli
- Computational
Chemistry and Physics Laboratory, School of Distance Education, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia
| | - Lee S. Ang
- Faculty
of Applied Sciences, Universiti Teknologi
MARA, Perlis Branch,
Arau Campus, Arau, Perlis 02600, Malaysia
| | - Nor Z. Yahaya
- Physics
Section, School of Distance Education, Universiti
Sains Malaysia, Pulau Pinang 11800, Malaysia
| | - Isao Watanabe
- Meson
Science Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
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4
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Han M, Seong S, Han S, Lee N, Noh J. Molecular
Self‐Assembly
of Phenylselenyl Chloride on a Au(111) Surface. B KOREAN CHEM SOC 2020. [DOI: 10.1002/bkcs.12116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Myoung‐Soo Han
- Department of Convergence Nanoscience Hanyang University Seongdong‐gu, Seoul 04763 Korea
| | - Sicheon Seong
- Department of Chemistry Hanyang University Seongdong‐gu, Seoul 04763 Korea
| | - Seulki Han
- Department of Chemistry Hanyang University Seongdong‐gu, Seoul 04763 Korea
| | - Nam‐Suk Lee
- National Institute for Nanomaterials Technology Pohang University of Science and Technology Pohang 37673 Korea
| | - Jaegeun Noh
- Department of Chemistry Hanyang University Seongdong‐gu, Seoul 04763 Korea
- Institute of Nano Science and Technology Hanyang University Seongdong‐gu, Seoul 04763 Korea
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5
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Kang X, Zhu M. Metal Nanoclusters Stabilized by Selenol Ligands. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1902703. [PMID: 31482648 DOI: 10.1002/smll.201902703] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/25/2019] [Indexed: 06/10/2023]
Abstract
The past decades have witnessed great advances in controllable synthesis, structure determination, and property investigation of metal nanoclusters. Selenolated nanoclusters, a special branch in the nanocluster family, have attracted great interest in these years. The electronegativity and atomic radius of selenium is different from sulfur, and thus the selenolated nanoclusters are anticipated to display different electronic/geometric structures and distinct chemical/physical properties relative to their thiolated analogues. This review covers the syntheses, structures, and properties of selenolated nanoclusters (including Au, Ag, Cu, and alloy nanoclusters). Ligand effects (between SeR and SR) on nanocluster properties, including optical absorption, stability, and electrochemical properties, are disclosed as well. At the end of the review, a scope for improvements and future perspectives of selenolated nanoclusters is highlighted. The review hopefully opens up new horizons for cluster scientists to synthesize more selenolated nanoclusters with novel structures and properties. This review is based on publications available up to May 2019.
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Affiliation(s)
- Xi Kang
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Anhui University, Hefei, Anhui, 230601, China
| | - Manzhou Zhu
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Anhui University, Hefei, Anhui, 230601, China
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6
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Herrer L, Ismael A, Martín S, Milan DC, Serrano JL, Nichols RJ, Lambert C, Cea P. Single molecule vs. large area design of molecular electronic devices incorporating an efficient 2-aminepyridine double anchoring group. NANOSCALE 2019; 11:15871-15880. [PMID: 31414113 DOI: 10.1039/c9nr05662a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
When a molecule is bound to external electrodes by terminal anchor groups, the latter are of paramount importance in determining the electrical conductance of the resulting molecular junction. Here we explore the electrical properties of a molecule with bidentate anchor groups, namely 4,4'-(1,4-phenylenebis(ethyne-2,1-diyl))bis(pyridin-2-amine), in both large area devices and at the single molecule level. We find an electrical conductance of 0.6 × 10-4G0 and 1.2 × 10-4G0 for the monolayer and for the single molecule, respectively. These values are approximately one order of magnitude higher than those reported for monodentate materials having the same molecular skeleton. A combination of theory and experiments is employed to understand the conductance of monolayer and single molecule electrical junctions featuring this new multidentate anchor group. Our results demonstrate that the molecule has a tilt angle of 30° with respect to the normal to the surface in the monolayer, while the break-off length in the single molecule junction occurs for molecules having a tilt angle estimated as 40°, which would account for the difference in their conductance values per molecule. The bidentate 2-aminepyridine anchor is of general interest as a contact group, since this terminal functionalized aromatic ring favours binding of the adsorbate to the metal contact resulting in enhanced conductance values.
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Affiliation(s)
- L Herrer
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain. and 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.
| | - A Ismael
- Department of Physics, University of Lancaster, Lancaster, LA1 4YB, UK. and Department of Physics, College of Education for Pure Science, Tikrit University, Tikrit, Iraq
| | - S Martín
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain. and Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK.
| | - D C Milan
- Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - J L Serrano
- 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. and Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK. and Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain
| | - R J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK.
| | - C Lambert
- Department of Physics, University of Lancaster, Lancaster, LA1 4YB, UK.
| | - P Cea
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain. and 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. and Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
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7
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Abendroth JM, Stemer DM, Bloom BP, Roy P, Naaman R, Waldeck DH, Weiss PS, Mondal PC. Spin Selectivity in Photoinduced Charge-Transfer Mediated by Chiral Molecules. ACS NANO 2019; 13:4928-4946. [PMID: 31016968 DOI: 10.1021/acsnano.9b01876] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Optical control and readout of electron spin and spin currents in thin films and nanostructures have remained attractive yet challenging goals for emerging technologies designed for applications in information processing and storage. Recent advances in room-temperature spin polarization using nanometric chiral molecular assemblies suggest that chemically modified surfaces or interfaces can be used for optical spin conversion by exploiting photoinduced charge separation and injection from well-coupled organic chromophores or quantum dots. Using light to drive photoexcited charge-transfer processes mediated by molecules with central or helical chirality enables indirect measurements of spin polarization attributed to the chiral-induced spin selectivity effect and of the efficiency of spin-dependent electron transfer relative to competitive relaxation pathways. Herein, we highlight recent approaches used to detect and to analyze spin selectivity in photoinduced charge transfer including spin-transfer torque for local magnetization, nanoscale charge separation and polarization, and soft ferromagnetic substrate magnetization- and chirality-dependent photoluminescence. Building on these methods through systematic investigation of molecular and environmental parameters that influence spin filtering should elucidate means to manipulate electron spins and photoexcited states for room-temperature optoelectronic and photospintronic applications.
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Affiliation(s)
- John M Abendroth
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Dominik M Stemer
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
- Department of Materials Science and Engineering , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Brian P Bloom
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Partha Roy
- Department of Chemistry , Central University of Rajasthan , Kishangarh 305817 Ajmer , India
| | - Ron Naaman
- Department of Chemical and Biological Physics , Weizmann Institute of Science , Rehovot 76100 , Israel
| | - David H Waldeck
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Paul S Weiss
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
- Department of Materials Science and Engineering , University of California, Los Angeles , Los Angeles , California 90095 , United States
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8
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Wang S, Wattanatorn N, Chiang N, Zhao Y, Kim M, Ma H, Jen AKY, Weiss PS. Photoinduced Charge Transfer in Single-Molecule p-n Junctions. J Phys Chem Lett 2019; 10:2175-2181. [PMID: 30995403 DOI: 10.1021/acs.jpclett.9b00855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We measured photoinduced charge separation in isolated individual C60-tethered 2,5-dithienylpyrrole triad (C60 triad) molecules with submolecular resolution using a custom-built laser-assisted scanning tunneling microscope. Laser illumination was introduced evanescently into the tunneling junction through total internal reflection, and the changes in tunneling current and electronic spectra caused by photoexcitation were measured and spatially resolved. Photoinduced charge separation was not detected for all C60 triad molecules, indicating that the conformations of the molecules may affect the excitation probability, lifetime, and/or charge distribution. A photoinduced signal was not observed for dodecanethiol molecules in the surrounding matrix or for control molecules without C60 moieties, as neither absorbs incident photons at this energy. This spectroscopic imaging technique has the potential to elucidate detailed photoinduced carrier dynamics, which are inaccessible via ensemble-scale (i.e., averaging) measurements, which can be used to direct the rational design and optimization of molecular p-n junctions and assemblies for energy harvesting.
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Affiliation(s)
- Shenkai Wang
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Natcha Wattanatorn
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Naihao Chiang
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Yuxi Zhao
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Moonhee Kim
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Hong Ma
- Department of Materials Science and Engineering , University of Washington , Seattle , Washington 98185 , United States
| | - Alex K-Y Jen
- Department of Materials Science and Engineering , University of Washington , Seattle , Washington 98185 , United States
| | - Paul S Weiss
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
- California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
- Department of Materials Science and Engineering , University of California, Los Angeles , Los Angeles , California 90095 , United States
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9
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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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10
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Thomas JC, Goronzy DP, Serino AC, Auluck HS, Irving OR, Jimenez-Izal E, Deirmenjian JM, Macháček J, Sautet P, Alexandrova AN, Baše T, Weiss PS. Acid-Base Control of Valency within Carboranedithiol Self-Assembled Monolayers: Molecules Do the Can-Can. ACS NANO 2018; 12:2211-2221. [PMID: 29393628 PMCID: PMC6350814 DOI: 10.1021/acsnano.7b09011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We use simple acid-base chemistry to control the valency in self-assembled monolayers of two different carboranedithiol isomers on Au{111}. Monolayer formation proceeds via Au-S bonding, where manipulation of pH prior to or during deposition enables the assembly of dithiolate species, monothiol/monothiolate species, or combination. Scanning tunneling microscopy (STM) images identify two distinct binding modes in each unmodified monolayer, where simultaneous spectroscopic imaging confirms different dipole offsets for each binding mode. Density functional theory calculations and STM image simulations yield detailed understanding of molecular chemisorption modes and their relation with the STM images, including inverted contrast with respect to the geometric differences found for one isomer. Deposition conditions are modified with controlled equivalents of either acid or base, where the coordination of the molecules in the monolayers is controlled by protonating or deprotonating the second thiol/thiolate on each molecule. This control can be exercised during deposition to change the valency of the molecules in the monolayers, a process that we affectionately refer to as the "can-can." This control enables us to vary the density of molecule-substrate bonds by a factor of 2 without changing the molecular density of the monolayer.
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Affiliation(s)
- John C. Thomas
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Dominic P. Goronzy
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Andrew C. Serino
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, United States
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Harsharn S. Auluck
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Olivia R. Irving
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Elisa Jimenez-Izal
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
- Kimika fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), and Donostia International Physics Center (DIPC), P. K. 1072, 20080 Donostia, Euskadi, Spain
| | - Jacqueline M. Deirmenjian
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Jan Macháček
- Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, v.v.i. 250 68 Husinec-Řež, č.p. 1001, Czech Republic
| | - Philippe Sautet
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Anastassia N. Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, United States
| | - Tomáš Baše
- Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, v.v.i. 250 68 Husinec-Řež, č.p. 1001, Czech Republic
| | - Paul S. Weiss
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, United States
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, United States
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11
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Arisnabarreta N, Ruano GD, Lingenfelder M, Patrito EM, Cometto FP. Comparative Study of the Adsorption of Thiols and Selenols on Au(111) and Au(100). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13733-13739. [PMID: 29110489 DOI: 10.1021/acs.langmuir.7b03038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The effect of the Au crystalline plane on the adsorption of different thiols and selenols is studied via reductive desorption (RD) and X-ray photoelectron spectroscopy (XPS) measurements. Self-assembled monolayers (SAMs) using aliphatic (ATs) and aromatic thiols (ArTs) on both Au(111) and Au(100) were prepared. The electrochemical stability of these SAMs on both surfaces is evaluated by comparing the position of the RD peaks. The longer the AT chain the more stable the SAM on Au(100) when compared to Au(111). By means of XPS measurements, we determine that the binding energy (BE) of the S 2p signal corresponding to the S atoms at the thiol/Au interface, commonly assigned at 162.0 eV, shifts 0.2 eV from Au(111) to Au(100) for SAMs prepared using thiols with the C* (C atom bonded to S) in sp3 hybridization, such as ATs. However, when the thiol presents the C* with an sp2 hybridization, such as in the case of ArTs, the BE remains at 162.0 eV regardless of the surface plane. Selenol-based SAMs were characterized comparatively on both Au(100) and Au(111). Our results show that selenol SAMs become even more electrochemically stable on Au(100) with respect to Au(111) than the analogue sulfur-based SAM. According to our results, we suggest that the electronic distribution around the Au-S/Se bond could be responsible for the different structural arrangements reported in the literature (gold adatoms, etc.), which should be dependent on the crystalline face (Au(hkl)-S) and the chemical nature of the environment of the adsorbates (sp3-C* vs sp2-C* and Au-SR vs Au-SeR).
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Affiliation(s)
- Nicolás Arisnabarreta
- Departamento de Fisicoquímica, Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba , X5000 Córdoba, Argentina
| | - Gustavo D Ruano
- Instituto de Física del Litoral (IFIS) , S3000 Santa Fe, Argentina
| | - Magalí Lingenfelder
- Max Planck-EPFL Laboratory for Molecular Nanoscience, EPFL , CH-1015 Lausanne, Switzerland
| | - E Martín Patrito
- Departamento de Fisicoquímica, Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba , X5000 Córdoba, Argentina
| | - Fernando P Cometto
- Departamento de Fisicoquímica, Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba , X5000 Córdoba, Argentina
- Max Planck-EPFL Laboratory for Molecular Nanoscience, EPFL , CH-1015 Lausanne, Switzerland
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12
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Pawlicki AA, Vilan A, Jurow M, Drain CM, Batteas JD. The influence of nearest-neighbour interactions and assembly dynamics on the transport properties of porphyrin supramolecular assemblies on Au(111). Faraday Discuss 2017; 204:349-366. [PMID: 28871297 DOI: 10.1039/c7fd00118e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Here we report on the effect of local molecular organization or "tertiary structure" on the charge transport properties of thiol-tethered tetraphenylporphyrin (ZnTPPF4-SC5SH) nanoscale clusters of ca. 5 nm in lateral dimension embedded within a dodecanethiol (C12) monolayer on Au(111). The structure of the clusters in the mixed monolayers and their resulting transport properties were monitored by Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM) and Spectroscopy (STS). The mixed films were deposited on Au(111) for a period of one to five days, during which the lateral dimensions of the ZnTPPF4-SC5SH islands that were formed after one day reduced by nearly 35% on average by five days, accompanied by a noticeable depletion of the surrounding C12 monolayer. These subtle changes in mixed monolayer morphology were accompanied by drastic differences in conductance. The ZnTPPF4-SC5SH clusters assembled for one day exhibited highly reproducible I-V spectra with simple tunneling behavior. By three days, this evolved into bias-induced switching of conductance, with a ∼100-1000 fold increase. Furthermore, current fluctuations started to become significant, and then dominated transport across the ZnTPPF4-SC5SH clusters assembled over five days. Our data suggests that this evolution can be understood by slow surface diffusion, enabling the ZnTPPF4-SC5SH molecules to overcome initial steric hindrance in the early stages of island formation in the C12 monolayer (at day one), to reach a more energetically-favored, close-packed organization, as noted by the decrease in island size (by day three). However, when desorption of the supporting matrix of C12 became pronounced (by day five), the ZnTPPF4-SC5SH clusters began to lose stabilization, and stochastic switching was then observed to dominate transport in the clusters, illustrating the critical nature of the local organization on these transport properties.
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Affiliation(s)
- Alison A Pawlicki
- Department of Materials Science and Engineering, Texas A&M University, PO Box 3003, College Station, TX 77842, USA.
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13
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Abendroth JM, Nakatsuka N, Ye M, Kim D, Fullerton EE, Andrews AM, Weiss PS. Analyzing Spin Selectivity in DNA-Mediated Charge Transfer via Fluorescence Microscopy. ACS NANO 2017; 11:7516-7526. [PMID: 28672111 DOI: 10.1021/acsnano.7b04165] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Understanding spin-selective interactions between electrons and chiral molecules is critical to elucidating the significance of electron spin in biological processes and to assessing the potential of chiral assemblies for organic spintronics applications. Here, we use fluorescence microscopy to visualize the effects of spin-dependent charge transport in self-assembled monolayers of double-stranded DNA on ferromagnetic substrates. Patterned DNA arrays provide background regions for every measurement to enable quantification of substrate magnetization-dependent fluorescence due to the chiral-induced spin selectivity effect. Fluorescence quenching of photoexcited dye molecules bound within DNA duplexes is dependent upon the rate of charge separation/recombination upon photoexcitation and the efficiency of DNA-mediated charge transfer to the surface. The latter process is modulated using an external magnetic field to switch the magnetization orientation of the underlying ferromagnetic substrates. We discuss our results in the context of the current literature on the chiral-induced spin selectivity effect across various systems.
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Affiliation(s)
| | | | | | - Dokyun Kim
- Center for Memory and Recording Research, University of California, San Diego , La Jolla, California 92093, United States
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego , La Jolla, California 92093, United States
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14
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Guttentag AI, Barr KK, Song TB, Bui KV, Fauman JN, Torres LF, Kes DD, Ciomaga A, Gilles J, Sullivan NF, Yang Y, Allara DL, Zharnikov M, Weiss PS. Hexagons to Ribbons: Flipping Cyanide on Au{111}. J Am Chem Soc 2016; 138:15580-15586. [DOI: 10.1021/jacs.6b06046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Andrew I. Guttentag
- California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, Los
Angeles, California 90095, United States
| | - Kristopher K. Barr
- California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, Los
Angeles, California 90095, United States
| | - Tze-Bin Song
- California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Material Science and Engineering, University of California, Los Angeles, Los
Angeles, California 90095, United States
| | - Kevin V. Bui
- Department
of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Industrial Engineering and Management Sciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Jacob N. Fauman
- Department
of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Physics, University of California, Santa Barbara, California 93106, United States
| | - Leticia F. Torres
- Department
of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Mathematics, University of San Francisco, San Francisco, California 94117, United States
| | - David D. Kes
- Department
of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Mathematics and Natural Sciences, California State University, Long Beach, California 90840, United States
| | - Adina Ciomaga
- Department
of Mathematics, Laboratoire Jacques Louis Lions, Université Paris Diderot, 5 Rue Thomas Mann, Paris 75013, France
| | - Jérôme Gilles
- Department
of Mathematics and Statistics, San Diego State University, San Diego, California 92182, United States
| | - Nichole F. Sullivan
- Department
of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Yang Yang
- California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Material Science and Engineering, University of California, Los Angeles, Los
Angeles, California 90095, United States
| | - David L. Allara
- Department
of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Michael Zharnikov
- Applied
Physical Chemistry, Heidelberg University, 69120 Heidelberg, Germany
| | - Paul S. Weiss
- California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, Los
Angeles, California 90095, United States
- Department
of Material Science and Engineering, University of California, Los Angeles, Los
Angeles, California 90095, United States
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15
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Andrews AM, Liao WS, Weiss PS. Double-Sided Opportunities Using Chemical Lift-Off Lithography. Acc Chem Res 2016; 49:1449-57. [PMID: 27064348 DOI: 10.1021/acs.accounts.6b00034] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We discuss the origins, motivation, invention, development, applications, and future of chemical lift-off lithography, in which a specified pattern of a self-assembled monolayer is removed, i.e., lifted off, using a reactive, patterned stamp that is brought into contact with the monolayer. For Au substrates, this process produces a supported, patterned monolayer of Au on the stamp in addition to the negative pattern in the original molecular monolayer. Both the patterned molecular monolayer on the original substrate and the patterned supported metal monolayer on the stamp are useful as materials and for further applications in sensing and other areas. Chemical lift-off lithography effectively lowers the barriers to and costs of high-resolution, large-area nanopatterning. On the patterned monolayer side, features in the single-nanometer range can be produced across large (square millimeter or larger) areas. Patterns smaller than the original stamp feature sizes can be produced by controlling the degree of contact between the stamp and the lifted-off monolayer. We note that this process is different than conventional lift-off processes in lithography in that chemical lift-off lithography removes material, whereas conventional lift-off is a positive-tone patterning method. Chemical lift-off lithography is in some ways similar to microtransfer printing. Chemical lift-off lithography has critical advantages in the preparation of biocapture surfaces because the molecules left behind are exploited to space and to orient functional(ized) molecules. On the supported metal monolayer side, a new two-dimensional material has been produced. The useful important chemical properties of Au (vis-à-vis functionalization with thiols) are retained, but the electronic and optical properties of bulk Au or even Au nanoparticles are not. These metal monolayers do not quench excitation and may be useful in optical measurements, particularly in combination with selective binding due to attached molecular recognition elements. In contrast to materials such as graphene that have bonding confined to two dimensions, these metal monolayers can be straightforwardly patterned-by patterning the stamp, the initial monolayer, or the initial substrate. Well-developed thiol-Au and related chemistries can be used on the supported monolayers. As there is little quenching and photoabsorption, spectroscopic imaging methods can be used on these functionalized materials. We anticipate that the properties of the metal monolayers can be tuned by varying the chemical, physical, and electronic connections made by and to the supporting molecular layers. That is, the amount of charge in the layer can be determined by controlling the density of S-Au (or other) connections and the molecular backbone and functionality, which determine the strength with which the chemical contact withdraws charge from the metal. This process should work for other coinage-metal substrates and additional systems where the binding of the outermost layers to the substrate is weaker than the molecule-substrate attachment.
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Affiliation(s)
- Anne M. Andrews
- California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, Los
Angeles, California 90095, United States
- Department
of Psychiatry, Hatos Center for Neuropharmacology, and Semel Institute
for Neuroscience and Human Behavior, University of California, Los Angeles, Los
Angeles, California 90095, United States
| | - Wei-Ssu Liao
- Department
of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Paul S. Weiss
- California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, Los
Angeles, California 90095, United States
- Department
of Materials Science and Engineering, University of California, Los Angeles, Los
Angeles, California 90095, United States
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16
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Thomas JC, Goronzy DP, Dragomiretskiy K, Zosso D, Gilles J, Osher SJ, Bertozzi AL, Weiss PS. Mapping Buried Hydrogen-Bonding Networks. ACS NANO 2016; 10:5446-51. [PMID: 27096290 DOI: 10.1021/acsnano.6b01717] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We map buried hydrogen-bonding networks within self-assembled monolayers of 3-mercapto-N-nonylpropionamide on Au{111}. The contributing interactions include the buried S-Au bonds at the substrate surface and the buried plane of linear networks of hydrogen bonds. Both are simultaneously mapped with submolecular resolution, in addition to the exposed interface, to determine the orientations of molecular segments and directional bonding. Two-dimensional mode-decomposition techniques are used to elucidate the directionality of these networks. We find that amide-based hydrogen bonds cross molecular domain boundaries and areas of local disorder.
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Affiliation(s)
- John C Thomas
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Dominic P Goronzy
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Konstantin Dragomiretskiy
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Mathematics, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Dominique Zosso
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Mathematics, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Jérôme Gilles
- Department of Mathematics and Statistics, San Diego State University , San Diego, California 92182, United States
| | - Stanley J Osher
- Department of Mathematics, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Andrea L Bertozzi
- Department of Mathematics, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Paul S Weiss
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States
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17
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Gethers ML, Thomas JC, Jiang S, Weiss NO, Duan X, Goddard WA, Weiss PS. Holey Graphene as a Weed Barrier for Molecules. ACS NANO 2015; 9:10909-10915. [PMID: 26426746 DOI: 10.1021/acsnano.5b03936] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate the use of "holey" graphene as a mask against molecular adsorption. Prepared porous graphene is transferred onto a Au{111} substrate, annealed, and then exposed to dilute solutions of 1-adamantanethiol. In the pores of the graphene lattice, we find islands of organized, self-assembled molecules. The bare Au in the pores can be regenerated by postdeposition annealing, and new molecules can be self-assembled in the exposed Au region. Graphene can serve as a robust, patternable mask against the deposition of self-assembled monolayers.
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Affiliation(s)
- Matthew L Gethers
- Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
- Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California , Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology , Pasadena, California 91125, United States
| | - John C Thomas
- Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
- Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California , Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology , Pasadena, California 91125, United States
| | - Shan Jiang
- Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
- Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California , Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology , Pasadena, California 91125, United States
| | - Nathan O Weiss
- Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
- Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California , Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology , Pasadena, California 91125, United States
| | - Xiangfang Duan
- Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
- Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California , Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology , Pasadena, California 91125, United States
| | - William A Goddard
- Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
- Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California , Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology , Pasadena, California 91125, United States
| | - Paul S Weiss
- Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
- Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California , Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology , Pasadena, California 91125, United States
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18
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Thomas JC, Schwartz JJ, Hohman JN, Claridge SA, Auluck HS, Serino AC, Spokoyny AM, Tran G, Kelly KF, Mirkin CA, Gilles J, Osher SJ, Weiss PS. Defect-Tolerant Aligned Dipoles within Two-Dimensional Plastic Lattices. ACS NANO 2015; 9:4734-4742. [PMID: 25867638 DOI: 10.1021/acsnano.5b01329] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Carboranethiol molecules self-assemble into upright molecular monolayers on Au{111} with aligned dipoles in two dimensions. The positions and offsets of each molecule's geometric apex and local dipole moment are measured and correlated with sub-Ångström precision. Juxtaposing simultaneously acquired images, we observe monodirectional offsets between the molecular apexes and dipole extrema. We determine dipole orientations using efficient new image analysis techniques and find aligned dipoles to be highly defect tolerant, crossing molecular domain boundaries and substrate step edges. The alignment observed, consistent with Monte Carlo simulations, forms through favorable intermolecular dipole-dipole interactions.
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Affiliation(s)
- John C Thomas
- †Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Jeffrey J Schwartz
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- §Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - J Nathan Hohman
- †Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Shelley A Claridge
- †Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- ⊥Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47904, United States
| | - Harsharn S Auluck
- †Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Andrew C Serino
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- ∥Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Alexander M Spokoyny
- †Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- ¶Department of Chemistry and the International Institute for Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Giang Tran
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- #Department of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Kevin F Kelly
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- ▽Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Chad A Mirkin
- ¶Department of Chemistry and the International Institute for Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Jerome Gilles
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- #Department of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
- ○Department of Mathematics and Statistics, San Diego State University, San Diego, California 92182, United States
| | - Stanley J Osher
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- #Department of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Paul S Weiss
- †Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- ‡California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- ∥Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
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19
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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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20
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Ossowski J, Wächter T, Silies L, Kind M, Noworolska A, Blobner F, Gnatek D, Rysz J, Bolte M, Feulner P, Terfort A, Cyganik P, Zharnikov M. Thiolate versus Selenolate: Structure, Stability, and Charge Transfer Properties. ACS NANO 2015; 9:4508-4526. [PMID: 25857927 DOI: 10.1021/acsnano.5b01109] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Selenolate is considered as an alternative to thiolate to serve as a headgroup mediating the formation of self-assembled monolayers (SAMs) on coinage metal substrates. There are, however, ongoing vivid discussions regarding the advantages and disadvantages of these anchor groups, regarding, in particular, the energetics of the headgroup-substrate interface and their efficiency in terms of charge transport/transfer. Here we introduce a well-defined model system of 6-cyanonaphthalene-2-thiolate and -selenolate SAMs on Au(111) to resolve these controversies. The exact structural arrangements in both types of SAMs are somewhat different, suggesting a better SAM-building ability in the case of selenolates. At the same time, both types of SAMs have similar packing densities and molecular orientations. This permitted reliable competitive exchange and ion-beam-induced desorption experiments which provided unequivocal evidence for a stronger bonding of selenolates to the substrate as compared to the thiolates. Regardless of this difference, the dynamic charge transfer properties of the thiolate- and selenolate-based adsorbates were found to be nearly identical, as determined by the core-hole-clock approach, which is explained by a redistribution of electron density along the molecular framework, compensating the difference in the substrate-headgroup bond strength.
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Affiliation(s)
- Jakub Ossowski
- †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - Tobias Wächter
- ‡Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Laura Silies
- §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
| | - Martin Kind
- §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
| | - Agnieszka Noworolska
- †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - Florian Blobner
- ∥Physikdepartment E20, Technische Universität München, 85747 Garching, Germany
| | - Dominika Gnatek
- †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - Jakub Rysz
- †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - Michael Bolte
- §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
| | - Peter Feulner
- ∥Physikdepartment E20, Technische Universität München, 85747 Garching, Germany
| | - Andreas Terfort
- §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
| | - Piotr Cyganik
- †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - Michael Zharnikov
- ‡Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
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21
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Hohman JN, Thomas JC, Zhao Y, Auluck H, Kim M, Vijselaar W, Kommeren S, Terfort A, Weiss PS. Exchange Reactions between Alkanethiolates and Alkaneselenols on Au{111}. J Am Chem Soc 2014; 136:8110-21. [DOI: 10.1021/ja503432f] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- J. Nathan Hohman
- California
NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - John C. Thomas
- California
NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Yuxi Zhao
- California
NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Harsharn Auluck
- California
NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Moonhee Kim
- California
NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Wouter Vijselaar
- Department
of Science and Technology, University of Twente, P.O. Box 217, 7500
AE Enschede, The Netherlands
| | - Sander Kommeren
- Department
of Science and Technology, University of Twente, P.O. Box 217, 7500
AE Enschede, The Netherlands
| | - Andreas Terfort
- Institut
für Anorganische und Analytische Chemie, Universität Frankfurt, Frankfurt 60438, Germany
| | - Paul S. Weiss
- California
NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
- Department
of Materials Science and Engineering, University of California, Los Angeles, California 90095, United States
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22
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Cometto FP, Calderón CA, Morán M, Ruano G, Ascolani H, Zampieri G, Paredes-Olivera P, Patrito EM. Formation, characterization, and stability of methaneselenolate monolayers on Au(111): an electrochemical high-resolution photoemission spectroscopy and DFT study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:3754-3763. [PMID: 24645647 DOI: 10.1021/la404996q] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We investigated the mechanism of formation and stability of self-assembled monolayers (SAMs) of methaneselenolate on Au(111) prepared by the immersion method in ethanolic solutions of dimethyl diselenide (DMDSe). The adsorbed species were characterized by electrochemical measurements and high-resolution photoelectron spectroscopy (HR-XPS). The importance of the headgroup on formation mechanism and the stability of the SAMs was addressed by comparatively studying methaneselenolate (MSe) and methanethiolate (MT) monolayers. Density Functional Theory (DFT) calculations were performed to identify the elementary reaction steps in the mechanisms of formation and decomposition of the monolayers. Reductive desorption and HR-XPS measurements indicated that a MSe monolayer is formed at short immersion times by the cleavage of the Se-Se bond of DMDSe. However, the monolayer decomposes at long immersion times at room temperature, as evidenced by the appearance of atomic Se on the surface. The decomposition is more pronounced for MSe than for MT monolayers. The MSe monolayer stability can be greatly improved by two modifications in the preparation method: immersion at low temperatures (-20 °C) and the addition of a reducing agent to the forming solution.
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Affiliation(s)
- F P Cometto
- Departamento de Fisicoquímica and ‡Departamento de Matemática y Física, Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba , 5000 Córdoba, Argentina
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23
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Romashov LV, Ananikov VP. Self-assembled selenium monolayers: from nanotechnology to materials science and adaptive catalysis. Chemistry 2013; 19:17640-60. [PMID: 24288138 DOI: 10.1002/chem.201302115] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Self-assembled monolayers (SAMs) of selenium have emerged into a rapidly developing field of nanotechnology with several promising opportunities in materials chemistry and catalysis. Comparison between sulfur-based self-assembled monolayers and newly developed selenium-based monolayers reveal outstanding complimentary features on surface chemistry and highlighted the key role of the headgroup element. Diverse structural properties and reactivity of organosulfur and organoselenium groups on the surface provide flexible frameworks to create new generations of materials and adaptive catalysts with unprecedented selectivity. Important practical utility of adaptive catalytic systems deals with development of sustainable technologies and industrial processes based on natural resources. Independent development of nanotechnology, materials science and catalysis has led to the discovery of common fundamental principles of the surface chemistry of chalcogen compounds.
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Affiliation(s)
- Leonid V Romashov
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991 (Russia)
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24
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Claridge SA, Liao WS, Thomas JC, Zhao Y, Cao H, Cheunkar S, Serino AC, Andrews AM, Weiss PS. From the bottom up: dimensional control and characterization in molecular monolayers. Chem Soc Rev 2013; 42:2725-45. [PMID: 23258565 PMCID: PMC3596502 DOI: 10.1039/c2cs35365b] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Self-assembled monolayers are a unique class of nanostructured materials, with properties determined by their molecular lattice structures, as well as the interfaces with their substrates and environments. As with other nanostructured materials, defects and dimensionality play important roles in the physical, chemical, and biological properties of the monolayers. In this review, we discuss monolayer structures ranging from surfaces (two-dimensional) down to single molecules (zero-dimensional), with a focus on applications of each type of structure, and on techniques that enable characterization of monolayer physical properties down to the single-molecule scale.
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Affiliation(s)
- Shelley A. Claridge
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Wei-Ssu Liao
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - John C. Thomas
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Yuxi Zhao
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Huan Cao
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Sarawut Cheunkar
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Andrew C. Serino
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Anne M. Andrews
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Psychiatry, University of California, Los Angeles, Los Angeles, California 90095, United States
- Semel Institute for Neuroscience & Human Behavior, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Paul S. Weiss
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- Department of Materials Science & Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
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25
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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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26
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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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27
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Cometto FP, Patrito EM, Paredes Olivera P, Zampieri G, Ascolani H. Electrochemical, high-resolution photoemission spectroscopy and vdW-DFT study of the thermal stability of benzenethiol and benzeneselenol monolayers on Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:13624-13635. [PMID: 22946792 DOI: 10.1021/la3024937] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The preparation and thermal stability of benzenethiol and benzeneselenol self-assembled monolayers (SAMs) grown on Au(111) have been investigated by electrochemical experiments and high-resolution photoemission spectroscopy. Both techniques confirm the formation of monolayers with high packing densities (θ = 0.27-0.29 ML) and good degrees of order in both cases. Despite many similarities between the two SAMs, the thermal desorption is distinctly different: whereas the benzenethiol SAM desorbs in a single steplike process, the desorption of the benzeneselenol SAM occurs with a much lower activation energy and involves the cleavage of some Se-C bonds and a change in molecular configuration from standing up to lying down. This behavior is explained by considering the different nature of the bonding of the headgroup with the metal surface and with the phenyl ring. Density functional theory calculations show that the breakage of the Se-C bond has a lower activation energy barrier than the breakage of the S-C bond.
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Affiliation(s)
- F P Cometto
- Departamento de Fisico Química, Instituto de Fisicoquímica de Córdoba, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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28
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Pathem BK, Zheng YB, Payton JL, Song TB, Yu BC, Tour JM, Yang Y, Jensen L, Weiss PS. Effect of Tether Conductivity on the Efficiency of Photoisomerization of Azobenzene-Functionalized Molecules on Au{111}. J Phys Chem Lett 2012; 3:2388-2394. [PMID: 26292120 DOI: 10.1021/jz300968m] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We establish the role of tether conductivity on the photoisomerization of azobenzene-functionalized molecules assembled as isolated single molecules in well-defined decanethiolate self-assembled monolayer matrices on Au{111}. We designed the molecules so as to tune the conductivity of the tethers that separate the functional moiety from the underlying Au substrate. By employing surface-enhanced Raman spectroscopy, time-course measurements of surfaces assembled with azobenzene functionalized with different tether conductivities were independently studied under constant UV light illumination. The decay constants from the analyses reveal that photoisomerization on the Au{111} surface is reduced when the conductivity of the tether is increased. Experimental results are compared with density functional theory calculations performed on single molecules attached to Au clusters.
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Affiliation(s)
| | | | - John L Payton
- ∥Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | | | - Byung-Chan Yu
- ⊥Department of Chemistry and The Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, United States
| | - James M Tour
- ⊥Department of Chemistry and The Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, United States
| | | | - Lasse Jensen
- ∥Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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29
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Park S, Wang G, Cho B, Kim Y, Song S, Ji Y, Yoon MH, Lee T. Flexible molecular-scale electronic devices. NATURE NANOTECHNOLOGY 2012; 7:438-42. [PMID: 22659606 DOI: 10.1038/nnano.2012.81] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 04/25/2012] [Indexed: 05/13/2023]
Abstract
Flexible materials and devices could be exploited in light-emitting diodes, electronic circuits, memory devices, sensors, displays, solar cells and bioelectronic devices. Nanoscale elements such as thin films, nanowires, nanotubes and nanoparticles can also be incorporated into the active films of mechanically flexible devices. Large-area devices containing extremely thin films of molecular materials represent the ultimate scaling of flexible devices based on organic materials, but the influence of bending and twisting on the electrical and mechanical stability of such devices has never been examined. Here, we report the fabrication and characterization of two-terminal electronic devices based on self-assembled monolayers of alkyl or aromatic thiol molecules on flexible substrates. We find that the charge transport characteristics of the devices remain stable under severe bending conditions (radius ≤ 1 mm) and a large number of repetitive bending cycles (≥1,000). The devices also remain reliable in various bending configurations, including twisted and helical structures.
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Affiliation(s)
- Sungjun Park
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Korea
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30
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Jewell AD, Kyran SJ, Rabinovich D, Sykes ECH. Effect of head-group chemistry on surface-mediated molecular self-assembly. Chemistry 2012; 18:7169-78. [PMID: 22532331 DOI: 10.1002/chem.201102956] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 01/16/2012] [Indexed: 11/07/2022]
Abstract
Surface molecular self-assembly is a fast advancing field with broad applications in sensing, patterning, device assembly, and biochemical applications. A vast number of practical systems utilize alkane thiols supported on gold surfaces. Whereas a strong Au-S bond facilitates robust self-assembly, the interaction is so strong that the surface is reconstructed, leaving etch pits that render the monolayers susceptible to degradation. By using different head group elements to adcust the molecule-surface interaction, a vast array of new systems with novel properties may be formed. In this paper we use a carefully chosen set of molecules to make a direct comparison of the self-assembly of thioether, selenoether, and phosphine species on Au(111). Using the herringbone reconstruction of gold as a sensitive readout of molecule-surface interaction strength, we correlate head-group chemistry with monolayer (ML) properties. It is demonstrated that the hard/soft rules of inorganic chemistry can be used to rationalize the observed trend of molecular interaction strengths with the soft gold surface, that is, P>Se>S. We find that the structure of the monolayers can be explained by the geometry of the molecules in terms of dipolar, quadrupolar, or van der Waals interactions between neighboring species driving the assembly of distinct ordered arrays. As this study directly compares one element with another in simple systems, it may serve as a guide for the design of self-assembled monolayers with novel structures and properties.
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Affiliation(s)
- April D Jewell
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA 02155, USA
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31
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Hohman JN, Kim M, Schüpbach B, Kind M, Thomas JC, Terfort A, Weiss PS. Dynamic double lattice of 1-adamantaneselenolate self-assembled monolayers on Au{111}. J Am Chem Soc 2011; 133:19422-31. [PMID: 21861500 DOI: 10.1021/ja2063988] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report a complex, dynamic double lattice for 1-adamantaneselenolate monolayers on Au{111}. Two lattices coexist, revealing two different binding modes for selenols on gold: molecules at bridge sites have lower conductance than molecules at three-fold hollow sites. The monolayer is dynamic, with molecules switching reversibly between the two site-dependent conductance states. Monolayer dynamics enable adsorbed molecules to reorganize according to the underlying gold electronic structure over long distances, which facilitates emergence of the self-organized rows of dimers. The low-conductance molecules assume a (7 × 7) all-bridge configuration, similar to the analogous 1-adamantanethiolate monolayers on Au{111}. The high-conductance molecules self-organize upon mild annealing into distinctive rows of dimers with long-range order, described by a (6√5 × 6√5)R15° unit cell.
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Affiliation(s)
- J Nathan Hohman
- California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
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32
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Artés JM, Díez-Pérez I, Sanz F, Gorostiza P. Direct measurement of electron transfer distance decay constants of single redox proteins by electrochemical tunneling spectroscopy. ACS NANO 2011; 5:2060-2066. [PMID: 21539019 DOI: 10.1021/nn103236e] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present a method to measure directly and at the single-molecule level the distance decay constant that characterizes the rate of electron transfer (ET) in redox proteins. Using an electrochemical tunneling microscope under bipotentiostatic control, we obtained current−distance spectroscopic recordings of individual redox proteins confined within a nanometric tunneling gap at a well-defined molecular orientation. The tunneling current decays exponentially, and the corresponding decay constant (β) strongly supports a two-step tunneling ET mechanism. Statistical analysis of decay constant measurements reveals differences between the reduced and oxidized states that may be relevant to the control of ET rates in enzymes and biological electron transport chains.
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Affiliation(s)
- Juan M Artés
- Institute for Bioengineering of Catalonia, Barcelona, Spain
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33
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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: 27] [Impact Index Per Article: 1.9] [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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34
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Takami T, Ye T, Pathem BK, Arnold DP, Sugiura KI, Bian Y, Jiang J, Weiss PS. Manipulating double-decker molecules at the liquid-solid interface. J Am Chem Soc 2010; 132:16460-6. [PMID: 21033714 DOI: 10.1021/ja105421k] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have used a scanning tunneling microscope (STM) to manipulate heteroleptic phthalocyaninato, naphthalocyaninato, and porphyrinato double-decker (DD) molecules at the liquid-solid interface between 1-phenyloctane solvent and graphite. We employed nanografting of phthalocyanines with eight octyl chains to place these molecules into a matrix of heteroleptic DD molecules; the overlayer structure is epitaxial on graphite. We have also used nanografting to place DD molecules in matrices of single-layer phthalocyanines with octyl chains. Rectangular scans with a STM at low bias voltage resulted in the removal of the adsorbed DD molecular layer and substituted the DD molecules with bilayer-stacked phthalocyanines from phenyloctane solution. Single heteroleptic DD molecules with lutetium sandwiched between naphthalocyanine and octaethylporphyrin were decomposed with voltage pulses from the probe tip; the top octaethylporphyrin ligand was removed, and the bottom naphthalocyanine ligand remained on the surface. A domain of decomposed molecules was formed within the DD molecular domain, and the boundary of the decomposed molecular domain self-cured to become rectangular. We demonstrated a molecular "sliding block puzzle" with cascades of DD molecules on the graphite surface.
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Affiliation(s)
- Tomohide Takami
- VRI, Inc., 4-13-13 Jingumae, Shibuya, Tokyo 150-0001, Japan.
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35
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Carbon graphite surfaces modified with two-dimensional arrays of N-acetyltripeptide-protected gold nanoparticles. Colloids Surf A Physicochem Eng Asp 2010. [DOI: 10.1016/j.colsurfa.2010.03.033] [Citation(s) in RCA: 1] [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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36
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Adaligil E, Shon YS, Slowinski K. Effect of headgroup on electrical conductivity of self-assembled monolayers on mercury: n-alkanethiols versus n-alkaneselenols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:1570-1573. [PMID: 20000324 DOI: 10.1021/la904180u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The relative efficiencies of electron tunneling across self-assembled monolayers (SAMs) of n-alkanethiols and n-alkaneselenols, CH(3)-(CH(2))(n)-XH, where n = 8, 9, 11, and X = S or Se, deposited on mercury electrodes were measured via electroreduction of Ru(NH(3))(6)(3+) in aqueous solutions. Electron tunneling rates across the monolayer films decay exponentially with the monolayer thickness with a tunneling coefficient, beta = 1.1 +/- 0.1 per CH(2) irrespective of the identity of the -XH headgroup. Electron tunneling rates across n-alkanethiol monolayers are ca. 4-fold larger than the rates measured across n-alkaneselenol monolayers containing the same number of carbon atoms, signifying the importance of headgroup/metal contact resistance in electron transfer through SAMs on mercury.
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Affiliation(s)
- Emel Adaligil
- Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Boulevard, Long Beach, California 90840, USA
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Electrochemical and spectroscopic study of C12H25X molecules adsorption on copper sheets, X (–SH, –S–S–, –SeH and –Se–Se–). Electrochim Acta 2010. [DOI: 10.1016/j.electacta.2009.10.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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38
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de la Llave E, Scherlis DA. Selenium-based self-assembled monolayers: the nature of adsorbate-surface interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:173-178. [PMID: 19919031 DOI: 10.1021/la903660y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In recent years, self-assembled monolayers (SAMs) of selenols have been characterized using electrochemistry, scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy, and other experimental approaches. Interest in the relative stability and conductance of the Se-Au interface as compared to S-Au prompted different investigations which have led to contradictory results. From the theoretical side, on the other hand, the study of selenol-based SAMs has concentrated on the investigation of the electron transport across the Se-Au contact, whereas the structural and the thermodynamic features of the monolayer were essentially neglected. In this Article, we examine the binding of selenols to the Au(111) surface using density functional theory with plane wave basis sets and periodic boundary conditions. Our calculations provide insights on the geometry of the headgroup, the stability of the monolayer, and the electronic properties of the bond. In particular, we propose that the presence of a conjugated backbone might be a major factor determining the relative conductance at the monolayer, by differentially enhancing the intramolecular electron transport in selenols with respect to thiols. This surmise, if confirmed, would explain the conflictive data coming from the available experiments.
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Affiliation(s)
- Ezequiel de la Llave
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina
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Han P, Kurland AR, Giordano AN, Nanayakkara SU, Blake MM, Pochas CM, Weiss PS. Heads and tails: simultaneous exposed and buried interface imaging of monolayers. ACS NANO 2009; 3:3115-3121. [PMID: 19772297 DOI: 10.1021/nn901030x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have simultaneously imaged the chemically bound head groups and exposed tail groups in bicomponent alkanethiolate self-assembled monolayers on Au{111} with molecular resolution. This has enabled us to resolve the controversy of scanning tunneling microscopy image interpretation and to measure the molecular polar tilt and azimuthal angles. Our local measurements demonstrate that ordered domains with different superstructures also have varied buried sulfur head group structures.
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Affiliation(s)
- Patrick Han
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Kim M, Hohman JN, Morin EI, Daniel TA, Weiss PS. Self-assembled monolayers of 2-Adamantanethiol on Au{111}: control of structure and displacement. J Phys Chem A 2009; 113:3895-903. [PMID: 19309101 DOI: 10.1021/jp810048n] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We have investigated the formation of 2-adamantanethiolate self-assembled monolayers on Au{111} and their displacement by n-dodecanethiol, using scanning tunneling microscopy, X-ray photoelectron spectroscopy, and infrared reflection absorption spectroscopy. Well-ordered 2-adamantanethiolate monolayers undergo rapid and significant molecular exchange upon exposure to n-dodecanethiol solutions, but their structures and intermolecular interactions template the growth of n-dodecanethiolate domains. Annealing 2-adamantanethiolate monolayers at 78 degrees C decreases the density of vacancy islands, while increasing the overall order and the average domain sizes in the films. This results in slower displacement by n-dodecanethiol molecules, as compared to unannealed monolayers. The secondary sulfur position on the adamantyl cage influences the lattice structure and exchange of 2-adamantanethiolate monolayers by alkanethiols.
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Affiliation(s)
- Moonhee Kim
- Department of Chemistry and Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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41
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Ie Y, Hirose T, Yao A, Yamada T, Takagi N, Kawai M, Aso Y. Synthesis of tripodal anchor units bearing selenium functional groups and their adsorption behaviour on gold. Phys Chem Chem Phys 2009; 11:4949-51. [DOI: 10.1039/b906286f] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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42
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Comparative assessment of n-dodecanethiol and n-dodecaneselenol monolayers on electroplated copper. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2007.11.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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43
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Zhu J, Brink M, McEuen PL. Single-electron force readout of nanoparticle electrometers attached to carbon nanotubes. NANO LETTERS 2008; 8:2399-2404. [PMID: 18578552 DOI: 10.1021/nl801295y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We introduce a new technique of probing the local potential inside a nanostructure employing Au nanoparticles as electrometers and using single-electron force microscopy to sense the charge states of the Au electrometers, which are sensitive to local potential variations. The Au nanoelectrometers are weakly coupled to a carbon nanotube through high-impedance molecular junctions. We demonstrate the operation of the Au nanoelectrometer, determine the impedance of the molecular junctions, and measure the local potential profile in a looped nanotube.
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Affiliation(s)
- Jun Zhu
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
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44
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Mekhalif Z, Fonder G, Auguste D, Laffineur F, Delhalle J. Impact of the anchoring groups X (–SH, –S–S–, –SeH and –Se–Se–) of CF3(CF2)3(CH2)11X molecules self-assembled on oxidised electroplated copper. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.02.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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45
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Ulgut B, Abruña HD. Electron Transfer through Molecules and Assemblies at Electrode Surfaces. Chem Rev 2008; 108:2721-36. [DOI: 10.1021/cr068060w] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Burak Ulgut
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Héctor D. Abruña
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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Bashir A, Käfer D, Müller J, Wöll C, Terfort A, Witte G. Selenium as a Key Element for Highly Ordered Aromatic Self‐Assembled Monolayers. Angew Chem Int Ed Engl 2008; 47:5250-2. [DOI: 10.1002/anie.200800883] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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47
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Bashir A, Käfer D, Müller J, Wöll C, Terfort A, Witte G. Selen als Schlüsselkomponente für hochgeordnete aromatische selbstorganisierte Monoschichten. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200800883] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Accurate measurements of electronic properties of molecular junctions are important for both fundamental and practical applications. Often the molecule-electrode contacts are poorly characterized, leading to wide variation in the measured resistance values. A new paper in this issue demonstrates the use of a reference molecule as an internal standard to compensate for the varying conditions of the molecular contact in conductive-tip atomic force microscopy measurements and yields consistent resistances relative to the reference despite variations in absolute resistance.
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Affiliation(s)
- Lloyd A Bumm
- Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 West Brooks Street, Norman, Oklahoma 73019-2061, USA.
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Bazan GC. Novel organic materials through control of multichromophore interactions. J Org Chem 2007; 72:8615-35. [PMID: 17887701 DOI: 10.1021/jo071176n] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The function of organic semiconducting and light-harvesting materials depends on the organization of the individual molecular components. Our group has tackled the problem of through-space delocalization via the design and synthesis of bichromphoric pairs held in close proximity by the [2.2]paracyclophane core. The linear and nonlinear optical properties of these molecules provide a challenge to theory. They are also useful in delineating the problem of intermolecular contacts in molecular conductivity measurements. Another area of research described here concerns conjugated polyelectrolytes. These macromolecules combine the properties of organic semiconductors and conventional polyelectrolytes. We have used these materials in the development of optically amplified biosensors and have also incorporated them into organic optoelectronic devices. Of particular interest to us is to derive useful structure/property relationships via molecular design that address important basic scientific problems and technological challenges.
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Affiliation(s)
- Guillermo C Bazan
- Department of Chemistry, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA.
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Weiss EA, Kriebel JK, Rampi MA, Whitesides GM. The study of charge transport through organic thin films: mechanism, tools and applications. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2007; 365:1509-37. [PMID: 17430810 DOI: 10.1098/rsta.2007.2029] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
In this paper, we discuss the current state of organic and molecular-scale electronics, some experimental methods used to characterize charge transport through molecular junctions and some theoretical models (superexchange and barrier tunnelling models) used to explain experimental results. Junctions incorporating self-assembled monolayers of organic molecules - and, in particular, junctions with mercury-drop electrodes - are described in detail, as are the issues of irreproducibility associated with such junctions (due, in part, to defects at the metal-molecule interface).
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Affiliation(s)
- Emily A Weiss
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
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