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Mejía L, Renaud N, Franco I. Signatures of Conformational Dynamics and Electrode-Molecule Interactions in the Conductance Profile During Pulling of Single-Molecule Junctions. J Phys Chem Lett 2018; 9:745-750. [PMID: 29369638 DOI: 10.1021/acs.jpclett.7b03323] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We demonstrate that conductance can act as a sensitive probe of conformational dynamics and electrode-molecule interactions during the equilibrium and nonequilibrium pulling of molecular junctions. To do so, we use a combination of classical molecular dynamics simulations and Landauer electron transport computations to investigate the conductance of a family of Au-alkanedithiol-Au junctions as they are mechanically elongated. The simulations show an overall decay of the conductance during pulling that is due to a decrease in the through-space electrode-molecule interactions, and that sensitivity depends on the electrode geometry. In addition, characteristic kinks induced by level alignment shifts (and to a lesser extent by quantum destructive interference) were also observed superimposed to the overall decay during pulling simulations. The latter effect depends on the variation of the molecular dihedral angles during pulling and therefore offers an efficient solution to experimentally monitor conformational dynamics at the single-molecule limit.
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Affiliation(s)
- Leopoldo Mejía
- Department of Chemistry, University of Rochester , Rochester, New York 14627-0216, United States
| | - Nicolas Renaud
- Netherlands eScience Center , Science Park 140 1098 XG Amsterdam, The Netherlands
| | - Ignacio Franco
- Department of Chemistry, University of Rochester , Rochester, New York 14627-0216, United States
- Department of Physics, University of Rochester , Rochester, New York 14627-0216, United States
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Pirrotta A, Solomon GC, Franco I, Troisi A. Excitonic Coupling Modulated by Mechanical Stimuli. J Phys Chem Lett 2017; 8:4326-4332. [PMID: 28837767 DOI: 10.1021/acs.jpclett.7b01828] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding energy transfer is of vital importance in a diverse range of applications from biological systems to photovoltaics. The ability to tune excitonic coupling in any of these systems, however, is generally limited. In this work, we have simulated a new class of single-molecule spectroscopy in which force microscopy is used to control the excitonic coupling between chromophores. Here we demonstrate that the excitonic coupling can be controlled by mechanical manipulation of the molecule (perylenediimide dimers and terrylenediimide-perylenediimide heterodimers) and can be tuned over a broad range of values (0.02-0.15 eV) that correspond to different regimes of exciton dynamics going from the folded to the elongated structure of the dimer. In all of the systems considered here, the switching from high to low coupling takes place simultaneously with the mechanical deformation detected by a strong increase and subsequent decay of the force. These simulations suggest that single-molecule force spectroscopy can be used to understand and eventually aid the design of excitonic devices.
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Affiliation(s)
- Alessandro Pirrotta
- Nano-Science Center and Department of Chemistry, University of Copenhagen , 2100 Copenhagen Ø, Denmark
| | - Gemma C Solomon
- Nano-Science Center and Department of Chemistry, University of Copenhagen , 2100 Copenhagen Ø, Denmark
| | - Ignacio Franco
- Department of Chemistry, University of Rochester , Rochester, New York 14627-0216, United States
| | - Alessandro Troisi
- Department of Chemistry, University of Liverpool , L69 7DZ Liverpool, United Kingdom
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Abstract
While one might assume that the force to break a chemical bond gives a measure of the bond strength, this intuition is misleading. If the force is loaded slowly, thermal fluctuations may break the bond before it is maximally stretched, and the breaking force will be less than the bond can sustain. Conversely, if the force is loaded rapidly it is more likely that the maximum breaking force is measured. Paradoxically, no clear differences in breaking force were observed in experiments on gold nanowires, despite being conducted under very different conditions. Here we explore the breaking behaviour of a single Au-Au bond and show that the breaking force is dependent on the loading rate. We probe the temperature and structural dependencies of breaking and suggest that the paradox can be explained by fast breaking of atomic wires and slow breaking of point contacts giving very similar breaking forces.
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Ozawa H, Baghernejad M, Al-Owaedi OA, Kaliginedi V, Nagashima T, Ferrer J, Wandlowski T, García-Suárez VM, Broekmann P, Lambert CJ, Haga MA. Synthesis and Single-Molecule Conductance Study of Redox-Active Ruthenium Complexes with Pyridyl and Dihydrobenzo[b]thiophene Anchoring Groups. Chemistry 2016; 22:12732-40. [PMID: 27472889 DOI: 10.1002/chem.201600616] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Indexed: 11/12/2022]
Abstract
The ancillary ligands 4'-(4-pyridyl)-2,2':6',2''-terpyridine and 4'-(2,3-dihydrobenzo[b]thiophene)-2,2'-6',2"-terpyridine were used to synthesize two series of mono- and dinuclear ruthenium complexes differing in their lengths and anchoring groups. The electrochemical and single-molecular conductance properties of these two series of ruthenium complexes were studied experimentally by means of cyclic voltammetry and the scanning tunneling microscopy-break junction technique (STM-BJ) and theoretically by means of density functional theory (DFT). Cyclic voltammetry data showed clear redox peaks corresponding to both the metal- and ligand-related redox reactions. Single-molecular conductance demonstrated an exponential decay of the molecular conductance with the increase in molecular length for both the series of ruthenium complexes, with decay constants of βPY =2.07±0.1 nm(-1) and βBT =2.16±0.1 nm(-1) , respectively. The contact resistance of complexes with 2,3-dihydrobenzo[b]thiophene (BT) anchoring groups is found to be smaller than the contact resistance of ruthenium complexes with pyridine (PY) anchors. DFT calculations support the experimental results and provided additional information on the electronic structure and charge transport properties in those metal|ruthenium complex|metal junctions.
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Affiliation(s)
- Hiroaki Ozawa
- Department of Applied Chemistry, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, 112-8551, Tokyo, Japan
| | - Masoud Baghernejad
- Department of Chemistry and Biochemistry, University of Bern, Freistrasse 3, 3012, Bern, Switzerland
| | - Oday A Al-Owaedi
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK. .,Department of Laser Physics, Women Faculty of Science, Babylon University, Hillah, Iraq.
| | - Veerabhadrarao Kaliginedi
- Department of Chemistry and Biochemistry, University of Bern, Freistrasse 3, 3012, Bern, Switzerland.
| | - Takumi Nagashima
- Department of Applied Chemistry, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, 112-8551, Tokyo, Japan
| | - Jaime Ferrer
- Departamento de Física, Universidad de Oviedo and CINN, 33007, Oviedo, Spain
| | - Thomas Wandlowski
- Department of Chemistry and Biochemistry, University of Bern, Freistrasse 3, 3012, Bern, Switzerland
| | | | - Peter Broekmann
- Department of Chemistry and Biochemistry, University of Bern, Freistrasse 3, 3012, Bern, Switzerland
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Masa-Aki Haga
- Department of Applied Chemistry, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, 112-8551, Tokyo, Japan.
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Yoshida K, Pobelov IV, Manrique DZ, Pope T, Mészáros G, Gulcur M, Bryce MR, Lambert CJ, Wandlowski T. Correlation of breaking forces, conductances and geometries of molecular junctions. Sci Rep 2015; 5:9002. [PMID: 25758349 PMCID: PMC4355744 DOI: 10.1038/srep09002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/29/2015] [Indexed: 01/02/2023] Open
Abstract
Electrical and mechanical properties of elongated gold-molecule-gold junctions formed by tolane-type molecules with different anchoring groups (pyridyl, thiol, amine, nitrile and dihydrobenzothiophene) were studied in current-sensing force spectroscopy experiments and density functional simulations. Correlations between forces, conductances and junction geometries demonstrate that aromatic tolanes bind between electrodes as single molecules or as weakly-conductive dimers held by mechanically-weak π - π stacking. In contrast with the other anchors that form only S-Au or N-Au bonds, the pyridyl ring also forms a highly-conductive cofacial link to the gold surface. Binding of multiple molecules creates junctions with higher conductances and mechanical strengths than the single-molecule ones.
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Affiliation(s)
- Koji Yoshida
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Ilya V Pobelov
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | | | - Thomas Pope
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Gábor Mészáros
- 1] Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland [2] Research Centre for Natural Sciences, HAS, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Murat Gulcur
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, United Kingdom
| | - Martin R Bryce
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, United Kingdom
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Thomas Wandlowski
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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Zhou XY, Peng ZL, Sun YY, Wang LN, Niu ZJ, Zhou XS. Conductance measurement of pyridyl-based single molecule junctions with Cu and Au contacts. NANOTECHNOLOGY 2013; 24:465204. [PMID: 24164714 DOI: 10.1088/0957-4484/24/46/465204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We studied the conductance of pyridyl-based single molecule junctions with Cu contacts by using an electrochemical jump-to-contact scanning tunneling microscopy break junction (ECSTM-BJ) approach. The single molecule junctions of 4,4'-bipyridine (BPY), 1,2-di(pyridin-4-yl)ethene (BPY-EE) and 1,2-di(pyridin-4-yl)ethane (BPY-EA) bridged with Cu clusters show three sets of conductance values. These values are smaller than the conductance values of single molecule junctions with Au electrodes measured by the traditional scanning tunneling microscopy break junction in acidic or neutral solutions, which can be attributed to the different electronic coupling efficiencies between molecules and electrodes. The consistent conductance of pyridyl-based molecules in acidic and neutral solutions may show that the protonated pyridyl group contacts to the electrode through the deprotonated form.
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Affiliation(s)
- Xiao-Yi Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, People's Republic of China
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Wu Y, Hong W, Akiyama T, Gautsch S, Kolivoska V, Wandlowski T, de Rooij NF. Batch fabrication of gold-gold nanogaps by E-beam lithography and electrochemical deposition. NANOTECHNOLOGY 2013; 24:235302. [PMID: 23676659 DOI: 10.1088/0957-4484/24/23/235302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report on the successful development of a well-controlled two-step batch nano-fabrication process to achieve nanometer-size gaps at the wafer scale. The technique is based on an optimized electron-beam lithography process, which enables the fabrication of nanogaps in the range (15 ± 4) nm. Following this first step, the feedback-controlled electrochemical deposition of gold from an aqueous HAuCl4-based electrolyte is applied to further reduce the size of the gap down to about 0.3-1.0 nm. This protocol was successfully demonstrated by fabricating more than 385 nanogaps on a 4 inch wafer. The reproducible fabrication of nanogaps in the range between 0.3 and 1.0 nm opens up new perspectives for addressing the electrical and reactivity properties of single molecules and clusters in confined space under well-controlled conditions.
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Affiliation(s)
- Yexian Wu
- Sensors, Actuators and Microsystems Laboratory (SAMLAB), École Polytechnique Fédérale de Lausanne (EPFL), CH-2002, Neuchâtel, Switzerland.
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Aradhya SV, Venkataraman L. Single-molecule junctions beyond electronic transport. NATURE NANOTECHNOLOGY 2013; 8:399-410. [PMID: 23736215 DOI: 10.1038/nnano.2013.91] [Citation(s) in RCA: 459] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 04/22/2013] [Indexed: 05/21/2023]
Abstract
The idea of using individual molecules as active electronic components provided the impetus to develop a variety of experimental platforms to probe their electronic transport properties. Among these, single-molecule junctions in a metal-molecule-metal motif have contributed significantly to our fundamental understanding of the principles required to realize molecular-scale electronic components from resistive wires to reversible switches. The success of these techniques and the growing interest of other disciplines in single-molecule-level characterization are prompting new approaches to investigate metal-molecule-metal junctions with multiple probes. Going beyond electronic transport characterization, these new studies are highlighting both the fundamental and applied aspects of mechanical, optical and thermoelectric properties at the atomic and molecular scales. Furthermore, experimental demonstrations of quantum interference and manipulation of electronic and nuclear spins in single-molecule circuits are heralding new device concepts with no classical analogues. In this Review, we present the emerging methods being used to interrogate multiple properties in single molecule-based devices, detail how these measurements have advanced our understanding of the structure-function relationships in molecular junctions, and discuss the potential for future research and applications.
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Affiliation(s)
- Sriharsha V Aradhya
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
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Pobelov IV, Mohos M, Yoshida K, Kolivoska V, Avdic A, Lugstein A, Bertagnolli E, Leonhardt K, Denuault G, Gollas B, Wandlowski T. Electrochemical current-sensing atomic force microscopy in conductive solutions. NANOTECHNOLOGY 2013; 24:115501. [PMID: 23448801 DOI: 10.1088/0957-4484/24/11/115501] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Insulated atomic force microscopy probes carrying gold conductive tips were fabricated and employed as bifunctional force and current sensors in electrolyte solutions under electrochemical potential control. The application of the probes for current-sensing imaging, force and current-distance spectroscopy as well as scanning electrochemical microscopy experiments was demonstrated.
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Affiliation(s)
- Ilya V Pobelov
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland.
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Chen IWP, Tseng WH, Gu MW, Su LC, Hsu CH, Chang WH, Chen CH. Tactile-feedback stabilized molecular junctions for the measurement of molecular conductance. Angew Chem Int Ed Engl 2013; 52:2449-53. [PMID: 23341350 DOI: 10.1002/anie.201207116] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 12/05/2012] [Indexed: 11/08/2022]
Abstract
Handling the (AFM) tip: The duration of stable molecular junctions was prolonged using a tactile feedback method in which the operator can sense the force of the AFM tip on the sample surface. The movement of the tip is adjusted accordingly, maintaining a more consistent current (i) and voltage (V), instead of having the tip move at a constant preset speed, as in the conventional setup.
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Affiliation(s)
- I-Wen Peter Chen
- Department of Applied Science, National Taitung University, Taitung, Taiwan 95002, Taiwan
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Chen IWP, Tseng WH, Gu MW, Su LC, Hsu CH, Chang WH, Chen CH. Tactile-Feedback Stabilized Molecular Junctions for the Measurement of Molecular Conductance. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201207116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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