1
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Qiao X, Sil A, Sangtarash S, Smith SM, Wu C, Robertson CM, Nichols RJ, Higgins SJ, Sadeghi H, Vezzoli A. Nuclear Magnetic Resonance Chemical Shift as a Probe for Single-Molecule Charge Transport. Angew Chem Int Ed Engl 2024; 63:e202402413. [PMID: 38478719 DOI: 10.1002/anie.202402413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Indexed: 04/05/2024]
Abstract
Existing modelling tools, developed to aid the design of efficient molecular wires and to better understand their charge-transport behaviour and mechanism, have limitations in accuracy and computational cost. Further research is required to develop faster and more precise methods that can yield information on how charge transport properties are impacted by changes in the chemical structure of a molecular wire. In this study, we report a clear semilogarithmic correlation between charge transport efficiency and nuclear magnetic resonance chemical shifts in multiple series of molecular wires, also accounting for the presence of chemical substituents. The NMR data was used to inform a simple tight-binding model that accurately captures the experimental single-molecule conductance values, especially useful in this case as more sophisticated density functional theory calculations fail due to inherent limitations. Our study demonstrates the potential of NMR spectroscopy as a valuable tool for characterising, rationalising, and gaining additional insights on the charge transport properties of single-molecule junctions.
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Affiliation(s)
- X Qiao
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - A Sil
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - S Sangtarash
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - S M Smith
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - C Wu
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
- Institute of Optoelectronic Materials and Devices, Faculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou, 341000, China
| | - C M Robertson
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - R J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - S J Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - H Sadeghi
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - A Vezzoli
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
- Stephenson Institute for Renewable Energy, University of Liverpool, Peach Street, Liverpool, L69 7ZF, United Kingdom
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2
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Jago D, Liu C, Daaoub AHS, Gaschk E, Walkey MC, Pulbrook T, Qiao X, Sobolev AN, Moggach SA, Costa-Milan D, Higgins SJ, Piggott MJ, Sadeghi H, Nichols RJ, Sangtarash S, Vezzoli A, Koutsantonis GA. An Orthogonal Conductance Pathway in Spiropyrans for Well-Defined Electrosteric Switching Single-Molecule Junctions. Small 2024; 20:e2306334. [PMID: 37817372 DOI: 10.1002/smll.202306334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Indexed: 10/12/2023]
Abstract
While a multitude of studies have appeared touting the use of molecules as electronic components, the design of molecular switches is crucial for the next steps in molecular electronics. In this work, single-molecule devices incorporating spiropyrans, made using break junction techniques, are described. Linear spiropyrans with electrode-contacting groups linked by alkynyl spacers to both the indoline and chromenone moieties have previously provided very low conductance values, and removing the alkynyl spacer has resulted in a total loss of conductance. An orthogonal T-shaped approach to single-molecule junctions incorporating spiropyran moieties in which the conducting pathway lies orthogonal to the molecule backbone is described and characterized. This approach has provided singlemolecule conductance features with good correlation to molecular length. Additional higher conducting states are accessible using switching induced by UV light or protonation. Theoretical modeling demonstrates that upon (photo)chemical isomerization to the merocyanine, two cooperating phenomena increase conductance: release of steric hindrance allows the conductance pathway to become more planar (raising the mid-bandgap transmission) and a bound state introduces sharp interference near the Fermi level of the electrodes similarly responding to the change in state. This design step paves the way for future use of spiropyrans in single-molecule devices and electrosteric switches.
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Affiliation(s)
- David Jago
- School of Molecular Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Chongguang Liu
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | | | - Emma Gaschk
- School of Molecular Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Mark C Walkey
- School of Molecular Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Thea Pulbrook
- School of Molecular Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Xiaohang Qiao
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Alexandre N Sobolev
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Stephen A Moggach
- School of Molecular Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - David Costa-Milan
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Matthew J Piggott
- School of Molecular Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Hatef Sadeghi
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Sara Sangtarash
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - George A Koutsantonis
- School of Molecular Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
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3
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Sil A, Alsaqer M, Spano CE, Larbi A, Higgins SJ, Robertson CM, Graziano M, Sangtarash S, Nichols RJ, Sadeghi H, Vezzoli A. Mechanical Manipulation of Quantum Interference in Single-Molecule Junctions. Small 2024:e2308865. [PMID: 38221684 DOI: 10.1002/smll.202308865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/07/2023] [Indexed: 01/16/2024]
Abstract
Mechanosensitive molecular junctions, where conductance is sensitive to an applied stress such as force or displacement, are a class of nanoelectromechanical systems unique for their ability to exploit quantum mechanical phenomena. Most studies so far relied on reconfiguration of the molecule-electrode interface to impart mechanosensitivity, but this approach is limited and, generally, poorly reproducible. Alternatively, devices that exploit conformational flexibility of molecular wires have been recently proposed. The mechanosensitive properties of molecular wires containing the 1,1'-dinaphthyl moiety are presented here. Rotation along the chemical bond between the two naphthyl units is possible, giving rise to two conformers (transoid and cisoid) that have distinctive transport properties. When assembled as single-molecule junctions, it is possible to mechanically trigger the transoid to cisoid transition, resulting in an exquisitely sensitive mechanical switch with high switching ratio (> 102 ). Theoretical modeling shows that charge reconfiguration upon transoid to cisoid transition is responsible for the observed behavior, with generation and subsequent lifting of quantum interference features. These findings expand the experimental toolbox of molecular electronics with a novel chemical structure with outstanding electromechanical properties, further demonstrating the importance of subtle changes in charge delocalization on the transport properties of single-molecule devices.
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Affiliation(s)
- Amit Sil
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Munirah Alsaqer
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Chiara E Spano
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
- Department of Electronics and Telecommunications, Politecnico di Torino, Corso Duca degli Abruzzi, Torino, 10129, Italy
| | - Adam Larbi
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Craig M Robertson
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Mariagrazia Graziano
- Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi, Torino, 10129, Italy
| | - Sara Sangtarash
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Hatef Sadeghi
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
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4
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Chelli Y, Ferri N, Vezzoli A, Davidson RJ, Morris J, Nichols RJ, Higgins SJ, Sangtarash S, Sadeghi H, Yufit DS, Beeby A. Connectivity-Dependent Conductance of 2,2'-Bipyridine-Based Metal Complexes. ACS Omega 2023; 8:48958-48965. [PMID: 38162767 PMCID: PMC10753655 DOI: 10.1021/acsomega.3c06555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 01/03/2024]
Abstract
The present work provides an insight into the effect of connectivity isomerization of metal-2,2'-bipyridine complexes. For that purpose, two new 2,2'-bipyridine (bpy) ligand systems, 4,4'-bis(4-(methylthio)phenyl)-2,2'-bipyridine (Lmeta) and 5,5'-bis(3,3-dimethyl-2,3-dihydrobenzothiophen-5-yl)-2,2'-bipyridine (Lpara) were synthesized and coordinated to rhenium and manganese to obtain the corresponding complexes MnLmeta(CO)3Br, ReLmeta(CO)3Br, MnLpara(CO)3Br, MoLpara(CO)4 and ReLpara(CO)3Br. The experimental and theoretical results revealed that coordination to the para system, i.e., the metal ion peripheral to the conductance path, gave a slightly increased conductance compared to the free ligand attributed to the reduced highest occupied molecular orbital (HOMO)-least unoccupied molecular orbital (LUMO) gap. The meta-based system formed a destructive quantum interference feature that reduced the conductance of a S···S contacted junction to below 10-5.5Go, reinforcing the importance of contact group connectivity for molecular wire conductance.
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Affiliation(s)
- Yahia Chelli
- School
of Engineering, University of Warwick, Library Road, Coventry CV4 7AL, U.K.
| | - Nicolò Ferri
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Andrea Vezzoli
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Ross J. Davidson
- Department
of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K.
| | - James Morris
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Richard J. Nichols
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Simon J. Higgins
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Sara Sangtarash
- School
of Engineering, University of Warwick, Library Road, Coventry CV4 7AL, U.K.
| | - Hatef Sadeghi
- School
of Engineering, University of Warwick, Library Road, Coventry CV4 7AL, U.K.
| | - Dmitry S. Yufit
- Department
of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew Beeby
- Department
of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K.
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5
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Bara-Estaún A, Planje IJ, Almughathawi R, Naghibi S, Vezzoli A, Milan DC, Lambert C, Martin S, Cea P, Nichols RJ, Higgins SJ, Yufit DS, Sangtarash S, Davidson RJ, Beeby A. Single-Molecule Conductance Behavior of Molecular Bundles. Inorg Chem 2023; 62:20940-20947. [PMID: 38078891 PMCID: PMC10751792 DOI: 10.1021/acs.inorgchem.3c01943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 10/18/2023] [Accepted: 11/27/2023] [Indexed: 12/26/2023]
Abstract
Controlling the orientation of complex molecules in molecular junctions is crucial to their development into functional devices. To date, this has been achieved through the use of multipodal compounds (i.e., containing more than two anchoring groups), resulting in the formation of tri/tetrapodal compounds. While such compounds have greatly improved orientation control, this comes at the cost of lower surface coverage. In this study, we examine an alternative approach for generating multimodal compounds by binding multiple independent molecular wires together through metal coordination to form a molecular bundle. This was achieved by coordinating iron(II) and cobalt(II) to 5,5'-bis(methylthio)-2,2'-bipyridine (L1) and (methylenebis(4,1-phenylene))bis(1-(5-(methylthio)pyridin-2-yl)methanimine) (L2) to give two monometallic complexes, Fe-1 and Co-1, and two bimetallic helicates, Fe-2 and Co-2. Using XPS, all of the complexes were shown to bind to a gold surface in a fac fashion through three thiomethyl groups. Using single-molecule conductance and DFT calculations, each of the ligands was shown to conduct as an independent wire with no impact from the rest of the complex. These results suggest that this is a useful approach for controlling the geometry of junction formation without altering the conductance behavior of the individual molecular wires.
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Affiliation(s)
| | - Inco J. Planje
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Renad Almughathawi
- Department
of Physics, Faculty of Science, Taibah University, Madinah 42353, Saudi Arabia
- Department
of Physics, University of Lancaster, Lancaster LA1 4YB, U.K.
| | - Saman Naghibi
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Andrea Vezzoli
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - David C. Milan
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Colin Lambert
- Department
of Physics, University of Lancaster, Lancaster LA1 4YB, U.K.
| | - Santiago Martin
- Instituto
de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain
- Departamento
de Química Física, Universidad
de Zaragoza, 50009 Zaragoza, Spain
- Laboratorio
de Microscopias Avanzadas (LMA), Universidad
de Zaragoza, 50018 Zaragoza, Spain
| | - Pilar Cea
- Instituto
de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain
- Departamento
de Química Física, Universidad
de Zaragoza, 50009 Zaragoza, Spain
- Laboratorio
de Microscopias Avanzadas (LMA), Universidad
de Zaragoza, 50018 Zaragoza, Spain
| | - Richard J. Nichols
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Simon J. Higgins
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Dmitry S. Yufit
- Department
of Chemistry, Durham University, South Rd, Durham DH1 3LE, U.K.
| | - Sara Sangtarash
- School
of Engineering, University of Warwick, Coventry CV4 7AL, U.K.
| | - Ross J. Davidson
- Department
of Chemistry, Durham University, South Rd, Durham DH1 3LE, U.K.
| | - Andrew Beeby
- Department
of Chemistry, Durham University, South Rd, Durham DH1 3LE, U.K.
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6
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Qiao X, Vezzoli A, Smith S, Higgins SJ, Davidson RJ, Beeby A, Nichols RJ. Single-Molecule Junction Formation in Deep Eutectic Solvents with Highly Effective Gate Coupling. J Phys Chem C Nanomater Interfaces 2023; 127:12802-12810. [PMID: 37435408 PMCID: PMC10331827 DOI: 10.1021/acs.jpcc.3c03129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/07/2023] [Indexed: 07/13/2023]
Abstract
The environment surrounding a molecular junction affects its charge-transport properties and, therefore, must be chosen with care. In the case of measurements in liquid media, the solvent must provide good solvation, grant junction stability, and, in the case of electrolyte gating experiments, allow efficient electrical coupling to the gate electrodes through control of the electrical double layer. We evaluated in this study the deep eutectic solvent mixture (DES) ethaline, which is a mixture of choline chloride and ethylene glycol (1:2), for single-molecule junction fabrication with break-junction techniques. In ethaline, we were able to (i) measure challenging and poorly soluble molecular wires, exploiting the improved solvation capabilities offered by DESs, and (ii) efficiently apply an electrostatic gate able to modulate the conductance of the junction by approximately an order of magnitude within a ∼1 V potential window. The electrochemical gating results on a Au-VDP-Au junction follow exceptionally well the single-level modeling with strong gate coupling (where VDP is 1,2-di(pyridine-4-yl)ethene). Ethaline is also an ideal solvent for the measurement of very short molecular junctions, as it grants a greatly reduced snapback distance of the metallic electrodes upon point-contact rupture. Our work demonstrates that DESs are viable alternatives to often relatively expensive ionic liquids, offering good versatility for single-molecule electrical measurements.
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Affiliation(s)
- Xiaohang Qiao
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Andrea Vezzoli
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Shaun Smith
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Simon J. Higgins
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
| | - Ross J. Davidson
- Department
of Chemistry, Durham University, South Rd, Durham DH1 3LE, U.K.
| | - Andrew Beeby
- Department
of Chemistry, Durham University, South Rd, Durham DH1 3LE, U.K.
| | - Richard J. Nichols
- Department
of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
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7
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Daaoub A, Morris JMF, Béland VA, Demay‐Drouhard P, Hussein A, Higgins SJ, Sadeghi H, Nichols RJ, Vezzoli A, Baumgartner T, Sangtarash S. Not So Innocent After All: Interfacial Chemistry Determines Charge-Transport Efficiency in Single-Molecule Junctions. Angew Chem Int Ed Engl 2023; 62:e202302150. [PMID: 37029093 PMCID: PMC10953449 DOI: 10.1002/anie.202302150] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/24/2023] [Accepted: 04/06/2023] [Indexed: 04/09/2023]
Abstract
Most studies in molecular electronics focus on altering the molecular wire backbone to tune the electrical properties of the whole junction. However, it is often overlooked that the chemical structure of the groups anchoring the molecule to the metallic electrodes influences the electronic structure of the whole system and, therefore, its conductance. We synthesised electron-accepting dithienophosphole oxide derivatives and fabricated their single-molecule junctions. We found that the anchor group has a dramatic effect on charge-transport efficiency: in our case, electron-deficient 4-pyridyl contacts suppress conductance, while electron-rich 4-thioanisole termini promote efficient transport. Our calculations show that this is due to minute changes in charge distribution, probed at the electrode interface. Our findings provide a framework for efficient molecular junction design, especially valuable for compounds with strong electron withdrawing/donating backbones.
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Affiliation(s)
- Abdalghani Daaoub
- Device Modelling GroupSchool of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| | - James M. F. Morris
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Vanessa A. Béland
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Paul Demay‐Drouhard
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Amaar Hussein
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Simon J. Higgins
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Hatef Sadeghi
- Device Modelling GroupSchool of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| | - Richard J. Nichols
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Andrea Vezzoli
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Thomas Baumgartner
- Department of ChemistryYork University4700 Keele StreetTorontoON, M3J 1P3Canada
| | - Sara Sangtarash
- Device Modelling GroupSchool of EngineeringUniversity of WarwickCoventryCV4 7ALUK
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8
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Zhou P, Qiao X, Milan DC, Higgins SJ, Vezzoli A, Nichols RJ. Enhanced charge transport across molecule-nanoparticle-molecule sandwiches. Phys Chem Chem Phys 2023; 25:7176-7183. [PMID: 36810584 DOI: 10.1039/d2cp05525b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The electrical properties of large area molecular devices consisting of gold nanoparticles (GNPs) sandwiched between a double layer of alkanedithiol linkers have been examined. These devices have been fabricated by a facile bottom-up assembly in which an alkanedithiol monolayer is first self-assembled on an underlying gold substrate followed by nanoparticle adsorption and then finally assembly of the top alkanedithiol layer. These devices are then sandwiched between the bottom gold substrates and a top eGaIn probe contact and current-voltage (I-V) curves recorded. Devices have been fabricated with 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol and 1,10-decanedithiol linkers. In all cases the electrical conductance of the double SAM junctions with GNPs is higher than the corresponding and much thinner single alkanedithiol SAM. Competing models for this enhanced conductance are discussed and it is suggested to have a topological origin arising from how the devices assemble or structure during the fabrication, which gives more efficient cross device electron transport pathways without the GNPs producing short circuits.
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Affiliation(s)
- P Zhou
- Yangzhou Polytechnic Institute, No. 199, Huayang West Road, Yangzhou City, Jiangsu Province, China.,Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK.
| | - X Qiao
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK.
| | - D C Milan
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK.
| | - S J Higgins
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK.
| | - A Vezzoli
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK.
| | - R J Nichols
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK.
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9
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Roemer M, Gillespie A, Jago D, Costa-Milan D, Alqahtani J, Hurtado-Gallego J, Sadeghi H, Lambert CJ, Spackman PR, Sobolev AN, Skelton BW, Grosjean A, Walkey M, Kampmann S, Vezzoli A, Simpson PV, Massi M, Planje I, Rubio-Bollinger G, Agraït N, Higgins SJ, Sangtarash S, Piggott MJ, Nichols RJ, Koutsantonis GA. 2,7- and 4,9-Dialkynyldihydropyrene Molecular Switches: Syntheses, Properties, and Charge Transport in Single-Molecule Junctions. J Am Chem Soc 2022; 144:12698-12714. [PMID: 35767015 DOI: 10.1021/jacs.2c02289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper describes the syntheses of several functionalized dihydropyrene (DHP) molecular switches with different substitution patterns. Regioselective nucleophilic alkylation of a 5-substituted dimethyl isophthalate allowed the development of a workable synthetic protocol for the preparation of 2,7-alkyne-functionalized DHPs. Synthesis of DHPs with surface-anchoring groups in the 2,7- and 4,9-positions is described. The molecular structures of several intermediates and DHPs were elucidated by X-ray single-crystal diffraction. Molecular properties and switching capabilities of both types of DHPs were assessed by light irradiation experiments, spectroelectrochemistry, and cyclic voltammetry. Spectroelectrochemistry, in combination with density functional theory (DFT) calculations, shows reversible electrochemical switching from the DHP forms to the cyclophanediene (CPD) forms. Charge-transport behavior was assessed in single-molecule scanning tunneling microscope (STM) break junctions, combined with density functional theory-based quantum transport calculations. All DHPs with surface-contacting groups form stable molecular junctions. Experiments show that the molecular conductance depends on the substitution pattern of the DHP motif. The conductance was found to decrease with increasing applied bias.
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Affiliation(s)
- Max Roemer
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Angus Gillespie
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - David Jago
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - David Costa-Milan
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Jehan Alqahtani
- Department of Physics, King Khalid University, Abha 62529, Saudi Arabia
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Juan Hurtado-Gallego
- Condensed Matter Physics Center (IFIMAC) and Instituto Universitatio de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Hatef Sadeghi
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Peter R Spackman
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Alexandre N Sobolev
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009, Australia
| | - Brian W Skelton
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009, Australia
| | - Arnaud Grosjean
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Mark Walkey
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Sven Kampmann
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Peter V Simpson
- School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia
| | - Massimiliano Massi
- School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia
| | - Inco Planje
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Gabino Rubio-Bollinger
- Condensed Matter Physics Center (IFIMAC) and Instituto Universitatio de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Nicolás Agraït
- Condensed Matter Physics Center (IFIMAC) and Instituto Universitatio de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia IMDEA-Nanociencia, E-28049 Madrid, Spain
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Sara Sangtarash
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Matthew J Piggott
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - George A Koutsantonis
- Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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10
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Naghibi S, Sangtarash S, Kumar VJ, Wu J, Judd MM, Qiao X, Gorenskaia E, Higgins SJ, Cox N, Nichols RJ, Sadeghi H, Low PJ, Vezzoli A. Redox-Addressable Single-Molecule Junctions Incorporating a Persistent Organic Radical. Angew Chem Int Ed Engl 2022; 61:e202116985. [PMID: 35289977 PMCID: PMC9322687 DOI: 10.1002/anie.202116985] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Indexed: 12/14/2022]
Abstract
Integrating radical (open-shell) species into non-cryogenic nanodevices is key to unlocking the potential of molecular electronics. While many efforts have been devoted to this issue, in the absence of a chemical/electrochemical potential the open-shell character is generally lost in contact with the metallic electrodes. Herein, single-molecule devices incorporating a 6-oxo-verdazyl persistent radical have been fabricated using break-junction techniques. The open-shell character is retained at room temperature, and electrochemical gating permits in situ reduction to a closed-shell anionic state in a single-molecule transistor configuration. Furthermore, electronically driven rectification arises from bias-dependent alignment of the open-shell resonances. The integration of radical character, transistor-like switching, and rectification in a single molecular component paves the way to further studies of the electronic, magnetic, and thermoelectric properties of open-shell species.
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Affiliation(s)
- Saman Naghibi
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | | | - Varshini J. Kumar
- School of Molecular SciencesUniversity of Western AustraliaCrawleyWestern Australia6009Australia
| | - Jian‐Zhong Wu
- School of ChemistrySouth China Normal UniversityGuangzhou510006P.R. China
| | - Martyna M. Judd
- Research School of ChemistryAustralian National UniversityCanberraATC 2601Australia
| | - Xiaohang Qiao
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Elena Gorenskaia
- School of Molecular SciencesUniversity of Western AustraliaCrawleyWestern Australia6009Australia
| | - Simon J. Higgins
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Nicholas Cox
- Research School of ChemistryAustralian National UniversityCanberraATC 2601Australia
| | - Richard J. Nichols
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Hatef Sadeghi
- School of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| | - Paul J. Low
- School of Molecular SciencesUniversity of Western AustraliaCrawleyWestern Australia6009Australia
| | - Andrea Vezzoli
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
- Stephenson Institute for Renewable EnergyUniversity of LiverpoolPeach StreetLiverpoolL69 7ZFUK
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11
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Naghibi S, Sangtarash S, Kumar VJ, Wu J, Judd MM, Qiao X, Gorenskaia E, Higgins SJ, Cox N, Nichols RJ, Sadeghi H, Low PJ, Vezzoli A. Redox‐Addressable Single‐Molecule Junctions Incorporating a Persistent Organic Radical**. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202116985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Saman Naghibi
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Sara Sangtarash
- School of Engineering University of Warwick Coventry CV4 7AL UK
| | - Varshini J. Kumar
- School of Molecular Sciences University of Western Australia Crawley Western Australia 6009 Australia
| | - Jian‐Zhong Wu
- School of Chemistry South China Normal University Guangzhou 510006 P.R. China
| | - Martyna M. Judd
- Research School of Chemistry Australian National University Canberra ATC 2601 Australia
| | - Xiaohang Qiao
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Elena Gorenskaia
- School of Molecular Sciences University of Western Australia Crawley Western Australia 6009 Australia
| | - Simon J. Higgins
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Nicholas Cox
- Research School of Chemistry Australian National University Canberra ATC 2601 Australia
| | - Richard J. Nichols
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Hatef Sadeghi
- School of Engineering University of Warwick Coventry CV4 7AL UK
| | - Paul J. Low
- School of Molecular Sciences University of Western Australia Crawley Western Australia 6009 Australia
| | - Andrea Vezzoli
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
- Stephenson Institute for Renewable Energy University of Liverpool Peach Street Liverpool L69 7ZF UK
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12
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Tao S, Zhang Q, Vezzoli A, Zhao C, Zhao C, Higgins SJ, Smogunov A, Dappe YJ, Nichols RJ, Yang L. Electrochemical gating for single-molecule electronics with hybrid Au|graphene contacts. Phys Chem Chem Phys 2022; 24:6836-6844. [PMID: 35244656 DOI: 10.1039/d1cp05486d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The single-molecular conductance of a redox active viologen molecular bridge between Au|graphene electrodes has been studied in an electrochemical gating configuration in an ionic liquid medium. A clear "off-on-off" conductance switching behaviour has been achieved through gating of the redox state when the electrochemical potential is swept. The Au|viologen|graphene junctions show single-molecule conductance maxima centred close to the equilibrium redox potentials for both reduction steps. The peak conductance of Au|viologen|graphene junctions during the first reduction is significantly higher than that of previously measured Au|viologen|Au junctions. This shows that even though the central viologen moiety is not directly linked to the enclosing electrodes, substituting one gold contact for a graphene one nevertheless has a significant impact on junction conductance values. The experimental data was compared against two theoretical models, namely a phase coherent tunnelling and an incoherent "hopping" model. The former is a simple gating monoelectronic model within density functional theory (DFT) which discloses the charge state evolution of the molecule with electrode potential. The latter model is the collective Kuznetsov Ulstrup model for 2-step sequential charge transport through the redox centre in the adiabatic limit. The comparison of both models to the experimental data is discussed for the first time. This work opens perspectives for graphene-based molecular transistors with more effective gating and fundamental understanding of electrochemical electron transfer at the single molecular level.
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Affiliation(s)
- Shuhui Tao
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, Suzhou, 215123, China. .,Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Qian Zhang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, Suzhou, 215123, China. .,Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Cezhou Zhao
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University, Suzhou, 215123, China
| | - Chun Zhao
- Department of Electrical and Electronic Engineering, Xi'an-Jiaotong Liverpool University, Suzhou, 215123, China
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Alexander Smogunov
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Li Yang
- Department of Chemistry, Xi'an-Jiaotong Liverpool University, Suzhou, 215123, China. .,Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
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13
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Xu W, Leary E, Sangtarash S, Jirasek M, González MT, Christensen KE, Abellán Vicente L, Agraït N, Higgins SJ, Nichols RJ, Lambert CJ, Anderson HL. A Peierls Transition in Long Polymethine Molecular Wires: Evolution of Molecular Geometry and Single-Molecule Conductance. J Am Chem Soc 2021; 143:20472-20481. [PMID: 34817985 DOI: 10.1021/jacs.1c10747] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Molecules capable of mediating charge transport over several nanometers with minimal decay in conductance have fundamental and technological implications. Polymethine cyanine dyes are fascinating molecular wires because up to a critical length, they have no bond-length alternation (BLA) and their electronic structure resembles a one-dimensional free-electron gas. Beyond this threshold, they undergo a symmetry-breaking Peierls transition, which increases the HOMO-LUMO gap. We have investigated cationic cyanines with central polymethine chains of 5-13 carbon atoms (Cy3+-Cy11+). The absorption spectra and crystal structures show that symmetry breaking is sensitive to the polarity of the medium and the size of the counterion. X-ray crystallography reveals that Cy9·PF6 and Cy11·B(C6F5)4 are Peierls distorted, with high BLA at one end of the π-system, away from the partially delocalized positive charge. This pattern of BLA distribution resembles that of solitons in polyacetylene. The single-molecule conductance is essentially independent of molecular length for the polymethine salts of Cy3+-Cy11+ with the large B(C6F5)4- counterion, but with the PF6- counterion, the conductance decreases for the longer molecules, Cy7+-Cy11+, because this smaller anion polarizes the π-system, inducing a symmetry-breaking transition. At higher bias (0.9 V), the conductance of the shorter chains, Cy3+-Cy7+, increases with length (negative attenuation factor, β = -1.6 nm-1), but the conductance still drops in Cy9+ and Cy11+ with the small polarizing PF6- counteranion.
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Affiliation(s)
- Wenjun Xu
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Edmund Leary
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Sara Sangtarash
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Michael Jirasek
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - M Teresa González
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Kirsten E Christensen
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Lydia Abellán Vicente
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Nicolás Agraït
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain.,Departamento de Física de la Materia Condensada, IFIMAC and Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Simon J Higgins
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, United Kingdom
| | - Richard J Nichols
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, United Kingdom
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Harry L Anderson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom
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14
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Xu W, Leary E, Hou S, Sangtarash S, González MT, Rubio‐Bollinger G, Wu Q, Sadeghi H, Tejerina L, Christensen KE, Agraït N, Higgins SJ, Lambert CJ, Nichols RJ, Anderson HL. Berichtigung: Unusual Length Dependence of the Conductance in Cumulene Molecular Wires. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Xu W, Leary E, Hou S, Sangtarash S, González MT, Rubio-Bollinger G, Wu Q, Sadeghi H, Tejerina L, Christensen KE, Agraït N, Higgins SJ, Lambert CJ, Nichols RJ, Anderson HL. Corrigendum: Unusual Length Dependence of the Conductance in Cumulene Molecular Wires. Angew Chem Int Ed Engl 2021; 60:9170. [PMID: 33844403 PMCID: PMC8173639 DOI: 10.1002/anie.202102667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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16
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Naher M, Milan DC, Al-Owaedi OA, Planje IJ, Bock S, Hurtado-Gallego J, Bastante P, Abd Dawood ZM, Rincón-García L, Rubio-Bollinger G, Higgins SJ, Agraït N, Lambert CJ, Nichols RJ, Low PJ. Molecular Structure-(Thermo)electric Property Relationships in Single-Molecule Junctions and Comparisons with Single- and Multiple-Parameter Models. J Am Chem Soc 2021; 143:3817-3829. [PMID: 33606524 DOI: 10.1021/jacs.0c11605] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The most probable single-molecule conductance of each member of a series of 12 conjugated molecular wires, 6 of which contain either a ruthenium or platinum center centrally placed within the backbone, has been determined. The measurement of a small, positive Seebeck coefficient has established that transmission through these molecules takes place by tunneling through the tail of the HOMO resonance near the middle of the HOMO-LUMO gap in each case. Despite the general similarities in the molecular lengths and frontier-orbital compositions, experimental and computationally determined trends in molecular conductance values across this series cannot be satisfactorily explained in terms of commonly discussed "single-parameter" models of junction conductance. Rather, the trends in molecular conductance are better rationalized from consideration of the complete molecular junction, with conductance values well described by transport calculations carried out at the DFT level of theory, on the basis of the Landauer-Büttiker model.
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Affiliation(s)
- Masnun Naher
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - David C Milan
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Oday A Al-Owaedi
- Department of Laser Physics, College of Science for Girls, The University of Babylon, Hilla 51001, Iraq
| | - Inco J Planje
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Sören Bock
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Juan Hurtado-Gallego
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain
| | - Pablo Bastante
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain
| | - Zahra Murtada Abd Dawood
- Department of Laser Physics, College of Science for Girls, The University of Babylon, Hilla 51001, Iraq
| | - Laura Rincón-García
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain
| | - Gabino Rubio-Bollinger
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain.,Condensed Matter Physics Center (IFIMAC) and Instituto Universitario de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Nicolás Agraït
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain.,Condensed Matter Physics Center (IFIMAC) and Instituto Universitario de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencia IMDEA-Nanociencia, E-28049 Madrid, Spain
| | - Colin J Lambert
- Department of Physics, University of Lancaster, Lancaster LA1 4YB, U.K
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Paul J Low
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
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17
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Planje IJ, Davidson RJ, Vezzoli A, Daaoub A, Sangtarash S, Sadeghi H, Martín S, Cea P, Lambert CJ, Beeby A, Higgins SJ, Nichols RJ. Selective Anchoring Groups for Molecular Electronic Junctions with ITO Electrodes. ACS Sens 2021; 6:530-537. [PMID: 33471521 DOI: 10.1021/acssensors.0c02205] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Indium tin oxide (ITO) is an attractive substrate for single-molecule electronics since it is transparent while maintaining electrical conductivity. Although it has been used before as a contacting electrode in single-molecule electrical studies, these studies have been limited to the use of carboxylic acid terminal groups for binding molecular wires to the ITO substrates. There is thus the need to investigate other anchoring groups with potential for binding effectively to ITO. With this aim, we have investigated the single-molecule conductance of a series of eight tolane or "tolane-like" molecular wires with a variety of surface binding groups. We first used gold-molecule-gold junctions to identify promising targets for ITO selectivity. We then assessed the propensity and selectivity of carboxylic acid, cyanoacrylic acid, and pyridinium-squarate to bind to ITO and promote the formation of molecular heterojunctions. We found that pyridinium squarate zwitterions display excellent selectivity for binding to ITO over gold surfaces, with contact resistivity comparable to that of carboxylic acids. These single-molecule experiments are complemented by surface chemical characterization with X-ray photoelectron spectroscopy, quartz crystal microbalance, contact angle determination, and nanolithography using an atomic force miscroscope. Finally, we report the first density-functional theory calculations involving ITO electrodes to model charge transport through ITO-molecule-gold heterojunctions.
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Affiliation(s)
- Inco J. Planje
- Department of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, United Kingdom
| | - Ross J. Davidson
- Department of Chemistry, Durham University, South Rd, Durham DH1 3LE, United Kingdom
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, United Kingdom
| | - Abdalghani Daaoub
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Sara Sangtarash
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Hatef Sadeghi
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Santiago Martín
- Instituto de Nanociencia y Materiales de Aragón (INMA), Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza 50009 Zaragoza, Spain
| | - Pilar Cea
- Instituto de Nanociencia y Materiales de Aragón (INMA), Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
- Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza 50009 Zaragoza, Spain
| | - Colin J. Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Andrew Beeby
- Department of Chemistry, Durham University, South Rd, Durham DH1 3LE, United Kingdom
| | - Simon J. Higgins
- Department of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, United Kingdom
| | - Richard J. Nichols
- Department of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, United Kingdom
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18
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Leary E, Kastlunger G, Limburg B, Rincón-García L, Hurtado-Gallego J, González MT, Bollinger GR, Agrait N, Higgins SJ, Anderson HL, Stadler R, Nichols RJ. Long-lived charged states of single porphyrin-tape junctions under ambient conditions. Nanoscale Horiz 2021; 6:49-58. [PMID: 33107543 DOI: 10.1039/d0nh00415d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The ability to control the charge state of individual molecules wired in two-terminal single-molecule junctions is a key challenge in molecular electronics, particularly in relation to the development of molecular memory and other computational componentry. Here we demonstrate that single porphyrin molecular junctions can be reversibly charged and discharged at elevated biases under ambient conditions due to the presence of a localised molecular eigenstate close to the Fermi edge of the electrodes. In particular, we can observe long-lived charge-states with lifetimes upwards of 1-10 seconds after returning to low bias and large changes in conductance, in excess of 100-fold at low bias. Our theoretical analysis finds charge-state lifetimes within the same time range as the experiments. The ambient operation demonstrates that special conditions such as low temperatures or ultra-high vacuum are not essential to observe hysteresis and stable charged molecular junctions.
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Affiliation(s)
- Edmund Leary
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, UK.
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19
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Wu C, Bates D, Sangtarash S, Ferri N, Thomas A, Higgins SJ, Robertson CM, Nichols RJ, Sadeghi H, Vezzoli A. Folding a Single-Molecule Junction. Nano Lett 2020; 20:7980-7986. [PMID: 33047599 PMCID: PMC7662913 DOI: 10.1021/acs.nanolett.0c02815] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 10/07/2020] [Indexed: 06/11/2023]
Abstract
Stimuli-responsive molecular junctions, where the conductance can be altered by an external perturbation, are an important class of nanoelectronic devices. These have recently attracted interest as large effects can be introduced through exploitation of quantum phenomena. We show here that significant changes in conductance can be attained as a molecule is repeatedly compressed and relaxed, resulting in molecular folding along a flexible fragment and cycling between an anti and a syn conformation. Power spectral density analysis and DFT transport calculations show that through-space tunneling between two phenyl fragments is responsible for the conductance increase as the molecule is mechanically folded to the syn conformation. This phenomenon represents a novel class of mechanoresistive molecular devices, where the functional moiety is embedded in the conductive backbone and exploits intramolecular nonbonding interactions, in contrast to most studies where mechanoresistivity arises from changes in the molecule-electrode interface.
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Affiliation(s)
- Chuanli Wu
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United
Kingdom
- School
of Chemistry and Materials Science, Nanjing
Normal University, Nanjing 210023, People’s Republic
of China
| | - Demetris Bates
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United
Kingdom
| | - Sara Sangtarash
- School
of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Nicoló Ferri
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United
Kingdom
| | - Aidan Thomas
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United
Kingdom
| | - Simon J. Higgins
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United
Kingdom
| | - Craig M. Robertson
- 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
| | - Hatef Sadeghi
- School
of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Andrea Vezzoli
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United
Kingdom
- Stephenson
Institute for Renewable Energy, University
of Liverpool, Peach Street, Liverpool L69 7ZF, United Kingdom
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20
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Wu C, Qiao X, Robertson CM, Higgins SJ, Cai C, Nichols RJ, Vezzoli A. A Chemically Soldered Polyoxometalate Single-Molecule Transistor. Angew Chem Int Ed Engl 2020; 59:12029-12034. [PMID: 32271489 PMCID: PMC7383859 DOI: 10.1002/anie.202002174] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/25/2020] [Indexed: 01/23/2023]
Abstract
Polyoxometalates have been proposed in the literature as nanoelectronic components, where they could offer key advantages with their structural versatility and rich electrochemistry. Apart from a few studies on their ensemble behaviour (as monolayers or thin films), this potential remains largely unexplored. We synthesised a pyridyl-capped Anderson-Evans polyoxometalate and used it to fabricate single-molecule junctions, using the organic termini to chemically "solder" a single cluster to two nanoelectrodes. Operating the device in an electrochemical environment allowed us to probe charge transport through different oxidation states of the polyoxometalate, and we report here an efficient three-state transistor behaviour. Conductance data fits a quantum tunnelling mechanism with different charge-transport probabilities through different charge states. Our results show the promise of polyoxometalates in nanoelectronics and give an insight on their single-entity electrochemical behaviour.
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Affiliation(s)
- Chuanli Wu
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
- School of Chemistry and Materials ScienceNanjing Normal UniversityNanjing210023P. R. China
| | - Xiaohang Qiao
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Craig M. Robertson
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Simon J. Higgins
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Chenxin Cai
- School of Chemistry and Materials ScienceNanjing Normal UniversityNanjing210023P. R. China
| | - Richard J. Nichols
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Andrea Vezzoli
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
- Stephenson Institute for Renewable EnergyUniversity of LiverpoolPeach StreetLiverpoolL69 7ZFUK
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21
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Reddy H, Wang K, Kudyshev Z, Zhu L, Yan S, Vezzoli A, Higgins SJ, Gavini V, Boltasseva A, Reddy P, Shalaev VM, Meyhofer E. Determining plasmonic hot-carrier energy
distributions via single-molecule transport
measurements. Science 2020; 369:423-426. [DOI: 10.1126/science.abb3457] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 05/21/2020] [Indexed: 01/07/2023]
Abstract
Hot carriers in plasmonic nanostructures,
generated via plasmon decay, play key roles in
applications such as photocatalysis and in
photodetectors that circumvent bandgap
limitations. However, direct experimental
quantification of steady-state energy
distributions of hot carriers in nanostructures
has so far been lacking. We present transport
measurements from single-molecule junctions,
created by trapping suitably chosen single
molecules between an ultrathin gold film
supporting surface plasmon polaritons and a
scanning probe tip, that can provide
quantification of plasmonic hot-carrier
distributions. Our results show that Landau
damping is the dominant physical mechanism of
hot-carrier generation in nanoscale systems with
strong confinement. The technique developed in
this work will enable quantification of plasmonic
hot-carrier distributions in nanophotonic and
plasmonic devices.
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Affiliation(s)
- Harsha Reddy
- School of Electrical and Computer
Engineering, Purdue University, West Lafayette, IN
47907, USA
| | - Kun Wang
- Department of Mechanical Engineering,
University of Michigan, Ann Arbor, MI 48109,
USA
| | - Zhaxylyk Kudyshev
- School of Electrical and Computer
Engineering, Purdue University, West Lafayette, IN
47907, USA
- Center for Science of Information,
Purdue University, West Lafayette, IN 47907,
USA
| | - Linxiao Zhu
- Department of Mechanical Engineering,
University of Michigan, Ann Arbor, MI 48109,
USA
| | - Shen Yan
- Department of Mechanical Engineering,
University of Michigan, Ann Arbor, MI 48109,
USA
| | - Andrea Vezzoli
- Department of Chemistry, University
of Liverpool, Liverpool L69 7ZD, UK
| | - Simon J. Higgins
- Department of Chemistry, University
of Liverpool, Liverpool L69 7ZD, UK
| | - Vikram Gavini
- Department of Mechanical Engineering,
University of Michigan, Ann Arbor, MI 48109,
USA
- Department of Materials Science and
Engineering, University of Michigan, Ann Arbor, MI
48109, USA
| | - Alexandra Boltasseva
- School of Electrical and Computer
Engineering, Purdue University, West Lafayette, IN
47907, USA
| | - Pramod Reddy
- Department of Mechanical Engineering,
University of Michigan, Ann Arbor, MI 48109,
USA
- Department of Materials Science and
Engineering, University of Michigan, Ann Arbor, MI
48109, USA
| | - Vladimir M. Shalaev
- School of Electrical and Computer
Engineering, Purdue University, West Lafayette, IN
47907, USA
| | - Edgar Meyhofer
- Department of Mechanical Engineering,
University of Michigan, Ann Arbor, MI 48109,
USA
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22
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Wu C, Qiao X, Robertson CM, Higgins SJ, Cai C, Nichols RJ, Vezzoli A. A Chemically Soldered Polyoxometalate Single‐Molecule Transistor. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202002174] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Chuanli Wu
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
- School of Chemistry and Materials Science Nanjing Normal University Nanjing 210023 P. R. China
| | - Xiaohang Qiao
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Craig M. Robertson
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Simon J. Higgins
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Chenxin Cai
- School of Chemistry and Materials Science Nanjing Normal University Nanjing 210023 P. R. China
| | - Richard J. Nichols
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Andrea Vezzoli
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
- Stephenson Institute for Renewable Energy University of Liverpool Peach Street Liverpool L69 7ZF UK
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23
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Wu C, Alqahtani A, Sangtarash S, Vezzoli A, Sadeghi H, Robertson CM, Cai C, Lambert CJ, Higgins SJ, Nichols RJ. In situ formation of H-bonding imidazole chains in break-junction experiments. Nanoscale 2020; 12:7914-7920. [PMID: 32232235 DOI: 10.1039/d0nr00630k] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
As a small molecule possessing both strong H-bond donor and acceptor functions, 1H-imidazole can participate in extensive homo- or heteromolecular H-bonding networks. These properties are important in Nature, as imidazole moieties are incorporated in many biologically-relevant compounds. Imidazole also finds applications ranging from corrosion inhibition to fire retardants and photography. We have found a peculiar behaviour of imidazole during scanning tunnelling microscopy-break junction (STM-BJ) experiments, in which oligomeric chains connect the two electrodes and allow efficient charge transport. We attributed this behaviour to the formation of hydrogen-bonding networks, as no evidence of such behaviour was found in 1-methylimidazole (incapable of participating in intramolecular hydrogen bonding). The results are supported by DFT calculations, which confirmed our hypothesis. These findings pave the road to the use of hydrogen-bonding networks for the fabrication of dynamic junctions based on supramolecular interactions.
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Affiliation(s)
- Chuanli Wu
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
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24
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Ferri N, Algethami N, Vezzoli A, Sangtarash S, McLaughlin M, Sadeghi H, Lambert CJ, Nichols RJ, Higgins SJ. Innenrücktitelbild: Hemilabile Ligands as Mechanosensitive Electrode Contacts for Molecular Electronics (Angew. Chem. 46/2019). Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201913163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Nicolò Ferri
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Norah Algethami
- Department of Physics Lancaster University Lancaster LA1 4YB UK
| | - Andrea Vezzoli
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Sara Sangtarash
- Department of Physics Lancaster University Lancaster LA1 4YB UK
- School of Engineering University of Warwick Coventry CV4 7AL UK
| | - Maeve McLaughlin
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Hatef Sadeghi
- Department of Physics Lancaster University Lancaster LA1 4YB UK
- School of Engineering University of Warwick Coventry CV4 7AL UK
| | | | - Richard J. Nichols
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Simon J. Higgins
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
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25
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Ferri N, Algethami N, Vezzoli A, Sangtarash S, McLaughlin M, Sadeghi H, Lambert CJ, Nichols RJ, Higgins SJ. Hemilabile Ligands as Mechanosensitive Electrode Contacts for Molecular Electronics. Angew Chem Int Ed Engl 2019; 58:16583-16589. [PMID: 31364249 PMCID: PMC6899542 DOI: 10.1002/anie.201906400] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Indexed: 11/21/2022]
Abstract
Single-molecule junctions that are sensitive to compression or elongation are an emerging class of nanoelectromechanical systems (NEMS). Although the molecule-electrode interface can be engineered to impart such functionality, most studies to date rely on poorly defined interactions. We focused on this issue by synthesizing molecular wires designed to have chemically defined hemilabile contacts based on (methylthio)thiophene moieties. We measured their conductance as a function of junction size and observed conductance changes of up to two orders of magnitude as junctions were compressed and stretched. Localised interactions between weakly coordinating thienyl sulfurs and the electrodes are responsible for the observed effect and allow reversible monodentate⇄bidentate contact transitions as the junction is modulated in size. We observed an up to ≈100-fold sensitivity boost of the (methylthio)thiophene-terminated molecular wire compared with its non-hemilabile (methylthio)benzene counterpart and demonstrate a previously unexplored application of hemilabile ligands to molecular electronics.
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Affiliation(s)
- Nicolò Ferri
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | | | - Andrea Vezzoli
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Sara Sangtarash
- Department of PhysicsLancaster UniversityLancasterLA1 4YBUK
- School of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| | - Maeve McLaughlin
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Hatef Sadeghi
- Department of PhysicsLancaster UniversityLancasterLA1 4YBUK
- School of EngineeringUniversity of WarwickCoventryCV4 7ALUK
| | | | - Richard J. Nichols
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
| | - Simon J. Higgins
- Department of ChemistryUniversity of LiverpoolCrown StreetLiverpoolL69 7ZDUK
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26
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Ferri N, Algethami N, Vezzoli A, Sangtarash S, McLaughlin M, Sadeghi H, Lambert CJ, Nichols RJ, Higgins SJ. Inside Back Cover: Hemilabile Ligands as Mechanosensitive Electrode Contacts for Molecular Electronics (Angew. Chem. Int. Ed. 46/2019). Angew Chem Int Ed Engl 2019. [DOI: 10.1002/anie.201913163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Nicolò Ferri
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Norah Algethami
- Department of Physics Lancaster University Lancaster LA1 4YB UK
| | - Andrea Vezzoli
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Sara Sangtarash
- Department of Physics Lancaster University Lancaster LA1 4YB UK
- School of Engineering University of Warwick Coventry CV4 7AL UK
| | - Maeve McLaughlin
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Hatef Sadeghi
- Department of Physics Lancaster University Lancaster LA1 4YB UK
- School of Engineering University of Warwick Coventry CV4 7AL UK
| | | | - Richard J. Nichols
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Simon J. Higgins
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
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27
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Naghibi S, Ismael AK, Vezzoli A, Al-Khaykanee MK, Zheng X, Grace IM, Bethell D, Higgins SJ, Lambert CJ, Nichols RJ. Synthetic Control of Quantum Interference by Regulating Charge on a Single Atom in Heteroaromatic Molecular Junctions. J Phys Chem Lett 2019; 10:6419-6424. [PMID: 31577147 PMCID: PMC7007252 DOI: 10.1021/acs.jpclett.9b02319] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A key area of activity in contemporary molecular electronics is the chemical control of conductance of molecular junctions and devices. Here we study and modify a range of pyrrolodipyridines (carbazole-like) molecular wires. We are able to change the electrical conductance and quantum interference patterns by chemically regulating the bridging nitrogen atom in the tricyclic ring system. A series of eight different N-substituted pyrrolodipyridines has been synthesized and subjected to single-molecule electrical characterization using an STM break junction. Correlations of these experimental data with theoretical calculations underline the importance of the pyrrolic nitrogen in facilitating conductance across the molecular bridge and controlling quantum interference. The large chemical modulation for the meta-connected series is not apparent for the para-series, showing the competition between (i) meta-connectivity quantum interference phenomena and (ii) the ability of the pyrrolic nitrogen to facilitate conductance, that can be modulated by chemical substitution.
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Affiliation(s)
- Saman Naghibi
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Ali K. Ismael
- Department
of Physics, Lancaster University, Lancaster LA1 4YB, U.K.
- Department
of Physics, College of Education for Pure Science, Tikrit University, Tikrit 34001, Iraq
| | - Andrea Vezzoli
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
- E-mail:
| | - Mohsin K. Al-Khaykanee
- Department
of Physics, Lancaster University, Lancaster LA1 4YB, U.K.
- Department
of Physics, College of Science, University
of Babylon, Babylon 51002, Iraq
| | - Xijia Zheng
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Iain M. Grace
- Department
of Physics, Lancaster University, Lancaster LA1 4YB, U.K.
| | - Donald Bethell
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Simon J. Higgins
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Colin J. Lambert
- Department
of Physics, Lancaster University, Lancaster LA1 4YB, U.K.
- E-mail:
| | - Richard J. Nichols
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
- E-mail:
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28
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Ferri N, Algethami N, Vezzoli A, Sangtarash S, McLaughlin M, Sadeghi H, Lambert CJ, Nichols RJ, Higgins SJ. Hemilabile Ligands as Mechanosensitive Electrode Contacts for Molecular Electronics. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201906400] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Nicolò Ferri
- Department of ChemistryUniversity of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Norah Algethami
- Department of PhysicsLancaster University Lancaster LA1 4YB UK
| | - Andrea Vezzoli
- Department of ChemistryUniversity of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Sara Sangtarash
- Department of PhysicsLancaster University Lancaster LA1 4YB UK
- School of EngineeringUniversity of Warwick Coventry CV4 7AL UK
| | - Maeve McLaughlin
- Department of ChemistryUniversity of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Hatef Sadeghi
- Department of PhysicsLancaster University Lancaster LA1 4YB UK
- School of EngineeringUniversity of Warwick Coventry CV4 7AL UK
| | | | - Richard J. Nichols
- Department of ChemistryUniversity of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Simon J. Higgins
- Department of ChemistryUniversity of Liverpool Crown Street Liverpool L69 7ZD UK
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29
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Alanazy A, Leary E, Kobatake T, Sangtarash S, González MT, Jiang HW, Bollinger GR, Agräit N, Sadeghi H, Grace I, Higgins SJ, Anderson HL, Nichols RJ, Lambert CJ. Cross-conjugation increases the conductance of meta-connected fluorenones. Nanoscale 2019; 11:13720-13724. [PMID: 31298678 DOI: 10.1039/c9nr01235d] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Charge transport is strongly suppressed by destructive quantum interference (DQI) in meta-connected 1,1'-biphenyl-containing molecules, resulting in low electrical conductance. Surprisingly, we have found that DQI is almost entirely overcome by adding a bridging carbonyl, to yield a cross-conjugated fluorenone. This contrasts with other π-systems, such as para-connected anthraquinone, where cross-conjugation results in low conductance.
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Affiliation(s)
- Asma Alanazy
- The Department of Mathematics, Lancaster University, LA1 4YF, UK
| | - Edmund Leary
- Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, UK. and Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, UK. and Departamento de Física de la Materia Condensada, IFIMAC and Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Takayuki Kobatake
- Department of Chemistry, Oxford University, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | - Sara Sangtarash
- Physics Department, Lancaster University, Lancaster LA1 4YB, UK.
| | - M Teresa González
- Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Hua-Wei Jiang
- Department of Chemistry, Oxford University, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | - Gabino Rubio Bollinger
- Departamento de Física de la Materia Condensada, IFIMAC and Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Nicolás Agräit
- Departamento de Física de la Materia Condensada, IFIMAC and Instituto "Nicolás Cabrera", Universidad Autónoma de Madrid, E-28049 Madrid, Spain and Fundación IMDEA Nanociencia, Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Hatef Sadeghi
- Physics Department, Lancaster University, Lancaster LA1 4YB, UK.
| | - Iain Grace
- Physics Department, Lancaster University, Lancaster LA1 4YB, UK.
| | - Simon J Higgins
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, UK.
| | - Harry L Anderson
- Department of Chemistry, Oxford University, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | - Richard J Nichols
- Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, UK. and Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, UK.
| | - Colin J Lambert
- Physics Department, Lancaster University, Lancaster LA1 4YB, UK.
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30
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Xu W, Leary E, Hou S, Sangtarash S, González MT, Rubio‐Bollinger G, Wu Q, Sadeghi H, Tejerina L, Christensen KE, Agraït N, Higgins SJ, Lambert CJ, Nichols RJ, Anderson HL. Unusual Length Dependence of the Conductance in Cumulene Molecular Wires. Angew Chem Int Ed Engl 2019; 58:8378-8382. [PMID: 31026371 PMCID: PMC6563095 DOI: 10.1002/anie.201901228] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/22/2019] [Indexed: 01/29/2023]
Abstract
Cumulenes are sometimes described as "metallic" because an infinitely long cumulene would have the band structure of a metal. Herein, we report the single-molecule conductance of a series of cumulenes and cumulene analogues, where the number of consecutive C=C bonds in the core is n=1, 2, 3, and 5. The [n]cumulenes with n=3 and 5 have almost the same conductance, and they are both more conductive than the alkene (n=1). This is remarkable because molecular conductance normally falls exponentially with length. The conductance of the allene (n=2) is much lower, because of its twisted geometry. Computational simulations predict a similar trend to the experimental results and indicate that the low conductance of the allene is a general feature of [n]cumulenes where n is even. The lack of length dependence in the conductance of [3] and [5]cumulenes is attributed to the strong decrease in the HOMO-LUMO gap with increasing length.
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Affiliation(s)
- Wenjun Xu
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOxfordOX1 3TAUK
| | - Edmund Leary
- Department of ChemistryDonnan and Robert Robinson LaboratoriesUniversity of LiverpoolLiverpoolL69 7ZDUK
- Surface Science Research CentreUniversity of LiverpoolOxford StreetLiverpoolL69 3BXUK
| | - Songjun Hou
- Department of PhysicsLancaster UniversityLancasterLA1 4YWUK
| | | | - M. Teresa González
- Instituto Madrileño de Estudios Avanzados (IMDEA)Calle Faraday 9, Campus Universitario de Cantoblanco28049MadridSpain
| | - Gabino Rubio‐Bollinger
- Departamento de Física de la Materia CondensadaIFIMAC and Instituto “Nicolás Cabrera”Universidad Autónoma de Madrid28049MadridSpain
| | - Qingqing Wu
- Department of PhysicsLancaster UniversityLancasterLA1 4YWUK
| | - Hatef Sadeghi
- Department of PhysicsLancaster UniversityLancasterLA1 4YWUK
| | - Lara Tejerina
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOxfordOX1 3TAUK
| | | | - Nicolás Agraït
- Instituto Madrileño de Estudios Avanzados (IMDEA)Calle Faraday 9, Campus Universitario de Cantoblanco28049MadridSpain
- Departamento de Física de la Materia CondensadaIFIMAC and Instituto “Nicolás Cabrera”Universidad Autónoma de Madrid28049MadridSpain
| | - Simon J. Higgins
- Department of ChemistryDonnan and Robert Robinson LaboratoriesUniversity of LiverpoolLiverpoolL69 7ZDUK
| | | | - Richard J. Nichols
- Department of ChemistryDonnan and Robert Robinson LaboratoriesUniversity of LiverpoolLiverpoolL69 7ZDUK
- Surface Science Research CentreUniversity of LiverpoolOxford StreetLiverpoolL69 3BXUK
| | - Harry L. Anderson
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOxfordOX1 3TAUK
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31
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Xu W, Leary E, Hou S, Sangtarash S, González MT, Rubio‐Bollinger G, Wu Q, Sadeghi H, Tejerina L, Christensen KE, Agraït N, Higgins SJ, Lambert CJ, Nichols RJ, Anderson HL. Unusual Length Dependence of the Conductance in Cumulene Molecular Wires. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201901228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Wenjun Xu
- Department of ChemistryUniversity of OxfordChemistry Research Laboratory Oxford OX1 3TA UK
| | - Edmund Leary
- Department of ChemistryDonnan and Robert Robinson LaboratoriesUniversity of Liverpool Liverpool L69 7ZD UK
- Surface Science Research CentreUniversity of Liverpool Oxford Street Liverpool L69 3BX UK
| | - Songjun Hou
- Department of PhysicsLancaster University Lancaster LA1 4YW UK
| | - Sara Sangtarash
- Department of PhysicsLancaster University Lancaster LA1 4YW UK
| | - M. Teresa González
- Instituto Madrileño de Estudios Avanzados (IMDEA) Calle Faraday 9, Campus Universitario de Cantoblanco 28049 Madrid Spain
| | - Gabino Rubio‐Bollinger
- Departamento de Física de la Materia CondensadaIFIMAC and Instituto “Nicolás Cabrera”Universidad Autónoma de Madrid 28049 Madrid Spain
| | - Qingqing Wu
- Department of PhysicsLancaster University Lancaster LA1 4YW UK
| | - Hatef Sadeghi
- Department of PhysicsLancaster University Lancaster LA1 4YW UK
| | - Lara Tejerina
- Department of ChemistryUniversity of OxfordChemistry Research Laboratory Oxford OX1 3TA UK
| | - Kirsten E. Christensen
- Department of ChemistryUniversity of OxfordChemistry Research Laboratory Oxford OX1 3TA UK
| | - Nicolás Agraït
- Instituto Madrileño de Estudios Avanzados (IMDEA) Calle Faraday 9, Campus Universitario de Cantoblanco 28049 Madrid Spain
- Departamento de Física de la Materia CondensadaIFIMAC and Instituto “Nicolás Cabrera”Universidad Autónoma de Madrid 28049 Madrid Spain
| | - Simon J. Higgins
- Department of ChemistryDonnan and Robert Robinson LaboratoriesUniversity of Liverpool Liverpool L69 7ZD UK
| | | | - Richard J. Nichols
- Department of ChemistryDonnan and Robert Robinson LaboratoriesUniversity of Liverpool Liverpool L69 7ZD UK
- Surface Science Research CentreUniversity of Liverpool Oxford Street Liverpool L69 3BX UK
| | - Harry L. Anderson
- Department of ChemistryUniversity of OxfordChemistry Research Laboratory Oxford OX1 3TA UK
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32
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Wang K, Vezzoli A, Grace IM, McLaughlin M, Nichols RJ, Xu B, Lambert CJ, Higgins SJ. Charge transfer complexation boosts molecular conductance through Fermi level pinning. Chem Sci 2019; 10:2396-2403. [PMID: 30881668 PMCID: PMC6385675 DOI: 10.1039/c8sc04199g] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 01/02/2019] [Indexed: 11/21/2022] Open
Abstract
Interference features in the transmission spectra can dominate charge transport in metal-molecule-metal junctions when they occur close to the contact Fermi energy (E F). Here, we show that by forming a charge-transfer complex with tetracyanoethylene (TCNE) we can introduce new constructive interference features in the transmission profile of electron-rich, thiophene-based molecular wires that almost coincide with E F. Complexation can result in a large enhancement of junction conductance, with very efficient charge transport even at relatively large molecular lengths. For instance, we report a conductance of 10-3 G 0 (∼78 nS) for the ∼2 nm long α-quaterthiophene:TCNE complex, almost two orders of magnitude higher than the conductance of the bare molecular wire. As the conductance of the complexes is remarkably independent of features such as the molecular backbone and the nature of the contacts to the electrodes, our results strongly suggest that the interference features are consistently pinned near to the Fermi energy of the metallic leads. Theoretical studies indicate that the semi-occupied nature of the charge-transfer orbital is not only important in giving rise to the latter effect, but also could result in spin-dependent transport for the charge-transfer complexes. These results therefore present a simple yet effective way to increase charge transport efficiency in long and poorly conductive molecular wires, with important repercussions in single-entity thermoelectronics and spintronics.
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Affiliation(s)
- Kun Wang
- Department of Physics and Astronomy & NanoSEC , University of Georgia , 220 Riverbend Road , Athens , GA 30602 , USA .
| | - Andrea Vezzoli
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , UK .
| | - Iain M Grace
- Department of Physics , Lancaster University , Lancaster LA1 4YB , UK .
| | - Maeve McLaughlin
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , UK .
| | - Richard J Nichols
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , UK .
| | - Bingqian Xu
- Department of Physics and Astronomy & NanoSEC , University of Georgia , 220 Riverbend Road , Athens , GA 30602 , USA .
- College of Engineering & NanoSEC , University of Georgia , 220 Riverbend Road , Athens , GA 30602 , USA
| | - Colin J Lambert
- Department of Physics , Lancaster University , Lancaster LA1 4YB , UK .
| | - Simon J Higgins
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , UK .
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33
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Leary E, Limburg B, Alanazy A, Sangtarash S, Grace I, Swada K, Esdaile LJ, Noori M, González MT, Rubio-Bollinger G, Sadeghi H, Hodgson A, Agraı̈t N, Higgins SJ, Lambert CJ, Anderson HL, Nichols RJ. Bias-Driven Conductance Increase with Length in Porphyrin Tapes. J Am Chem Soc 2018; 140:12877-12883. [DOI: 10.1021/jacs.8b06338] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Edmund Leary
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, United Kingdom
- Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, United Kingdom
| | - Bart Limburg
- Department of Chemistry, Chemistry Research Laboratory, Oxford University, Oxford OX1 3TA, United Kingdom
| | - Asma Alanazy
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
- Department of Mathematics and Statistics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Sara Sangtarash
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Iain Grace
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Katsutoshi Swada
- Department of Chemistry, Chemistry Research Laboratory, Oxford University, Oxford OX1 3TA, United Kingdom
| | - Louisa J. Esdaile
- Department of Chemistry, Chemistry Research Laboratory, Oxford University, Oxford OX1 3TA, United Kingdom
| | - Mohammed Noori
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
- Physics Department, College of Science, University of Thi Qar, Thi Qar 0964, Iraq
| | - M. Teresa González
- Instituto Madrileño de Estudios Avanzados (IMDEA), Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Gabino Rubio-Bollinger
- Departamento de Física de la Materia Condensada, IFIMAC and Instituto “Nicolás Cabrera”, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Hatef Sadeghi
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Andrew Hodgson
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, United Kingdom
- Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, United Kingdom
| | - Nicolás Agraı̈t
- Instituto Madrileño de Estudios Avanzados (IMDEA), Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
- Departamento de Física de la Materia Condensada, IFIMAC and Instituto “Nicolás Cabrera”, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Simon J. Higgins
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, United Kingdom
| | - Colin J. Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YW, United Kingdom
| | - Harry L. Anderson
- Department of Chemistry, Chemistry Research Laboratory, Oxford University, Oxford OX1 3TA, United Kingdom
| | - Richard J. Nichols
- Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, United Kingdom
- Surface Science Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, United Kingdom
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34
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Brooke RJ, Szumski DS, Vezzoli A, Higgins SJ, Nichols RJ, Schwarzacher W. Dual Control of Molecular Conductance through pH and Potential in Single-Molecule Devices. Nano Lett 2018; 18:1317-1322. [PMID: 29357253 DOI: 10.1021/acs.nanolett.7b04995] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
One of the principal aims of single-molecule electronics is to create practical devices out of individual molecules. Such devices are expected to play a particularly important role as novel sensors thanks to their response to wide ranging external stimuli. Here we show that the conductance of a molecular junction can depend on two independent stimuli simultaneously. Using a scanning tunnelling microscope break-junction technique (STM-BJ), we found that the conductance of 4,4'-vinylenedipyridine (44VDP) molecular junctions with Ni contacts depends on both the electrochemically applied gate voltage and the pH of the environment. Hence, not only can the Ni|44VDP|Ni junction function as a pH-sensitive switch, but the value of the pH at which switching takes place can be tuned electrically. Furthermore, through the simultaneous control of pH and potential the STM-BJ technique delivers unique insight into the acid-base reaction, including the observation of discrete proton transfers to and from a single molecule.
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Affiliation(s)
- Richard J Brooke
- H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Doug S Szumski
- H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - 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
| | - Walther Schwarzacher
- H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
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35
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Sangtarash S, Vezzoli A, Sadeghi H, Ferri N, O'Brien HM, Grace I, Bouffier L, Higgins SJ, Nichols RJ, Lambert CJ. Gateway state-mediated, long-range tunnelling in molecular wires. Nanoscale 2018; 10:3060-3067. [PMID: 29376529 DOI: 10.1039/c7nr07243k] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
If the factors controlling the decay in single-molecule electrical conductance G with molecular length L could be understood and controlled, then this would be a significant step forward in the design of high-conductance molecular wires. For a wide variety of molecules conducting by phase coherent tunnelling, conductance G decays with length following the relationship G = Ae-βL. It is widely accepted that the attenuation coefficient β is determined by the position of the Fermi energy of the electrodes relative to the energy of frontier orbitals of the molecular bridge, whereas the terminal anchor groups which bind to the molecule to the electrodes contribute to the pre-exponential factor A. We examine this premise for several series of molecules which contain a central conjugated moiety (phenyl, viologen or α-terthiophene) connected on either side to alkane chains of varying length, with each end terminated by thiol or thiomethyl anchor groups. In contrast with this expectation, we demonstrate both experimentally and theoretically that additional electronic states located on thiol anchor groups can significantly decrease the value of β, by giving rise to resonances close to EF through coupling to the bridge moiety. This interplay between the gateway states and their coupling to a central conjugated moiety in the molecular bridges creates a new design strategy for realising higher-transmission molecular wires by taking advantage of the electrode-molecule interface properties.
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Affiliation(s)
- Sara Sangtarash
- Quantum Technology Centre, Physics Department, Lancaster University, Lancaster LA1 4YB, UK.
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36
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Leary E, Roche C, Jiang HW, Grace I, González MT, Rubio-Bollinger G, Romero-Muñiz C, Xiong Y, Al-Galiby Q, Noori M, Lebedeva MA, Porfyrakis K, Agrait N, Hodgson A, Higgins SJ, Lambert CJ, Anderson HL, Nichols RJ. Detecting Mechanochemical Atropisomerization within an STM Break Junction. J Am Chem Soc 2018; 140:710-718. [DOI: 10.1021/jacs.7b10542] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Edmund Leary
- Department
of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, U.K
- Surface Science
Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, U.K
| | - Cécile Roche
- Chemistry
Research Laboratory, Department of Chemistry, Oxford University, Oxford OX1 3TA, U.K
| | - Hua-Wei Jiang
- Chemistry
Research Laboratory, Department of Chemistry, Oxford University, Oxford OX1 3TA, U.K
| | - Iain Grace
- Department
of Physics, Lancaster University, Lancaster, U.K
| | - M. Teresa González
- Instituto Madrileño de Estudios Advanzados (IMDEA), Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | | | | | - Yaoyao Xiong
- Chemistry
Research Laboratory, Department of Chemistry, Oxford University, Oxford OX1 3TA, U.K
| | - Qusiy Al-Galiby
- Department
of Physics, Lancaster University, Lancaster, U.K
- Department
of Physics, College of Education, University of Al-Qadisiyah, 58002 Iraq
| | - Mohammed Noori
- Department
of Physics, Lancaster University, Lancaster, U.K
- Department
of Physics, Collage of Science, Thi-Qar University, Thi-Qar 00964, Iraq
| | | | | | - Nicolás Agrait
- Instituto Madrileño de Estudios Advanzados (IMDEA), Calle Faraday 9, Campus Universitario de Cantoblanco, 28049 Madrid, Spain
| | - Andrew Hodgson
- Department
of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, U.K
- Surface Science
Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, U.K
| | - Simon J. Higgins
- Department
of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, U.K
| | | | - Harry L. Anderson
- Chemistry
Research Laboratory, Department of Chemistry, Oxford University, Oxford OX1 3TA, U.K
| | - Richard J. Nichols
- Department
of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, U.K
- Surface Science
Research Centre and Department of Chemistry, University of Liverpool, Oxford Street, Liverpool L69 3BX, U.K
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37
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Davidson RJ, Milan DC, Al-Owaedi OA, Ismael AK, Nichols RJ, Higgins SJ, Lambert CJ, Yufit DS, Beeby A. Conductance of ‘bare-bones’ tripodal molecular wires. RSC Adv 2018; 8:23585-23590. [PMID: 35540267 PMCID: PMC9081744 DOI: 10.1039/c8ra01257a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 06/18/2018] [Indexed: 12/27/2022] Open
Abstract
Controlling the orientation of molecular conductors on the electrode surfaces is a critical factor in the development of single-molecule conductors. In the current study, we used the scanning tunnelling microscopy-based break junction (STM-BJ) technique to explore ‘bare-bones’ tripodal molecular wires, employing different anchor groups (AGs) at the ‘top’ and ‘bottom’ of the tripod. The triarylphosphine tris(4-(methylthio)phenyl)phosphine and its corresponding phosphine sulfide showed only a single high conductance feature in the resulting 1- and 2-dimensional conductance histograms, whereas analogous molecules with fewer than three thiomethyl AGs did not show clear conductance features. Thus, by systematic molecular modifications and with the aid of supporting DFT calculations, the binding geometry, with respect to the surface, was elucidated. When venturing into the field of tripodal molecular conductors the geometry of the tripod with respect to the surface is a critical factor affecting conductance. Here we examine the behaviour of a tripodal conductor by systematic modifications of a triarylphosphine system.![]()
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Affiliation(s)
| | - David C. Milan
- Department of Chemistry
- University of Liverpool
- Liverpool
- UK
| | - Oday A. Al-Owaedi
- Department of Physics
- University of Lancaster
- UK
- Department of Laser Physics
- Women Faculty of Science
| | - Ali K. Ismael
- Department of Physics
- University of Lancaster
- UK
- Department of Physics
- College of Education for Pure Science
| | | | | | | | | | - Andrew Beeby
- Department of Chemistry
- Durham University
- Durham
- UK
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38
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Vezzoli A, Brooke RJ, Ferri N, Brooke C, Higgins SJ, Schwarzacher W, Nichols RJ. Charge transport at a molecular GaAs nanoscale junction. Faraday Discuss 2018; 210:397-408. [DOI: 10.1039/c8fd00016f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The use of semiconducting electrodes in molecular junctions is an elegant way to impart new properties to nanodevices. Here we report metal-molecule(s)–metal Schottky photodiodes whose behaviour can be tuned by appropriate choice of molecule and doping density, giving further insights into the molecule–semiconductor interface.
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Affiliation(s)
- Andrea Vezzoli
- Department of Chemistry
- University of Liverpool
- Liverpool L69 7ZD
- UK
| | - Richard J. Brooke
- H. H. Wills Physics Laboratory
- University of Bristol
- Bristol BS8 1TL
- UK
| | - Nicolò Ferri
- Department of Chemistry
- University of Liverpool
- Liverpool L69 7ZD
- UK
| | - Carly Brooke
- Department of Chemistry
- University of Liverpool
- Liverpool L69 7ZD
- UK
| | - Simon J. Higgins
- Department of Chemistry
- University of Liverpool
- Liverpool L69 7ZD
- UK
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39
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Vezzoli A, Brooke RJ, Higgins SJ, Schwarzacher W, Nichols RJ. Single-Molecule Photocurrent at a Metal-Molecule-Semiconductor Junction. Nano Lett 2017; 17:6702-6707. [PMID: 28985083 DOI: 10.1021/acs.nanolett.7b02762] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We demonstrate here a new concept for a metal-molecule-semiconductor nanodevice employing Au and GaAs contacts that acts as a photodiode. Current-voltage traces for such junctions are recorded using a STM, and the "blinking" or "I(t)" method is used to record electrical behavior at the single-molecule level in the dark and under illumination, with both low and highly doped GaAs samples and with two different types of molecular bridge: nonconjugated pentanedithiol and the more conjugated 1,4-phenylene(dimethanethiol). Junctions with highly doped GaAs show poor rectification in the dark and a low photocurrent, while junctions with low doped GaAs show particularly high rectification ratios in the dark (>103 for a 1.5 V bias potential) and a high photocurrent in reverse bias. In low doped GaAs, the greater thickness of the depletion layer not only reduces the reverse bias leakage current, but also increases the volume that contributes to the photocurrent, an effect amplified by the point contact geometry of the junction. Furthermore, since photogenerated holes tunnel to the metal electrode assisted by the HOMO of the molecular bridge, the choice of the latter has a strong influence on both the steady state and transient metal-molecule-semiconductor photodiode response. The control of junction current via photogenerated charge carriers adds new functionality to single-molecule nanodevices.
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Affiliation(s)
- Andrea Vezzoli
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Richard J Brooke
- H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Walther Schwarzacher
- H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
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40
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Ismael AK, Wang K, Vezzoli A, Al‐Khaykanee MK, Gallagher HE, Grace IM, Lambert CJ, Xu B, Nichols RJ, Higgins SJ. Side‐Group‐Mediated Mechanical Conductance Switching in Molecular Junctions. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201709419] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ali Khalid Ismael
- Department of Physics Lancaster University Lancaster LA1 4YB UK
- Department of Physics, College of Education for Pure Science Tikrit University Tikrit Iraq
| | - Kun Wang
- College of Engineering & Department of Physics and Astronomy University of Georgia 220 Riverbend Road Athens GA 30602 USA
| | - Andrea Vezzoli
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Mohsin K. Al‐Khaykanee
- Department of Physics Lancaster University Lancaster LA1 4YB UK
- Department of Physics College of Science University of Babylon Iraq
| | - Harry E. Gallagher
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Iain M. Grace
- Department of Physics Lancaster University Lancaster LA1 4YB UK
| | | | - Bingqian Xu
- College of Engineering & Department of Physics and Astronomy University of Georgia 220 Riverbend Road Athens GA 30602 USA
| | - Richard J. Nichols
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Simon J. Higgins
- Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK
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41
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Ismael AK, Wang K, Vezzoli A, Al-Khaykanee MK, Gallagher HE, Grace IM, Lambert CJ, Xu B, Nichols RJ, Higgins SJ. Side-Group-Mediated Mechanical Conductance Switching in Molecular Junctions. Angew Chem Int Ed Engl 2017; 56:15378-15382. [PMID: 29044889 DOI: 10.1002/anie.201709419] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/13/2017] [Indexed: 11/11/2022]
Abstract
A key target in molecular electronics has been molecules having switchable electrical properties. Switching between two electrical states has been demonstrated using such stimuli as light, electrochemical voltage, complexation and mechanical modulation. A classic example of the latter is the switching of 4,4'-bipyridine, leading to conductance modulation of around 1 order of magnitude. Here, we describe the use of side-group chemistry to control the properties of a single-molecule electromechanical switch, which can be cycled between two conductance states by repeated compression and elongation. While bulky alkyl substituents inhibit the switching behavior, π-conjugated side-groups reinstate it. DFT calculations show that weak interactions between aryl moieties and the metallic electrodes are responsible for the observed phenomenon. This represents a significant expansion of the single-molecule electronics "tool-box" for the design of junctions with electromechanical properties.
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Affiliation(s)
- Ali Khalid Ismael
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.,Department of Physics, College of Education for Pure Science, Tikrit University, Tikrit, Iraq
| | - Kun Wang
- College of Engineering & Department of Physics and Astronomy, University of Georgia, 220 Riverbend Road, Athens, GA, 30602, USA
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Mohsin K Al-Khaykanee
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.,Department of Physics, College of Science, University of Babylon, Iraq
| | - Harry E Gallagher
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Iain M Grace
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Bingqian Xu
- College of Engineering & Department of Physics and Astronomy, University of Georgia, 220 Riverbend Road, Athens, GA, 30602, USA
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
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42
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Al-Owaedi OA, Bock S, Milan DC, Oerthel MC, Inkpen MS, Yufit DS, Sobolev AN, Long NJ, Albrecht T, Higgins SJ, Bryce MR, Nichols RJ, Lambert CJ, Low PJ. Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions. Nanoscale 2017; 9:9902-9912. [PMID: 28678257 DOI: 10.1039/c7nr01829k] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Metal complexes are receiving increased attention as molecular wires in fundamental studies of the transport properties of metal|molecule|metal junctions. In this context we report the single-molecule conductance of a systematic series of d8 square-planar platinum(ii) trans-bis(alkynyl) complexes with terminal trimethylsilylethynyl (C[triple bond, length as m-dash]CSiMe3) contacting groups, e.g. trans-Pt{C[triple bond, length as m-dash]CC6H4C[triple bond, length as m-dash]CSiMe3}2(PR3)2 (R = Ph or Et), using a combination of scanning tunneling microscopy (STM) experiments in solution and theoretical calculations using density functional theory and non-equilibrium Green's function formalism. The measured conductance values of the complexes (ca. 3-5 × 10-5G0) are commensurate with similarly structured all-organic oligo(phenylene ethynylene) and oligo(yne) compounds. Based on conductance and break-off distance data, we demonstrate that a PPh3 supporting ligand in the platinum complexes can provide an alternative contact point for the STM tip in the molecular junctions, orthogonal to the terminal C[triple bond, length as m-dash]CSiMe3 group. The attachment of hexyloxy side chains to the diethynylbenzene ligands, e.g. trans-Pt{C[triple bond, length as m-dash]CC6H2(Ohex)2C[triple bond, length as m-dash]CSiMe3}2(PPh3)2 (Ohex = OC6H13), hinders contact of the STM tip to the PPh3 groups and effectively insulates the molecule, allowing the conductance through the full length of the backbone to be reliably measured. The use of trialkylphosphine (PEt3), rather than triarylphosphine (PPh3), ancillary ligands at platinum also eliminates these orthogonal contacts. These results have significant implications for the future design of organometallic complexes for studies in molecular junctions.
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Affiliation(s)
- Oday A Al-Owaedi
- Department of Physics, University of Lancaster, Lancaster, LA1 4YB, UK. and Department of Laser Physics, Women Faculty of Science, Babylon University, Hilla, Iraq
| | - Sören Bock
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia
| | - David C Milan
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | | | - Michael S Inkpen
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Dmitry S Yufit
- Department of Chemistry, Durham University, South Rd, Durham, DH1 3LE, UK
| | - Alexandre N Sobolev
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia and Centre for Microscopy Characterization and Analysis, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia
| | - Nicholas J Long
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Tim Albrecht
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Martin R Bryce
- Department of Chemistry, Durham University, South Rd, Durham, DH1 3LE, UK
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK
| | - Colin J Lambert
- Department of Physics, University of Lancaster, Lancaster, LA1 4YB, UK.
| | - Paul J Low
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth 6009, Australia
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43
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Vezzoli A, Grace IM, Brooke C, Nichols RJ, Lambert CJ, Higgins SJ. Soft versus hard junction formation for α-terthiophene molecular wires and their charge transfer complexes. J Chem Phys 2017. [DOI: 10.1063/1.4969077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Iain M. Grace
- Quantum Technology Centre, Physics Department Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Carly Brooke
- 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
| | - Colin J. Lambert
- Quantum Technology Centre, Physics Department Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Simon J. Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
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Bock S, Al‐Owaedi OA, Eaves SG, Milan DC, Lemmer M, Skelton BW, Osorio HM, Nichols RJ, Higgins SJ, Cea P, Long NJ, Albrecht T, Martín S, Lambert CJ, Low PJ. Single-Molecule Conductance Studies of Organometallic Complexes Bearing 3-Thienyl Contacting Groups. Chemistry 2017; 23:2133-2143. [PMID: 27897344 PMCID: PMC5396322 DOI: 10.1002/chem.201604565] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Indexed: 01/09/2023]
Abstract
The compounds and complexes 1,4-C6 H4 (C≡C-cyclo-3-C4 H3 S)2 (2), trans-[Pt(C≡C-cyclo-3-C4 H3 S)2 (PEt3 )2 ] (3), trans-[Ru(C≡C-cyclo-3-C4 H3 S)2 (dppe)2 ] (4; dppe=1,2-bis(diphenylphosphino)ethane) and trans-[Ru(C≡C-cyclo-3-C4 H3 S)2 {P(OEt)3 }4 ] (5) featuring the 3-thienyl moiety as a surface contacting group for gold electrodes have been prepared, crystallographically characterised in the case of 3-5 and studied in metal|molecule|metal junctions by using both scanning tunnelling microscope break-junction (STM-BJ) and STM-I(s) methods (measuring the tunnelling current (I) as a function of distance (s)). The compounds exhibit similar conductance profiles, with a low conductance feature being more readily identified by STM-I(s) methods, and a higher feature by the STM-BJ method. The lower conductance feature was further characterised by analysis using an unsupervised, automated multi-parameter vector classification (MPVC) of the conductance traces. The combination of similarly structured HOMOs and non-resonant tunnelling mechanism accounts for the remarkably similar conductance values across the chemically distinct members of the family 2-5.
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Affiliation(s)
- Sören Bock
- School of Chemistry and BiochemistryUniversity of Western Australia35 Stirling HighwayCrawley6009WAAustralia
| | - Oday A. Al‐Owaedi
- Department of PhysicsLancaster UniversityLancasterLA1 4YBUK
- Department of Laser Physics, Women Faculty of ScienceBabylon UniversityIraq
| | - Samantha G. Eaves
- School of Chemistry and BiochemistryUniversity of Western Australia35 Stirling HighwayCrawley6009WAAustralia
- Department of ChemistryDurham UniversitySouth Rd.DurhamDH1 3LEUK
| | - David C. Milan
- Department of ChemistryUniversity of LiverpoolCrown St.LiverpoolL69 7ZDUK
| | - Mario Lemmer
- Department of ChemistryImperial College LondonLondonSW7 2AZUK
| | - Brian W. Skelton
- School of Chemistry and BiochemistryUniversity of Western Australia35 Stirling HighwayCrawley6009WAAustralia
- Centre for Microscopy, Characterisation and AnalysisUniversity of Western AustraliaCrawleyWestern Australia6009Australia
| | - Henrry M. Osorio
- Departamento de Química Física, Facultad de CienciasUniversidad de Zaragoza50009ZaragozaSpain
- Instituto de Nanociencia de Aragón (INA) y Laboratorio de Microscopias, Avanzadas (LMA), Edificio I+D Campus Rio EbroUniversidad de ZaragozaC/Mariano Esquillor, s/n50018ZaragozaSpain
- Departamento de FísicaEscuela Politécnica NacionalAv. Ladrón de Guevara, E11-253170525QuitoEcuador
| | - Richard J. Nichols
- Department of ChemistryUniversity of LiverpoolCrown St.LiverpoolL69 7ZDUK
| | - Simon J. Higgins
- Department of ChemistryUniversity of LiverpoolCrown St.LiverpoolL69 7ZDUK
| | - Pilar Cea
- Departamento de Química Física, Facultad de CienciasUniversidad de Zaragoza50009ZaragozaSpain
- Instituto de Nanociencia de Aragón (INA) y Laboratorio de Microscopias, Avanzadas (LMA), Edificio I+D Campus Rio EbroUniversidad de ZaragozaC/Mariano Esquillor, s/n50018ZaragozaSpain
| | | | - Tim Albrecht
- Department of ChemistryImperial College LondonLondonSW7 2AZUK
| | - Santiago Martín
- Departamento de Química Física, Facultad de CienciasUniversidad de Zaragoza50009ZaragozaSpain
- Instituto de Ciencias de Materiales de Aragón (ICMA)Universidad de Zaragoza-CSIC50009ZaragozaSpain
| | | | - Paul J. Low
- School of Chemistry and BiochemistryUniversity of Western Australia35 Stirling HighwayCrawley6009WAAustralia
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Abstract
In most single- or few-molecule devices, the contact electrodes are simple ohmic resistors. Here we describe a new type of single-molecule device in which metal and semiconductor contact electrodes impart a function, namely, current rectification, which is then modified by a molecule bridging the gap. We study junctions with the structure Au STM tip/X/n-GaAs substrate, where "X" is either a simple alkanedithiol or a conjugated unit bearing thiol/methylthiol contacts, and we detect current jumps corresponding to the attachment and detachment of single molecules. From the magnitudes of the current jumps we can deduce values for the conductance decay constant with molecule length that agree well with values determined from Au/molecule/Au junctions. The ability to impart functionality to a single-molecule device through the properties of the contacts as well as through the properties of the molecule represents a significant extension of the single-molecule electronics "tool-box".
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Affiliation(s)
- Andrea Vezzoli
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Richard J Brooke
- H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Nicolò Ferri
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Simon J Higgins
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Walther Schwarzacher
- H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
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Milan DC, Krempe M, Ismael AK, Movsisyan LD, Franz M, Grace I, Brooke RJ, Schwarzacher W, Higgins SJ, Anderson HL, Lambert CJ, Tykwinski RR, Nichols RJ. The single-molecule electrical conductance of a rotaxane-hexayne supramolecular assembly. Nanoscale 2017; 9:355-361. [PMID: 27924336 DOI: 10.1039/c6nr06355a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Oligoynes are archetypical molecular wires due to their 1-D chain of conjugated carbon atoms and ability to transmit charge over long distances by coherent tunneling. However, the stability of the oligoyne can be an issue. Here we address this problem by two stabilization methods, namely sterically shielding endgroups, and rotaxination to produce an insulated molecular wire. We demonstrate the threading of a hexayne within a macrocycle to form a rotaxane and report measurements of the electrical conductance of this single supramolecular assembly within an STM break junction. The macrocycle is retained around the hexayne through the use of 3,5-diphenylpyridine stoppers at both ends of the molecular wire, which also serve as chemisorption contacts to the gold electrodes of the junction. Molecular conductance was measured for both the supramolecular assembly and also for the molecular wire in the absence of the macrocycle. The threaded macrocycle, which at room temperature is mobile along the length of the hexayne between the stoppers, has only a minimal impact on the conductance. However, the probability of molecular junction formation in a given break junction formation cycle is notably lower with the rotaxane. In seeking to understand the conductance behavior, the electronic properties of these molecular assemblies and the electrical behavior of the junctions have been investigated by using DFT-based computational methods.
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Affiliation(s)
- David C Milan
- Department of Chemistry, University of Liverpool, Crown St, Liverpool, L69 7ZD, UK.
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Liang J, Smith RE, Vezzoli A, Xie L, Milan DC, Davidson R, Beeby A, Low PJ, Higgins SJ, Mao B, Nichols RJ. Electrochemically grafted single molecule junctions exploiting a chemical protection strategy. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.10.095] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Abstract
It is now possible to reliably measure single molecule conductance in a wide variety of environments including organic liquids, ultrahigh vacuum, water, ionic liquids, and electrolytes. The most commonly used methods deploy scanning probe microscopes, mechanically formed break junctions, or lithographically formed nanogap contacts. Molecules are generally captured between a pair of facing electrodes, and the junction current response is measured as a function of bias voltage. Gating electrodes can also be added so that the electrostatic potential at the molecular bridge can be independently controlled by this third noncontacting electrode. This can also be achieved in an electrolytic environment using a four-electrode bipotentiostatic configuration, which allows independent electrode potential control of the two contacting electrodes. This is commonly realized using an electrochemical STM and enables single molecule electrical characterization as a function of electrode potential and redox state of the molecular bridge. This has emerged as a powerful tool in modern interfacial electrochemistry and nanoelectrochemistry for studying charge transport across single molecules as a function of electrode potential and the electrolytic environments. Such measurements are possible in electrolytes ranging from aqueous buffers to nonaqueous ionic liquids. In this Account, we illustrate a number of examples of single molecule electrical measurements under electrode potential control use a scanning tunneling microscope (STM) and demonstrate how these can help in the understanding of charge transport in single molecule junctions. Examples showing charge transport following phase coherent tunneling to incoherent charge hopping across redox active molecular bridges are shown. In the case of bipyridinium (or viologen) molecular wires, it is shown how electrochemical reduction leads to an increase of the single molecule conductance, which is controlled by the liquid electrochemical gating. This has been referred to as to a "single molecule transistor configuration" with the gate voltage being provided by the controllable potential achieved through the electrochemical double layer. It is shown how the electrolyte medium can control such gating, with ionic liquids providing more efficient gate coupling than aqueous electrolytes. Control of the conductance of viologen molecular wires can also be achieved by encapsulating the viologen redox moiety within a molecular cage, thereby controlling its immediate environment. Molecular conductance can also be gated through multiple redox states. This has been shown for the redox moiety pyrrolo-tetrathiafulvalene, which undergoes single molecule electrochemical transistor gating through three redox states in molecular junctions. Charge transport through this junction follows a two-step hopping mechanism, demonstrating the role of the redox center in electron transfer across the molecular bridge. Recent electrolyte gating studies of rigid, conjugated redox-active metal complexes with tailored terpyridine coordinating ligands and anchors are also presented. These aforementioned studies have all been performed with gold electrode contacts. The Account concludes with recent data showing that it is now possible to study single molecule electrochemical gating with nickel electrodes. This opens up new perspectives for studying interfacial charge transfer with a wide variety of other electrode materials including semiconductor electrodes and also points toward future opportunities for coupling molecular spintronics and nanoelectrochemistry.
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Affiliation(s)
- Richard J. Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Simon J. Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom
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49
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Al-Owaedi OA, Milan DC, Oerthel MC, Bock S, Yufit DS, Howard JAK, Higgins SJ, Nichols RJ, Lambert CJ, Bryce MR, Low PJ. Experimental and Computational Studies of the Single-Molecule Conductance of Ru(II) and Pt(II) trans-Bis(acetylide) Complexes. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00472] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oday A. Al-Owaedi
- Department
of Physics, University of Lancaster, Lancaster LA1 4YB, U.K
- Department of Laser Physics, Women Faculty of Science, Babylon University, Hilla, Iraq
| | - David C. Milan
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | | | - Sören Bock
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
| | - Dmitry S. Yufit
- Department
of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | | | - Simon J. Higgins
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Richard J. Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Colin J. Lambert
- Department
of Physics, University of Lancaster, Lancaster LA1 4YB, U.K
| | - Martin R. Bryce
- Department
of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | - Paul J. Low
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
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50
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Zhang W, Gan S, Vezzoli A, Davidson RJ, Milan DC, Luzyanin KV, Higgins SJ, Nichols RJ, Beeby A, Low PJ, Li B, Niu L. Single-Molecule Conductance of Viologen-Cucurbit[8]uril Host-Guest Complexes. ACS Nano 2016; 10:5212-5220. [PMID: 27055002 DOI: 10.1021/acsnano.6b00786] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The local molecular environment is a critical factor which should be taken into account when measuring single-molecule electrical properties in condensed media or in the design of future molecular electronic or single molecule sensing devices. Supramolecular interactions can be used to control the local environment in molecular assemblies and have been used to create microenvironments, for instance, for chemical reactions. Here, we use supramolecular interactions to create microenvironments which influence the electrical conductance of single molecule wires. Cucurbit[8]uril (CB[8]) with a large hydrophobic cavity was used to host the viologen (bipyridinium) molecular wires forming a 1:1 supramolecular complex. Significant increases in the viologen wire single molecule conductances are observed when it is threaded into CB[8] due to large changes of the molecular microenvironment. The results were interpreted within the framework of a Marcus-type model for electron transfer as arising from a reduction in outer-sphere reorganization energy when the viologen is confined within the hydrophobic CB[8] cavity.
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Affiliation(s)
- Wei Zhang
- State Key Laboratory of Electroanalytical Chemistry, CAS Center for Excellence in Nanoscience, c/o Engineering Laboratory for Modern Analytical Techniques, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, China
- University of Chinese Academy of Sciences , Beijing 100049, China
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Shiyu Gan
- State Key Laboratory of Electroanalytical Chemistry, CAS Center for Excellence in Nanoscience, c/o Engineering Laboratory for Modern Analytical Techniques, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, China
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Ross J Davidson
- Department of Chemistry, Durham University , South Road, Durham DH1 3LE, United Kingdom
| | - David C Milan
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Konstantin V Luzyanin
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - 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
| | - Andrew Beeby
- Department of Chemistry, Durham University , South Road, Durham DH1 3LE, United Kingdom
| | - Paul J Low
- School of Chemistry and Biochemistry, University of Western Australia , 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Buyi Li
- Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
| | - Li Niu
- State Key Laboratory of Electroanalytical Chemistry, CAS Center for Excellence in Nanoscience, c/o Engineering Laboratory for Modern Analytical Techniques, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, China
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