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Erpenbeck A, Ke Y, Peskin U, Thoss M. How an electrical current can stabilize a molecular nanojunction. NANOSCALE 2023; 15:16333-16343. [PMID: 37766513 DOI: 10.1039/d3nr02176a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
The stability of molecular junctions under transport is of the utmost importance for the field of molecular electronics. This question is often addressed within the paradigm of current-induced heating of nuclear degrees of freedom or current-induced forces acting upon the nuclei. At the same time, an essential characteristic of the failure of a molecular electronic device is its changing conductance - typically from a finite value for the intact device to zero for a device that lost its functionality. In this publication, we focus on the current-induced changes in the molecular conductance, which are inherent to molecular junctions at the limit of mechanical stability. We employ a numerically exact framework based on the hierarchical equations of motion approach, which treats both electronic and nuclear degrees of freedom on an equal footing and does not impose additional assumptions. Studying generic model systems for molecular junctions with dissociative potentials for a wide range of parameters spanning the adiabatic and the nonadiabatic regime, we find that molecular junctions that exhibit a decrease in conductance upon dissociation are more stable than junctions that are more conducting in their dissociated state. This represents a new mechanism that stabilizes molecular junctions under current. Moreover, we identify characteristic signatures in the current of breaking junctions related to the interplay between changes in the conductance and the nuclear configuration and show how these are related to properties of the leads rather than characteristics of the molecule itself.
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Affiliation(s)
- André Erpenbeck
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
| | - Yaling Ke
- Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
| | - Uri Peskin
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Michael Thoss
- Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
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2
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Ke Y, Kaspar C, Erpenbeck A, Peskin U, Thoss M. Nonequilibrium reaction rate theory: Formulation and implementation within the hierarchical equations of motion approach. J Chem Phys 2022; 157:034103. [DOI: 10.1063/5.0098545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The study of chemical reactions in environments under nonequilibrium conditions has been of interest recently in a variety of contexts, including current-induced reactions in molecular junctions and scanning tunneling microscopy experiments. In this work, we outline a fully quantum mechanical, numerically exact approach to describe chemical reaction rates in such nonequilibrium situations. The approach is based on an extension of the flux correlation function formalism to nonequilibrium conditions and uses a mixed real and imaginary time hierarchical equations of motion approach for the calculation of rate constants. As a specific example, we investigate current-induced intramolecular proton transfer reactions in a molecular junction for different applied bias voltages and molecule-lead coupling strengths.
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Affiliation(s)
- Yaling Ke
- Institute of Physics, Albert-Ludwigs-Universität Freiburg, Germany
| | | | | | - Uri Peskin
- Chemistry, Technion Israel Institute of Technology, Israel
| | - Michael Thoss
- University of Freiburg Institute of Physics, Germany
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3
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Ke Y, Erpenbeck A, Peskin U, Thoss M. Unraveling current-induced dissociation mechanisms in single-molecule junctions. J Chem Phys 2021; 154:234702. [PMID: 34241274 DOI: 10.1063/5.0053828] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Understanding current-induced bond rupture in single-molecule junctions is both of fundamental interest and a prerequisite for the design of molecular junctions, which are stable at higher-bias voltages. In this work, we use a fully quantum mechanical method based on the hierarchical quantum master equation approach to analyze the dissociation mechanisms in molecular junctions. Considering a wide range of transport regimes, from off-resonant to resonant, non-adiabatic to adiabatic transport, and weak to strong vibronic coupling, our systematic study identifies three dissociation mechanisms. In the weak and intermediate vibronic coupling regime, the dominant dissociation mechanism is stepwise vibrational ladder climbing. For strong vibronic coupling, dissociation is induced via multi-quantum vibrational excitations triggered either by a single electronic transition at high bias voltages or by multiple electronic transitions at low biases. Furthermore, the influence of vibrational relaxation on the dissociation dynamics is analyzed and strategies for improving the stability of molecular junctions are discussed.
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Affiliation(s)
- Yaling Ke
- Institute of Physics, Albert-Ludwig University Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
| | - André Erpenbeck
- School of Chemistry, The Raymond and Beverley Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Uri Peskin
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Michael Thoss
- Institute of Physics, Albert-Ludwig University Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
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4
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Preston RJ, Gelin MF, Kosov DS. First-passage time theory of activated rate chemical processes in electronic molecular junctions. J Chem Phys 2021; 154:114108. [PMID: 33752339 DOI: 10.1063/5.0045652] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Confined nanoscale spaces, electric fields, and tunneling currents make the molecular electronic junction an experimental device for the discovery of new out-of-equilibrium chemical reactions. Reaction-rate theory for current-activated chemical reactions is developed by combining the Keldysh nonequilibrium Green's function treatment of electrons, Fokker-Planck description of the reaction coordinate, and Kramers first-passage time calculations. The nonequilibrium Green's functions (NEGF) provide an adiabatic potential as well as a diffusion coefficient and temperature with local dependence on the reaction coordinate. Van Kampen's Fokker-Planck equation, which describes a Brownian particle moving in an external potential in an inhomogeneous medium with a position-dependent friction and diffusion coefficient, is used to obtain an analytic expression for the first-passage time. The theory is applied to several transport scenarios: a molecular junction with a single reaction coordinate dependent molecular orbital and a model diatomic molecular junction. We demonstrate the natural emergence of Landauer's blowtorch effect as a result of the interplay between the configuration dependent viscosity and diffusion coefficients. The resultant localized heating in conjunction with the bond-deformation due to current-induced forces is shown to be the determining factors when considering chemical reaction rates, each of which results from highly tunable parameters within the system.
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Affiliation(s)
- Riley J Preston
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Maxim F Gelin
- School of Sciences, Hangzhou Dianzi University, 310018 Hangzhou, China
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
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5
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Preston RJ, Honeychurch TD, Kosov DS. Cooling molecular electronic junctions by AC current. J Chem Phys 2020; 153:121102. [PMID: 33003743 DOI: 10.1063/5.0019178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electronic current flowing in a molecular electronic junction dissipates significant amounts of energy to vibrational degrees of freedom, straining and rupturing chemical bonds and often quickly destroying the integrity of the molecular device. The infamous mechanical instability of molecular electronic junctions critically limits performance and lifespan and raises questions as to the technological viability of single-molecule electronics. Here, we propose a practical scheme for cooling the molecular vibrational temperature via application of an AC voltage over a large, static operational DC voltage bias. Using nonequilibrium Green's functions, we computed the viscosity and diffusion coefficient experienced by nuclei surrounded by a nonequilibrium "sea" of periodically driven, current-carrying electrons. The effective molecular junction temperature is deduced by balancing the viscosity and diffusion coefficients. Our calculations show the opportunity of achieving in excess of 40% cooling of the molecular junction temperature while maintaining the same average current.
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Affiliation(s)
- Riley J Preston
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Thomas D Honeychurch
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
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6
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Kuperman M, Nagar L, Peskin U. Mechanical Stabilization of Nanoscale Conductors by Plasmon Oscillations. NANO LETTERS 2020; 20:5531-5537. [PMID: 32538634 PMCID: PMC7467764 DOI: 10.1021/acs.nanolett.0c02187] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 06/15/2020] [Indexed: 06/10/2023]
Abstract
External driving of the Fermion reservoirs interacting with a nanoscale charge-conductor is shown to enhance its mechanical stability during resonant tunneling. This counterintuitive cooling effect is predicted despite the net energy flow into the device. Field-induced plasmon oscillations stir the energy distribution of charge carriers near the reservoir's chemical potentials into a nonequilibrium state with favored transport of low-energy electrons. Consequently, excess heating of mechanical degrees of freedom in the conductor is suppressed. We demonstrate and analyze this effect for a generic model of mechanical instability in nanoelectronic devices, covering a broad range of parameters. Plasmon-induced stabilization is suggested as a feasible strategy to confront a major problem of current-induced heating and breakdown of nanoscale systems operating far from equilibrium.
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Affiliation(s)
- Maayan Kuperman
- Schulich
Faculty of Chemistry and The Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology, Haifa 32000, Israel
| | - Linoy Nagar
- Schulich
Faculty of Chemistry and The Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology, Haifa 32000, Israel
| | - Uri Peskin
- Schulich
Faculty of Chemistry and The Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology, Haifa 32000, Israel
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7
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Rabanzo-Castillo KM, Hanif M, Söhnel T, Leitao EM. Synthesis, characterisation and electronic properties of naphthalene bridged disilanes. Dalton Trans 2019; 48:13971-13980. [PMID: 31483424 DOI: 10.1039/c9dt03058a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Synthesis of naphthalene bridged disilanes 2R (R = Me, Ph) was performed via catalytic dehydrocoupling. Using RhCl(PPh3)3 as a catalyst, an intramolecular Si-Si bond was readily formed from the corresponding disilyl precursors 1R (R = Me, Ph). For catalytic reactions using (C6F5)3B(OH2), bridged siloxanes (3Ph and 3Me) were observed. Attempts to install the 1,8-naphthalene bridge directly onto a disilane resulted in an unusual product (4), containing two silicon centres bridged through one naphthyl group, and another naphthyl group attached to a single Si centre. In order for this product to form, both a Si to Si hydrogen shift rearrangement as well as Si-Si bond cleavage occurred. The effects of phenyl and methyl substitutions on the structure and electronic properties of the synthesised compounds was investigated by single crystal X-ray diffraction, as well as IR and multinuclear NMR spectroscopic analysis. In addition, theoretical UV-Vis absorption maxima were evaluated using density functional theory (TD-SCF) on a B3LYP/6-31(++)G** level of theory and compared with experimental UV-Vis spectroscopic data.
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Affiliation(s)
- Kristel M Rabanzo-Castillo
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand. and The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand
| | - Muhammad Hanif
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand.
| | - Tilo Söhnel
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand. and The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand
| | - Erin M Leitao
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand. and The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand
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8
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Stuyver T, Danovich D, Joy J, Shaik S. External electric field effects on chemical structure and reactivity. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2019. [DOI: 10.1002/wcms.1438] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Thijs Stuyver
- Institute of Chemistry The Hebrew University Jerusalem Israel
- Algemene Chemie Vrije Universiteit Brussel Brussels Belgium
| | - David Danovich
- Institute of Chemistry The Hebrew University Jerusalem Israel
| | - Jyothish Joy
- Institute of Chemistry The Hebrew University Jerusalem Israel
| | - Sason Shaik
- Institute of Chemistry The Hebrew University Jerusalem Israel
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9
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Sarsa A, Alcaraz-Pelegrina JM, Le Sech C. Exclusion principle repulsion effects on the covalent bond beyond the Born-Oppenheimer approximation. Phys Chem Chem Phys 2019; 21:10411-10416. [PMID: 31065634 DOI: 10.1039/c9cp01063g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The changes in the covalent bond of the hydrogen molecule limited in space by a spherical hard boundary are studied. The sphere is moved along an axis parallel or orthogonal to the molecular axis. The diffusion Monte Carlo approach is used to solve the Schrödinger equation with the relevant boundary conditions and to evaluate the changes in the bond energy versus the location of the sphere. The vertical and lateral quantum forces exerted on the sphere are evaluated by calculating the energy derivative versus the distances to the sphere. The results show that the quantum forces present an important dependence on the distance and vanish rapidly as the separation between the sphere and the molecule increases. In the limiting case the molecular bond breaks due to the electronic depletion induced in the covalent bond. An application of this study is the modelisation of the forces exerted on the passivated cantilever of an atomic force microscope probing the electron cloud in the contact mode in the Pauli exclusion regime.
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Affiliation(s)
- A Sarsa
- Departamento de Física, Campus de Rabanales Edif. C2, Universidad de Córdoba, E-14071 Córdoba, Spain.
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10
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Fung ED, Gelbwaser D, Taylor J, Low J, Xia J, Davydenko I, Campos LM, Marder S, Peskin U, Venkataraman L. Breaking Down Resonance: Nonlinear Transport and the Breakdown of Coherent Tunneling Models in Single Molecule Junctions. NANO LETTERS 2019; 19:2555-2561. [PMID: 30821465 DOI: 10.1021/acs.nanolett.9b00316] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The promise of the field of single-molecule electronics is to reveal a new class of quantum devices that leverages the strong electronic interactions inherent to subnanometer scale systems. Here, we form Au-molecule-Au junctions using a custom scanning tunneling microscope and explore charge transport through current-voltage measurements. We focus on the resonant tunneling regime of two molecules, one that is primarily an electron conductor and one that conducts primarily holes. We find that in the high bias regime, junctions that do not rupture demonstrate reproducible and pronounced negative differential resistance (NDR)-like features followed by hysteresis with peak-to-valley ratios exceeding 100 in some cases. Furthermore, we show that both junction rupture and NDR are induced by charging of the molecular orbital dominating transport and find that the charging is reversible at lower bias and with time with kinetic time scales on the order of hundreds of milliseconds. We argue that these results cannot be explained by existing models of charge transport and likely require theoretical advances describing the transition from coherent to sequential tunneling. Our work also suggests new rules for operating single-molecule devices at high bias to obtain highly nonlinear behavior.
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Affiliation(s)
- E-Dean Fung
- Department of Applied Physics and Applied Mathematics , Columbia University , New York , New York 10027 , United States
| | - David Gelbwaser
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 United States
| | - Jeffrey Taylor
- Department of Applied Physics and Applied Mathematics , Columbia University , New York , New York 10027 , United States
| | - Jonathan Low
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Jianlong Xia
- School of Chemistry, Chemical Engineering, and Life Science , Wuhan University of Technology , Wuhan 430070 , China
| | - Iryna Davydenko
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics , Georgia Institute of Technology , Atlanta , Georgia 30332-0400 , United States
| | - Luis M Campos
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Seth Marder
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics , Georgia Institute of Technology , Atlanta , Georgia 30332-0400 , United States
| | - Uri Peskin
- Schulich Faculty of Chemistry , Technion-Israel Institute of Technology , Haifa 32000 , Israel
| | - Latha Venkataraman
- Department of Applied Physics and Applied Mathematics , Columbia University , New York , New York 10027 , United States
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
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11
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Kershaw VF, Kosov DS. Non-equilibrium Green’s function theory for non-adiabatic effects in quantum transport: Inclusion of electron-electron interactions. J Chem Phys 2019; 150:074101. [DOI: 10.1063/1.5058735] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Vincent F. Kershaw
- College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia
| | - Daniel S. Kosov
- College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia
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12
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Gelbwaser-Klimovsky D, Aspuru-Guzik A, Thoss M, Peskin U. High-Voltage-Assisted Mechanical Stabilization of Single-Molecule Junctions. NANO LETTERS 2018; 18:4727-4733. [PMID: 29923410 DOI: 10.1021/acs.nanolett.8b01127] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Resonant tunneling is an efficient mechanism for charge transport through nanoscale conductance junctions due to the relatively high currents involved. However, continuous charging and discharging cycles of the nanoconductor during resonant tunneling often lead to mechanical instability. The realization of efficient nanoscale electronic components therefore depends to a large extent on the ability to mechanically stabilize them during resonant transport. In this work, we focus on single-molecule junctions, demonstrating that their mechanical stability during resonant transport can be increased by increasing the bias voltage. This counter-intuitive effect is attributed to the energy dependence of the molecule-lead coupling densities, which promote the rate of transport-induced cooling of molecular vibrations at higher voltages. The required energy dependence is characteristic of realistic electrodes (such as graphene), which cannot be modeled within the commonly invoked wide-band approximation. Our research provides new guidelines for the design of mechanically stable molecular devices operating in the regime of resonant charge transport and demonstrates these guidelines while considering realistic features of single-molecule junctions.
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Affiliation(s)
- David Gelbwaser-Klimovsky
- Department of Chemistry and Chemical Biology , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Alán Aspuru-Guzik
- Department of Chemistry and Chemical Biology , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Michael Thoss
- Institute of Physics , University of Freiburg , Hermann-Herder-Strasse 3 , D-79104 Freiburg , Germany
| | - Uri Peskin
- Schulich Faculty of Chemistry , Technion-Israel Institute of Technology , Haifa 32000 , Israel
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13
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Shaik S, Ramanan R, Danovich D, Mandal D. Structure and reactivity/selectivity control by oriented-external electric fields. Chem Soc Rev 2018; 47:5125-5145. [PMID: 29979456 DOI: 10.1039/c8cs00354h] [Citation(s) in RCA: 240] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This is a tutorial on use of external-electric-fields (EEFs) as effectors of chemical change. The tutorial instructs readers how to conceptualize and design electric-field effects on bonds, structures, and reactions. Most effects can be comprehended as the field-induced stabilization of ionic structures. Thus, orienting the field along the "bond axis" will facilitate bond breaking. Similarly, orienting the field along the "reaction axis", the direction in which "electron pairs transform" from reactants- to products-like, will catalyse the reaction. Flipping the field's orientation along the reaction-axis will cause inhibition. Orienting the field off-reaction-axis will control stereo-selectivity and remove forbidden-orbital mixing. Two-directional fields may control both reactivity and selectivity. Increasing the field strength for concerted reactions (e.g., Diels-Alder's) will cause mechanistic-switchover to stepwise mechanisms with ionic intermediates. Examples of bond breaking and control of reactivity/selectivity and mechanisms are presented and analysed from the "ionic perspective". The tutorial projects the unity of EEF effects, "giving insight and numbers".
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Affiliation(s)
- Sason Shaik
- Institute of Chemistry, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
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14
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Zhen S, Mao JC, Chen L, Ding S, Luo W, Zhou XS, Qin A, Zhao Z, Tang BZ. Remarkable Multichannel Conductance of Novel Single-Molecule Wires Built on Through-Space Conjugated Hexaphenylbenzene. NANO LETTERS 2018; 18:4200-4205. [PMID: 29911870 DOI: 10.1021/acs.nanolett.8b01082] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Through-bond conjugated molecules are the major frameworks for traditional molecular wires, while through-space conjugated units are rarely utilized and studied although they have shown unique conducting potential. Herein, we present novel single-molecule wires built on through-space conjugated hexaphenylbenzene. Their conductance, measured by the scanning tunneling microscopy based break-junction technique, increases with the improvement of through-space conjugation and finally reaches a remarkable value (12.28 nS) which greatly exceeds that of conventional through-bond conjugated counterpart (2.45 nS). The multichannel conducting model by integrating through-space and through-bond conjugations could be a promising strategy for the further design of robust single-molecule wires with advanced conductance and stability.
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Affiliation(s)
- Shijie Zhen
- Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Jin-Chuan Mao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry , Zhejiang Normal University , Jinhua , Zhejiang 321004 , China
| | - Long Chen
- Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Siyang Ding
- Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Wenwen Luo
- Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Xiao-Shun Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry , Zhejiang Normal University , Jinhua , Zhejiang 321004 , China
| | - Anjun Qin
- Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Zujin Zhao
- Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
| | - Ben Zhong Tang
- Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , China
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction , The Hong Kong University of Science & Technology , Clear Water Bay , Kowloon, Hong Kong , China
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15
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Foti G, Vázquez H. Origin of Vibrational Instabilities in Molecular Wires with Separated Electronic States. J Phys Chem Lett 2018; 9:2791-2796. [PMID: 29741892 DOI: 10.1021/acs.jpclett.8b00940] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Current-induced heating in molecular junctions stems from the interaction between tunneling electrons and localized molecular vibrations. If the electronic excitation of a given vibrational mode exceeds heat dissipation, a situation known as vibrational instability is established, which can seriously compromise the integrity of the junction. Using out of equilibrium first-principles calculations, we demonstrate that vibrational instabilities can take place in the general case of molecular wires with separated unoccupied electronic states. From the ab initio results, we derive a model to characterize unstable vibrational modes and construct a diagram that maps mode stability. These results generalize previous theoretical work and predict vibrational instabilities in a new regime.
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Affiliation(s)
- Giuseppe Foti
- Institute of Physics , Academy of Sciences of the Czech Republic , Cukrovarnicka 10 , Prague , Czech Republic
| | - Héctor Vázquez
- Institute of Physics , Academy of Sciences of the Czech Republic , Cukrovarnicka 10 , Prague , Czech Republic
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16
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Thoss M, Evers F. Perspective: Theory of quantum transport in molecular junctions. J Chem Phys 2018; 148:030901. [DOI: 10.1063/1.5003306] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michael Thoss
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg, Germany
| | - Ferdinand Evers
- Institute of Theoretical Physics, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
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17
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Foti G, Vázquez H. Adsorbate-driven cooling of carbene-based molecular junctions. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2017; 8:2060-2068. [PMID: 29090108 PMCID: PMC5647705 DOI: 10.3762/bjnano.8.206] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/07/2017] [Indexed: 06/07/2023]
Abstract
We study the role of an NH2 adsorbate on the current-induced heating and cooling of a neighboring carbene-based molecular circuit. We use first-principles methods of inelastic tunneling transport based on density functional theory and non-equilibrium Green's functions to calculate the rates of emission and absorbtion of vibrations by tunneling electrons, the population of vibrational modes and the energy stored in them. We find that the charge rearrangement resulting from the adsorbate gates the carbene electronic structure and reduces the density of carbene states near the Fermi level as a function of bias. These effects result in the cooling of carbene modes at all voltages compared to the "clean" carbene-based junction. We also find that the direct influence of adsorbate states is significantly smaller and tends to heat adsorbate vibrations. Our results highlight the important role of molecular adsorbates not only on the electronic and elastic transport properties but also on the current-induced energy exchange and stability under bias of single-molecule circuits.
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Affiliation(s)
- Giuseppe Foti
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, Prague, Czech Republic
| | - Héctor Vázquez
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, Prague, Czech Republic
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18
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Su TA, Li H, Klausen RS, Kim NT, Neupane M, Leighton JL, Steigerwald ML, Venkataraman L, Nuckolls C. Silane and Germane Molecular Electronics. Acc Chem Res 2017; 50:1088-1095. [PMID: 28345881 DOI: 10.1021/acs.accounts.7b00059] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This Account provides an overview of our recent efforts to uncover the fundamental charge transport properties of Si-Si and Ge-Ge single bonds and introduce useful functions into group 14 molecular wires. We utilize the tools of chemical synthesis and a scanning tunneling microscopy-based break-junction technique to study the mechanism of charge transport in these molecular systems. We evaluated the fundamental ability of silicon, germanium, and carbon molecular wires to transport charge by comparing conductances within families of well-defined structures, the members of which differ only in the number of Si (or Ge or C) atoms in the wire. For each family, this procedure yielded a length-dependent conductance decay parameter, β. Comparison of the different β values demonstrates that Si-Si and Ge-Ge σ bonds are more conductive than the analogous C-C σ bonds. These molecular trends mirror what is seen in the bulk. The conductance decay of Si and Ge-based wires is similar in magnitude to those from π-based molecular wires such as paraphenylenes However, the chemistry of the linkers that attach the molecular wires to the electrodes has a large influence on the resulting β value. For example, Si- and Ge-based wires of many different lengths connected with a methyl-thiomethyl linker give β values of 0.36-0.39 Å-1, whereas Si- and Ge-based wires connected with aryl-thiomethyl groups give drastically different β values for short and long wires. This observation inspired us to study molecular wires that are composed of both π- and σ-orbitals. The sequence and composition of group 14 atoms in the σ chain modulates the electronic coupling between the π end-groups and dictates the molecular conductance. The conductance behavior originates from the coupling between the subunits, which can be understood by considering periodic trends such as bond length, polarizability, and bond polarity. We found that the same periodic trends determine the electric field-induced breakdown properties of individual Si-Si, Ge-Ge, Si-O, Si-C, and C-C bonds. Building from these studies, we have prepared a system that has two different, alternative conductance pathways. In this wire, we can intentionally break a labile, strained silicon-silicon bond and thereby shunt the current through the secondary conduction pathway. This type of in situ bond-rupture provides a new tool to study single molecule reactions that are induced by electric fields. Moreover, these studies provide guidance for designing dielectric materials as well as molecular devices that require stability under high voltage bias. The fundamental studies on the structure/function relationships of the molecular wires have guided the design of new functional systems based on the Si- and Ge-based wires. For example, we exploited the principle of strain-induced Lewis acidity from reaction chemistry to design a single molecule switch that can be controllably switched between two conductive states by varying the distance between the tip and substrate electrodes. We found that the strain intrinsic to the disilaacenaphthene scaffold also creates two state conductance switching. Finally, we demonstrate the first example of a stereoelectronic conductance switch, and we demonstrate that the switching relies crucially on the electronic delocalization in Si-Si and Ge-Ge wire backbones. These studies illustrate the untapped potential in using Si- and Ge-based wires to design and control charge transport at the nanoscale and to allow quantum mechanics to be used as a tool to design ultraminiaturized switches.
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Affiliation(s)
- Timothy A. Su
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | - Haixing Li
- Columbia University, Department of Applied Physics
and Applied Math, New York, New York 10027, United States
| | - Rebekka S. Klausen
- Johns Hopkins University, Department of Chemistry, Baltimore, Maryland 21228, United States
| | - Nathaniel T. Kim
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | - Madhav Neupane
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | - James L. Leighton
- Columbia University, Department of Chemistry, New York, New York 10027, United States
| | | | - Latha Venkataraman
- Columbia University, Department of Chemistry, New York, New York 10027, United States
- Columbia University, Department of Applied Physics
and Applied Math, New York, New York 10027, United States
| | - Colin Nuckolls
- Columbia University, Department of Chemistry, New York, New York 10027, United States
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19
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Hamon P, Shaw‐Taberlet JA, Toupet L, Stueger H, Hamon J, Lapinte C. Electronic Interactions in the Electroactive Iron σ‐Ethynyl‐2‐Phenyltetramethyldisilanes [Cp*(dppe)Fe–C≡C–{Si(CH
3
)
2
}
2
–1,4‐C
6
H
4
X](PF
6
)
n
(
n
= 0, 1). Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201700094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Paul Hamon
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS Université de Rennes 1 35042 Rennes France
| | | | - Loic Toupet
- Institut de Phisique de Rennes, UMR 6251 CNRS Université de Rennes 1 35042 Rennes France
| | - Harald Stueger
- Institut für Anorganische Chemie Technische Universität Graz Stremayrgasse 16 A‐8010 Graz Austria
| | - Jean‐René Hamon
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS Université de Rennes 1 35042 Rennes France
| | - Claude Lapinte
- Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS Université de Rennes 1 35042 Rennes France
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