1
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Sil A, Hamilton L, Morris JMF, Daaoub AHS, Burrows JHH, Robertson CM, Luzyanin K, Higgins SJ, Sadeghi H, Nichols RJ, Sangtarash S, Vezzoli A. Zero-Bias Anti-Ohmic Behaviour in Diradicaloid Molecular Wires. Angew Chem Int Ed Engl 2024:e202410304. [PMID: 39003723 DOI: 10.1002/anie.202410304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 07/11/2024] [Accepted: 07/12/2024] [Indexed: 07/15/2024]
Abstract
Open-shell materials bearing multiple spin centres provide a key route to efficient charge transport in single-molecule electronic devices. They have narrow energy gaps, and their molecular orbitals align closely to the Fermi level of the metallic electrodes, thus allowing efficient electronic transport and higher conductance. Maintaining and stabilising multiple open-shell states-especially in contact with metallic electrodes-is however very challenging, generally requiring a continuous chemical or electrochemical potential to avoid self-immolation of the open-shell character. To overcome this issue, we designed, synthesised, and measured the conductance of a series of bis(indeno) fused acenes, where stability is imparted by a close-shell quinoidal conformation in resonance with the diradical electronic configuration. We show here that these compounds have anti-ohmic behaviour, with conductance increasing with increasing molecular length, at an unprecedented rate and across the entire bias window (± 1 . 3 V ${\pm 1.3\ V}$ ). Density Functional Theory (DFT) calculations support our findings, showing the rapidly narrowing HOMO-LUMO gap, unique to these diradicaloid structures, is responsible for the observed behaviour. Our results provide a framework for achieving efficient transport in neutral compounds and demonstrate the promise that diradicaloid materials have in single-molecule electronics, owing to their great stability and unique electronic structure.
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Affiliation(s)
- Amit Sil
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Lewis Hamilton
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - James M F Morris
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Abdalghani H S Daaoub
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - James H H Burrows
- 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
| | - Konstantin Luzyanin
- 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
| | - Hatef Sadeghi
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Richard J Nichols
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Sara Sangtarash
- Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Andrea Vezzoli
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
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2
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Clay CD, Mueller CM, Rich CC, Schatz GC, Bruggeman PJ, Frontiera RR. Evidence for Superoxide-Initiated Oxidation of Aniline in Water by Pulsed, Atmospheric Pressure Plasma. J Phys Chem Lett 2024; 15:6918-6926. [PMID: 38935645 DOI: 10.1021/acs.jpclett.4c01323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
Plasma-driven solution electrochemistry (PDSE) uses plasma-generated reactive species to drive redox reactions in solution. Nonthermal, atmospheric pressure plasmas, when irradiating water, produce many redox species. While PDSE is a promising chemical tool, there is limited insight into the mechanisms of the reactions due to the variety of short-lived reagents produced. In this study, we use aniline as a model system for studying redox mechanisms of PDSE. We show that the plasma irradiation of aqueous aniline solutions drives the formation of polyaniline oligomer, which is suppressed under acidic starting conditions. The addition of (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO), a radical scavenger, decreases the formation of oligomer by 80%, and the addition of superoxide dismutase fully hinders oligomerization. These results lead us to conclude that the oligomerization of aniline by plasma irradiation is initiated by superoxide. This discovery provides novel insights into PDSE mechanisms and illustrates a potential method of harnessing superoxide for chemical reactions.
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Affiliation(s)
- Collin D Clay
- University of Minnesota - Twin Cities, Department of Chemistry, Smith Hall, 207 Pleasant St SE, Minneapolis, Minnesota 55455-0431, United States
| | - Chelsea M Mueller
- Northwestern University, Department of Chemistry, 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Christopher C Rich
- University of Minnesota - Twin Cities, Department of Chemistry, Smith Hall, 207 Pleasant St SE, Minneapolis, Minnesota 55455-0431, United States
| | - George C Schatz
- Northwestern University, Department of Chemistry, 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Peter J Bruggeman
- University of Minnesota - Twin Cities, Department of Mechanical Engineering, 111 Church Street SE, Minneapolis, Minnesota 55455, United States
| | - Renee R Frontiera
- University of Minnesota - Twin Cities, Department of Chemistry, Smith Hall, 207 Pleasant St SE, Minneapolis, Minnesota 55455-0431, United States
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3
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Li L, Louie S, Orchanian NM, Nuckolls C, Venkataraman L. Long-Range Gating in Single-Molecule One-Dimensional Topological Insulators. J Am Chem Soc 2024. [PMID: 38832840 DOI: 10.1021/jacs.4c05699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Single-molecule one-dimensional topological insulator (1D TI) is a class of molecular wires that exhibit increasing conductance with wire length. This unique trend is due to the coupling between the two low-lying topological edge states of 1D TIs described by the Su-Schrieffer-Heeger model. In principle, this quantum phenomenon within 1D TIs can be utilized to achieve long-range gating in molecular conductors. Here, we study electron transport through a single-edge state of doubly oxidized oligophenylene bis(triarylamine) to understand the effect of the edge state coupling on conductance. We find that conductance is elevated by approximately 1 order of magnitude compared to a control molecule with the same conductance pathway. Density function theory calculations further support that the increase in conductance is due to the interaction between the edge states of 1D TIs. This work demonstrates a new gating paradigm in molecular electronics, while also providing a deeper understanding of how edge states interact and affect electron transport within 1D TIs.
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Affiliation(s)
- Liang Li
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Shayan Louie
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Nicholas M Orchanian
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
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4
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Lv X, Li C, Guo MM, Hong W, Chen LC, Zhang QC, Chen ZN. Hydroxyl Group as the 'Bridge' to Enhance the Single-Molecule Conductance by Hyperconjugation. Molecules 2024; 29:2440. [PMID: 38893316 PMCID: PMC11173964 DOI: 10.3390/molecules29112440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 05/17/2024] [Accepted: 05/20/2024] [Indexed: 06/21/2024] Open
Abstract
For designing single-molecule devices that have both conjugation systems and structural flexibility, a hyperconjugated molecule with a σ-π bond interaction is considered an ideal candidate. In the investigation of conductance at the single-molecule level, since few hyperconjugation systems have been involved, the strategy of building hyperconjugation systems and the mechanism of electron transport within this system remain unexplored. Based on the skipped-conjugated structure, we present a rational approach to construct a hyperconjugation molecule using a hydroxyl group, which serves as a bridge to interact with the conjugated fragments. The measurement of single-molecule conductance reveals a two-fold conductance enhancement of the hyperconjugation system having the 'bridging' hydroxyl group compared to hydroxyl-free derivatives. Theoretical studies demonstrate that the hydroxyl group in the hyperconjugation system connects the LUMO of the two conjugated fragments and opens a through-space channel for electron transport to enhance the conductance.
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Affiliation(s)
- Xin Lv
- Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China; (X.L.); (C.L.); (M.-M.G.); (Z.-N.C.)
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007, China
- Fujian College, University of Chinese Academy of Sciences, Fuzhou 350002, China
| | - Chang Li
- Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China; (X.L.); (C.L.); (M.-M.G.); (Z.-N.C.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Meng-Meng Guo
- Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China; (X.L.); (C.L.); (M.-M.G.); (Z.-N.C.)
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China;
| | - Li-Chuan Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China;
| | - Qian-Chong Zhang
- Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China; (X.L.); (C.L.); (M.-M.G.); (Z.-N.C.)
- Fujian College, University of Chinese Academy of Sciences, Fuzhou 350002, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
| | - Zhong-Ning Chen
- Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China; (X.L.); (C.L.); (M.-M.G.); (Z.-N.C.)
- Fujian College, University of Chinese Academy of Sciences, Fuzhou 350002, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
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5
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Almughathawi R, Hou S, Wu Q, Lambert CJ. Signatures of Topological States in Conjugated Macrocycles. NANO LETTERS 2024; 24. [PMID: 38591962 PMCID: PMC11057032 DOI: 10.1021/acs.nanolett.3c04796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 04/03/2024] [Accepted: 04/03/2024] [Indexed: 04/10/2024]
Abstract
Single-molecule electrical junctions possess a molecular core connected to source and drain electrodes via anchor groups, which feed and extract electricity from specific atoms within the core. As the distance between electrodes increases, the electrical conductance typically decreases, which is a feature shared by classical Ohmic conductors. Here we analyze the electrical conductance of cycloparaphenylene (CPP) macrocycles and demonstrate that they can exhibit a highly nonclassical increase in their electrical conductance as the distance between electrodes increases. We demonstrate that this is due to the topological nature of the de Broglie wave created by electrons injected into the macrocycle from the source. Although such topological states do not exist in isolated macrocycles, they are created when the molecule is in contact with the source. They are predicted to be a generic feature of conjugated macrocycles and open a new avenue to implementing highly nonclassical transport behavior in molecular junctions.
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Affiliation(s)
- Renad Almughathawi
- Physics
Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
- Physics
Department, Faculty of science, Taibah University, Medina 42353, Saudi Arabia
| | - Songjun Hou
- Physics
Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
| | - Qingqing Wu
- Physics
Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
| | - Colin J. Lambert
- Physics
Department, Lancaster University, LA1 4YB Lancaster, United Kingdom
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6
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Miller PD, Mengell J, Shultz DA, Kirk ML. Metal-Ligand Exchange Coupling Alters the Open-Shell Ligand Electronic Structure in a Bis(semiquinone) Complex. Inorg Chem 2024; 63:6493-6499. [PMID: 38517353 DOI: 10.1021/acs.inorgchem.4c00380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
The electronic structure of the bis(dioxolene) bridging ligand -SQ2Th2- is responsive to metal-ligand magnetic exchange coupling. Comparison of the crystal structure of (NiSQ)2Th2 to that of (ZnSQ)2Th2 indicates an open-shell biradical ground state for the dinuclear Ni(II) complex compared to the closed-shell quinoidal character found in the dinuclear Zn(II) complex. Consistent with a comparison of bond lengths obtained by X-ray diffraction, the analysis of the variable-temperature magnetic susceptibility data for crystalline (NiSQ)2Th2 yields reduced SQ-SQ radical-radical magnetic exchange coupling (JSQ-SQ = -203 cm-1) compared to that of (ZnSQ)2Th2 (JSQ-SQ = -321 cm-1). The reduced SQ-SQ exchange coupling in (NiSQ)2Th2 derives from an attenuation of the SQ spin densities, which in turn is derived from the Ni-SQ antiferromagnetic exchange interactions. This reduction in SQ--SQ exchange that we observe for (NiSQ)2Th2 correlates with an effective lengthening of the bridge unit by ∼2.1 Å relative to that of (ZnSQ)2Th2. This magnitude of the effective increase in the bridge distance is consistent with the (NiSQ)2Th2 JSQ-SQ value lying between those of (ZnSQ)2Th2 and (ZnSQ)2Th3. The ability to modulate spin populations on an organic radical via pairwise Ni-SQ magnetic exchange interactions is a general way to affect electronic coupling in the Th-Th bridge. Our results suggest that metal-radical exchange coupling represents a powerful mechanism for tuning organic molecular electronic structure, with important implications for molecular electronics and molecular electron transport.
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Affiliation(s)
- Paul D Miller
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Joshua Mengell
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - David A Shultz
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
- The Center for High Technology Materials, The University of New Mexico, Albuquerque, New Mexico 87106, United States
- Center for Quantum Information and Control (CQuIC), The University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
- Center for Computational Chemistry, The University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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7
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Cossaboon TA, Kazmi S, Tineo M, Hoy EP. Assessing the importance of multireference correlation in predicting reversed conductance decay. Phys Chem Chem Phys 2024; 26:6696-6707. [PMID: 38321937 DOI: 10.1039/d3cp01110k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
In a classical electronic resistor, conductance decays as the device length increases according to Ohm's Law. While most molecular series display a comparable exponential decay in conductance with increasing molecular length, a class of single-molecule device series exists where conductance instead increases with molecular/device length, a phenomenon called reversed conductance decay. While reversals of conductance decay have been repeatedly theoretically predicted, they have been far more difficult to demonstrate experimentally. Previous studies have suggested that theoretical multi-reference(static) correlation errors may be a major cause of this discrepancy, yet most single-molecule transport methods are unable to treat multireference correlation. Using our unique multireference transport method based on non-equilibrium Green's function and multiconfigurational pair-density functional theory (NEGF-MCPDFT), we examined a previously predicted case of reversed conductance decay in systems of linear chains of phenyl rings with varying lengths and electrode designs. We compare our NEGF-MCPDFT results to those of non-multireference NEGF methods to quantify the exact role of static correlation in conductance decay reversals and clarify their relative importance to geometric and electrode design/coupling considerations.
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Affiliation(s)
- Tanner A Cossaboon
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA.
| | - Samir Kazmi
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA.
| | - Matthew Tineo
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA.
| | - Erik P Hoy
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA.
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8
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Deng JR, González MT, Zhu H, Anderson HL, Leary E. Ballistic Conductance through Porphyrin Nanoribbons. J Am Chem Soc 2024; 146:3651-3659. [PMID: 38301131 PMCID: PMC10870699 DOI: 10.1021/jacs.3c07734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 11/22/2023] [Accepted: 11/22/2023] [Indexed: 02/03/2024]
Abstract
The search for long molecular wires that can transport charge with maximum efficiency over many nanometers has driven molecular electronics since its inception. Single-molecule conductance normally decays with length and is typically far below the theoretical limit of G0 (77.5 μS). Here, we measure the conductances of a family of edge-fused porphyrin ribbons (lengths 1-7 nm) that display remarkable behavior. The low-bias conductance is high across the whole series. Charging the molecules in situ results in a dramatic realignment of the frontier orbitals, increasing the conductance to 1 G0 (corresponding to a current of 20 μA). This behavior is most pronounced in the longer molecules due to their smaller HOMO-LUMO gaps. The conductance-voltage traces frequently exhibit peaks at zero bias, showing that a molecular energy level is in resonance with the Fermi level. This work lays the foundations for long, perfectly transmissive, molecular wires with technological potential.
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Affiliation(s)
- Jie-Ren Deng
- Department
of Chemistry, Chemistry Research Laboratory, Oxford University, Oxford OX1 3TA, U.K.
| | - M. Teresa González
- Fundación
IMDEA Nanociencia, Calle
Faraday 9, Campus de Cantoblanco, 28049 Madrid, Spain
| | - He Zhu
- Department
of Chemistry, Chemistry Research Laboratory, Oxford University, Oxford OX1 3TA, U.K.
| | - Harry L. Anderson
- Department
of Chemistry, Chemistry Research Laboratory, Oxford University, Oxford OX1 3TA, U.K.
| | - Edmund Leary
- Fundación
IMDEA Nanociencia, Calle
Faraday 9, Campus de Cantoblanco, 28049 Madrid, Spain
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9
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Miller PD, Shultz DA, Mengell J, Kirk ML, Wojtas L. Variation from closed-shell to open shell electronic structures in oligothiophene bis(dioxolene) complexes. Chem Sci 2023; 14:12264-12276. [PMID: 37969598 PMCID: PMC10631215 DOI: 10.1039/d3sc02341a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 10/07/2023] [Indexed: 11/17/2023] Open
Abstract
A series of oligothiophene bis(dioxolene) complexes, SQ-Thn-SQ (SQ = S = ½TpCum,MeZnII(3-tert-butyl-orthosemiquinonate); TpCum,Me = tris(5-cumenyl-3-methylpyrazolyl)borate anion) have been synthesized, structurally characterized, and studied as a function of the number of thiophene bridging units, n (n = 0-3) using a combination of variable-temperature (VT) electronic absorption and EPR spectroscopies, and VT magnetic susceptibility measurements. The thiophene bridge bond lengths determined by X-ray crystallography display dramatic differences across the SQ-Thn-SQ series. Bridge bond deviation values (Σ|Δi|) display a progressive change in the nature of the bridge fragment bonding as the number of thiophene groups increases, with quinoidal bridge character for n = 1 (SQ-Th-SQ) and biradical character with "aromatic" bridge bond lengths for n = 3 (SQ-Th3-SQ). Remarkably, for n = 2 (SQ-Th2-SQ) the nature of the bridge fragment is intermediate between quinoid and biradical aromatic, which we describe as having open-shell character as opposed to biradicaloid since the open-shell biradical configuration does not have the correct symmetry to mix with the quinoidal ground-state configuration. This bridge bonding character is reflected in the energies of the lowest lying open-shell states for these three molecules. The SQ-Th-SQ molecule is diamagnetic at all temperatures studied, and we provide evidence for SQ-SQ antiferromagnetic exchange coupling and population of triplet states in SQ-Th2-SQ and SQ-Th3-SQ, with JSQ-SQ(ave) = -279 cm-1 (VT EPR/electronic absorption/magnetic susceptibility) and JSQ-SQ = -117 cm-1 (VT EPR/electronic absorption/magnetic susceptibility), respectively. The results have been interpreted in the context of state configurational mixing within a simplified 4-electron, 3-orbital model that explicitly contains contributions of a bridge fragment. Variable-temperature spectroscopic- and magnetic susceptibility data are consistent with two low-lying open-shell states for SQ-Th3-SQ, but three low-lying states (one closed-shell and two open-shell) for SQ-Th2-SQ. This model provides a simple symmetry-based framework to understand the continuum of electronic and geometric structures of this class of molecules as a function of the number of thiophene units in the bridge.
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Affiliation(s)
- Paul D Miller
- Department of Chemistry, North Carolina State University Raleigh North Carolina 27695-8204 USA
| | - David A Shultz
- Department of Chemistry, North Carolina State University Raleigh North Carolina 27695-8204 USA
| | - Joshua Mengell
- Department of Chemistry and Chemical Biology, The University of New Mexico MSC03 2060, 1 University of New Mexico Albuquerque NM 87131-0001 USA
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico MSC03 2060, 1 University of New Mexico Albuquerque NM 87131-0001 USA
- The Center for High Technology Materials, The University of New Mexico Albuquerque New Mexico 87106 USA
- Center for Quantum Information and Control (CQuIC), The University of New Mexico Albuquerque New Mexico 87131-0001 USA
| | - Lukasz Wojtas
- Department of Chemistry, University of South Florida 4202 E. Fowler Avenue, CHE 205 Tampa FL 33620-5250 USA
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10
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Li L, Prindle CR, Shi W, Nuckolls C, Venkataraman L. Radical Single-Molecule Junctions. J Am Chem Soc 2023; 145:18182-18204. [PMID: 37555594 DOI: 10.1021/jacs.3c04487] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Radicals are unique molecular systems for applications in electronic devices due to their open-shell electronic structures. Radicals can function as good electrical conductors and switches in molecular circuits while also holding great promise in the field of molecular spintronics. However, it is both challenging to create stable, persistent radicals and to understand their properties in molecular junctions. The goal of this Perspective is to address this dual challenge by providing design principles for the synthesis of stable radicals relevant to molecular junctions, as well as offering current insight into the electronic properties of radicals in single-molecule devices. By exploring both the chemical and physical properties of established radical systems, we will facilitate increased exploration and development of radical-based molecular systems.
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Affiliation(s)
- Liang Li
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Claudia R Prindle
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Wanzhuo Shi
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
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11
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Bajaj A, Ali ME. Anti-ohmic nanoconductors: myth, reality and promise. Phys Chem Chem Phys 2023; 25:9607-9616. [PMID: 36942699 DOI: 10.1039/d3cp00366c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The recent accomplishment in the design of molecular nanowires characterized by increasing conductance with length has led to the origin of an extraordinary new family of molecular junctions referred to as "anti-ohmic" wires. Herein, this highly desirable, non-classical behavior, has been examined for molecules long-enough to exhibit pronounced diradical character in their ground state within the unrestricted DFT formalism with spin symmetry breaking. We demonstrate that highly conjugated acenes signal higher resistance in an open-shell singlet (OSS) configuration as compared to their closed-shell counterparts. This anomaly has been further proven for experimentally certified cumulene wires, which reveals phenomenal modulation in the transport characteristics such that an increasing conductance is observed in the closed-shell limit, while higher cumulenes in the OSS ground state yield regular decay of conductance.
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Affiliation(s)
- Ashima Bajaj
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab-140306, India.
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab-140306, India.
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