1
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Chen Z, Woltering SL, Limburg B, Tsang MY, Baugh J, Briggs GAD, Mol JA, Anderson HL, Thomas JO. Connections to the Electrodes Control the Transport Mechanism in Single-Molecule Transistors. Angew Chem Int Ed Engl 2024; 63:e202401323. [PMID: 38410064 DOI: 10.1002/anie.202401323] [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: 01/19/2024] [Revised: 02/23/2024] [Accepted: 02/26/2024] [Indexed: 02/28/2024]
Abstract
When designing a molecular electronic device for a specific function, it is necessary to control whether the charge-transport mechanism is phase-coherent transmission or particle-like hopping. Here we report a systematic study of charge transport through single zinc-porphyrin molecules embedded in graphene nanogaps to form transistors, and show that the transport mechanism depends on the chemistry of the molecule-electrode interfaces. We show that van der Waals interactions between molecular anchoring groups and graphene yield transport characteristic of Coulomb blockade with incoherent sequential hopping, whereas covalent molecule-electrode amide bonds give intermediately or strongly coupled single-molecule devices that display coherent transmission. These findings demonstrate the importance of interfacial engineering in molecular electronic circuits.
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Affiliation(s)
- Zhixin Chen
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
| | - Steffen L Woltering
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, Oxford, OX1 3TA, UK
| | - Bart Limburg
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, Oxford, OX1 3TA, UK
| | - Ming-Yee Tsang
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
| | - Jonathan Baugh
- Institute for Quantum Computing, University of Waterloo, 200 University Avenue West, N2 L 3G1, Waterloo, ON, Canada
| | - G Andrew D Briggs
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
| | - Jan A Mol
- School of Physical and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Harry L Anderson
- Department of Chemistry, University of Oxford Chemistry Research Laboratory, Oxford, OX1 3TA, UK
| | - James O Thomas
- Department of Materials, University of Oxford, 16 Parks Road, Oxford, OX1 3PH, UK
- School of Physical and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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2
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Alshammari M, Alhunayhin SMN, Hughes DL, Chambrier I, Cammidge AN. Scramble-Free Synthesis of Unhindered trans-A 2B 2-Mesoaryl Porphyrins via Bromophenyl Dipyrromethanes. Org Lett 2024; 26:1561-1565. [PMID: 38373336 PMCID: PMC10913071 DOI: 10.1021/acs.orglett.3c04215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/24/2024] [Accepted: 02/14/2024] [Indexed: 02/21/2024]
Abstract
Trans-disubstituted porphyrins are highly valuable intermediates across diverse fields, but they pose a significant synthesis challenge in some cases due to scrambling and formation of complex mixtures. Conditions that minimize scrambling also lower yields, but steric hindrance around the meso-aryl substituent can effectively suppress scrambling altogether. Here we report a straightforward approach to valuable trans-A2B2 porphyrin intermediates that are otherwise very difficult to obtain, through use of removable blocking bromide substituents.
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Affiliation(s)
- Muteb
H. Alshammari
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | | | - David L. Hughes
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Isabelle Chambrier
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Andrew N. Cammidge
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
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3
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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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4
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Ornago L, Zwick P, van der Poel S, Brandl T, El Abbassi M, Perrin ML, Dulić D, van der Zant HSJ, Mayor M. Influence of Peripheral Alkyl Groups on Junction Configurations in Single-Molecule Electronics. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:1413-1422. [PMID: 38293692 PMCID: PMC10823531 DOI: 10.1021/acs.jpcc.3c06970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 12/28/2023] [Accepted: 12/28/2023] [Indexed: 02/01/2024]
Abstract
The addition of a lateral alkyl chain is a well-known strategy to reduce π-stacked ensembles of molecules in solution, with the intention to minimize the interactions between the molecules' backbones. In this paper, we study whether this concept generalizes to single-molecule junctions by using a combination of mechanically controllable break junction (MCBJ) measurements and clustering-based data analysis with two small series of model compounds decorated with various bulky groups. The systematic study suggests that introducing alkyl side chains also favors the formation of electrode-molecule configurations that are not observed in their absence, thereby inducing broadening of the conductance peak in the one-dimensional histograms. Thus, the introduction of alkyl chains in aromatic compounds for molecular electronics must be carefully designed and optimized for the specific purpose, balancing between increased solubility and the possibility of additional junction configurations.
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Affiliation(s)
- Luca Ornago
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Patrick Zwick
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Sebastiaan van der Poel
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Thomas Brandl
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Maria El Abbassi
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Mickael L. Perrin
- Transport
at Nanoscale Interfaces Laboratory, Empa,
Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Department
of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland
- Quantum
Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Diana Dulić
- Department
of Physics and Department of Electrical Engineering, Faculty of Physical
and Mathematical Sciences, University of
Chile, Avenida Blanco
Encalada 2008, Santiago 8330015, Chile
| | - Herre S. J. van der Zant
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Marcel Mayor
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
- Institute
for Nanotechnology (INT), Karlsruhe Institute
of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany
- Lehn
Institute of Functional Materials (LIFM), School of Chemistry, Sun Yat-Sen University (SYSU), Guangzhou 510275, China
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5
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Bousfiha A, Amiri N, Akhssas F, Berthelot M, Echaubard J, Pirrotta M, Cattey H, Fleurat-Lessard P, Roger J, Devillers CH. Synthesis of meso,β-Fused Thiazinamine-Porphyrins via Oxidative C-N Fusion of Pyrimidinyl-Substituted Porphyrins. Org Lett 2023; 25:7979-7983. [PMID: 37910169 DOI: 10.1021/acs.orglett.3c03062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
5,15-Bis(pyrimidin-2-ylthio)porphyrins have been synthesized. Their electrochemical oxidation leads to the formation of mono- and bis-C-N-fused thiopyrimidinium intermediates depending on the applied charge and potential. These latter undergo nucleophilic attack with water during workup that drives the ring opening of the pyrimidinium moiety. When piperidine is added before or after workup, the neutral fused porphyrinthiazin-2-amines are generated, and they exhibit a significant bathochromic shift of their Soret and Q bands.
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Affiliation(s)
- Asmae Bousfiha
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Nesrine Amiri
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Fatima Akhssas
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Mathieu Berthelot
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Julie Echaubard
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Marc Pirrotta
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Hélène Cattey
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Paul Fleurat-Lessard
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Julien Roger
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
| | - Charles H Devillers
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR6302, CNRS, Univ. Bourgogne, 9 avenue Alain Savary, 21000 Dijon, France
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6
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Xu H, Fan H, Luan Y, Yan S, Martin L, Miao R, Pauly F, Meyhofer E, Reddy P, Linke H, Wärnmark K. Electrical Conductance and Thermopower of β-Substituted Porphyrin Molecular Junctions─Synthesis and Transport. J Am Chem Soc 2023; 145:23541-23555. [PMID: 37874166 PMCID: PMC10623571 DOI: 10.1021/jacs.3c07258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Indexed: 10/25/2023]
Abstract
Molecular junctions offer significant potential for enhancing thermoelectric power generation. Quantum interference effects and associated sharp features in electron transmission are expected to enable the tuning and enhancement of thermoelectric properties in molecular junctions. To systematically explore the effect of quantum interferences, we designed and synthesized two new classes of porphyrins, P1 and P2, with two methylthio anchoring groups in the 2,13- and 2,12-positions, respectively, and their Zn complexes, Zn-P1 and Zn-P2. Past theory suggests that P1 and Zn-P1 feature destructive quantum interference in single-molecule junctions with gold electrodes and may thus show high thermopower, while P2 and Zn-P2 do not. Our detailed experimental single-molecule break-junction studies of conductance and thermopower, the latter being the first ever performed on porphyrin molecular junctions, revealed that the electrical conductance of the P1 and Zn-P1 junctions is relatively close, and the same holds for P2 and Zn-P2, while there is a 6 times reduction in the electrical conductance between P1 and P2 type junctions. Further, we observed that the thermopower of P1 junctions is slightly larger than for P2 junctions, while Zn-P1 junctions show the largest thermopower and Zn-P2 junctions show the lowest. We relate the experimental results to quantum transport theory using first-principles approaches. While the conductance of P1 and Zn-P1 junctions is robustly predicted to be larger than those of P2 and Zn-P2, computed thermopowers depend sensitively on the level of theory and the single-molecule junction geometry. However, the predicted large difference in conductance and thermopower values between Zn-P1 and Zn-P2 derivatives, suggested in previous model calculations, is not supported by our experimental and theoretical findings.
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Affiliation(s)
- Hailiang Xu
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
- Department
of Chemistry, Centre of Analysis and Synthesis, Lund University, Box 121, 22100 Lund, Sweden
| | - Hao Fan
- Department
of Chemistry, Centre of Analysis and Synthesis, Lund University, Box 121, 22100 Lund, Sweden
| | - Yuxuan Luan
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - Shen Yan
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - León Martin
- Institute
of Physics and Centre for Advanced Analytics and Predictive Sciences, University of Augsburg, 86159 Augsburg, Germany
| | - Ruijiao Miao
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - Fabian Pauly
- Institute
of Physics and Centre for Advanced Analytics and Predictive Sciences, University of Augsburg, 86159 Augsburg, Germany
| | - Edgar Meyhofer
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
| | - Pramod Reddy
- Department
of Mechanical Engineering, University of
Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Materials Science and Engineering, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Heiner Linke
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
- Solid State
Physics, Lund University, Box 118, 22100 Lund, Sweden
| | - Kenneth Wärnmark
- NanoLund, Lund University, Box 118, 22100 Lund, Sweden
- Department
of Chemistry, Centre of Analysis and Synthesis, Lund University, Box 121, 22100 Lund, Sweden
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7
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Zhang C, Zhou X, Zhu C, Zong Y, Cao H. STM studies on porphyrins and phthalocyanines at the liquid/solid interface for molecular-scale electronics. Dalton Trans 2023; 52:11017-11024. [PMID: 37529933 DOI: 10.1039/d3dt01518a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
Porphyrins and phthalocyanines are promising candidates for single-molecule electronics. Among the many characterization tools, scanning tunneling microscopy (STM) represents a very powerful one to gain insight into the electronic properties at the molecular level, by correlating the charge transport behaviours of π-conjugated molecules with ultrahigh resolution imaging. In view of the sophistication of molecular self-assembly in the presence of a solution phase, in this frontier, we focus on STM studies on porphyrins and phthalocyanines at the liquid/solid interface, placing emphasis on the electronic and magnetic properties, as well as the switching behaviour of surface-confined or surface-anchored molecules. Furthermore, we have also addressed the topics of potential that can be exploited in this area.
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Affiliation(s)
- Chunmei Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, China.
| | - Xin Zhou
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, China.
| | - Chunlei Zhu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, China.
| | - Yufen Zong
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, China.
| | - Hai Cao
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, China.
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8
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Carella A, Ciuti S, Wiedemann HTA, Kay CWM, van der Est A, Carbonera D, Barbon A, Poddutoori PK, Di Valentin M. The electronic structure and dynamics of the excited triplet state of octaethylaluminum(III)-porphyrin investigated with advanced EPR methods. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 353:107515. [PMID: 37364432 DOI: 10.1016/j.jmr.2023.107515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/14/2023] [Accepted: 06/18/2023] [Indexed: 06/28/2023]
Abstract
The photoexcited triplet state of octaethylaluminum(III)-porphyrin (AlOEP) was investigated by time-resolved Electron Paramagnetic Resonance, Electron Nuclear Double Resonance and Electron Spin Echo Envelope Modulation in an organic glass at 10 and 80 K. This main group element porphyrin is unusual because the metal has a small ionic radius and is six-coordinate with axial covalent and coordination bonds. It is not known whether triplet state dynamics influence its magnetic resonance properties as has been observed for some transition metal porphyrins. Together with density functional theory modelling, the magnetic resonance data of AlOEP allow the temperature dependence of the zero-field splitting (ZFS) parameters, D and E, and the proton AZZ hyperfine coupling (hfc) tensor components of the methine protons, in the zero-field splitting frame to be determined. The results provide evidence that the ZFS, hfc and spin-lattice relaxation are indeed influenced by the presence of a dynamic process that is discussed in terms of Jahn-Teller dynamic effects. Thus, these effects should be taken into account when interpreting EPR data from larger complexes containing AlOEP.
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Affiliation(s)
- Angelo Carella
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Susanna Ciuti
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Haakon T A Wiedemann
- Department of Chemistry, Saarland University, Campus B 2.2, 66123 Saarbrücken, Germany
| | - Christopher W M Kay
- Department of Chemistry, Saarland University, Campus B 2.2, 66123 Saarbrücken, Germany; London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - Arthur van der Est
- Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario, Canada
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Antonio Barbon
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy.
| | - Prashanth K Poddutoori
- Department of Chemistry & Biochemistry, University of Minnesota Duluth, 1038 University Drive, Duluth, MN 55812, USA
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy.
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9
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Costa T, Peixoto M, Pineiro M, Seixas de Melo JS. Solvent-Driven Self-Organization of Meso-Substituted Porphyrins: Morphological Analysis from Fluorescence Lifetime Imaging Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5727-5737. [PMID: 37043283 PMCID: PMC10134502 DOI: 10.1021/acs.langmuir.2c03468] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 03/02/2023] [Indexed: 06/19/2023]
Abstract
A morphological analysis of different thin films of meso-tetra-p-(di-p-phenylamino)phenylporphyrin, H2T(TPA)4P, was made by fluorescence lifetime imaging microscopy (FLIM) and scanning electron microscopy (SEM). A comprehensive study of H2T(TPA)4P was undertaken through UV/vis absorption and fluorescence techniques in different solvents, solvent mixtures and in thin films. In solution, occurrence of intramolecular energy transfer from the triphenylamine (TPA) moieties to the porphyrin core, with quenching efficiencies in the order of 94-97%, is observed. The energy transfer rate constants are determined assuming Förster's dipole-dipole and Dexter's electron exchange mechanisms. In drop-cast-prepared thin films, from samples with different solvent mixtures, the photoluminescence (PL) quantum yield (ΦPL) decreases ∼1 order of magnitude compared to the solution behavior. FLIM and SEM experiments showed the self-organization and morphology of H2T(TPA)4P in thin films to be highly dependent on the solvent mixture used to prepare the film. In chloroform, the solvent's evaporation results in the formation of elongated and overlapped microrod structures. Introduction of a cosolvent, namely, a polar cosolvent, promotes changes in the morphology of the self-assembled structures, with the formation of three-dimensional spherical structures and hollow spheres. H2T(TPA)4P dispersed in a polymer matrix shows enhanced ΦPL values when compared to the drop-cast films. FLIM images showed coexistence of three different states or domains: aggregated, interface, and nonaggregated or less-aggregated states. This work highlights the importance of FLIM in the morphological characterization of heterogeneous films, together with the photophysical characterization of nano- and microdomains.
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10
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11
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Lyu J, Wong ZM, Sun H, Yang SW, Xu GQ. Self-assembled molecular nanowires on prepatterned Ge(001) surfaces. Chem Sci 2022; 13:5674-5679. [PMID: 35694329 PMCID: PMC9116370 DOI: 10.1039/d2sc00490a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/17/2022] [Indexed: 11/26/2022] Open
Abstract
It is a long-standing goal to fabricate conductive molecular nanowires (NWs) on semiconductor surfaces. Anchoring molecules to pre-patterned surface nanostructures is a practical approach to construct molecular NWs on semiconductor surfaces. Previously, well-ordered inorganic Ge NWs were deduced to spontaneously grow onto Pt/Ge(001) surfaces after annealing at an elevated temperature. In this work, we further demonstrate that organic 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecular NWs can self-assemble onto the atomic NWs on Pt/Ge(001) surfaces. The outer nitrogen atoms in TCNQ molecules hybridize with under-coordinated Ge atoms in Ge NWs with an energy release of ∼1.14 eV per molecule, and electrons transfer from Ge NWs to the frontier orbitals of anchored TCNQs resulting in a negatively charged state. This largely tailors the electronic configurations of TCNQs and Pt/Ge(001) surfaces, enhancing the electron transport along the dimer row direction. The TCNQ molecular NWs coupled with the Ge NWs represent an exemplary showcase for the fabrication of molecular NWs on semiconductor surfaces. We reported a strategy for the self-assembly of molecular nanowires (NWs) on Ge(001) surfaces.![]()
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Affiliation(s)
- Jing Lyu
- Department of Chemistry, National University of Singapore 3 Science Drive 3 117543 Singapore
| | - Zicong Marvin Wong
- Institute of High Performance Computing, Agency for Science, Technology and Research 1 Fusionopolis Way, #16-16 Connexis 138632 Singapore
| | - Haicheng Sun
- Department of Chemistry, National University of Singapore 3 Science Drive 3 117543 Singapore
| | - Shuo-Wang Yang
- Institute of High Performance Computing, Agency for Science, Technology and Research 1 Fusionopolis Way, #16-16 Connexis 138632 Singapore
| | - Guo Qin Xu
- Department of Chemistry, National University of Singapore 3 Science Drive 3 117543 Singapore
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12
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Schosser WM, Hsu C, Zwick P, Beltako K, Dulić D, Mayor M, van der Zant HSJ, Pauly F. Mechanical conductance tunability of a porphyrin-cyclophane single-molecule junction. NANOSCALE 2022; 14:984-992. [PMID: 34989747 PMCID: PMC8772887 DOI: 10.1039/d1nr06484c] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The possibility to study quantum interference phenomena at ambient conditions is an appealing feature of molecular electronics. By connecting two porphyrins in a cofacial cyclophane, we create an attractive platform for mechanically controlling electric transport through the intramolecular extent of π-orbital overlap of the porphyrins facing each other and through the angle of xanthene bridges with regard to the porphyrin planes. We analyze theoretically the evolution of molecular configurations in the pulling process and the corresponding changes in electric conduction by combining density functional theory (DFT) with Landauer scattering theory of phase-coherent elastic transport. Predicted conductances during the stretching process show order of magnitude variations caused by two robust destructive quantum interference features that span through the whole electronic gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Mechanically-controlled break junction (MCBJ) experiments at room temperature verify the mechanosensitive response of the molecular junctions. During the continuous stretching of the molecule, they show conductance variations of up to 1.5 orders of magnitude over single breaking events. Uncommon triple- and quadruple-frequency responses are observed in periodic electrode modulation experiments with amplitudes of up to 10 Å. This further confirms the theoretically predicted double transmission dips caused by the spatial and energetic rearrangement of molecular orbitals, with contributions from both through-space and through-bond transport.
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Affiliation(s)
- Werner M Schosser
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany.
| | - Chunwei Hsu
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft 2628 CJ, The Netherlands.
| | - Patrick Zwick
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
| | - Katawoura Beltako
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany.
| | - Diana Dulić
- Department of Physics, Department of Electrical Engineering, Faculty of Physical and Mathematical Sciences, University of Chile, Avenida Blanco Encalada 2008, Santiago 8330015, Chile
| | - Marcel Mayor
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
- Institute for Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), P. O. Box 3640, 76021 Karlsruhe, Germany
- Lehn Institute of Functional Materials (LIFM), School of Chemistry, Sun Yat-Sen University (SYSU), 510275 Guangzhou, China
| | - Herre S J van der Zant
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft 2628 CJ, The Netherlands.
| | - Fabian Pauly
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany.
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Hsu C, Schosser WM, Zwick P, Dulić D, Mayor M, Pauly F, van der Zant HSJ. Mechanical compression in cofacial porphyrin cyclophane pincers. Chem Sci 2022; 13:8017-8024. [PMID: 35919422 PMCID: PMC9278344 DOI: 10.1039/d2sc00937d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 06/12/2022] [Indexed: 11/21/2022] Open
Abstract
Intra- and intermolecular interactions are dominating chemical processes, and their concerted interplay enables complex nonequilibrium states like life. While the responsible basic forces are typically investigated spectroscopically, a conductance measurement to probe and control these interactions in a single molecule far out of equilibrium is reported here. Specifically, by separating macroscopic metal electrodes, two π-conjugated, bridge-connected porphyrin decks are peeled off on one side, but compressed on the other side due to the covalent mechanical fixation. We observe that the conductance response shows an exceptional exponential rise by two orders of magnitude in individual breaking events during the stretching. Theoretical studies atomistically explain the measured conductance behavior by a mechanically activated increase in through-bond transport and a simultaneous strengthening of through-space coupling. Our results not only reveal the various interacting intramolecular transport channels in a molecular set of levers, but also the molecules' potential to serve as molecular electro-mechanical sensors and switches. A two-order conductance increase upon stretching in porphyrin cyclophane pincer junctions is measured. Atomistic studies explain experimental observations by characteristic intramolecular changes in through-space and through-bond transport.![]()
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Affiliation(s)
- Chunwei Hsu
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft 2628 CJ, The Netherlands
| | | | - Patrick Zwick
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Diana Dulić
- Department of Physics, Department of Electrical Engineering, Faculty of Physical and Mathematical Sciences, University of Chile, Avenida Blanco Encalada 2008, Santiago 8330015, Chile
| | - Marcel Mayor
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
- Institute for Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), P. O. Box 3640, 76021 Karlsruhe, Germany
- Lehn Institute of Functional Materials (LIFM), School of Chemistry, Sun Yat-Sen University (SYSU), 510275 Guangzhou, China
| | - Fabian Pauly
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
| | - Herre S. J. van der Zant
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft 2628 CJ, The Netherlands
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