51
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Wang A, Zhou R, Zhou L, Sun K, Zhou J, Wei S, Jiang J. Arginine-Substituted Phthalocyanine with Concentration-Driven Self-Disaggregation Performance: Synthesis, Properties and Mechanistic Study. Chem Asian J 2016; 11:3008-3013. [DOI: 10.1002/asia.201601133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Indexed: 01/03/2023]
Affiliation(s)
- Ao Wang
- Institute of Chemical Industry of Forest Products, CAF; Key Lab of Biomass Energy and Material, Jiangsu Province; National Engineering Lab. For Biomass Chemical Utilization; Key and Open Lab. Of Forest Chemical Engineering, SFA; Institute of Chemical Industry of Forest Products, CAF; No. 16, Suojin 5th Village Nanjing 210042 China
- School of Chemistry and Materials Science; Jiangsu Key Laboratory of Biofunctional Materials; Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials; Key Laboratory of Applied Photochemistry; Nanjing Normal University; Wenyuan Road No.1 Nanjing 210023 China
| | - Rongrong Zhou
- School of Chemistry and Materials Science; Jiangsu Key Laboratory of Biofunctional Materials; Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials; Key Laboratory of Applied Photochemistry; Nanjing Normal University; Wenyuan Road No.1 Nanjing 210023 China
| | - Lin Zhou
- School of Chemistry and Materials Science; Jiangsu Key Laboratory of Biofunctional Materials; Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials; Key Laboratory of Applied Photochemistry; Nanjing Normal University; Wenyuan Road No.1 Nanjing 210023 China
| | - Kang Sun
- Institute of Chemical Industry of Forest Products, CAF; Key Lab of Biomass Energy and Material, Jiangsu Province; National Engineering Lab. For Biomass Chemical Utilization; Key and Open Lab. Of Forest Chemical Engineering, SFA; Institute of Chemical Industry of Forest Products, CAF; No. 16, Suojin 5th Village Nanjing 210042 China
| | - Jiahong Zhou
- School of Chemistry and Materials Science; Jiangsu Key Laboratory of Biofunctional Materials; Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials; Key Laboratory of Applied Photochemistry; Nanjing Normal University; Wenyuan Road No.1 Nanjing 210023 China
| | - Shaohua Wei
- School of Chemistry and Materials Science; Jiangsu Key Laboratory of Biofunctional Materials; Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials; Key Laboratory of Applied Photochemistry; Nanjing Normal University; Wenyuan Road No.1 Nanjing 210023 China
| | - Jianchun Jiang
- Institute of Chemical Industry of Forest Products, CAF; Key Lab of Biomass Energy and Material, Jiangsu Province; National Engineering Lab. For Biomass Chemical Utilization; Key and Open Lab. Of Forest Chemical Engineering, SFA; Institute of Chemical Industry of Forest Products, CAF; No. 16, Suojin 5th Village Nanjing 210042 China
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52
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Gupta A, Aparoy P. Insights into the structure activity relationship of mPGES-1 inhibitors: Hints for better inhibitor design. Int J Biol Macromol 2016; 88:624-32. [DOI: 10.1016/j.ijbiomac.2016.03.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 03/19/2016] [Accepted: 03/19/2016] [Indexed: 10/22/2022]
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53
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Hauptmann N, Robles R, Abufager P, Lorente N, Berndt R. AFM Imaging of Mercaptobenzoic Acid on Au(110): Submolecular Contrast with Metal Tips. J Phys Chem Lett 2016; 7:1984-1990. [PMID: 27183144 DOI: 10.1021/acs.jpclett.6b00684] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A self-assembled monolayer of mercaptobenzoic acid (MBA) on Au(110) is investigated with scanning tunneling and atomic force microscopy (STM and AFM) and density functional calculations. High-resolution AFM images obtained with metallic tips show clear contrasts between oxygen atoms and phenyl moieties. The contrast above the oxygen atoms is due to attractive covalent interactions, which is different than previously reported high-resolution images, where Pauli repulsion dominated the image contrast. We show that the bonding of MBA to the substrate occurs mainly through dispersion interactions, whereas the thiol-Au bond contributes only a quarter of the adsorption energy. No indication of Au adatoms mediating the thiol-Au interaction was found in contrast to other thiol-bonded systems. However, MBA lifts the Au(110)-(2 × 1) reconstruction.
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Affiliation(s)
- Nadine Hauptmann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , 24098 Kiel, Germany
| | - Roberto Robles
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Paula Abufager
- Instituto de Física de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), and Universidad Nacional de Rosario, Avenida Pellegrini 250, 2000 Rosario, Argentina
| | - Nicolas Lorente
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5 and Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , 24098 Kiel, Germany
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54
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Hapala P, Švec M, Stetsovych O, van der Heijden NJ, Ondráček M, van der Lit J, Mutombo P, Swart I, Jelínek P. Mapping the electrostatic force field of single molecules from high-resolution scanning probe images. Nat Commun 2016; 7:11560. [PMID: 27230940 PMCID: PMC4894979 DOI: 10.1038/ncomms11560] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 04/08/2016] [Indexed: 01/06/2023] Open
Abstract
How electronic charge is distributed over a molecule determines to a large extent its chemical properties. Here, we demonstrate how the electrostatic force field, originating from the inhomogeneous charge distribution in a molecule, can be measured with submolecular resolution. We exploit the fact that distortions typically observed in high-resolution atomic force microscopy images are for a significant part caused by the electrostatic force acting between charges of the tip and the molecule of interest. By finding a geometrical transformation between two high-resolution AFM images acquired with two different tips, the electrostatic force field or potential over individual molecules and self-assemblies thereof can be reconstructed with submolecular resolution. The chemical properties of molecules are largely determined by the distribution of charge across them. Here, the authors demonstrate how the electrostatic force field, originating from the inhomogeneous charge distribution in a molecule, can be measured with sub-molecular resolution.
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Affiliation(s)
- Prokop Hapala
- Department of Thin Films and Nanostructures, Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Martin Švec
- Department of Thin Films and Nanostructures, Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Oleksandr Stetsovych
- Department of Thin Films and Nanostructures, Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Nadine J van der Heijden
- Department of Chemistry, Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands
| | - Martin Ondráček
- Department of Thin Films and Nanostructures, Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Joost van der Lit
- Department of Chemistry, Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands
| | - Pingo Mutombo
- Department of Thin Films and Nanostructures, Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic
| | - Ingmar Swart
- Department of Chemistry, Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80 000, 3508 TA Utrecht, The Netherlands
| | - Pavel Jelínek
- Department of Thin Films and Nanostructures, Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 00 Prague, Czech Republic
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55
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Majzik Z, Cuenca AB, Pavliček N, Miralles N, Meyer G, Gross L, Fernández E. Synthesis of a Naphthodiazaborinine and Its Verification by Planarization with Atomic Force Microscopy. ACS NANO 2016; 10:5340-5345. [PMID: 27111055 DOI: 10.1021/acsnano.6b01484] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Aiming to study new motifs, potentially active as functional materials, we performed the synthesis of a naphthodiazaborinine (the BN isostere of the phenalenyl anion) that is bonded to a hindered di-ortho-substituted aryl system (9-anthracene). We used atomic force microscopy (AFM) and succeeded in both the verification of the original nonplanar structure of the molecule and the planarization of the skeleton by removing H atoms that cause steric hindrance. This study demonstrated that planarization by atomic manipulation is a possible route for extending molecular identification by AFM to nonplanar molecular systems that are difficult to probe with AFM directly.
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Affiliation(s)
- Zsolt Majzik
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - Ana B Cuenca
- Department Química Física i Inorgànica, University Rovira i Virgili , 43007 Tarragona, Spain
| | - Niko Pavliček
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - Núria Miralles
- Department Química Física i Inorgànica, University Rovira i Virgili , 43007 Tarragona, Spain
| | - Gerhard Meyer
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - Leo Gross
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - Elena Fernández
- Department Química Física i Inorgànica, University Rovira i Virgili , 43007 Tarragona, Spain
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56
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Sakai Y, Lee AJ, Chelikowsky JR. First-Principles Atomic Force Microscopy Image Simulations with Density Embedding Theory. NANO LETTERS 2016; 16:3242-3246. [PMID: 27050710 DOI: 10.1021/acs.nanolett.6b00741] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present an efficient first-principles method for simulating noncontact atomic force microscopy (nc-AFM) images using a "frozen density" embedding theory. Frozen density embedding theory enables one to efficiently compute the tip-sample interaction by considering a sample as a frozen external field. This method reduces the extensive computational load of first-principles AFM simulations by avoiding consideration of the entire tip-sample system and focusing on the tip alone. We demonstrate that our simulation with frozen density embedding theory accurately reproduces full density functional theory simulations of freestanding hydrocarbon molecules while the computational time is significantly reduced. Our method also captures the electronic effect of a Cu(111) substrate on the AFM image of pentacene and reproduces the experimental AFM image of Cu2N on a Cu(100) surface. This approach is applicable for theoretical imaging applications on large molecules, two-dimensional materials, and materials surfaces.
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Affiliation(s)
- Yuki Sakai
- Center for Computational Materials, Institute for Computational Engineering and Sciences, ‡Department of Chemical Engineering, §Department of Physics, The University of Texas at Austin , Austin, Texas 78712, United States
| | - Alex J Lee
- Center for Computational Materials, Institute for Computational Engineering and Sciences, ‡Department of Chemical Engineering, §Department of Physics, The University of Texas at Austin , Austin, Texas 78712, United States
| | - James R Chelikowsky
- Center for Computational Materials, Institute for Computational Engineering and Sciences, ‡Department of Chemical Engineering, §Department of Physics, The University of Texas at Austin , Austin, Texas 78712, United States
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57
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Imaging single-molecule reaction intermediates stabilized by surface dissipation and entropy. Nat Chem 2016; 8:678-83. [DOI: 10.1038/nchem.2506] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 03/16/2016] [Indexed: 12/25/2022]
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58
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Kocić N, Liu X, Chen S, Decurtins S, Krejčí O, Jelínek P, Repp J, Liu SX. Control of Reactivity and Regioselectivity for On-Surface Dehydrogenative Aryl–Aryl Bond Formation. J Am Chem Soc 2016; 138:5585-93. [DOI: 10.1021/jacs.5b13461] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Nemanja Kocić
- Institute
of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Xunshan Liu
- Department
of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Songjie Chen
- Department
of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Silvio Decurtins
- Department
of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Ondřej Krejčí
- Institute of Physics of Czech Academy of Sciences, 16200 Prague, Czech Republic
- Charles University in Prague, Faculty of Mathematics
and Physics, Department of Surface and Plasma Science, 18000 Prague, Czech Republic
| | - Pavel Jelínek
- Institute of Physics of Czech Academy of Sciences, 16200 Prague, Czech Republic
| | - Jascha Repp
- Institute
of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Shi-Xia Liu
- Department
of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
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59
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Sweetman A, Rashid MA, Jarvis SP, Dunn JL, Rahe P, Moriarty P. Visualizing the orientational dependence of an intermolecular potential. Nat Commun 2016; 7:10621. [PMID: 26879386 PMCID: PMC4757755 DOI: 10.1038/ncomms10621] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 01/05/2016] [Indexed: 11/30/2022] Open
Abstract
Scanning probe microscopy can now be used to map the properties of single molecules with intramolecular precision by functionalization of the apex of the scanning probe tip with a single atom or molecule. Here we report on the mapping of the three-dimensional potential between fullerene (C60) molecules in different relative orientations, with sub-Angstrom resolution, using dynamic force microscopy (DFM). We introduce a visualization method which is capable of directly imaging the variation in equilibrium binding energy of different molecular orientations. We model the interaction using both a simple approach based around analytical Lennard-Jones potentials, and with dispersion-force-corrected density functional theory (DFT), and show that the positional variation in the binding energy between the molecules is dominated by the onset of repulsive interactions. Our modelling suggests that variations in the dispersion interaction are masked by repulsive interactions even at displacements significantly larger than the equilibrium intermolecular separation.
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Affiliation(s)
- Adam Sweetman
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Mohammad A. Rashid
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Samuel P. Jarvis
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Janette L. Dunn
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Philipp Rahe
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Philip Moriarty
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
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60
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Mönig H, Hermoso DR, Díaz Arado O, Todorović M, Timmer A, Schüer S, Langewisch G, Pérez R, Fuchs H. Submolecular Imaging by Noncontact Atomic Force Microscopy with an Oxygen Atom Rigidly Connected to a Metallic Probe. ACS NANO 2016; 10:1201-9. [PMID: 26605698 DOI: 10.1021/acsnano.5b06513] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In scanning probe microscopy, the imaging characteristics in the various interaction channels crucially depend on the chemical termination of the probe tip. Here we analyze the contrast signatures of an oxygen-terminated copper tip with a tetrahedral configuration of the covalently bound terminal O atom. Supported by first-principles calculations we show how this tip termination can be identified by contrast analysis in noncontact atomic force and scanning tunneling microscopy (NC-AFM, STM) on a partially oxidized Cu(110) surface. After controlled tip functionalization by soft indentations of only a few angstroms in an oxide nanodomain, we demonstrate that this tip allows imaging an organic molecule adsorbed on Cu(110) by constant-height NC-AFM in the repulsive force regime, revealing its internal bond structure. In established tip functionalization approaches where, for example, CO or Xe is deliberately picked up from a surface, these probe particles are only weakly bound to the metallic tip, leading to lateral deflections during scanning. Therefore, the contrast mechanism is subject to image distortions, artifacts, and related controversies. In contrast, our simulations for the O-terminated Cu tip show that lateral deflections of the terminating O atom are negligible. This allows a detailed discussion of the fundamental imaging mechanisms in high-resolution NC-AFM experiments. With its structural rigidity, its chemically passivated state, and a high electron density at the apex, we identify the main characteristics of the O-terminated Cu tip, making it a highly attractive complementary probe for the characterization of organic nanostructures on surfaces.
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Affiliation(s)
- Harry Mönig
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany
- Center for Nanotechnology (CeNTech) , Heisenbergstrasse 11, 48149 Münster, Germany
| | | | - Oscar Díaz Arado
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany
- Center for Nanotechnology (CeNTech) , Heisenbergstrasse 11, 48149 Münster, Germany
| | | | - Alexander Timmer
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany
- Center for Nanotechnology (CeNTech) , Heisenbergstrasse 11, 48149 Münster, Germany
| | - Simon Schüer
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany
- Center for Nanotechnology (CeNTech) , Heisenbergstrasse 11, 48149 Münster, Germany
| | - Gernot Langewisch
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany
- Center for Nanotechnology (CeNTech) , Heisenbergstrasse 11, 48149 Münster, Germany
| | | | - Harald Fuchs
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany
- Center for Nanotechnology (CeNTech) , Heisenbergstrasse 11, 48149 Münster, Germany
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61
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Korolkov VV, Svatek SA, Summerfield A, Kerfoot J, Yang L, Taniguchi T, Watanabe K, Champness NR, Besley NA, Beton PH. van der Waals-Induced Chromatic Shifts in Hydrogen-Bonded Two-Dimensional Porphyrin Arrays on Boron Nitride. ACS NANO 2015; 9:10347-10355. [PMID: 26348583 DOI: 10.1021/acsnano.5b04443] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The fluorescence of a two-dimensional supramolecular network of 5,10,15,20-tetrakis(4-carboxylphenyl)porphyrin (TCPP) adsorbed on hexagonal boron nitride (hBN) is red-shifted due to, primarily, adsorbate-substrate van der Waals interactions. TCPP is deposited from solution on hBN and forms faceted islands with typical dimensions of 100 nm and either square or hexagonal symmetry. The molecular arrangement is stabilized by in-plane hydrogen bonding as determined by a combination of molecular-resolution atomic force microscopy performed under ambient conditions and density functional theory; a similar structure is observed on MoS2 and graphite. The fluorescence spectra of submonolayers of TCPP on hBN are red-shifted by ∼30 nm due to the distortion of the molecule arising from van der Waals interactions, in agreement with time-dependent density functional theory calculations. Fluorescence intensity variations are observed due to coherent partial reflections at the hBN interface, implying that such hybrid structures have potential in photonic applications.
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Affiliation(s)
| | | | | | | | | | - Takashi Taniguchi
- The National Institute for Materials Science, Advanced Materials Laboratory , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- The National Institute for Materials Science, Advanced Materials Laboratory , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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62
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Corso M, Ondráček M, Lotze C, Hapala P, Franke KJ, Jelínek P, Pascual JI. Charge Redistribution and Transport in Molecular Contacts. PHYSICAL REVIEW LETTERS 2015; 115:136101. [PMID: 26451568 DOI: 10.1103/physrevlett.115.136101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Indexed: 06/05/2023]
Abstract
The forces between two single molecules brought into contact, and their connection with charge transport through the molecular junction, are studied here using non contact AFM, STM, and density functional theory simulations. A carbon monoxide molecule approaching an acetylene molecule (C_{2}H_{2}) initially feels weak attractive electrostatic forces, partly arising from charge reorganization in the presence of molecular . We find that the molecular contact is chemically passive, and protects the electron tunneling barrier from collapsing, even in the limit of repulsive forces. However, we find subtle conductance and force variations at different contacting sites along the C_{2}H_{2} molecule attributed to a weak overlap of their respective frontier orbitals.
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Affiliation(s)
- Martina Corso
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
- Centro de Fisica de Materiales CSIC/UPV-EHU, 20018 Donostia-San Sebastian, Spain
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
| | - Martin Ondráček
- Institute of Physics of the Academy of Sciences of the Czech Republic, 162 00 Prague, Czech Republic
| | - Christian Lotze
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Prokop Hapala
- Institute of Physics of the Academy of Sciences of the Czech Republic, 162 00 Prague, Czech Republic
| | - Katharina J Franke
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Pavel Jelínek
- Institute of Physics of the Academy of Sciences of the Czech Republic, 162 00 Prague, Czech Republic
| | - J Ignacio Pascual
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
- CIC nanoGUNE, 20018 Donostia-San Sebastian, Spain
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63
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Measuring the mechanical properties of molecular conformers. Nat Commun 2015; 6:8338. [PMID: 26388232 PMCID: PMC4595718 DOI: 10.1038/ncomms9338] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 08/12/2015] [Indexed: 11/15/2022] Open
Abstract
Scanning probe-actuated single molecule manipulation has proven to be an exceptionally powerful tool for the systematic atomic-scale interrogation of molecular adsorbates. To date, however, the extent to which molecular conformation affects the force required to push or pull a single molecule has not been explored. Here we probe the mechanochemical response of two tetra(4-bromophenyl)porphyrin conformers using non-contact atomic force microscopy where we find a large difference between the lateral forces required for manipulation. Remarkably, despite sharing very similar adsorption characteristics, variations in the potential energy surface are capable of prohibiting probe-induced positioning of one conformer, while simultaneously permitting manipulation of the alternative conformational form. Our results are interpreted in the context of dispersion-corrected density functional theory calculations which reveal significant differences in the diffusion barriers for each conformer. These results demonstrate that conformational variation significantly modifies the mechanical response of even simple porpyhrins, potentially affecting many other flexible molecules. Manipulation of single molecules can be achieved using scanning probe microscopy but the influence of molecular conformation on this process has, until now, been unclear. Here, the authors probe two different types of porphyrin conformer on a surface and see strong differences in their mechanochemical response.
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64
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Jarvis SP. Resolving Intra- and Inter-Molecular Structure with Non-Contact Atomic Force Microscopy. Int J Mol Sci 2015; 16:19936-59. [PMID: 26307976 PMCID: PMC4581333 DOI: 10.3390/ijms160819936] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 07/24/2015] [Accepted: 07/30/2015] [Indexed: 11/25/2022] Open
Abstract
A major challenge in molecular investigations at surfaces has been to image individual molecules, and the assemblies they form, with single-bond resolution. Scanning probe microscopy, with its exceptionally high resolution, is ideally suited to this goal. With the introduction of methods exploiting molecularly-terminated tips, where the apex of the probe is, for example, terminated with a single CO, Xe or H2 molecule, scanning probe methods can now achieve higher resolution than ever before. In this review, some of the landmark results related to attaining intramolecular resolution with non-contact atomic force microscopy (NC-AFM) are summarised before focussing on recent reports probing molecular assemblies where apparent intermolecular features have been observed. Several groups have now highlighted the critical role that flexure in the tip-sample junction plays in producing the exceptionally sharp images of both intra- and apparent inter-molecular structure. In the latter case, the features have been identified as imaging artefacts, rather than real intermolecular bonds. This review discusses the potential for NC-AFM to provide exceptional resolution of supramolecular assemblies stabilised via a variety of intermolecular forces and highlights the potential challenges and pitfalls involved in interpreting bonding interactions.
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Affiliation(s)
- Samuel Paul Jarvis
- School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2RD, UK.
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65
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Huber F, Matencio S, Weymouth AJ, Ocal C, Barrena E, Giessibl FJ. Intramolecular Force Contrast and Dynamic Current-Distance Measurements at Room Temperature. PHYSICAL REVIEW LETTERS 2015; 115:066101. [PMID: 26296122 DOI: 10.1103/physrevlett.115.066101] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Indexed: 06/04/2023]
Abstract
Scanning probe microscopy can be used to probe the internal atomic structure of flat organic molecules. This technique requires an unreactive tip and has, until now, been demonstrated only at liquid helium and liquid nitrogen temperatures. We demonstrate intramolecular and intermolecular force contrast at room temperature on PTCDA molecules adsorbed on a Ag/Si(111)-(√[3]×√[3]) surface. The oscillating force sensor allows us to dynamically measure the vertical decay constant of the tunneling current. The precision of this method is increased by quantifying the transimpedance of the current to voltage converter and accounting for the tip oscillation. This measurement yields a clear contrast between neighboring molecules, which we attribute to the different charge states.
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Affiliation(s)
- F Huber
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - S Matencio
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
| | - A J Weymouth
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - C Ocal
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
| | - E Barrena
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
| | - F J Giessibl
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
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66
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Chemical structure imaging of a single molecule by atomic force microscopy at room temperature. Nat Commun 2015; 6:7766. [PMID: 26178193 PMCID: PMC4518281 DOI: 10.1038/ncomms8766] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 06/05/2015] [Indexed: 11/08/2022] Open
Abstract
Atomic force microscopy is capable of resolving the chemical structure of a single molecule on a surface. In previous research, such high resolution has only been obtained at low temperatures. Here we demonstrate that the chemical structure of a single molecule can be clearly revealed even at room temperature. 3,4,9,10-perylene tetracarboxylic dianhydride, which is strongly adsorbed onto a corner-hole site of a Si(111)-(7 × 7) surface in a bridge-like configuration is used for demonstration. Force spectroscopy combined with first-principle calculations clarifies that chemical structures can be resolved independent of tip reactivity. We show that the submolecular contrast over a central part of the molecule is achieved in the repulsive regime due to differences in the attractive van der Waals interaction and the Pauli repulsive interaction between different sites of the molecule.
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67
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68
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Sweetman A, Goubet N, Lekkas I, Pileni MP, Moriarty P. Nano-contact microscopy of supracrystals. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1229-36. [PMID: 26114081 PMCID: PMC4462851 DOI: 10.3762/bjnano.6.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 05/04/2015] [Indexed: 05/13/2023]
Abstract
BACKGROUND Highly ordered three-dimensional colloidal crystals (supracrystals) comprised of 7.4 nm diameter Au nanocrystals (with a 5% size dispersion) have been imaged and analysed using a combination of scanning tunnelling microscopy and dynamic force microscopy. RESULTS By exploring the evolution of both the force and tunnel current with respect to tip-sample separation, we arrive at the surprising finding that single nanocrystal resolution is readily obtained in tunnelling microscopy images acquired more than 1 nm into the repulsive (i.e., positive force) regime of the probe-nanocrystal interaction potential. Constant height force microscopy has been used to map tip-sample interactions in this regime, revealing inhomogeneities which arise from the convolution of the tip structure with the ligand distribution at the nanocrystal surface. CONCLUSION Our combined STM-AFM measurements show that the contrast mechanism underpinning high resolution imaging of nanoparticle supracrystals involves a form of nanoscale contact imaging, rather than the through-vacuum tunnelling which underpins traditional tunnelling microscopy and spectroscopy.
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Affiliation(s)
- Adam Sweetman
- The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K
| | - Nicolas Goubet
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, Monaris, F-75005, Paris, France
- CNRS, UMR 8233, Monaris, F-75005, Paris, France
| | - Ioannis Lekkas
- The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K
| | - Marie Paule Pileni
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, Monaris, F-75005, Paris, France
- CNRS, UMR 8233, Monaris, F-75005, Paris, France
- CEA/IRAMIS, CEA Saclay, 91191, Gif-sur-Yvette, France
| | - Philip Moriarty
- The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K
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69
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Gross L, Schuler B, Mohn F, Moll N, Repp J, Meyer G. Atomic Resolution on Molecules with Functionalized Tips. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/978-3-319-15588-3_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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70
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Korolkov VV, Svatek SA, Allen S, Roberts CJ, Tendler SJB, Taniguchi T, Watanabe K, Champness NR, Beton PH. Bimolecular porous supramolecular networks deposited from solution on layered materials: graphite, boron nitride and molybdenum disulphide. Chem Commun (Camb) 2015; 50:8882-5. [PMID: 24969532 DOI: 10.1039/c4cc03720k] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A two-dimensional porous network formed from perylene tetracarboxylic diimide (PTCDI) and melamine may be deposited from solution on the surfaces of highly oriented pyrolytic graphite (HOPG), hexagonal boron nitride (hBN) and molybdenum disulphide (MoS2). Images acquired using high resolution atomic force microscopy (AFM) operating under ambient conditions have revealed that the network forms extended ordered monolayers (>1 μm(2)) on HOPG and hBN whereas on MoS2 much smaller islands are observed.
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Affiliation(s)
- Vladimir V Korolkov
- School of Physics & Astronomy, The University of Nottingham, Nottingham NG7 2RD, UK.
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71
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Moreno C, Stetsovych O, Shimizu TK, Custance O. Imaging three-dimensional surface objects with submolecular resolution by atomic force microscopy. NANO LETTERS 2015; 15:2257-62. [PMID: 25756297 DOI: 10.1021/nl504182w] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Submolecular imaging by atomic force microscopy (AFM) has recently been established as a stunning technique to reveal the chemical structure of unknown molecules, to characterize intramolecular charge distributions and bond ordering, as well as to study chemical transformations and intermolecular interactions. So far, most of these feats were achieved on planar molecular systems because high-resolution imaging of three-dimensional (3D) surface structures with AFM remains challenging. Here we present a method for high-resolution imaging of nonplanar molecules and 3D surface systems using AFM with silicon cantilevers as force sensors. We demonstrate this method by resolving the step-edges of the (101) anatase surface at the atomic scale by simultaneously visualizing the structure of a pentacene molecule together with the atomic positions of the substrate and by resolving the contour and probe-surface force field on a C60 molecule with intramolecular resolution. The method reported here holds substantial promise for the study of 3D surface systems such as nanotubes, clusters, nanoparticles, polymers, and biomolecules using AFM with high resolution.
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Affiliation(s)
- César Moreno
- †National Institute for Materials Science (NIMS), 1-2-1 Sengen, 305-0047 Tsukuba, Ibaraki Japan
- ‡International Center for Young Scientists, NIMS, 1-2-1 Sengen, 305-0047 Tsukuba, Ibaraki Japan
| | - Oleksandr Stetsovych
- †National Institute for Materials Science (NIMS), 1-2-1 Sengen, 305-0047 Tsukuba, Ibaraki Japan
- §Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, Prague, Czech Rebublic
| | - Tomoko K Shimizu
- †National Institute for Materials Science (NIMS), 1-2-1 Sengen, 305-0047 Tsukuba, Ibaraki Japan
- §JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Oscar Custance
- †National Institute for Materials Science (NIMS), 1-2-1 Sengen, 305-0047 Tsukuba, Ibaraki Japan
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72
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Jarvis SP, Sweetman AM, Lekkas I, Champness NR, Kantorovich L, Moriarty P. Simulated structure and imaging of NTCDI on Si(1 1 1)-7 × 7 : a combined STM, NC-AFM and DFT study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:054004. [PMID: 25414147 DOI: 10.1088/0953-8984/27/5/054004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The adsorption of naphthalene tetracarboxylic diimide (NTCDI) on Si(1 1 1)-7 × 7 is investigated through a combination of scanning tunnelling microscopy (STM), noncontact atomic force microscopy (NC-AFM) and density functional theory (DFT) calculations. We show that NTCDI adopts multiple planar adsorption geometries on the Si(1 1 1)-7 × 7 surface which can be imaged with intramolecular bond resolution using NC-AFM. DFT calculations reveal adsorption is dominated by covalent bond formation between the molecular oxygen atoms and the surface silicon adatoms. The chemisorption of the molecule is found to induce subtle distortions to the molecular structure, which are observed in NC-AFM images.
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Affiliation(s)
- S P Jarvis
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
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73
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Aakeröy CB, Wijethunga TK, Desper J. Molecular electrostatic potential dependent selectivity of hydrogen bonding. NEW J CHEM 2015. [DOI: 10.1039/c4nj01324g] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A molecular electrostatic potential based approach for anticipating the outcome of hydrogen-bond interactions in a competitive scenario is described.
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Affiliation(s)
| | | | - John Desper
- Department of Chemistry
- Kansas State University
- Manhattan
- USA
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74
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Otero-Irurueta G, Hernández-Rodríguez I, Martínez JI, Palacios-Rivera R, Palomares FJ, López MF, Gallego AI, Delgado S, Zamora F, Méndez J, Martín-Gago JA. On-surface self-organization of a robust metal–organic cluster based on copper(i) with chloride and organosulphur ligands. Chem Commun (Camb) 2015; 51:3243-6. [DOI: 10.1039/c4cc08471c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Vacuum sublimation of a metal–organic cluster leading to supramolecular wires on surfaces.
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Affiliation(s)
- Gonzalo Otero-Irurueta
- Center for Mechanical Technology & Automation-TEMA
- University of Aveiro
- 3810-193 Aveiro
- Portugal
| | | | - José I. Martínez
- Instituto Ciencia de Materiales de Madrid - CSIC
- 28049-Madrid
- Spain
| | | | | | - María F. López
- Instituto Ciencia de Materiales de Madrid - CSIC
- 28049-Madrid
- Spain
| | - Almudena I. Gallego
- Departamento de Quimica Inorganica
- Universidad Autónoma de Madrid, UAM
- E-28049 Madrid
- Spain
| | - Salomé Delgado
- Departamento de Quimica Inorganica
- Universidad Autónoma de Madrid, UAM
- E-28049 Madrid
- Spain
| | - Félix Zamora
- Departamento de Quimica Inorganica
- Universidad Autónoma de Madrid, UAM
- E-28049 Madrid
- Spain
- Universidad Autónoma de Madrid
| | - Javier Méndez
- Instituto Ciencia de Materiales de Madrid - CSIC
- 28049-Madrid
- Spain
| | - José A. Martín-Gago
- Instituto Ciencia de Materiales de Madrid - CSIC
- 28049-Madrid
- Spain
- Centro de Astrobiología
- INTA-CSIC
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75
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Mistry A, Moreton B, Schuler B, Mohn F, Meyer G, Gross L, Williams A, Scott P, Costantini G, Fox DJ. The Synthesis and STM/AFM Imaging of ‘Olympicene’ Benzo[cd]pyrenes. Chemistry 2014; 21:2011-8. [DOI: 10.1002/chem.201404877] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Indexed: 11/10/2022]
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76
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Stirling J, Lekkas I, Sweetman A, Djuranovic P, Guo Q, Pauw B, Granwehr J, Lévy R, Moriarty P. Critical assessment of the evidence for striped nanoparticles. PLoS One 2014; 9:e108482. [PMID: 25402426 PMCID: PMC4234314 DOI: 10.1371/journal.pone.0108482] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 07/30/2014] [Indexed: 11/18/2022] Open
Abstract
There is now a significant body of literature which reports that stripes form in the ligand shell of suitably functionalised Au nanoparticles. This stripe morphology has been proposed to strongly affect the physicochemical and biochemical properties of the particles. We critique the published evidence for striped nanoparticles in detail, with a particular focus on the interpretation of scanning tunnelling microscopy (STM) data (as this is the only technique which ostensibly provides direct evidence for the presence of stripes). Through a combination of an exhaustive re-analysis of the original data, in addition to new experimental measurements of a simple control sample comprising entirely unfunctionalised particles, we show that all of the STM evidence for striped nanoparticles published to date can instead be explained by a combination of well-known instrumental artefacts, or by issues with data acquisition/analysis protocols. We also critically re-examine the evidence for the presence of ligand stripes which has been claimed to have been found from transmission electron microscopy, nuclear magnetic resonance spectroscopy, small angle neutron scattering experiments, and computer simulations. Although these data can indeed be interpreted in terms of stripe formation, we show that the reported results can alternatively be explained as arising from a combination of instrumental artefacts and inadequate data analysis techniques.
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Affiliation(s)
- Julian Stirling
- School of Physics and Astronomy, The University of Nottingham, Nottingham, United Kingdom
- * E-mail:
| | - Ioannis Lekkas
- School of Physics and Astronomy, The University of Nottingham, Nottingham, United Kingdom
| | - Adam Sweetman
- School of Physics and Astronomy, The University of Nottingham, Nottingham, United Kingdom
| | - Predrag Djuranovic
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Quanmin Guo
- School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom
| | - Brian Pauw
- International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, Japan
| | - Josef Granwehr
- Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, The University of Nottingham, Nottingham, United Kingdom
| | - Raphaël Lévy
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Philip Moriarty
- School of Physics and Astronomy, The University of Nottingham, Nottingham, United Kingdom
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77
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Hämäläinen SK, van der Heijden N, van der Lit J, den Hartog S, Liljeroth P, Swart I. Intermolecular contrast in atomic force microscopy images without intermolecular bonds. PHYSICAL REVIEW LETTERS 2014; 113:186102. [PMID: 25396382 DOI: 10.1103/physrevlett.113.186102] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Indexed: 05/19/2023]
Abstract
Intermolecular features in atomic force microscopy images of organic molecules have been ascribed to intermolecular bonds. A recent theoretical study [P. Hapala et al., Phys. Rev. B 90, 085421 (2014)] showed that these features can also be explained by the flexibility of molecule-terminated tips. We probe this effect by carrying out atomic force microscopy experiments on a model system that contains regions where intermolecular bonds should and should not exist between close-by molecules. Intermolecular features are observed in both regions, demonstrating that intermolecular contrast cannot be directly interpreted as intermolecular bonds.
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Affiliation(s)
- Sampsa K Hämäläinen
- Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, 00076 Aalto, Finland
| | - Nadine van der Heijden
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Joost van der Lit
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Stephan den Hartog
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Peter Liljeroth
- Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, 00076 Aalto, Finland
| | - Ingmar Swart
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
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78
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Sang H, Jarvis SP, Zhou Z, Sharp P, Moriarty P, Wang J, Wang Y, Kantorovich L. Identifying tips for intramolecular NC-AFM imaging via in situ fingerprinting. Sci Rep 2014; 4:6678. [PMID: 25327642 PMCID: PMC4202218 DOI: 10.1038/srep06678] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 09/29/2014] [Indexed: 11/09/2022] Open
Abstract
A practical experimental strategy is proposed that could potentially enable greater control of the tip apex in non-contact atomic force microscopy experiments. It is based on a preparation of a structure of interest alongside a reference surface reconstruction on the same sample. Our proposed strategy is as follows. Spectroscopy measurements are first performed on the reference surface to identify the tip apex structure using a previously collected database of responses of different tips to this surface. Next, immediately following the tip identification protocol, the surface of interest is studied (imaging, manipulation and/or spectroscopy). The prototype system we choose is the mixed Si(111)-7×7 and Ag:Si(111)-(√3 × √3) R30° surface which can be prepared on the same sample with a controlled ratio of reactive and passivated regions. Using an "in silico" approach based on ab initio density functional calculations and a set of tips with varying chemical reactivities, we show how one can perform tip fingerprinting using the Si(111)-7×7 reference surface. Then it is found by examining the imaging of a naphthalene tetracarboxylic diimide (NTCDI) molecule adsorbed on Ag:Si(111)-(√3 × √3) R30° surface that negatively charged tips produce the best intramolecular contrast attributed to the enhancement of repulsive interactions.
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Affiliation(s)
- Hongqian Sang
- School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, U.K
| | - Samuel P. Jarvis
- The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K
| | - Zhichao Zhou
- School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China
| | - Peter Sharp
- The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K
| | - Philip Moriarty
- The School of Physics and Astronomy, The University of Nottingham, Nottingham, NG7 2RD, U.K
| | - Jianbo Wang
- School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China
| | - Yu Wang
- School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072, China
| | - Lev Kantorovich
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, U.K
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