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Liv L, Özerdem Z. First DFT-supported point of care and novel electrochemical biosensing: Determination of yellow fever NS1 antibody in human plasma. Int J Biol Macromol 2024; 269:132169. [PMID: 38723801 DOI: 10.1016/j.ijbiomac.2024.132169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/10/2024] [Accepted: 05/05/2024] [Indexed: 05/13/2024]
Abstract
In our study, we developed a point of care electrochemical biosensing platform based on the functionalized cysteine-positioned gold electrode to diagnose yellow fever disease from human plasma samples. The developed platform underwent characterization through diverse methods encompassing cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and density-functional theory. The capacitive interaction between yellow fever virus non-structural antigen and antibody gave a cathodic signal at approximately -260 mV, and increased in proportion to the amount of non-structural antibody. The created electrochemical biosensor has an ability to detect 96 ag/mL of the yellow fever non-structural antibody with an extensive analytical range varied from 0.1 fg/mL to 1 μg/mL. The interference effects of various substances that could be found in human plasma, and the performance of the method were examined from the point of recovery and relative standard deviation for human plasma samples; hereby, the results confirmed the unprecedented selectivity and accuracy of the proposed method.
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Affiliation(s)
- Lokman Liv
- Electrochemistry Laboratory, Chemistry Group, The Scientific and Technological Research Council of Turkey, National Metrology Institute, (TUBITAK UME), 41470 Gebze, Kocaeli, Turkey.
| | - Zekihan Özerdem
- Electrochemistry Laboratory, Chemistry Group, The Scientific and Technological Research Council of Turkey, National Metrology Institute, (TUBITAK UME), 41470 Gebze, Kocaeli, Turkey; Department of Chemistry, Bogazici University, 34342 Bebek, Istanbul, Turkey
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2
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Chen X, Dhirani AA. Thin Film Resistance Gating by Redox Charge Exchange: Evidence for a Quantum Transition State. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38710102 DOI: 10.1021/acsami.4c02058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Field effect transistors (FETs) and related devices have enabled tremendous advances in electronics, as well as studies of fundamental phenomena. FETs are classically actuated as fields charge/discharge materials, thereby modifying their resistance. Here, we develop charge exchange transistors (CETs) that comprise thin films whose resistance is modified by quantum charge exchange processes, e.g., redox and bonding. We first use CETs to probe the metallocene-thin film interaction during cyclic voltammetry. Remarkably, CETs reveal transient resistance peaks associated with charge transfer during both oxidation and reduction. Our data combined with kinetics and density functional theory modeling are consistent with a multistep redox pathway, including the formation/destruction of a quantum transition state that overlaps molecule + thin film band states. As a further proof-of-principle demonstration, we also use CETs to monitor n-alkanethiol self-assembly on thin Au films in real-time. CETs exhibit monotonic resistance increase consistent with previously reported fast-then-slow kinetics attributed to thiol-thin film bond formation (charge localization) and etching and/or molecule reorganization.
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Affiliation(s)
- Xiaoyang Chen
- Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Al-Amin Dhirani
- Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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3
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Behrooz Azizi, Farhadi K, Samadi N. Lable-Free Gold Nanoparticles in the Presence of Ammonium Pyrrolidine Dithiocarbamate as a Selective and Sensitive Silver Ion Colorimetric Probe. JOURNAL OF ANALYTICAL CHEMISTRY 2020. [DOI: 10.1134/s1061934820120035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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The Potential of X-ray Photoelectron Spectroscopy for Determining Interface Dipoles of Self-Assembled Monolayers. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10175735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the current manuscript we assess to what extent X-ray photoelectron spectroscopy (XPS) is a suitable tool for probing the dipoles formed at interfaces between self-assembled monolayers and metal substrates. To that aim, we perform dispersion-corrected, slab-type band-structure calculations on a number of biphenyl-based systems bonded to an Au(111) surface via different docking groups. In addition to changing the docking chemistry (and the associated interface dipoles), the impacts of polar tail group substituents and varying dipole densities are also investigated. We find that for densely packed monolayers the shifts of the peak positions of the simulated XP spectra are a direct measure for the interface dipoles. In the absence of polar tail group substituents they also directly correlate with adsorption-induced work function changes. At reduced dipole densities this correlation deteriorates, as work function measurements probe the difference between the Fermi level of the substrate and the electrostatic energy far above the interface, while core level shifts are determined by the local electrostatic energy in the region of the atom from which the photoelectron is excited.
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5
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Zhao Q, Yang Y, Wang H, Lei W, Liu Y, Wang S. Gold nanoparticles modified hollow carbon system for dual-responsive release and chemo-photothermal synergistic therapy of tumor. J Colloid Interface Sci 2019; 554:239-249. [PMID: 31301524 DOI: 10.1016/j.jcis.2019.07.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 07/01/2019] [Accepted: 07/03/2019] [Indexed: 02/06/2023]
Abstract
Thermochemotherapy has shown a synergistic anti-cancer efficiency and can enhance the therapeutic effect of simple chemotherapy. The photothermal conversion characteristics of carriers are vital in thermo-chemotherapy. Therefore, hollow mesoporous carbon (HMC) with excellent heating efficiency and a large specific surface area was used to ensure the high loading capacity. Next, approximately 4 nm spherical gold nanoparticles (NPs) were employed as gatekeepers of the tunnels of HMC by Au-S bonds, which have the same size as HMC mesopores. Additionally, the gold NPs could avoid the premature release of the drug and enhance the photothermal properties of the delivery system. The surface of the carriers was modified with polyethylene glycol (PEG) to increase the biocompatibility and dispersity of doxorubicin (DOX) loaded DOX/HMC-Au@PEG. DOX release was markedly accelerated in the presence of glutathione (GSH) and near-infrared (NIR), indicating that the system had redox and NIR dual-triggered drug release characteristics. Cytotoxicity experiments proved that combined therapy induced the highest cell killing level. Additionally, the combination index (CI) of DOX/HMC-Au@PEG was 0.452, indicating the synergistic effect of chemotherapy and photo-thermal therapy (PTT). In vivo antitumor experiments were also carried out and showed the same trend. In general, the results of this study indicated that DOX/HMC-Au@PEG has great potential in dual-triggered drug delivery and thermochemotherapy.
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Affiliation(s)
- Qinfu Zhao
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning Province 110016, PR China
| | - Yang Yang
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning Province 110016, PR China
| | - Huili Wang
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning Province 110016, PR China
| | - Wei Lei
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning Province 110016, PR China
| | - Yixuan Liu
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning Province 110016, PR China
| | - Siling Wang
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning Province 110016, PR China.
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6
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Schuster S, Füser M, Asyuda A, Cyganik P, Terfort A, Zharnikov M. Photoisomerization of azobenzene-substituted alkanethiolates on Au(111) substrates in the context of work function variation: the effect of structure and packing density. Phys Chem Chem Phys 2019; 21:9098-9105. [PMID: 31017144 DOI: 10.1039/c9cp00255c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Photoisomerization of a series of custom-designed, azobenzene-substituted alkanethiolate (AT) self-assembled monolayers (SAMs) on Au(111) substrates was studied in the context of work function variation, using Kelvin probe measurements as a transduction technique. These SAMs featured variable packing density (by ∼14%; due to the odd-even effects) and, as an option, were additionally decorated with the electron donating/withdrawing -CH3 and -CF3 tail group, respectively, which induce additional dipole moments. The efficiency of photoisomerization and the respective extent of work function variation (ΔΦ) were found to be quite low and independent of the packing density in the SAMs, within the given odd-even packing density variation. They could only be increased, up to ca. 40 meV for ΔΦ, by mixing the azobenzene-substituted ATs with shorter "matrix" molecules, which were introduced for a partial release of the sterical constraints. The ΔΦ values for the SAMs decorated with the -CH3 and -CF3 tail groups were found to be lower than those for the monolayers without such a decoration, which correlated well with the theoretical estimates for the change of the dipole moment of the relevant molecules upon the photoisomerization.
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Affiliation(s)
- Swen Schuster
- Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
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Verwüster E, Wruss E, Zojer E, Hofmann OT. Exploring the driving forces behind the structural assembly of biphenylthiolates on Au(111). J Chem Phys 2018; 147:024706. [PMID: 28711043 DOI: 10.1063/1.4991344] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this contribution, we use dispersion-corrected density functional theory to study inter- and intramolecular interactions in a prototypical self-assembled monolayer (SAM) consisting of biphenylthiolates bonded to Au(111) via thiolate groups. The goal is to identify the nature of the interactions that drive the monolayer into a specific conformation. Particular focus is laid on sampling realistic structures rather than high symmetry model configurations. This is achieved by studying conceptually different local minimum structures of the SAM that are obtained via exploring the potential energy surface from systematically varied starting geometries. The six obtained packing motifs differ in the relative arrangement of the two molecules in the unit cell (co-planar versus herringbone) and in the intramolecular configuration (twisted versus planar rings). We find that van der Waals interactions within the organic adsorbate and between the adsorbate and substrate are the main reason that these molecular assemblies can form stable structures at all. The van der Waals interactions are, however, very similar for all observed motifs; by analyzing various types of interactions in the course of three notional SAM-formation steps, we find that the main driving force stabilizing the actual global minimum structure originates from electrostatic interactions between the molecules.
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Affiliation(s)
- Elisabeth Verwüster
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Elisabeth Wruss
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Egbert Zojer
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Oliver T Hofmann
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
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8
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Rodriguez-Gonzalez S, Xie Z, Galangau O, Selvanathan P, Norel L, Van Dyck C, Costuas K, Frisbie CD, Rigaut S, Cornil J. HOMO Level Pinning in Molecular Junctions: Joint Theoretical and Experimental Evidence. J Phys Chem Lett 2018; 9:2394-2403. [PMID: 29660279 DOI: 10.1021/acs.jpclett.8b00575] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A central issue in molecular electronics in order to build functional devices is to assess whether changes in the electronic structure of isolated compounds by chemical derivatization are retained once the molecules are inserted into molecular junctions. Recent theoretical studies have suggested that this is not always the case due to the occurrence of pinning effects making the alignment of the transporting levels insensitive to the changes in the electronic structure of the isolated systems. We explore here this phenomenon by investigating at both the experimental and theoretical levels the I/ V characteristics of molecular junctions incorporating three different three-ring phenylene ethynylene derivatives designed to exhibit a significant variation of the HOMO level in the isolated state. At the theoretical level, our NEGF/DFT calculations performed on junctions including the three compounds show that, whereas the HOMO of the molecules varies by 0.61 eV in the isolated state, their alignment with respect to the Fermi level of the gold electrodes in the junction is very similar (within 0.1 eV). At the experimental level, the SAMs made of the three compounds have been contacted by a conducting AFM probe to measure their I/ V characteristics. The alignment of the HOMO with respect to the Fermi level of the gold electrodes has been deduced by fitting the I/ V curves, using a model based on a single-level description (Newns-Anderson model). The extracted values are found to be very similar for the three derivatives, in full consistency with the theoretical predictions, thus providing clear evidence for a HOMO level pinning effect.
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Affiliation(s)
- S Rodriguez-Gonzalez
- Laboratory for Chemistry of Novel Materials , University of Mons , B-7000 Mons , Belgium
| | - Z Xie
- Department of Chemical Engineering and Materials Science , and Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - O Galangau
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - P Selvanathan
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - L Norel
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - C Van Dyck
- National Institute for Nanotechnology (NINT) , University of Alberta , Edmonton , Alberta T6G 2M9 , Canada
| | - K Costuas
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - C D Frisbie
- Department of Chemical Engineering and Materials Science , and Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - S Rigaut
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226 , Rennes F-3500 , France
| | - J Cornil
- Laboratory for Chemistry of Novel Materials , University of Mons , B-7000 Mons , Belgium
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9
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Niu Y, Li W, Peng Q, Geng H, Yi Y, Wang L, Nan G, Wang D, Shuai Z. MOlecular MAterials Property Prediction Package (MOMAP) 1.0: a software package for predicting the luminescent properties and mobility of organic functional materials. Mol Phys 2018. [DOI: 10.1080/00268976.2017.1402966] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Yingli Niu
- Department of Physics, School of Science, Beijing Jiaotong University, Beijing, China
| | - Wenqiang Li
- Department of Chemistry, Tsinghua University, Beijing, China
| | - Qian Peng
- Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Hua Geng
- Department of Chemistry, Capital Normal University, Beijing, China
| | - Yuanping Yi
- Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Linjun Wang
- Department of Chemistry, Zhejiang University, Hangzhou, China
| | - Guangjun Nan
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China
| | - Dong Wang
- Department of Chemistry, Tsinghua University, Beijing, China
| | - Zhigang Shuai
- Department of Chemistry, Tsinghua University, Beijing, China
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10
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Ruthenium(II) σ-arylacetylide complexes as redox active units for (multi-)functional molecular devices. Polyhedron 2018. [DOI: 10.1016/j.poly.2017.08.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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11
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Vilan A, Cahen D. Chemical Modification of Semiconductor Surfaces for Molecular Electronics. Chem Rev 2017; 117:4624-4666. [PMID: 28230354 DOI: 10.1021/acs.chemrev.6b00746] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Inserting molecular monolayers within metal/semiconductor interfaces provides one of the most powerful expressions of how minute chemical modifications can affect electronic devices. This topic also has direct importance for technology as it can help improve the efficiency of a variety of electronic devices such as solar cells, LEDs, sensors, and possible future bioelectronic ones. The review covers the main aspects of using chemistry to control the various aspects of interface electrostatics, such as passivation of interface states and alignment of energy levels by intrinsic molecular polarization, as well as charge rearrangement with the adjacent metal and semiconducting contacts. One of the greatest merits of molecular monolayers is their capability to form excellent thin dielectrics, yielding rich and unique current-voltage characteristics for transport across metal/molecular monolayer/semiconductor interfaces. We explain the interplay between the monolayer as tunneling barrier on the one hand, and the electrostatic barrier within the semiconductor, due to its space-charge region, on the other hand, as well as how different monolayer chemistries control each of these barriers. Practical tools to experimentally identify these two barriers and distinguish between them are given, followed by a short look to the future. This review is accompanied by another one, concerning the formation of large-area molecular junctions and charge transport that is dominated solely by molecules.
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Affiliation(s)
- Ayelet Vilan
- Department of Materials & Interfaces, Weizmann Institute of Science , Rehovot, Israel 76100
| | - David Cahen
- Department of Materials & Interfaces, Weizmann Institute of Science , Rehovot, Israel 76100
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Obersteiner V, Egger D, Zojer E. Impact of Anchoring Groups on Ballistic Transport: Single Molecule vs Monolayer Junctions. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2015; 119:21198-21208. [PMID: 26401191 PMCID: PMC4568541 DOI: 10.1021/acs.jpcc.5b06110] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 07/31/2015] [Indexed: 05/20/2023]
Abstract
Tuning the transport properties of molecular junctions by chemically modifying the molecular structure is one of the key challenges for advancing the field of molecular electronics. In the present contribution, we investigate current-voltage characteristics of differently linked metal-molecule-metal systems that comprise either a single molecule or a molecular assembly. This is achieved by employing density functional theory in conjunction with a Green's function approach. We show that the conductance of a molecular system with a specific anchoring group is fundamentally different depending on whether a single molecule or a continuous monolayer forms the junction. This is a consequence of collective electrostatic effects that arise from dipolar elements contained in the monolayer and from interfacial charge rearrangements. As a consequence of these collective effects, the "ideal" choice for an anchoring group is clearly different for monolayer and single molecule devices. A particularly striking effect is observed for pyridine-docked systems. These are subject to Fermi-level pinning at high molecular packing densities, causing an abrupt increase of the junction current already at small voltages.
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Affiliation(s)
- Veronika Obersteiner
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - David
A. Egger
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovoth 76100, Israel
| | - Egbert Zojer
- Institute
of Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
- E-mail:
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13
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Masillamani AM, Osella S, Liscio A, Fenwick O, Reinders F, Mayor M, Palermo V, Cornil J, Samorì P. Light-induced reversible modification of the work function of a new perfluorinated biphenyl azobenzene chemisorbed on Au (111). NANOSCALE 2014; 6:8969-8977. [PMID: 24968023 DOI: 10.1039/c4nr01880j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We describe the synthesis of a novel biphenyl azobenzene derivative exhibiting: (i) a protected thiol anchoring group in the α-position to readily form self-assembled monolayers (SAMs) on Au surfaces; and (ii) a terminal perfluorinated benzene ring in the ω-position to modify the surface properties. The design of this molecule ensured both an efficient in situ photoswitching between the trans and cis isomers when chemisorbed on Au(111), due to the presence of a biphenyl bridge between the thiol protected anchoring group and the azo dye, and a significant variation of the work function of the SAM in the two isomeric states, induced by the perfluorinated phenyl head group. By exploiting the light responsive nature of the chemisorbed molecules, it is possible to dynamically modify in situ the work function of the SAM-covered electrode, as demonstrated both experimentally and by quantum-chemical calculations, revealing changes in work function up to 220 meV. These findings are relevant for tuning the work function of metallic electrodes, and hence to dynamically modulate charge injection at metal-semiconductor interfaces for organic opto-electronic applications.
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15
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Zhang T, Ma Z, Wang L, Xi J, Shuai Z. Interface electronic structures of reversible double-docking self-assembled monolayers on an Au(111) surface. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2014; 372:20130018. [PMID: 24615153 PMCID: PMC3949364 DOI: 10.1098/rsta.2013.0018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Double-docking self-assembled monolayers (DDSAMs), namely self-assembled monolayers (SAMs) formed by molecules possessing two docking groups, provide great flexibility to tune the work function of metal electrodes and the tunnelling barrier between metal electrodes and the SAMs, and thus offer promising applications in both organic and molecular electronics. Based on the dispersion-corrected density functional theory (DFT) in comparison with conventional DFT, we carry out a systematic investigation on the dual configurations of a series of DDSAMs on an Au(111) surface. Through analysing the interface electronic structures, we obtain the relationship between single molecular properties and the SAM-induced work-function modification as well as the level alignment between the metal Fermi level and molecular frontier states. The two possible conformations of one type of DDSAM on a metal surface reveal a strong difference in the work-function modification and the electron/hole tunnelling barriers. Fermi-level pinning is found to be a key factor to understand the interface electronic properties.
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Affiliation(s)
- Tian Zhang
- Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China
| | - Zhongyun Ma
- School of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, People's Republic of China
| | - Linjun Wang
- Service de Chimie des Matériaux Nouveaux, Université de Mons, Place du Parc 20, Mons 7000, Belgium
| | - Jinyang Xi
- Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China
| | - Zhigang Shuai
- Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China
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16
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Osella S, Cornil D, Cornil J. Work function modification of the (111) gold surface covered by long alkanethiol-based self-assembled monolayers. Phys Chem Chem Phys 2014; 16:2866-73. [DOI: 10.1039/c3cp54217c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Liu L, Xie H, Bostic HE, Jin L, Best MD, Zhang XP, Zhan W. Effects of oriented surface dipole on photoconversion efficiency in an alkane/lipid-hybrid-bilayer-based photovoltaic model system. Chemphyschem 2013; 14:2777-85. [PMID: 23794419 DOI: 10.1002/cphc.201300293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Indexed: 11/08/2022]
Abstract
When a phospholipid monolayer containing a zinc-coordinated porphyrin species formed atop a self-assembled monolayer of heptadecafluoro-1-decanethiol (CF3(CF2)7(CH2)2SH) is subjected to photoelectrochemical current generation, a significant modulation effect is observed. Compared with devices that contain similar photoactive lipid monolayers but formed on 1-dodecanethiol SAMs, these fluorinated hybrid bilayers produce a >60% increase in cathodic currents and a similar decrease in anodic currents. Photovoltages recorded from these hybrid bilayers are found to vary in the same fashion. The modulation of photovoltaic responses in these hybrid-bilayer-based devices is explained by the opposite surface dipoles associated with the thiols employed in this study, which in one case (fluorothiol) increase and in another (alkanethiol) decrease the work function of the underlying gold substrates. A similar trend of photovoltage/photocurrent modulation is also observed if fullerene is used as the photoagent in these devices. Our results reveal the intricacy of orientated surface dipole in influencing the photovoltaic processes, and its subtle interplay with other factors related to the photoagents, such as their location and orientation within the organic matrix.
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Affiliation(s)
- Lixia Liu
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA
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18
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Cornil D, Li H, Wood C, Pourtois G, Brédas JL, Cornil J. Work-Function Modification of Au and Ag Surfaces upon Deposition of Self-Assembled Monolayers: Influence of the Choice of the Theoretical Approach and the Thiol Decomposition Scheme. Chemphyschem 2013; 14:2939-46. [DOI: 10.1002/cphc.201300450] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Indexed: 11/09/2022]
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Wang Y, Zeiri O, Meshi L, Stellacci F, Weinstock IA. Regioselective placement of alkanethiolate domains on tetrahedral and octahedral gold nanocrystals. Chem Commun (Camb) 2012; 48:9765-7. [DOI: 10.1039/c2cc34697d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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20
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Lacher S, Matsuo Y, Nakamura E. Molecular and supramolecular control of the work function of an inorganic electrode with self-assembled monolayer of umbrella-shaped fullerene derivatives. J Am Chem Soc 2011; 133:16997-7004. [PMID: 21923177 DOI: 10.1021/ja2067675] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The surface properties of inorganic substrates can be altered by coating with organic molecules, which may result in the improvement of the properties suitable for electronic or biological applications. This article reports a systematic experimental study on the influence of the molecular and supramolecular properties of umbrella-shaped penta(organo)[60]fullerene derivatives, and on the work function and the water contact angle of indium-tin oxide (ITO) and gold surfaces. We could relate these macroscopic characteristics to single-molecular level properties, such as ionization potential and molecular dipole. The results led us to conclude that the formation of a SAM of a polar compound generates an electronic field through intermolecular interaction of the molecular charges, and this field makes the overall dipole of the SAM much smaller than the one expected from the simple sum of the dipoles of all molecules in the SAM. This effect, which was called depolarization and previously discussed theoretically, is now quantitatively probed by experiments. The important physical properties in surface science such as work function, ionization potential, and water contact angles have been mutually correlated at the level of molecular structures and molecular orientations on the substrate surface. We also found that the SAMs on ITO and gold operate under the same principle except that the "push-back" effect operates specifically for gold. The study also illustrates the ability of the photoelectron yield spectroscopy technique to rapidly measure the work function of a SAM-covered substrate and the ionization potential value of a molecule on the surface.
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Affiliation(s)
- Sebastian Lacher
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Ma Z, Rissner F, Wang L, Heimel G, Li Q, Shuai Z, Zojer E. Electronic structure of pyridine-based SAMs on flat Au(111) surfaces: extended charge rearrangements and Fermi level pinning. Phys Chem Chem Phys 2011; 13:9747-60. [PMID: 21503307 DOI: 10.1039/c0cp02168g] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Density functional theory calculations are used to investigate the electronic structure of pyridine-based self-assembled monolayers (SAMs) on an Au(111) surface. We find that, when using pyridine docking groups, the bonding-induced charge rearrangements are frequently found to extend well onto the molecular backbone. This is in contrast to previous observations for the chemisorption of other SAMs, e.g., organic thiolates on gold, and can be explained by a pinning of the lowest unoccupied states of the SAM at the metal Fermi-level. The details of the pinning process, especially the parts of the molecules most affected by the charge rearrangements, strongly depend on the length of the molecular backbone and the tail-group substituent. We also mention methodological shortcomings of conventional density functional theory that can impact the quantitative details regarding the circumstances under which pinning occurs and highlight a number of peculiarities associated with bond dipoles that arise from Fermi-level pinning.
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Affiliation(s)
- ZhongYun Ma
- Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, 100190 Beijing, People's Republic of China
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Ikeda K, Suzuki S, Uosaki K. Crystal face dependent chemical effects in surface-enhanced Raman scattering at atomically defined gold facets. NANO LETTERS 2011; 11:1716-1722. [PMID: 21417470 DOI: 10.1021/nl200251a] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Among electromagnetic and chemical (CM) contributions to surface-enhanced Raman scattering (SERS), the former is becoming controllable according to the recent progress in nanofabrication of plasmonic metal structures. However, it is still difficult to control the latter effect. Here, the degree of each contribution to SERS signals is examined on well-defined single crystalline facets of gold by using optical field localization within sphere-plane type plasmonic cavities. Crystal face dependent SERS studies of aminobenzenthiol adsorbates clearly show the distinction between CM enhancements on different surfaces, suggesting that the CM-activity of "SERS-hotspots" is closely related to interfacial dipoles formed at metal-molecular junctions.
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Affiliation(s)
- Katsuyoshi Ikeda
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
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Schmidt C, Witt A, Witte G. Tailoring the Cu(100) work function by substituted benzenethiolate self-assembled monolayers. J Phys Chem A 2011; 115:7234-41. [PMID: 21413776 DOI: 10.1021/jp200328r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The structure and electronic interface properties of five differently substituted benzenethiol based self-assembled monolayers (SAMs) on Cu(100) have been studied by means of low energy electron diffraction, thermal desorption spectroscopy, X-ray absorption spectroscopy (NEXAFS), and UV photoelectron spectroscopy. Because highly ordered SAMs are formed of which lateral density had been precisely determined, effective molecular dipole moments were derived from the measured work function shifts. These values are compared with gas phase dipole moments computed by quantum chemical calculations for the individual thiol molecules considering the molecular orientation determined from NEXAFS data. Furthermore, this comparison yields clear evidence for a coverage dependent depolarization effect of the adsorbed molecules within the SAMs.
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Affiliation(s)
- Christian Schmidt
- Molecular Solids, Department of Physics, Philipps-University, Marburg, Germany
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Battocchio C, Fratoddi I, Venditti I, Yarzhemsky V, Norov Y, Russo M, Polzonetti G. EXAFS in total reflection (reflEXAFS) for the study of organometallic Pd(II) thiol complexes based self-assembled monolayers on gold. Chem Phys 2011. [DOI: 10.1016/j.chemphys.2010.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Crivillers N, Liscio A, Di Stasio F, Van Dyck C, Osella S, Cornil D, Mian S, Lazzerini GM, Fenwick O, Orgiu E, Reinders F, Braun S, Fahlman M, Mayor M, Cornil J, Palermo V, Cacialli F, Samorì P. Photoinduced work function changes by isomerization of a densely packed azobenzene-based SAM on Au: a joint experimental and theoretical study. Phys Chem Chem Phys 2011; 13:14302-10. [DOI: 10.1039/c1cp20851a] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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