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A Theoretical Investigation about Photoswitching of Azobenzene Adsorbed on Ag Nanoparticles. CRYSTALS 2022. [DOI: 10.3390/cryst12020248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The optical properties of hybrid systems composed of silver nanoparticles (NPs) and azobenzene molecules were systematically investigated by combining the real-time time-dependent density functional theory (RT-TDDFT) approach with the classical electrodynamics finite difference time domain (FDTD) technique for the solution of Maxwell’s equations. In order to reflect the chemical interaction between azobenzene and metal more exactly, except for adsorbed molecules, a Ag cluster separated from NP was also dealt, using RT-TDDFT. We studied the different factors affecting the surface-enhanced absorption spectra. It was found that the electric field amplified by plasmon resonance of Ag NPs can have an overall enhancement to the molecular light absorption throughout the whole energy range. The resonance between the electron and the plasmon excitation results in a larger percentage of enhancement in the absorption spectrum the closer the resonance peak is. The enhancement ratio of the resonance peak is the largest. The plasmon–exciton coupling and the optical properties of different isolate isomers influence the line shape of the absorption spectra. The dipole interaction and electronic transfer between azobenzene molecules and Ag NPs also change the shape of spectroscopy from the absorption enhancement ratio and the location of the peak. Physical and chemical factors lead to photoswitching in these hybrid systems together.
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2
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Horsley JR, Wang X, Yu J, Abell AD. Exploiting conformationally gated electron transfer in self-assembled azobenzene-containing cyclic peptides using light. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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3
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Duanghathaipornsuk S, Reaver NGF, Cameron BD, Kim DS. Adsorption Kinetics of Glycated Hemoglobin on Aptamer Microarrays with Antifouling Surface Modification. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:4647-4657. [PMID: 33797255 DOI: 10.1021/acs.langmuir.1c00446] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Aptamers are oligonucleotides that bind with high affinity to target molecules of interest. One such target is glycated hemoglobin (gHb), a biomarker for assessing glycemic control and diabetes diagnosis. By the coupling of aptamers with surface plasmon resonance (SPR) sensing surfaces, a fast, reliable and inexpensive assay for gHb can be developed. In this study, we tested the affinity of SPR-sensing surfaces, composed of aptamers and antifouling self-assembled monolayers (SAMs), to hemoglobin (Hb) and gHb. First, we developed a gHb-targeted aptamer (GHA) through a modified Systematic Evolution of Ligands by EXponential (SELEX) enrichment process and tested its affinity to gHb using the Nano-Affi protocol. GHA was used to produce three distinct SAM-SPR-sensing surfaces: (Type-1) a SAM of GHA directly attached to a sensor surface; (Type-2) GHA attached to a SAM of 11-mercaptoundecanoic acid (11MUA) on a sensor surface; (Type-3) GHA attached to a binary SAM of 11MUA and 3,6-dioxa-8-mercaptooctan-1-ol (DMOL) on a sensor surface. Type-2 and Type-3 surfaces were characterized by cyclic voltammetry and electrochemical impedance spectroscopy to confirm that GHA bound to the underlying SAMs. The adsorption kinetics for Hb and gHb interacting with each SPR sensing surface were used to quantify their respective affinities. The Type-1 surface without antifouling modification had a dissociation constant ratio (KD,Hb/KD,gHb) of 9.7, as compared to 809.3 for the Type-3 surface, demonstrating a higher association of GHA to gHb for sensor surfaces with antifouling modifications than those without. The enhanced selectivity of GHA to gHb can likely be attributed to the inclusion of DMOL in the SAM-modified surface, which reduced interference from nonspecific adsorption of proteins. Results suggest that pairing aptamers with antifouling SAMs can significantly improve their target affinity, potentially allowing for the development of novel, low cost, and fast assays.
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Affiliation(s)
- Surachet Duanghathaipornsuk
- Department of Chemical Engineering, 2801 W. Bancroft St., University of Toledo, Toledo, Ohio 43606, United States
| | - Nathan G F Reaver
- Engineering School of Sustainable Infrastructure and the Environment Environmental Engineering Sciences, University of Florida, Gainesville, Florida 32611, United States
- Water Institute, University of Florida, Gainesville, Florida 32611, United States
| | - Brent D Cameron
- Department of Bioengineering, 2801 W. Bancroft St., University of Toledo, Toledo, Ohio 43606, United States
| | - Dong-Shik Kim
- Department of Chemical Engineering, 2801 W. Bancroft St., University of Toledo, Toledo, Ohio 43606, United States
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4
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Riaz S, Friedrichs G. Vibrational sum-frequency generation study of molecular structure, sterical constraints and nonlinear optical switching contrast of mixed alkyl-azobenzene self-assembled monolayers. Z PHYS CHEM 2020. [DOI: 10.1515/zpch-2020-1655] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Abstract
Self-assembled monolayers (SAMs) of azobenzene (AB) functionalized alkyl thiols on gold diluted with simple alkyl thiols provide a straightforward way to photochromic surfaces with high and tunable photoswitching efficiency. Trans-cis isomerization of the AB molecule changes the physical properties of the surface, including the nonlinear optical (NLO) response. Vibrational sum-frequency generation (VSFG) spectroscopy as a nonlinear type of laser spectroscopy offers surface- and orientation-sensitive insight into the molecular structure of mixed SAMs. In this study, VSFG as well as ultraviolet-visible (UV/Vis) spectroscopy has been employed to investigate the morphology, molecular structure, and NLO response of mixed SAMs with systematically varied surface composition. Methylazobenzene (MeAB) has been used as the molecular switch with the methyl substituent serving as orientational VSFG marker. Both short-chain and long-chain alkyl thiol co-ligands have been used to gain insight into the interplay between SAM structure and sterical constraints that are known to limit the free switching volume. Underlining the dominating role of sterical effects for controlling photochromic properties, a strong inhibition of the photoswitching efficiency and NLO response has been observed for the SAMs with an alkyl thiol co-ligand long enough to spatially extend into the layer of the MeAB chromophore. Overall, with <12% signal change, the relative NLO switching contrasts remained low in all cases. VSFG spectral trends clearly revealed that the presumably higher photoswitching efficiency upon dilution with the co-ligand is counteracted by a loss of structural order of the chromophore.
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Affiliation(s)
- Saira Riaz
- Islamabad College for Girls , F-6/2 , Islamabad, 44000 , Pakistan
| | - Gernot Friedrichs
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel , Max-Eyth-Str. 1, 24118 , Kiel , Germany
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5
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Kunfi A, Bernadett Vlocskó R, Keresztes Z, Mohai M, Bertóti I, Ábrahám Á, Kiss É, London G. Photoswitchable Macroscopic Solid Surfaces Based On Azobenzene-Functionalized Polydopamine/Gold Nanoparticle Composite Materials: Formation, Isomerization and Ligand Exchange. Chempluschem 2020; 85:797-805. [PMID: 31967410 DOI: 10.1002/cplu.201900674] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/07/2020] [Indexed: 12/21/2022]
Abstract
The facile preparation of dynamic interfaces is presented based on the combination of photoisomerizable azobenzenes and polydopamine (PDA)/Au nanoparticle composite materials. Azobenzenes with different spacer lengths (C3 , C6 ) and surface-binding groups (SH, NH2 ) were synthesized. The polymer layer on macroscopic quartz surface was prepared by the facile aerobic autopolymerisation of dopamine hydrochloride under basic conditions. The presence of redox-active catechol moieties meant that gold nanoparticles were formed on the polymer surface. The obtained UV-Vis spectroscopic results confirmed that following their successful assembly, the switching of azobenzenes on PDA/Au was not affected by the surface binding group and the spacer length of the azobenzene molecules under the measurement conditions. Furthermore, facilitated by the curved nature of the Au particles, the surface-bound azobenzene layer could be reconstructed by ligand-exchange processes, and the photochemical characterization of the mixed layer was performed.
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Affiliation(s)
- Attila Kunfi
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Department of Organic Chemistry, University of Szeged, Dóm tér 8, 6720, Szeged, Hungary
| | - Rita Bernadett Vlocskó
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2., 1117, Budapest, Hungary
| | - Zsófia Keresztes
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2., 1117, Budapest, Hungary
| | - Miklós Mohai
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2., 1117, Budapest, Hungary
| | - Imre Bertóti
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2., 1117, Budapest, Hungary
| | - Ágnes Ábrahám
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2., 1117, Budapest, Hungary.,Laboratory of Interfaces and Nanostructures, Eötvös Loránd University, Pázmány Péter stny. 1/A, 1117, Budapest, Hungary
| | - Éva Kiss
- Laboratory of Interfaces and Nanostructures, Eötvös Loránd University, Pázmány Péter stny. 1/A, 1117, Budapest, Hungary
| | - Gábor London
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2., 1117, Budapest, Hungary
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6
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Rusch TR, Hammerich M, Herges R, Magnussen OM. Molecular platforms as versatile building blocks for multifunctional photoswitchable surfaces. Chem Commun (Camb) 2019; 55:9511-9514. [DOI: 10.1039/c9cc04528g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Structurally well-defined arrangements of multiple functional groups can be prepared by self-assembly of mixed monolayers based on molecular platforms.
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Affiliation(s)
- Talina R. Rusch
- Institute of Experimental and Applied Physics
- Kiel University
- Kiel
- Germany
| | | | - Rainer Herges
- Otto Diels Institute of Organic Chemistry
- Kiel University
- Kiel
- Germany
| | - Olaf M. Magnussen
- Institute of Experimental and Applied Physics
- Kiel University
- Kiel
- Germany
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7
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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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8
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Yadav K, Mahapatra S, Halbritter T, Heckel A, Gopakumar TG. Low-Threshold Reversible Electron-Induced and Selective Photoinduced Switching of Azobenzene Derivatives under Ambient Conditions. J Phys Chem Lett 2018; 9:6326-6333. [PMID: 30346779 DOI: 10.1021/acs.jpclett.8b02875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Mono-carboxyl-functionalized azobenzene and arylazopyrazole have been employed for electron-induced and photoinduced switching under ambient conditions. The microscopic structure and the switching behavior is understood using scanning tunneling microscopy. The carboxyl functional group in these molecules offers low threshold energy for the electron-induced reversible switching compared with nonfunctionalized azobenzene. The low threshold is understood using charged intermediate states during the switching. A selectivity has been observed for the photoinduced switching. Because of strong hydrogen bonding, only the free phenyl groups in the molecules change their configuration.
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Affiliation(s)
- Khushboo Yadav
- Department of Chemistry , Indian Institute of Technology Kanpur , Kanpur 208016 , India
| | - Sayantan Mahapatra
- Department of Chemistry , Indian Institute of Technology Kanpur , Kanpur 208016 , India
| | - Thomas Halbritter
- Institute for Organic Chemistry and Chemical Biology , Goethe-University Frankfurt , Max-von-Laue-Str. 9 , 60438 Frankfurt , Germany
| | - Alexander Heckel
- Institute for Organic Chemistry and Chemical Biology , Goethe-University Frankfurt , Max-von-Laue-Str. 9 , 60438 Frankfurt , Germany
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9
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Schlimm A, Stucke N, Flöser BM, Rusch T, Krahmer J, Näther C, Strunskus T, Magnussen OM, Tuczek F. Influence of a Metal Substrate on Small-Molecule Activation Mediated by a Surface-Adsorbed Complex. Chemistry 2018; 24:10732-10744. [DOI: 10.1002/chem.201800911] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 03/29/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Alexander Schlimm
- Institute of Inorganic Chemistry; Christian Albrechts University Kiel; Max-Eyth-Strasse 2 24118 Kiel Germany
| | - Nadja Stucke
- Institute of Inorganic Chemistry; Christian Albrechts University Kiel; Max-Eyth-Strasse 2 24118 Kiel Germany
| | - Benedikt M. Flöser
- Institute of Inorganic Chemistry; Christian Albrechts University Kiel; Max-Eyth-Strasse 2 24118 Kiel Germany
| | - Talina Rusch
- Institute of Experimental and Applied Physics; Christian Albrechts University Kiel; Leibnizstrasse 19 24118 Kiel Germany
| | - Jan Krahmer
- Institute of Inorganic Chemistry; Christian Albrechts University Kiel; Max-Eyth-Strasse 2 24118 Kiel Germany
| | - Christian Näther
- Institute of Inorganic Chemistry; Christian Albrechts University Kiel; Max-Eyth-Strasse 2 24118 Kiel Germany
| | - Thomas Strunskus
- Institute for Materials Science-Multicomponent Materials; Christian Albrechts University Kiel; Kaiserstrasse 2 24143 Kiel Germany
| | - Olaf M. Magnussen
- Institute of Experimental and Applied Physics; Christian Albrechts University Kiel; Leibnizstrasse 19 24118 Kiel Germany
| | - Felix Tuczek
- Institute of Inorganic Chemistry; Christian Albrechts University Kiel; Max-Eyth-Strasse 2 24118 Kiel Germany
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10
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Affiliation(s)
- Evgeny Katz
- Department of Chemistry and Biomolecular Science; Clarkson University; Potsdam, NY 13699-5810 USA
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11
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Bronsch W, Moldt T, Boie L, Gahl C, Weinelt M. Delocalized versus localized excitations in the photoisomerization of azobenzene-functionalized alkanethiolate SAMs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:484002. [PMID: 29022887 DOI: 10.1088/1361-648x/aa9309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Self-assembled monolayers of azobenzene-functionalized alkanethiolates form molecular ensembles with preferential orientation and significant excitonic coupling among the azobenzene chromophores. We have studied their optical switching with differential reflectance and two-photon-photoemission spectroscopy tuning the excitation wavelength through the excitonically broadened S2 absorption band. While the effective isomerization cross-section increases towards shorter wavelengths, the fraction of cis molecules in the photostationary state decreases. We attribute this observation to the absorption of the cis isomer in the SAM. The photoisomerization in the SAM thereby follows the behavior of non-interacting chromophores in solution, despite the formation of H-aggregates. Our study thus reveals that photoswitching occurs via localized excitations while strongly excitonically coupled, delocalized states do not contribute significantly.
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Affiliation(s)
- Wibke Bronsch
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
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12
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Cocchi C, Draxl C. Understanding the effects of packing and chemical terminations on the optical excitations of azobenzene-functionalized self-assembled monolayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:394005. [PMID: 28664870 DOI: 10.1088/1361-648x/aa7ca7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In a first-principles study based on many-body perturbation theory, we analyze the optical excitations of azobenzene-functionalized self-assembled monolayers (SAMs) with increasing packing density and different terminations, considering for comparison the corresponding gas-phase molecules and dimers. Intermolecular coupling increases with the density of the chromophores independently of the functional groups. The intense [Formula: see text] resonance that triggers photo-isomerization is present in the spectra of isolated dimers and diluted SAMs, but it is almost completely washed out in tightly packed architectures. Intermolecular coupling is partially inhibited by mixing differently functionalized azobenzene derivatives, in particular when large groups are involved. In this way, the excitation band inducing the photo-isomerization process is partially preserved and the effects of dense packing partly counterbalanced. Our results suggest that a tailored design of azobenzene-functionalized SAMs which optimizes the interplay between the packing density of the chromophores and their termination can lead to significant improvements in the photo-switching efficiency of these systems.
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Affiliation(s)
- Caterina Cocchi
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany. European Theoretical Spectroscopic Facility (ETSF
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13
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Jeong H, Kim D, Xiang D, Lee T. High-Yield Functional Molecular Electronic Devices. ACS NANO 2017; 11:6511-6548. [PMID: 28578582 DOI: 10.1021/acsnano.7b02967] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
An ultimate goal of molecular electronics, which seeks to incorporate molecular components into electronic circuit units, is to generate functional molecular electronic devices using individual or ensemble molecules to fulfill the increasing technical demands of the miniaturization of traditional silicon-based electronics. This review article presents a summary of recent efforts to pursue this ultimate aim, covering the development of reliable device platforms for high-yield ensemble molecular junctions and their utilization in functional molecular electronic devices, in which distinctive electronic functionalities are observed due to the functional molecules. In addition, other aspects pertaining to the practical application of molecular devices such as manufacturing compatibility with existing complementary metal-oxide-semiconductor technology, their integration, and flexible device applications are also discussed. These advances may contribute to a deeper understanding of charge transport characteristics through functional molecular junctions and provide a desirable roadmap for future practical molecular electronics applications.
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Affiliation(s)
- Hyunhak Jeong
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
| | - Dongku Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
| | - Dong Xiang
- Key Laboratory of Optical Information Science and Technology, Institute of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University , Tianjin 300071, China
| | - Takhee Lee
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 08826, Korea
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14
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Mulas A, He X, Hervault YM, Norel L, Rigaut S, Lagrost C. Dual-Responsive Molecular Switches Based on Dithienylethene-RuII
Organometallics in Self-Assembled Monolayers Operating at Low Voltage. Chemistry 2017; 23:10205-10214. [DOI: 10.1002/chem.201701903] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Indexed: 12/27/2022]
Affiliation(s)
- Andrea Mulas
- Institut des Sciences Chimiques de Rennes, UMR 6226; CNRS-Université de Rennes 1; Campus de Beaulieu 35042 Rennes Cedex France
| | - Xiaoyan He
- Institut des Sciences Chimiques de Rennes, UMR 6226; CNRS-Université de Rennes 1; Campus de Beaulieu 35042 Rennes Cedex France
| | - Yves-Marie Hervault
- Institut des Sciences Chimiques de Rennes, UMR 6226; CNRS-Université de Rennes 1; Campus de Beaulieu 35042 Rennes Cedex France
| | - Lucie Norel
- Institut des Sciences Chimiques de Rennes, UMR 6226; CNRS-Université de Rennes 1; Campus de Beaulieu 35042 Rennes Cedex France
| | - Stéphane Rigaut
- Institut des Sciences Chimiques de Rennes, UMR 6226; CNRS-Université de Rennes 1; Campus de Beaulieu 35042 Rennes Cedex France
| | - Corinne Lagrost
- Institut des Sciences Chimiques de Rennes, UMR 6226; CNRS-Université de Rennes 1; Campus de Beaulieu 35042 Rennes Cedex France
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15
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Cocchi C, Moldt T, Gahl C, Weinelt M, Draxl C. Optical properties of azobenzene-functionalized self-assembled monolayers: Intermolecular coupling and many-body interactions. J Chem Phys 2016; 145:234701. [DOI: 10.1063/1.4971436] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Caterina Cocchi
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
- European Theoretical Spectroscopic Facility (ETSF)
| | - Thomas Moldt
- Fachbereich Physik, Freie Universität Berlin, Berlin, Germany
| | - Cornelius Gahl
- Fachbereich Physik, Freie Universität Berlin, Berlin, Germany
| | - Martin Weinelt
- Fachbereich Physik, Freie Universität Berlin, Berlin, Germany
| | - Claudia Draxl
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
- European Theoretical Spectroscopic Facility (ETSF)
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16
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Moldt T, Przyrembel D, Schulze M, Bronsch W, Boie L, Brete D, Gahl C, Klajn R, Tegeder P, Weinelt M. Differing Isomerization Kinetics of Azobenzene-Functionalized Self-Assembled Monolayers in Ambient Air and in Vacuum. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10795-10801. [PMID: 27681851 DOI: 10.1021/acs.langmuir.6b01690] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Azobenzenealkanethiols in self-assembled monolayers (SAMs) on Au(111) exhibit reversible trans-cis photoisomerization when diluted with alkanethiol spacers. Using these mixed SAMs, we show switching of the linear optical and second-harmonic response. The effective switching of these surface optical properties relies on a reasonably large cross section and a high photoisomerization yield as well as a long lifetime of the metastable cis isomer. We quantified the switching process by X-ray absorption spectroscopy. The cross sections for the trans-cis and cis-trans photoisomerization with 365 and 455 nm light, respectively, are 1 order of magnitude smaller than in solution. In vacuum, the 365 nm photostationary state comprises 50-74% of the molecules in the cis form, limited by their rapid thermal isomerization back to the trans state. In contrast, the 455 nm photostationary state contains nearly 100% trans-azobenzene. We determined time constants for the thermal cis-trans isomerization of only a few minutes in vacuum and in a dry nitrogen atmosphere but of more than 1 day in ambient air. Our results suggest that adventitious water adsorbed on the surface of the SAM stabilizes the polar cis configuration of azobenzene under ambient conditions. The back reaction rate constants differing by 2 orders of magnitude underline the huge influence of the environment and, accordingly, its importance when comparing various experiments.
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Affiliation(s)
- Thomas Moldt
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Daniel Przyrembel
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Michael Schulze
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany
| | - Wibke Bronsch
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Larissa Boie
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Daniel Brete
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Cornelius Gahl
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
| | - Rafal Klajn
- Department of Organic Chemistry, Weizmann Institute of Science , 76100 Rehovot, Israel
| | - Petra Tegeder
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany
| | - Martin Weinelt
- Fachbereich Physik, Freie Universität Berlin , 14195 Berlin, Germany
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17
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Köhntopp A, Dittner M, Temps F. Femtosecond Time-Resolved Dynamics of trans-Azobenzene on Gold Nanoparticles. J Phys Chem Lett 2016; 7:1088-1095. [PMID: 26959865 DOI: 10.1021/acs.jpclett.6b00102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report a first femtosecond time-resolved transient absorption study of the photoinduced ultrafast dynamics of trans-azobenzene (AB) on gold nanoparticles (AuNPs). The observed changes in optical density following excitation at λ = 357 nm were analyzed by using temperature-dependent Mie theory and by Lorentzian band fitting to disentangle the ultrafast relaxation of the local surface plasmon resonance (LSPR) excitation of the Au core and the electronic deactivation of the attached AB ligands. The analysis of the dynamics associated with the AB photochrome yielded lifetime constants of τ1 = 1.2 ± 0.2 ps and τ2 = 4.7 ± 1.1 ps. Both values together indicate surprisingly little difference in the dynamics of the AB ligand on the AuNPs vs in solution. Our results thus highlight the extraordinarily efficient electronic decoupling of the azo chromophore and the Au core by the alkyl linker chain.
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Affiliation(s)
- Anja Köhntopp
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel , Olshausenstraße 40, D-24098 Kiel, Germany
| | - Mark Dittner
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel , Olshausenstraße 40, D-24098 Kiel, Germany
| | - Friedrich Temps
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel , Olshausenstraße 40, D-24098 Kiel, Germany
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18
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Roling O, Stricker L, Voskuhl J, Lamping S, Ravoo BJ. Supramolecular surface adhesion mediated by azobenzene polymer brushes. Chem Commun (Camb) 2016; 52:1964-6. [DOI: 10.1039/c5cc08968a] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Surface immobilised polymer brushes containing azobenzenes were prepared using microcontact chemistry and surface-initiated atom transfer radical polymerisation. Two surfaces bearing brushes can be glued together in the presence of a β-cyclodextrin polymer.
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Affiliation(s)
- Oliver Roling
- Organic Chemistry Institute and Center for Soft Nanoscience
- Westfälische Wilhelms-Universität Münster
- 48149 Münster
- Germany
| | - Lucas Stricker
- Organic Chemistry Institute and Center for Soft Nanoscience
- Westfälische Wilhelms-Universität Münster
- 48149 Münster
- Germany
| | - Jens Voskuhl
- Organic Chemistry Institute and Center for Soft Nanoscience
- Westfälische Wilhelms-Universität Münster
- 48149 Münster
- Germany
| | - Sebastian Lamping
- Organic Chemistry Institute and Center for Soft Nanoscience
- Westfälische Wilhelms-Universität Münster
- 48149 Münster
- Germany
| | - Bart Jan Ravoo
- Organic Chemistry Institute and Center for Soft Nanoscience
- Westfälische Wilhelms-Universität Münster
- 48149 Münster
- Germany
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19
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Affiliation(s)
- Melanie Hammerich
- Otto Diels-Institute
for
Organic Chemistry, University of Kiel, Otto-Hahn-Platz 4, Kiel D-24119, Germany
| | - Rainer Herges
- Otto Diels-Institute
for
Organic Chemistry, University of Kiel, Otto-Hahn-Platz 4, Kiel D-24119, Germany
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20
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Krekiehn NR, Müller M, Jung U, Ulrich S, Herges R, Magnussen OM. UV/Vis Spectroscopy Studies of the Photoisomerization Kinetics in Self-Assembled Azobenzene-Containing Adlayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:8362-8370. [PMID: 26134857 DOI: 10.1021/acs.langmuir.5b01645] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Direct comparative studies of the photoisomerization of azobenzene derivatives in self-assembled adlayers on Au and as free molecules in dichloromethane solution were performed using UV/vis spectroscopy. For all studied systems a highly reversible trans-cis isomerization in the adlayer is observed. Quantitative studies of the absorbance changes and photoisomerization kinetics reveal that in azobenzenes mounted as freestanding vertical groups on the surface via triazatriangulene-based molecular platforms photoswitching is nearly uninhibited by the local environment in the adlayer. The blue-shift of the π-π* transition in adlayers of these molecules is in good agreement with theoretical studies of the effect of excitonic coupling between the molecules. In contrast, in azobenzene-containing thiol self-assembled monolayers the fraction of photoswitching molecules and the photoisomerization kinetics are significantly reduced compared to free molecules in solution.
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Affiliation(s)
- N R Krekiehn
- †Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Leibnizstr. 19, 24118 Kiel, Germany
| | - M Müller
- †Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Leibnizstr. 19, 24118 Kiel, Germany
| | - U Jung
- †Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Leibnizstr. 19, 24118 Kiel, Germany
| | - S Ulrich
- ‡Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität zu Kiel, Otto-Hahn-Platz 4, 24098 Kiel, Germany
| | - R Herges
- ‡Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität zu Kiel, Otto-Hahn-Platz 4, 24098 Kiel, Germany
| | - O M Magnussen
- †Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Leibnizstr. 19, 24118 Kiel, Germany
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21
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Moldt T, Brete D, Przyrembel D, Das S, Goldman JR, Kundu PK, Gahl C, Klajn R, Weinelt M. Tailoring the properties of surface-immobilized azobenzenes by monolayer dilution and surface curvature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1048-57. [PMID: 25544061 DOI: 10.1021/la504291n] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Photoswitching in densely packed azobenzene self-assembled monolayers (SAMs) is strongly affected by steric constraints and excitonic coupling between neighboring chromophores. Therefore, control of the chromophore density is essential for enhancing and manipulating the photoisomerization yield. We systematically compare two methods to achieve this goal: First, we assemble monocomponent azobenzene-alkanethiolate SAMs on gold nanoparticles of varying size. Second, we form mixed SAMs of azobenzene-alkanethiolates and "dummy" alkanethiolates on planar substrates. Both methods lead to a gradual decrease of the chromophore density and enable efficient photoswitching with low-power light sources. X-ray spectroscopy reveals that coadsorption from solution yields mixtures with tunable composition. The orientation of the chromophores with respect to the surface normal changes from a tilted to an upright position with increasing azobenzene density. For both systems, optical spectroscopy reveals a pronounced excitonic shift that increases with the chromophore density. In spite of exciting the optical transition of the monomer, the main spectral change in mixed SAMs occurs in the excitonic band. In addition, the photoisomerization yield decreases only slightly by increasing the azobenzene-alkanethiolate density, and we observed photoswitching even with minor dilutions. Unlike in solution, azobenzene in the planar SAM can be switched back almost completely by optical excitation from the cis to the original trans state within a short time scale. These observations indicate cooperativity in the photoswitching process of mixed SAMs.
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Affiliation(s)
- Thomas Moldt
- Fachbereich Physik, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
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22
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Ulrich S, Jung U, Strunskus T, Schütt C, Bloedorn A, Lemke S, Ludwig E, Kipp L, Faupel F, Magnussen O, Herges R. X-ray spectroscopy characterization of azobenzene-functionalized triazatriangulenium adlayers on Au(111) surfaces. Phys Chem Chem Phys 2015; 17:17053-62. [DOI: 10.1039/c5cp01447f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
NEXAFS spectroscopy analysis confirms perpendicular standing azobenzene functionalities connected to flat-lying platform molecules adsorbed on Au(111) single crystals.
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Affiliation(s)
- Sandra Ulrich
- Institut für Organische Chemie
- Christian-Albrechts-Universität Kiel
- Otto-Hahn-Platz 4
- Germany
| | - Ulrich Jung
- Institut für Experimentelle und Angewandte Physik der Christian-Albrechts-Universität Kiel
- 24118 Kiel
- Germany
| | - Thomas Strunskus
- Technische Fakultät der Christian-Albrechts-Universität Kiel
- 24143 Kiel
- Germany
| | - Christian Schütt
- Institut für Organische Chemie
- Christian-Albrechts-Universität Kiel
- Otto-Hahn-Platz 4
- Germany
| | - Andreas Bloedorn
- Institut für Experimentelle und Angewandte Physik der Christian-Albrechts-Universität Kiel
- 24118 Kiel
- Germany
| | - Sonja Lemke
- Institut für Experimentelle und Angewandte Physik der Christian-Albrechts-Universität Kiel
- 24118 Kiel
- Germany
| | - Eric Ludwig
- Institut für Experimentelle und Angewandte Physik der Christian-Albrechts-Universität Kiel
- 24118 Kiel
- Germany
| | - Lutz Kipp
- Institut für Experimentelle und Angewandte Physik der Christian-Albrechts-Universität Kiel
- 24118 Kiel
- Germany
| | - Franz Faupel
- Technische Fakultät der Christian-Albrechts-Universität Kiel
- 24143 Kiel
- Germany
| | - Olaf Magnussen
- Institut für Experimentelle und Angewandte Physik der Christian-Albrechts-Universität Kiel
- 24118 Kiel
- Germany
| | - Rainer Herges
- Institut für Organische Chemie
- Christian-Albrechts-Universität Kiel
- Otto-Hahn-Platz 4
- Germany
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23
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Simoncelli S, Aramendía PF. Mechanistic insight into the Z–E isomerization catalysis of azobenzenes mediated by bare and core–shell gold nanoparticles. Catal Sci Technol 2015. [DOI: 10.1039/c4cy01442a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We explored the catalytic effect of 15 nm diameter gold nanoparticles (AuNPs) upon the thermal Z–E isomerization reaction of azobenzene and nine 4 and 4-4′ substituted azobenzenes (ABs).
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Affiliation(s)
- Sabrina Simoncelli
- Centro de Investigaciones en Bionanociencias “Elizabeth Jares-Erijman” (CIBION-CONICET)
- Godoy Cruz 2390, Argentina
- Instituto de Química Física de Materiales
- Ambiente y Energía (INQUIMAE-CONICET)
- Pabellón 2, Ciudad Universitaria
| | - Pedro F. Aramendía
- Centro de Investigaciones en Bionanociencias “Elizabeth Jares-Erijman” (CIBION-CONICET)
- Godoy Cruz 2390, Argentina
- Departamento de Química Inorgánica
- Analítica y Química Física
- Facultad de Ciencias Exactas y Naturales
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24
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Minisini B, Messager G, Piyanzina I, Delorme N, Bardeau JF. Vibrational analysis of [4-[(E)-phenylazo] phenyl]ethanol based on the comparison between the experimental and DFT calculated Raman spectra. J STRUCT CHEM+ 2014. [DOI: 10.1134/s0022476614050072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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25
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Jacob H, Ulrich S, Jung U, Lemke S, Rusch T, Schütt C, Petersen F, Strunskus T, Magnussen O, Herges R, Tuczek F. Monitoring the reversible photoisomerization of an azobenzene-functionalized molecular triazatriangulene platform on Au(111) by IRRAS. Phys Chem Chem Phys 2014; 16:22643-50. [PMID: 25242068 DOI: 10.1039/c4cp03438d] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spectroscopic evidence of a reversible, photoinduced trans ↔ cis photoisomerization is provided for an azobenzene-functionalized triazatriangulene (TATA) platform on Au(111). As shown by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), these molecules form a well-ordered self-assembled monolayer (SAM) on Au(111). The surface-adsorbed azo-TATA platforms are also investigated by infrared reflection absorption spectroscopy (IRRAS); a methoxy marker group at the upper phenyl ring of the azo moiety is employed to monitor the switching state. The IRRAS data are analyzed by comparison with theoretical and transmission IR spectra as well as bulk and surface-enhanced Raman spectroscopic (SERS) data. IRRAS shows that the methoxy group is oriented perpendicular to the surface in trans- and tilted with respect to the surface normal in cis-configuration. This indicates that the photoswitching capability of the azobenzene moieties is retained on the gold surface. The lifetime of the cis-configuration is, however, reduced by a factor of ∼10(3) with respect to the homogeneous solution.
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Affiliation(s)
- Hanne Jacob
- Institut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany.
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26
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Jung U, Kubitschke J, Herges R, Magnussen O. Studies of the molecular switching of azobenzene-functionalized platform adlayers on Au(111) by chronoamperometry. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.06.123] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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27
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Valley DT, Onstott M, Malyk S, Benderskii AV. Steric hindrance of photoswitching in self-assembled monolayers of azobenzene and alkane thiols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11623-11631. [PMID: 23924041 DOI: 10.1021/la402144g] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Surface-bound azobenzenes exhibit reversible photoswitching via trans-cis photoisomerization and have been proposed for a variety of applications such as photowritable optical media, liquid crystal displays, molecular electronics, and smart wetting surfaces. We report a novel synthetic route using simple protection chemistry to form azobenzene-functionalized SAMs on gold and present a mechanistic study of the molecular order, orientation, and conformation in these self-assembled monolayers (SAMs). We use vibrational sum-frequency generation (VSFG) to characterize their vibrational modes, molecular orientation, and photoisomerization kinetics. Trans-cis conformational change of azobenzene leads to the change in the orientation of the nitrile marker group detected by VSFG. Mixed SAMs of azobenzene and alkane thiols are used to investigate the steric hindrance effects. While 100% azobenzene SAMs do not exhibit photoisomerization due to tight packing, we observe reversible switching (>10 cycles) in mixed SAMs with only 34% and 50% of alkane thiol spacers.
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Affiliation(s)
- David T Valley
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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28
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Müller M, Jung U, Gusak V, Ulrich S, Holz M, Herges R, Langhammer C, Magnussen O. Localized surface plasmon resonance investigations of photoswitching in azobenzene-functionalized self-assembled monolayers on Au. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:10693-10699. [PMID: 23909478 DOI: 10.1021/la401825f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Localized plasmon resonance (LSPR) spectroscopy, employing gold nanodisk substrates, is applied for studies of photoswitching in self-assembled monolayers of azobenzene-containing thiols. By choosing customized samples in which the sharp LSPR resonance is well separated from the spectral regime of the molecular absorption bands, the photoisomerization kinetics of the adlayer can be monitored in real time. Quantitative data on the photoinduced trans-cis and cis-trans isomerization processes in inert gas atmosphere were obtained as a function of irradiation intensity and temperature, demonstrating the high sensitivity of this technique to such processes in functional adlayers.
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Affiliation(s)
- Mathias Müller
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 19, 24118 Kiel, Germany
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29
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Yeung CL, Charlesworth S, Iqbal P, Bowen J, Preece JA, Mendes PM. Different formation kinetics and photoisomerization behavior of self-assembled monolayers of thiols and dithiolanes bearing azobenzene moieties. Phys Chem Chem Phys 2013; 15:11014-24. [PMID: 23712584 DOI: 10.1039/c3cp42104j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Self-assembled monolayers (SAMs) containing azobenzene moieties are very attractive for a wide range of applications, including molecular electronics and photonics, bio-interface engineering and sensoring. However, very little is known about the aggregation and photoswitching behavior that azobenzene units undergo during the SAM formation process. Here, we demonstrate that the formation of thiol-based SAMs containing azobenzenes (denoted as AzoSH) on gold surfaces is characterised by a two-step adsorption kinetics, while a three-step assembly process has been identified for dithiolane-based SAMs containing azobenzenes (denoted AzoSS). The H-aggregation on the AzoSS SAMs was found to be remarkably dependent on the time of self-assembly, with less aggregation as a function of time. While photoisomerization of the AzoSH was suppressed for all different assembly times, the reversible trans-cis photoisomerization of AzoSS SAMs formed over 24 hours was clearly observed upon alternating UV and Vis light irradiation. We contend that detailed information on formation kinetics and related optical properties is of crucial importance for elucidating the photoswitching capabilities of azobenzene-based SAMs.
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Affiliation(s)
- Chun L Yeung
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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30
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Kibena E, Marandi M, Mäeorg U, Venarusso LB, Maia G, Matisen L, Kasikov A, Sammelselg V, Tammeveski K. Electrochemical modification of gold electrodes with azobenzene derivatives by diazonium reduction. Chemphyschem 2013; 14:1043-54. [PMID: 23420610 DOI: 10.1002/cphc.201200934] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Indexed: 11/10/2022]
Abstract
An electrochemical study of Au electrodes electrografted with azobenzene (AB), Fast Garnet GBC (GBC) and Fast Black K (FBK) diazonium compounds is presented. Electrochemical quartz crystal microbalance, ellipsometry and atomic force microscopy investigations reveal the formation of multilayer films. The elemental composition of the aryl layers is examined by X-ray photoelectron spectroscopy. The electrochemical measurements reveal a quasi-reversible voltammogram of the Fe(CN)6 (3-/4-) redox couple on bare Au and a sigmoidal shape for the GBC- and FBK-modified Au electrodes, thus demonstrating that electron transfer is blocked due to the surface modification. The electrografted AB layer results in strongest inhibition of the Fe(CN)6 (3-/4-) response compared with other aryl layers. The same tendencies are observed for oxygen reduction; however, the blocking effect is not as strong as in the Fe(CN)6 (3-/4-) redox system. The electrochemical impedance spectroscopy measurements allowed the calculation of low charge-transfer rates to the Fe(CN)6 (3-) probe for the GBC- and FBK-modified Au electrodes in relation to bare Au. From these measurements it can be concluded that the FBK film is less compact or presents more pinholes than the electrografted GBC layer.
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Affiliation(s)
- Elo Kibena
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
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31
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de Villeneuve CH, Michalik F, Chazalviel JN, Rück-Braun K, Allongue P. Quantitative IR readout of fulgimide monolayer switching on Si(111) surfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:416-421. [PMID: 23132750 DOI: 10.1002/adma.201201546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 08/06/2012] [Indexed: 06/01/2023]
Abstract
Creating photoactive monolayers of photochromes is of considerable technological interest. This paper describes the construct of fulgimide monolayers on silicon surfaces and presents a quantitative IR analysis studies of their composition and switching properties. The scheme on top shows the structure of the starting C-form terminated Si(111) surface and the graph below sketches the surface composition at the photostationnary states under visisble and UV irradiation, as derived from in situ IR spectroscopy after several UV/vis irradiation cycles.
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32
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Chi H, Mya KY, Lin T, He C, Wang F, Chin WS. Thermally stable azobenzene dyes through hybridization with POSS. NEW J CHEM 2013. [DOI: 10.1039/c2nj40977a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Zhou W, Yu H. Different morphologies of self-assembled nanofibers fabricated with amphiphilic low-molecular-weight azopyridinium salts. RSC Adv 2013. [DOI: 10.1039/c3ra44065f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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34
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Tseng CW, Huang DC, Tao YT. Electric bistability induced by incorporating self-assembled monolayers/aggregated clusters of azobenzene derivatives in pentacene-based thin-film transistors. ACS APPLIED MATERIALS & INTERFACES 2012; 4:5483-5491. [PMID: 22974132 DOI: 10.1021/am3013906] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Composite films of pentacene and a series of azobenzene derivatives are prepared and used as the active channel material in top-contact, bottom-gate field-effect transistors. The transistors exhibit high field-effect mobility as well as large I-V hysteresis as a function of the gate bias history. The azobenzene moieties, incorporated either in the form of self-assembled monolayer or discrete multilayer clusters at the dielectric surface, result in electric bistability of the pentacene-based transistor either by photoexcitation or gate biasing. The direction of threshold voltage shifts, size of hysteresis, response time, and retention characteristics all strongly depend on the substituent on the benzene ring. The results show that introducing a monolayer of azobenzene moieties results in formation of charge carrier traps responsible for slower switching between the bistable states and longer retention time. With clusters of azobenzene moieties as the trap sites, the switching is faster but the retention is shorter. Detailed film structure analyses and correlation with the transistor/memory properties of these devices are provided.
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35
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Pathem BK, Zheng YB, Payton JL, Song TB, Yu BC, Tour JM, Yang Y, Jensen L, Weiss PS. Effect of Tether Conductivity on the Efficiency of Photoisomerization of Azobenzene-Functionalized Molecules on Au{111}. J Phys Chem Lett 2012; 3:2388-2394. [PMID: 26292120 DOI: 10.1021/jz300968m] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We establish the role of tether conductivity on the photoisomerization of azobenzene-functionalized molecules assembled as isolated single molecules in well-defined decanethiolate self-assembled monolayer matrices on Au{111}. We designed the molecules so as to tune the conductivity of the tethers that separate the functional moiety from the underlying Au substrate. By employing surface-enhanced Raman spectroscopy, time-course measurements of surfaces assembled with azobenzene functionalized with different tether conductivities were independently studied under constant UV light illumination. The decay constants from the analyses reveal that photoisomerization on the Au{111} surface is reduced when the conductivity of the tether is increased. Experimental results are compared with density functional theory calculations performed on single molecules attached to Au clusters.
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Affiliation(s)
| | | | - John L Payton
- ∥Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | | | - Byung-Chan Yu
- ⊥Department of Chemistry and The Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, United States
| | - James M Tour
- ⊥Department of Chemistry and The Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, United States
| | | | - Lasse Jensen
- ∥Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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36
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Heinemann N, Grunau J, Leißner T, Andreyev O, Kuhn S, Jung U, Zargarani D, Herges R, Magnussen O, Bauer M. Reversible switching in self-assembled monolayers of azobenzene thiolates on Au (111) probed by threshold photoemission. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.03.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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37
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Wang SY, Huang DC, Tao YT. Self-assembled Azobenzenethiol Monolayer on Electrode Surfaces: Effect of Photo-switching on the Surface and Electrical Property. J CHIN CHEM SOC-TAIP 2012. [DOI: 10.1002/jccs.201100467] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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38
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Jung U, Kuhn S, Cornelissen U, Tuczek F, Strunskus T, Zaporojtchenko V, Kubitschke J, Herges R, Magnussen O. Azobenzene-containing triazatriangulenium adlayers on Au(111): structural and spectroscopic characterization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5899-5908. [PMID: 21506548 DOI: 10.1021/la104654p] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Adlayers of different azobenzene-functionalized derivatives of the triazatriangulenium (TATA) platform on Au(111) surfaces were studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), gap-mode surface-enhanced Raman spectroscopy (gap-mode SERS), and cyclic voltammetry (CV). The chemical composition of the adlayers is in good agreement with the molecular structure, i.e., different chemical groups attached to the azobenzene functionality were identified. Furthermore, the presence of the azobenzene moieties in the adlayers was verified by the vibration spectra and electrochemical data. These results indicate that the molecules remain intact upon adsorption with the freestanding functional groups oriented perpendicularly to the TATA platform and thus also to the substrate surface.
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Affiliation(s)
- Ulrich Jung
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Leibnizstr. 19, 24118 Kiel, Germany
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39
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Heinemann N, Leissner T, Grunau J, Rohwer T, Andreyev O, Bauer M. Two-photon photoemission from ex-situ prepared butanethiol SAMs on Au (111). Chem Phys 2011. [DOI: 10.1016/j.chemphys.2011.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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40
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Wang G, Kim TW, Lee T. Electrical transport characteristics through molecular layers. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm12702k] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Carlos Lima J, Rodríguez L. Applications of gold(i) alkynyl systems: a growing field to explore. Chem Soc Rev 2011; 40:5442-56. [DOI: 10.1039/c1cs15123a] [Citation(s) in RCA: 204] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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