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Pang B, Iqbal D, Sarfraz A, Biedermann PU, Erbe A. Differences in perchlorate adsorption to azobenzene monolayers on gold formed from thioacetate and thiol precursors. Z PHYS CHEM 2022. [DOI: 10.1515/zpch-2021-3143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Modification of metal surfaces with complex molecules opens interesting opportunities to build additional functionality into these surfaces. In this work, self assembled monolayers (SAMs) based on the same photoswitchable azobenzene motif but with different head groups have been synthesized and their SAMs on Au(111)/Si substrates have been characterized. 3-[(4-phenylazo)phenoxy]propyl thiol (PAPT) and its acetyl group protected analog, 3-[(4-phenylazo)phenoxy]propyl thioacetate (PAPA), have been synthesized. SAMs from PAPT and PAPA have been characterized by infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ellipsometry and cyclic voltammetry (CV). The SAM-forming units of both SAMs are the same, as confirmed by IR and XPS, and the SAMs have similar surface coverage, as evidenced by analysis of the reductive desorption peaks in CVs. The tilt angle of the azobenzene moiety was ca. 75° with respect to the surface normal as determined by IR spectroscopy, i.e., the molecules are lying quite flat on the gold surface. Despite similar surface coverages, the CVs for PAPT in aqueous perchlorate solution show a typical perchlorate adsorption peak to gold, whereas the corresponding experiments with PAPA show no perchlorate adsorption at all. In conclusion, SAM formation can lead to an increase in the number of electrochemically accessible surface sites on the final, SAM covered surface. Whether the amount of such sites increases or decreases, depends on the precursor. The precursor most likely affects the adsorption mechanism and thus the atomic surface structure of the metal at the metal/SAM interface. Thus, details of the SAM formation mechanism, which is affected by the precursor used, can have quite strong effects on the electrochemical properties, and likely also electrocatalytic properties, of the resulting modified surface.
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Affiliation(s)
- Beibei Pang
- Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str., 1, 40237 Düsseldorf , Germany
| | - Danish Iqbal
- Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str., 1, 40237 Düsseldorf , Germany
| | - Adnan Sarfraz
- Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str., 1, 40237 Düsseldorf , Germany
| | - P. Ulrich Biedermann
- Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str., 1, 40237 Düsseldorf , Germany
| | - Andreas Erbe
- Department of Materials Science and Engineering , NTNU, Norwegian University of Science and Technology , 7491 Trondheim , Norway
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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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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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Kaneta M, Honda T, Onda K, Han M. Repeated photoswitching performance of azobenzenes adsorbed on gold surfaces: a balance between space, intermolecular interactions, and phase separation. NEW J CHEM 2017. [DOI: 10.1039/c6nj03121h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A delicate balance between space, intermolecular interactions, and phase separation plays an important role in forming repeatedly photoswitchable monolayers.
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Affiliation(s)
- Mitsuyuki Kaneta
- Department of Chemistry and Department of Electronic Chemistry
- Tokyo Institute of Technology
- Yokohama 226-8502
- Japan
| | - Takumu Honda
- Department of Chemistry and Department of Electronic Chemistry
- Tokyo Institute of Technology
- Yokohama 226-8502
- Japan
| | - Ken Onda
- School of Science
- Tokyo Institute of Technology
- Yokohama 226-8502
- Japan
- JST
| | - Mina Han
- Department of Chemistry and Department of Electronic Chemistry
- Tokyo Institute of Technology
- Yokohama 226-8502
- Japan
- Department of Chemistry and Biotechnology
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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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7
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Luboch E, Szarmach M, Buczkowska A, Wagner-Wysiecka E, Kania M, Danikiewicz W. Synthesis of thiol derivatives of azobenzocrown ethers. The preliminary studies on recognition of alkali metal ions by gold nanoparticles functionalized with azobenzocrown and lipoic acid. J INCL PHENOM MACRO 2015; 83:321-334. [PMID: 26549980 PMCID: PMC4630251 DOI: 10.1007/s10847-015-0567-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/18/2015] [Indexed: 01/23/2023]
Abstract
The article presents the synthesis of novel 13- and 16-membered azobenzocrown derivatives with peripheral thiol moieties and preliminary studies assessing their possible application in plasmonic sensors based on gold nanoparticles. The effect of the length of the chain connecting the macrocycle with the thiol group and the effect of the presence of the additional functional compound, i.e. lipoic acid, on the sensor response was analyzed. Colloidal gold nanoparticles modified with a 16-membered crown with a thiol group on oxyethylene (compound 12) or oxybutylene (compound 13) linker was found to have good properties, allowing for detection of potassium ions in aqueous solutions at concentrations 8-20 mM for bifunctionalized nanogold and 4-26 mM for less stable, colloidal gold modified only with thiol derivatives of azobenzocrowns. The response towards potassium cations of bifunctionalized nanogold modified with compound 13 was more stable in time than for the system incorporating compound 12. Compound 13, obtained with the highest yield among all presented thiol derivatives of azobenzocrowns, was selected for further, more detailed, studies.
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Affiliation(s)
- Elżbieta Luboch
- Department of Chemistry and Technology of Functional Materials, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland
| | - Mirosław Szarmach
- Department of Chemistry and Technology of Functional Materials, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland
| | - Anna Buczkowska
- Department of Chemistry and Technology of Functional Materials, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland
| | - Ewa Wagner-Wysiecka
- Department of Chemistry and Technology of Functional Materials, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland
| | - Magdalena Kania
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Witold Danikiewicz
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
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8
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Pardo WA, Mir M, Samitier J. Signal enhancement in ultraflat electrochemical DNA biosensors. Electrophoresis 2015; 36:1905-11. [DOI: 10.1002/elps.201500049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/29/2015] [Accepted: 04/29/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Wilmer A. Pardo
- Nanobioengineering Laboratory; Institute for Bioengineering of Catalonia (IBEC); Barcelona Spain
- Department of Electronics; University of Barcelona (UB); Barcelona Spain
| | - Mònica Mir
- Nanobioengineering Laboratory; Institute for Bioengineering of Catalonia (IBEC); Barcelona Spain
- The Biomedical Research Networking Center in Bioengineering; Biomaterials and Nanomedicine (CIBER-BBN); Zaragoza Spain
| | - Josep Samitier
- Nanobioengineering Laboratory; Institute for Bioengineering of Catalonia (IBEC); Barcelona Spain
- The Biomedical Research Networking Center in Bioengineering; Biomaterials and Nanomedicine (CIBER-BBN); Zaragoza Spain
- Department of Electronics; University of Barcelona (UB); Barcelona Spain
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9
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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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10
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Nerngchamnong N, Wu H, Sotthewes K, Yuan L, Cao L, Roemer M, Lu J, Loh KP, Troadec C, Zandvliet HJW, Nijhuis CA. Supramolecular structure of self-assembled monolayers of ferrocenyl terminated n-alkanethiolates on gold surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13447-13455. [PMID: 25325611 DOI: 10.1021/la503493x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
It is important to understand the structure of redox-active self-assembled monolayers (SAMs) down to the atomic scale, since these SAMS are widely used as model systems in studies of mechanisms of charge transport or to realize electronic functionality in molecular electronic devices. We studied the supramolecular structure of SAMs of n-alkanethiolates with ferrocenyl (Fc) end groups (S(CH2)nFc, n = 3 or 4) on Au(111) by scanning tunneling microscopy (STM). In this system, the tilt angle of the Fc units with respect to the surface normal (α) depends on the value of n because the Au-S-C bond angle is fixed. The ordered domains of the SAMs were imaged by STM after annealing at 70 °C at ultrahigh vacuum conditions. High resolution electron energy loss spectroscopy (HREELS) and cyclic voltammetry show that this annealing step only removed physisorbed material and did not affect the structure of the SAM. The STM images revealed the presence of row defects at intervals of 4 nm, that is, six molecules. We determined by near edge X-ray absorption fine structure spectroscopy (NEXAFS) that the Fc units of the SAMs of SC3Fc are more parallel to the Au(111) plane with a tilt angle α = 60.2° than the Fc units of SC4Fc SAMs (α = 45.4°). These tilt angles are remarkably close to the tilt angles measured by X-ray diffraction data of bulk crystals (bc-plane). Based on our data, we conclude that the molecules are standing up and the SAMs pack into lattices that are distorted from their bulk crystal structures (because of the build-up stain due to the differences in size between the Fc units and thiolate anchoring groups).
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Affiliation(s)
- Nisachol Nerngchamnong
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543
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11
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Wickramasinghe HK, Chaigneau M, Yasukuni R, Picardi G, Ossikovski R. Billion-fold increase in tip-enhanced Raman signal. ACS NANO 2014; 8:3421-3426. [PMID: 24601546 DOI: 10.1021/nn406263m] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A billion-fold increase in the Raman signal over conventional tip-enhanced Raman spectroscopy/microscopy (TERS) is reported. It is achieved by introducing a stimulating beam confocal with the pump beam into a conventional TERS setup. A stimulated TERS spectrum, closely corresponding to its spontaneous TERS counterpart, is obtained by plotting the signal intensity of the strongest Raman peak of an azobenzene thiol self-assembled monolayer versus the stimulating laser frequency. The stimulated TERS image of azobenzene thiol molecules grafted onto Au ⟨111⟩ clearly shows the surface distribution of the molecules, whereas, when compared to the simultaneously recorded surface topography, it presents an image contrast of different nature. The experimentally obtained stimulated gain is estimated at 1.0 × 10(9), which is in reasonable agreement with the theoretically predicted value. In addition to the signal increase, the signal-to-noise ratio was 3 orders of magnitude higher than in conventional spontaneous TERS. The proposed stimulated TERS technique offers the possibility for a substantially faster imaging of the surface with respect to normal TERS.
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Affiliation(s)
- H Kumar Wickramasinghe
- Department of Electrical Engineering and Computer Science, University of California , Irvine, California 92697, United States
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12
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Yimer YY, Jha KC, Tsige M. Epitaxial transfer through end-group coordination modulates the odd-even effect in an alkanethiol monolayer assembly. NANOSCALE 2014; 6:3496-3502. [PMID: 24553572 DOI: 10.1039/c3nr05671f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Short spacer length and high end-group coordination lead to the top network acting as a template for the buried sulfur-gold interface of n-alkanethiols (SH-(CH2)n-OH or SH-(CH2)n-CH3) on gold {111}. Annealing and templating both drive toward a higher sampling of the spatially favorable bridge adsorption sites. The hydrogen-bonded network increases in strength by increasing the number of hydrogens participating per oxygen, from 1.75 to 1.98 for n = 14-30. Higher n leads to better packing (five times for hydroxyl-terminated and seven times for methyl-terminated for n = 14-30) and stability of monolayers, while lower n results in better epitaxial transfer (transfer coefficient ratio = 13.5 for {SH-(CH2)14-OH}/{SH-(CH2)30-CH3}) and actuation. Odd values of n for the hydroxyl-terminated n-alkanethiols lead to lattice spacing of an average of 0.04 ± 0.01 Å higher than even values. There is a structural transition in properties around spacer length n = 24-27. Characterization of monolayer assembly through correlation between adatom and network layers provides recursive design principles for actuation and sensing applications.
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Affiliation(s)
- Yeneneh Y Yimer
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325, USA.
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Picardi G, Królikowska A, Yasukuni R, Chaigneau M, Escude M, Mourier V, Licitra C, Ossikovski R. Exchange of Methyl- and Azobenzene-Terminated Alkanethiols on Polycrystalline Gold Studied by Tip-Enhanced Raman Mapping. Chemphyschem 2014; 15:276-82. [DOI: 10.1002/cphc.201300918] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Indexed: 11/07/2022]
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Jin H, Zhou Y, Huang W, Zheng Y, Zhu X, Yan D. Three-component vesicle aggregation driven by adhesion interactions between Au nanoparticles and polydopamine-coated nanotubes. Chem Commun (Camb) 2014; 50:6157-60. [DOI: 10.1039/c4cc00609g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Large-scale and robust vesicle aggregates were obtained through three-component molecular recognition among cell-sized polymer vesicles, carbon nanotubes and Au nanoparticles driven by adhesion interactions between Au and polydopamine.
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Affiliation(s)
- Haibao Jin
- School of Chemistry and Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai 200240, China
| | - Yongfeng Zhou
- School of Chemistry and Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai 200240, China
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials
| | - Wei Huang
- School of Chemistry and Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai 200240, China
| | - Yongli Zheng
- School of Chemistry and Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai 200240, China
| | - Xinyuan Zhu
- School of Chemistry and Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai 200240, China
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials
| | - Deyue Yan
- School of Chemistry and Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai 200240, China
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials
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15
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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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16
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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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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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Ishikawa D, Ito E, Han M, Hara M. Effect of the steric molecular structure of azobenzene on the formation of self-assembled monolayers with a photoswitchable surface morphology. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4622-4631. [PMID: 23249363 DOI: 10.1021/la302552v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The growth processes of self-assembled monolayers (SAMs) of two azobenzene disulfides formed on flat gold surfaces were studied to confirm the effect of the intermolecular interactions between azobenzene molecules on the light-triggered surface morphologies of the SAMs. Scanning tunneling microscopy (STM), atomic force microscopy (AFM), thermal desorption spectroscopy (TDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) absorption spectroscopy were employed to study the SAMs and their growth processes. The SAMs studied were of bulky-substituted azobenzene disulfide (Et-2S), and nonsubstituted azobenzene disulfide (Me-2S), formed on a gold-covered substrate, and had a twisted and a planar structure, respectively. STM-based imaging of the initial stage of the self-assembly of the Et-2S molecules revealed that cleavage of the disulfide bond occurred on the gold surface, and phase-separated domains composed of azobenzenethiolate and dodecanethiolate were formed. Time-dependent AFM-based imaging illustrated the mechanism through which the Et-2S SAM grew-it was through the formation of dendritic aggregates and islands-eventually resulting in phase-separated domains with a wormlike structure. This wormlike structure showed noticeable changes in its surface morphology upon irradiation with UV and visible light. On the other hand, while the growth process for the Me-2S SAM was similar to that of the Et-2S SAM, the final Me-2S SAM had smooth domains whose morphology did not exhibit photoswitchability. The TD and XP spectra of the SAMs showed that the number of adsorbed Et-2S molecules reached a point of saturation after a 24 h long immersion while the number of Me-2S molecules increased even after a 336 h long immersion. Furthermore, the area occupied by the azobenzene moiety in the Et-2S SAM was constant regardless of the immersion time, whereas that in the Me-2S SAM decreased with the immersion time. These results indicated that the strength of the interactions between the azobenzene molecules significantly influenced the aggregate-forming ability in SAMs.
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Affiliation(s)
- Daisuke Ishikawa
- Department of Electronic Chemistry, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8502, Japan
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Zhu L, Yan H, Ang CY, Nguyen KT, Li M, Zhao Y. Photoswitchable Supramolecular Catalysis by Interparticle Host-Guest Competitive Binding. Chemistry 2012; 18:13979-83. [DOI: 10.1002/chem.201202711] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Indexed: 12/12/2022]
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20
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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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21
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Utecht M, Klamroth T, Saalfrank P. Optical absorption and excitonic coupling in azobenzenes forming self-assembled monolayers: a study based on density functional theory. Phys Chem Chem Phys 2011; 13:21608-14. [PMID: 22071571 DOI: 10.1039/c1cp22793a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on the analysis of optical absorption spectra, it has recently been speculated that the excitonic coupling between individual azobenzene-functionalized alkanethiols arranged in a self-assembled monolayer (SAM) on a gold surface could be strong enough to hinder collective trans-cis isomerization-on top of steric hindrance [Gahl et al., J. Am. Chem. Soc., 2010, 132, 1831]. Using models of SAMs of increasing complexity (dimer, linear N-mers, and two-dimensionally arranged N-mers) and density functional theory on the (TD-) B3LYP/6-31G* level, we determine optical absorption spectra, the nature and magnitude of excitonic couplings, and the corresponding spectral shifts. It is found that at inter-monomer distances of about 20 Å and above, TD-B3LYP excitation frequencies (and signal intensities) can be well described by the frequently used point-dipole approximation. Further, calculated blue shifts in optical absorption spectra account for the experimental observations made for azobenzene/gold SAMs, and hint to the fact that they can indeed be responsible for reduced switching probability in densely packed self-assembled structures.
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Affiliation(s)
- Manuel Utecht
- Universität Potsdam, Institut für Chemie, Karl-Liebknecht-Straße 24-25, D-14476 Potsdam-Golm, Germany
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22
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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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Chaigneau M, Picardi G, Ossikovski R. Molecular arrangement in self-assembled azobenzene-containing thiol monolayers at the individual domain level studied through polarized near-field Raman spectroscopy. Int J Mol Sci 2011; 12:1245-58. [PMID: 21541056 PMCID: PMC3083703 DOI: 10.3390/ijms12021245] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 02/10/2011] [Accepted: 02/11/2011] [Indexed: 11/17/2022] Open
Abstract
6-[4-(phenylazo)phenoxy]hexane-1-thiol self-assembled monolayers deposited on a gold surface form domain-like structures possessing a high degree of order with virtually all the molecules being identically oriented with respect to the surface plane. We show that, by using polarized near-field Raman spectroscopy, it is possible to derive the Raman scattering tensor of the ordered layer and consequently, the in-plane molecular orientation at the individual domain level. More generally, this study extends the application domain of the near-field Raman scattering selection rules from crystals to ordered organic structures.
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Affiliation(s)
- Marc Chaigneau
- LPICM, Ecole Polytechnique, CNRS, 91128 Palaiseau, France; E-Mails: (M.C.); (G.P.)
| | - Gennaro Picardi
- LPICM, Ecole Polytechnique, CNRS, 91128 Palaiseau, France; E-Mails: (M.C.); (G.P.)
- NCSR, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland
| | - Razvigor Ossikovski
- LPICM, Ecole Polytechnique, CNRS, 91128 Palaiseau, France; E-Mails: (M.C.); (G.P.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +33-169-334-367; Fax: +33-169-334-333
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Zhang Z, Wang Y, Yan F, Peng D, Ma Z. Photosensitive Azopolymer Brushes via Atom Transfer Radical Polymerization for Protein Sensing. CHINESE J CHEM 2011. [DOI: 10.1002/cjoc.201190044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Jung U, Filinova O, Kuhn S, Zargarani D, Bornholdt C, Herges R, Magnussen O. Photoswitching behavior of azobenzene-containing alkanethiol self-assembled monolayers on Au surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:13913-13923. [PMID: 20806964 DOI: 10.1021/la1015109] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The photoisomerization of self-assembled monolayers of azobenzene-containing alkanethiols, as well as of mixed monolayers of these substances with n-alkanethiol spacer molecules on Au surfaces, was studied by photoelectrochemical measurements and surface plasmon resonance spectroscopy. A strong dependence on the molecular structure of the adsorbates was found, specifically on the linker between the azobenzene moiety and the alkanethiol: while molecules with an amide group were photoinactive, those with an ether group exhibited pronounced, reversible photoisomerization in pure and mixed adlayers. Both trans-cis and cis-trans isomerization followed first-order kinetics with time constants that suggest high quantum efficiencies for these processes.
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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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Yu HZ, Wang YQ, Cai SM, Liu ZF. Structural and electrochemical investigations of self-assembled monolayers of azobenzenealkanethiol and ferrocenealkanethiol containing amido linkages. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19971010214] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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Gahl C, Schmidt R, Brete D, McNellis ER, Freyer W, Carley R, Reuter K, Weinelt M. Structure and excitonic coupling in self-assembled monolayers of azobenzene-functionalized alkanethiols. J Am Chem Soc 2010; 132:1831-8. [PMID: 20099853 DOI: 10.1021/ja903636q] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Optical properties and the geometric structure of self-assembled monolayers of azobenzene-functionalized alkanethiols have been investigated by UV/visible and near edge X-ray absorption fine structure spectroscopy in combination with density-functional theory. By attaching a trifluoro-methyl end group to the chromophore both the molecular tilt and twist angle of the azobenzene moiety are accessible. Based on this detailed structural analysis the energetic shifts observed in optical reflection spectroscopy can be qualitatively described within an extended dipole model. This substantiates sizable excitonic coupling among the azobenzene chromophores as an important mechanism that hinders trans to cis isomerization in densely packed self-assembled monolayers.
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Affiliation(s)
- Cornelius Gahl
- Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin, Germany.
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Han M, Ishikawa D, Honda T, Ito E, Hara M. Light-driven molecular switches in azobenzene self-assembled monolayers: effect of molecular structure on reversible photoisomerization and stable cis state. Chem Commun (Camb) 2010; 46:3598-600. [DOI: 10.1039/b921801g] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gap-mode SERS studies of azobenzene-containing self-assembled monolayers on Au(111). J Colloid Interface Sci 2010; 341:366-75. [DOI: 10.1016/j.jcis.2009.09.040] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 09/15/2009] [Accepted: 09/21/2009] [Indexed: 11/20/2022]
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30
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Switching behavior and optical absorbance of azobenzene-functionalized alkanethiols in different environments. J Photochem Photobiol A Chem 2009. [DOI: 10.1016/j.jphotochem.2009.02.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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31
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Weidner T, Bretthauer F, Ballav N, Motschmann H, Orendi H, Bruhn C, Siemeling U, Zharnikov M. Correlation between the molecular structure and photoresponse in aliphatic self-assembled monolayers with azobenzene tailgroups. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:11691-11700. [PMID: 18823085 DOI: 10.1021/la802454w] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We have compared the structural and photoisomerization properties of self-assembled monolayers (SAMs) comprising either the trans or cis isomers of azobenzene terminated dithiolane with in-chain amide unit, viz., 4-(phenyldiazenyl)phenyl-4-(1,2-dithiolane-3-yl)-butylcarboxamide ( 1). These films were prepared on Au(111) from solutions of both isomers. Structure and composition of the SAMs were studied by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. The photoresponse of the films was monitored in real time by ellipsometry. SAMs fabricated from the trans isomer were found to be densely packed and highly ordered. These films did not show any discernible photoresponse upon irradiation with UV light, which, under favorable conditions, triggers the trans- cis isomerization. In contrast, films prepared from solutions containing predominantly the cis isomer were loosely packed and mostly disordered but exhibited reversible photoreactivity. The results confirm that steric effects, i.e., available free volume, play a dominant role for the photoresponse of aliphatic SAMs bearing the photoactive azobenzene group. The crystal structure of 1 ( trans isomer) exhibits a row-like aggregation of neighboring molecules by weak hydrogen bonds and can be taken as a model for the arrangement of 1 in the monolayer films. Further, in addition to the surface coordination behavior, we have also mimicked the chemisorption of the 1,2-dithiolane moiety onto the gold substrate in molecular coordination chemistry in oxidative addition reactions with the zero-valent platinum complex [Pt(PPh 3) 4].
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Affiliation(s)
- Tobias Weidner
- Angewandte Physikalische Chemie, Universitat Heidelberg, 69120 Heidelberg, Germany.
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Miyake K, Hori Y, Ikeda T, Asakawa M, Shimizu T, Sasaki S. Alkyl chain length dependence of the self-organized structure of alkyl-substituted phthalocyanines. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:4708-4714. [PMID: 18380508 DOI: 10.1021/la702564m] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The alkyl chain length on alkyl-substituted phthalocyanines (C(n)OPc) dependence of their self-organized structures was examined in this study. STM results indicated that the symmetry of ordered structures decreased as the alkyl chain became longer, with the exception of C(6)OPc, which preferentially formed a quasi-3-fold symmetrical structure. This could be explained by the fact that the C(n)OPc molecules are most likely to form densely packed structures. With C(n)OPc, when n = 4 to 10, the self-organized structures were dependent on the competition between how densely the molecules were arranged and how loose the intermolecular interaction energy was, caused by the formation of the densely packed structure. However, with C(n)OPc, when n = 10-18, the molecules tended to form densely packed structures by reducing the symmetry, even though the C(n)OPc molecules were distorted. When C(12)OPc and cobalt phthalocyanine were coadsorbed, the mixed system exhibited a four-fold symmetrical structure, which is rarely observed in C(12)OPc.
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Affiliation(s)
- Koji Miyake
- Advanced Manufacturing Research Institute (AMRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan.
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Stiller B, Karageorgiev P, Jüngling T, Prescher D, Zetzsche T, Dietel R, Knochenhauer G, Brehmer L. Optically Induced Switching of Azobenzene Containing Self Assembling Monolayers Investigated by Kelvin Probe and Scanning Force Microscopy. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587250108023673] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- B. Stiller
- a Institute of thin film technology and microsensorics , Kantstrasse 55, D-14513 , Teltow , Germany
| | - P. Karageorgiev
- b Institute of Physics, Dept. of physics of condensed matter, University of Potsdam , PF 601553, D-14415 , Potsdam , Germany
| | - Th. Jüngling
- a Institute of thin film technology and microsensorics , Kantstrasse 55, D-14513 , Teltow , Germany
| | - D. Prescher
- a Institute of thin film technology and microsensorics , Kantstrasse 55, D-14513 , Teltow , Germany
| | - Th. Zetzsche
- a Institute of thin film technology and microsensorics , Kantstrasse 55, D-14513 , Teltow , Germany
| | - R. Dietel
- b Institute of Physics, Dept. of physics of condensed matter, University of Potsdam , PF 601553, D-14415 , Potsdam , Germany
| | - G. Knochenhauer
- a Institute of thin film technology and microsensorics , Kantstrasse 55, D-14513 , Teltow , Germany
| | - L. Brehmer
- b Institute of Physics, Dept. of physics of condensed matter, University of Potsdam , PF 601553, D-14415 , Potsdam , Germany
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35
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Haddox RM, Finklea HO. Proton-Coupled Electron Transfer of an Osmium Aquo Complex on a Self-Assembled Monolayer on Gold. J Phys Chem B 2004. [DOI: 10.1021/jp035967e] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert M. Haddox
- Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045
| | - Harry O. Finklea
- Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045
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36
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Investigations on the monolayer structure of thiol SAMs and the influence of conjugated π-bonds on the electronic molecular conductivity. Electrochim Acta 2003. [DOI: 10.1016/j.electacta.2003.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Anderson MR, Baltzersen R. Reductive desorption of 11-mercaptoundecanoic acid monolayers modified by covalent attachment of 1,3- and 1,4-phenylenediamine. J Colloid Interface Sci 2003; 263:516-21. [PMID: 12909042 DOI: 10.1016/s0021-9797(03)00291-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
1,3- and 1,4-phenylenediamine were covalently attached to a self-assembled monolayer of 11-mercaptoundecanoic acid by formation of an amide bond. Bonding of the phenylenediamine isomers was confirmed by the presence of infrared features attributable to ring vibrational modes, the amide I vibration, and the amide II vibration in the reflection-absorption infrared spectrum of the modified interface. Reductive desorption peak potentials were shifted by 120 mV for the monolayer modified by 1,4-phenylenediamine and by 90 mV for the monolayer modified by 1,3-phenylenediamine relative to the desorption potential of the unmodified 11-mercaptoundecanoic acid monolayer. These potential shifts represent 23 and 17 kJ/mol stabilization of the monolayers modified by 1,4- and 1,3-phenylenediamine, respectively. Some of the additional stabilization energy is attributed to lateral hydrogen bonding between the amide groups and unreacted carboxylic acid groups in the monolayer. The difference between the stabilization energies for the interfaces modified with the different phenylenediamine isomers is attributed to structural differences between the isomeric monolayers influencing the molecular packing of the modified interface.
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Affiliation(s)
- Mark R Anderson
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0212, USA.
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Zhang WW, Li HF, Liu L, Xie JL, Lu CS, Zhou Y, Ren XM, Meng QJ. Preparation and electrochemistry of azobenzene self-assembled monolayers on gold--long range tunneling and end-group hydrogen bonding effect. J Colloid Interface Sci 2003; 261:82-7. [PMID: 12725827 DOI: 10.1016/s0021-9797(02)00143-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A series of thiol-functionalied azobenzene derivatives (RAzoCnSH: R=H for n=3-6, abbreviated as AzoCnSH; R=CH(3)CONH for n=4, abbreviated as aaAzoC4SH) on gold electrodes were prepared and their self-assembly and electrochemical properties were studied by cyclic voltammetry. They all formed uniform and reproducible self-assembled monolayers (SAMs) on gold and showed well-behaved voltammetric responses in aqueous solution. Both the length of the alkyl chain spacer and the H-bonding of the end acetamino group had effects on the stability and the electrochemical kinetics of the SAMs, and the effect of the H-bonding was dominant. The surface coverage of the SAMs (AzoCnSH) is gradually increased with an increase of the alkyl chain spacer length, whereas the presence of the terminal acetamino group leads to a greater increase of the surface coverage. At a low scan rate, voltammetric responses corresponding to an irreversible two-electron, two-proton reduction/oxidation of the trans-azobenzene redox center were obtained in the range of +300 mV and -800 mV, which exhibited very large peak-to-peak splitting. At a high scan rate of 500 mV/s, two steps of reversible one-electron, one-proton reduction/oxidation corresponding to the cis-isomer in azobenzene-thiol SAMs (n is odd) was clearly observed between +300 and -200 mV. The apparent electron-transfer rate is decreased with increasing distance between the azobenzene redox center and the gold electrode. The existence of the end acetamino group which restricted the conformational change during the redox process also led to a decrease of the standard rate constant, and this restriction effect is more predominant than the distance effect.
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Affiliation(s)
- Wen-Wei Zhang
- Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, 22 Hankou Road, Nanjing 210093, PR China
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Akiyama H, Tamada K, Nagasawa J, Abe K, Tamaki T. Photoreactivity in Self-Assembled Monolayers Formed from Asymmetric Disulfides Having para-Substituted Azobenzenes. J Phys Chem B 2003. [DOI: 10.1021/jp026103g] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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40
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Fujii S, Akiba U, Fujihira M. Geometry for self-assembling of spherical hydrocarbon cages with methane thiolates on au(111). J Am Chem Soc 2002; 124:13629-35. [PMID: 12418918 DOI: 10.1021/ja026214t] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An organodisulfide with a pair of adamantane moieties was synthesized, and its self-assembled monolayer (SAM) was formed on Au(111). The adamantane moieties are almost spherical and much bulkier than alkyl chains. The structure was characterized by scanning tunneling microscopy. Two-dimensional crystals of the SAM were found to be four orientationally different hexagonals with almost the same lattice constant with 4 radical 3a/3 and 7a/3 (a = 0.2884 nm, the Au lattice constant). The structure is assigned to four of the high-order commensurate adlayers. The present study of geometry and energetics for self-assembling of such an organosulfur compound with spherical cages provides a new insight into the probable SAM structure of various thiolate derivatives on Au(111).
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Affiliation(s)
- Shintaro Fujii
- Contribution from the Department of Biomolecular Engineering, Tokyo Institute of Technology, 4259 Nagatsuta Midori-ku, Yokohama, 226-8501, Japan
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41
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Zhang WW, Ren XM, Li HF, Lu CS, Hu CJ, Zhu HZ, Meng QJ. Study on self-assembled monolayers of functionalized azobenzene thiols on gold: XPS, electrochemical properties, and surface-enhanced Raman spectroscopy. J Colloid Interface Sci 2002; 255:150-7. [PMID: 12702380 DOI: 10.1006/jcis.2002.8455] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Self-assembled monolayers (SAMs) of 4-acetamino-4'-(4-mercaptobutoxy)azobenzene (CH3)CONH-ph-N=N-ph-O(CH2)(4)SH, abbr. aaAzoC4SH) and 4-mercaptobutoxy azobenzene (ph-N=N-ph-O(CH2)(4)SH, abbr. AzoC4SH) on a gold surface have been studied by X-ray photoelectron spectroscopy (XPS), FT Raman spectroscopy, and electrochemistry. A surface-enhanced Raman scattering (SERS)-active system with a "sandwiched" structure of Ag/R-Azo-C4S-/Au was conveniently obtained by the method of Tollen's test. The relationship between the SERS effect and the structural nature of the system indicates that the enhancement correlates to both the silver islands above and the gold substrate underneath. The redox behaviors of the self-assembly on gold electrodes showed that the SAMs of the two compounds exhibit well-behaved voltammetric responses in a Britton-Robinson buffer corresponding to the irreversible two-electron, two-proton reduction-oxidation of azobenzene. The apparent electron-transfer rate kinetics is very sluggish, and the rate constant k(app) of aaAzoC4SH/Au (1.34 x 10(-6) s(-1)) is lower than that of AzoC4SH/Au (1.63 x 10(-4) s(-1)), which may be attributed to the different spatial restriction of close-packing structures on the conformational change accompanied by electron and proton transfer in the SAMs.
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Affiliation(s)
- Wen-Wei Zhang
- Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, People's Republic of China
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42
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Naraoka R, Kaise G, Kajikawa K, Okawa H, Ikezawa H, Hashimoto K. Nonlinear optical property of hemicyanine self-assembled monolayers on gold and its adsorption kinetics probed by optical second-harmonic generation and surface plasmon resonance spectroscopy. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)01041-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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43
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Mannsfeld SCB, Canzler TW, Fritz T, Proehl H, Leo K, Stumpf S, Goretzki G, Gloe K. The Structure of [4-(Phenylazo)phenoxy]hexane-1-thiol Self-Assembled Monolayers on Au(111). J Phys Chem B 2002. [DOI: 10.1021/jp012771a] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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44
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Im JH, Kwon OP, Kim JH, Lee SH. New Amphiphilic Rodlike Polymers with Pendent Hemicyanine Groups. 2. Monolayer Behavior. Macromolecules 2000. [DOI: 10.1021/ma0010940] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jung-Hyuk Im
- Department of Molecular Science and Technology, Ajou University, Suwon, Korea 442-749
| | - O-Pil Kwon
- Department of Molecular Science and Technology, Ajou University, Suwon, Korea 442-749
| | - Jae-Ho Kim
- Department of Molecular Science and Technology, Ajou University, Suwon, Korea 442-749
| | - Suck-Hyun Lee
- Department of Molecular Science and Technology, Ajou University, Suwon, Korea 442-749
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Fukushima H, Seki S, Nishikawa T, Takiguchi H, Tamada K, Abe K, Colorado R, Graupe M, Shmakova OE, Lee TR. Microstructure, Wettability, and Thermal Stability of Semifluorinated Self-Assembled Monolayers (SAMs) on Gold. J Phys Chem B 2000. [DOI: 10.1021/jp0003499] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gustina D, Markava E, Muzikante I, Stiller B, Brehmer L. Photoisomerisation process of self-assembled monolayers of some novel azobenzenes. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/1099-0712(199911/12)9:6<245::aid-amo388>3.0.co;2-m] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Stiller B, Knochenhauer G, Markava E, Gustina D, Muzikante I, Karageorgiev P, Brehmer L. Self-assembled monolayers of novel azobenzenes for optically induced switching. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 1999. [DOI: 10.1016/s0928-4931(99)00050-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Orientational structure in hemicyanine self-assembled films studied by absorption spectroscopy and optical second-harmonic generation. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(99)00604-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Venkataramanan M, Skanth G, Bandyopadhyay K, Vijayamohanan K, Pradeep T. Self-assembled Monolayers of Two Aromatic Disulfides and a Diselenide on Polycrystalline Silver Films: An Investigation by SERS and XPS. J Colloid Interface Sci 1999; 212:553-561. [PMID: 10092387 DOI: 10.1006/jcis.1998.6081] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Self-assembled monolayers of diphenyldisufide (DDS), naphthalenedisulfide (NDS), and diphenyldiselenide (DDSe) on polycrystalline silver films have been investigated by surface enhanced Raman spectroscopy (SERS) and X-ray photoelectron spectroscopy (XPS). DDS adsorbs on Ag through a homolytic cleavage of the S-S bond and resultant thiolate at the surface decomposes upon prolonged exposure to air. The geometry of the molecule is such that the benzene ring is almost horizontal to the surface. The Raman spectrum has been assigned in the light of ab-initio molecular orbital calculations. In DDSe, the Se-Se bond is retained upon adsorption and the molecule sticks up. In contrast, NDS is highly reactive on the microscopically rough surface so that a stable monolayer could not be prepared. A temperature dependent Raman study of the DDS monolayer shows the absence of any reorientation at the surface as one would expect from the adsorption geometry. XPS study complements the SERS data and shows the presence of Ag2S on an NDS exposed surface. Copyright 1999 Academic Press.
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Affiliation(s)
- M Venkataramanan
- Regional Sophisticated Instrumentation Centre, Indian Institute of Technology, Madras-, 600036, India
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Kondoh H, Nozoye H. Low-Temperature Ordered Phase of Methylthiolate Monolayers on Au(111). J Phys Chem B 1999. [DOI: 10.1021/jp984286u] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- H. Kondoh
- National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305-8565, Japan
| | - H. Nozoye
- National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305-8565, Japan
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