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Wu H, Li G, Hou J, Sotthewes K. Probing surface properties of organic molecular layers by scanning tunneling microscopy. Adv Colloid Interface Sci 2023; 318:102956. [PMID: 37393823 DOI: 10.1016/j.cis.2023.102956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/21/2023] [Accepted: 06/23/2023] [Indexed: 07/04/2023]
Abstract
In view of the relevance of organic thin layers in many fields, the fundamentals, growth mechanisms, and dynamics of thin organic layers, in particular thiol-based self-assembled monolayers (SAMs) on Au(111) are systematically elaborated. From both theoretical and practical perspectives, dynamical and structural features of the SAMs are of great intrigue. Scanning tunneling microscopy (STM) is a remarkably powerful technique employed in the characterization of SAMs. Numerous research examples of investigation about the structural and dynamical properties of SAMs using STM, sometimes combined with other techniques, are listed in the review. Advanced options to enhance the time resolution of STM are discussed. Additionally, we elaborate on the extremely diverse dynamics of various SAMs, such as phase transitions and structural changes at the molecular level. In brief, the current review is expected to supply a better understanding and novel insights regarding the dynamical events happening in organic SAMs and how to characterize these processes.
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Affiliation(s)
- Hairong Wu
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China; Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China.
| | - Genglin Li
- College of Science, China University of Petroleum-Beijing, Beijing 102249, China
| | - Jirui Hou
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China; Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China
| | - Kai Sotthewes
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, the Netherlands.
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2
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Sirviö JA, Mikola M, Ahola J, Heiskanen JP, Filonenko S, Ämmälä A. Highly effective fractionation chemistry to overcome the recalcitrance of softwood lignocellulose. Carbohydr Polym 2023; 312:120815. [PMID: 37059543 DOI: 10.1016/j.carbpol.2023.120815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 02/14/2023] [Accepted: 03/12/2023] [Indexed: 03/18/2023]
Abstract
The efficient fractionation and thus production of individual biomass components are pivotal processes in the biorefinery concept. However, the recalcitrant nature of lignocellulose biomass, especially in the case of softwood, is one of the main obstacles to the wider application of biomass-based chemicals and materials. In this study, the use of aqueous acidic systems in the presence of thiourea was studied for the fractionation of softwood in mild conditions. Despite relatively low temperature (100 °C) and treatment times (30-90 min), notable high lignin removal efficiency (approximately 90 %) was obtained. Chemical characterization and the isolation of minor fraction of cationic, water-soluble lignin indicated that the fractionation proceed via nucleophilic addition of thiourea to lignin, resulting in dissolution of lignin in acidic water in relatively mild conditions. Besides high fractionation efficiency, both fiber and lignin fractions were obtained with bright color, significantly elevating their usability in material applications.
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Affiliation(s)
- Juho Antti Sirviö
- Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland.
| | - Marja Mikola
- Chemical Process Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland
| | - Juha Ahola
- Chemical Process Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland
| | - Juha P Heiskanen
- Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 4300, FI-90014 Oulu, Finland
| | | | - Ari Ämmälä
- Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland
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3
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Scherrer D, Vogel D, Drechsler U, Olziersky A, Sparr C, Mayor M, Lörtscher E. Reaktionsverfolgung von Festphasensynthesen in selbstassemblierenden Monolagen mit oberflächenverstärkter Raman‐Spektroskopie. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Dominik Scherrer
- Science and Technology Department, IBM Research Europe Säumerstrasse 4 8803 Rüschlikon Schweiz
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Schweiz
| | - David Vogel
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Schweiz
| | - Ute Drechsler
- Science and Technology Department, IBM Research Europe Säumerstrasse 4 8803 Rüschlikon Schweiz
| | - Antonis Olziersky
- Science and Technology Department, IBM Research Europe Säumerstrasse 4 8803 Rüschlikon Schweiz
| | - Christof Sparr
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Schweiz
| | - Marcel Mayor
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Schweiz
- Institute for Nanotechnology (INT) Karlsruhe Institute of Technology (KIT) P. O. Box 3640 76021 Karlsruhe Deutschland
- Lehn Institute of Functional Materials (LIFM) School of Chemistry Sun Yat-Sen University (SYSU) Guangzhou 510275 VR China
| | - Emanuel Lörtscher
- Science and Technology Department, IBM Research Europe Säumerstrasse 4 8803 Rüschlikon Schweiz
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4
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Scherrer D, Vogel D, Drechsler U, Olziersky A, Sparr C, Mayor M, Lörtscher E. Monitoring Solid-Phase Reactions in Self-Assembled Monolayers by Surface-Enhanced Raman Spectroscopy. Angew Chem Int Ed Engl 2021; 60:17981-17988. [PMID: 34048139 PMCID: PMC8456949 DOI: 10.1002/anie.202102319] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 05/18/2021] [Indexed: 12/27/2022]
Abstract
Nanopatterned surfaces enhance incident electromagnetic radiation and thereby enable the detection and characterization of self-assembled monolayers (SAMs), for instance in surface-enhanced Raman spectroscopy (SERS). Herein, Au nanohole arrays, developed and characterized as SERS substrates, are exemplarily used for monitoring a solid-phase deprotection and a subsequent copper(I)-catalyzed azide-alkyne cycloaddition "click" reaction, performed directly on the corresponding SAMs. The SERS substrate was found to be highly reliable in terms of signal reproducibility and chemical stability. Furthermore, the intermediates and the product of the solid-phase synthesis were identified by SERS. The spectra of the immobilized compounds showed minor differences compared to spectra of the microcrystalline solids. With its uniform SERS signals and the high chemical stability, the platform paves the way for monitoring molecular manipulations in surface functionalization applications.
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Affiliation(s)
- Dominik Scherrer
- Science and Technology Department, IBM Research EuropeSäumerstrasse 48803RüschlikonSwitzerland
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 194056BaselSwitzerland
| | - David Vogel
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 194056BaselSwitzerland
| | - Ute Drechsler
- Science and Technology Department, IBM Research EuropeSäumerstrasse 48803RüschlikonSwitzerland
| | - Antonis Olziersky
- Science and Technology Department, IBM Research EuropeSäumerstrasse 48803RüschlikonSwitzerland
| | - Christof Sparr
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 194056BaselSwitzerland
| | - Marcel Mayor
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 194056BaselSwitzerland
- Institute for Nanotechnology (INT)Karlsruhe Institute of Technology (KIT)P. O. Box 364076021KarlsruheGermany
- Lehn Institute of Functional Materials (LIFM)School of ChemistrySun Yat-Sen University (SYSU)Guangzhou510275P.R. China
| | - Emanuel Lörtscher
- Science and Technology Department, IBM Research EuropeSäumerstrasse 48803RüschlikonSwitzerland
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5
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Karaboduk K. Modification of screen-printed gold electrode with 1,4-dithiothreitol: application to sensitive voltammetric determination of Sudan II. FOOD QUALITY AND SAFETY 2021. [DOI: 10.1093/fqsafe/fyaa039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Abstract
Objectives
The aim of this study is to investigate the electrochemical behavior of Sudan II (SuII) using a screen-printed gold electrode (SPGE) modified with 1,4-dithiothreitol (DTT) and to determine the amount of Sudan II by voltammetry.
Materials and Methods
A DTT-modified screen-printed gold electrode (DTT/SPGE) was fabricated and its application for differential pulse voltammetric (DPV) determination of SuII was reported. Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry and electrochemical impedance spectroscopy were used for the characterization of the modified electrode. The effects of instrumental and chemical parameters were optimized for the determination of SuII. The fabricated electrode was used for the analysis of SuII in fortified and real samples. High-performance liquid chromatography was preferred as a reference method for the evaluation of the obtained voltammetric results.
Results
The electrochemical studies and FT-IR demonstrated that the SPGE was modified with DTT. The obtained peak current at DTT/SPGE was 6.67 times higher than that recorded with SPGE. At the optimized conditions of DPV in pH = 2.5 of H2SO4, the oxidation peak current of SuII was proportional to its concentration in range: 0.001–1.500 μmol l–1 with a detection limit of 0.0002 μmol l–1 (S/N = 3). For the analysis of SuII, 101.67%–104.33% of recovery percentage was obtained.
Conclusions
A new electrode was successfully improved for the determination of SuII. This highly selective and sensitive electrode supplied the fast determination of SuII in ketchup, chili sauce and salsa dip sauce. In addition, voltammetric and chromatographic results are found to be consistent.
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Affiliation(s)
- Kuddusi Karaboduk
- Life Sciences Application and Research Center, Gazi University, Golbasi, Ankara, Turkey
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Luo W, Legge SM, Luo J, Lagugné-Labarthet F, Workentin MS. Investigation of Au SAMs Photoclick Derivatization by PM-IRRAS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1014-1022. [PMID: 31922420 DOI: 10.1021/acs.langmuir.9b03782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work, we present a clean one-step process for modifying headgroups of self-assembled monolayers (SAMs) on gold using photo-enabled click chemistry. A thiolated, cyclopropenone-caged strained alkyne precursor was first functionalized onto a flat gold substrate through self-assembly. Exposure of the cyclopropenone SAM to UVA light initiated the efficient photochemical decarbonylation of the cyclopropenone moiety, revealing the strained alkyne capable of undergoing the interfacial strain-promoted alkyne-azide cycloaddition (SPAAC). Irradiated SAMs were derivatized with a series of model azides with varied hydrophobicity to demonstrate the generality of this chemical system for the modification and fine-tuning of the surface chemistry on gold substrates. SAMs were characterized at each step with polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) to confirm the successful functionalization and reactivity. Furthermore, to showcase the compatibility of this approach with biochemical applications, cyclopropenone SAMs were irradiated and modified with azide-bearing cell adhesion peptides to promote human fibroblast cell adhesion, and then imaged by live-cell fluorescence microscopy. Thus, the "photoclick" methodology reported here represents an improved, versatile, catalyst-free protocol that allows for a high degree of control over the modification of material surfaces, with applicability in materials science as well as biochemistry.
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Affiliation(s)
- Wilson Luo
- Department of Chemistry and the Centre for Materials and Biomaterials Research , Western University , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada
| | - Sydney M Legge
- Department of Chemistry and the Centre for Materials and Biomaterials Research , Western University , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada
| | - Johnny Luo
- Department of Biochemistry , Western University , London , Ontario N6A 5C1 , Canada
- Lawson Health Research Institute , London , Ontario N6C 2R5 , Canada
| | - François Lagugné-Labarthet
- Department of Chemistry and the Centre for Materials and Biomaterials Research , Western University , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada
| | - Mark S Workentin
- Department of Chemistry and the Centre for Materials and Biomaterials Research , Western University , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada
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Bohli N, Belkilani M, Casanova-Chafer J, Llobet E, Abdelghani A. Multiwalled carbon nanotube based aromatic volatile organic compound sensor: sensitivity enhancement through 1-hexadecanethiol functionalisation. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:2364-2373. [PMID: 31886113 PMCID: PMC6902881 DOI: 10.3762/bjnano.10.227] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 11/08/2019] [Indexed: 05/25/2023]
Abstract
Aromatic volatile organic compound (VOC) sensors are attracting growing interest as a response to the pressing market need for sensitive, fast response, low power consumption and stable sensors. Benzene and toluene detection is subject to several potential applications such as air monitoring in chemical industries or even biosensing of human breath. In this work, we report the fabrication of a room temperature toluene and benzene sensor based on multiwall carbon nanotubes (MWCNTs) decorated with gold nanoparticles and functionalised with a long-chain thiol self-assembled monolayer, 1-hexadecanethiol (HDT). High-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) were performed to characterize the gold nanoparticle decoration and to examine the thiol monolayer bonding to the MWCNTs. The detection of aromatic vapours using Au-MWCNT and HDT/Au-MWCNT sensors down to the ppm range shows that the presence of the self-assembled layer increases the sensitivity (up to 17 times), selectivity and improves the response dynamics of the sensors.
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Affiliation(s)
- Nadra Bohli
- Carthage University, National Institute of Applied Science and Technology, Research Unit of Nanobiotechnology and Valorisation of Medicinal Plants UR17ES22, Bp 676, Centre Urbain Nord, 1080 Charguia Cedex, Tunisia
| | - Meryem Belkilani
- Carthage University, National Institute of Applied Science and Technology, Research Unit of Nanobiotechnology and Valorisation of Medicinal Plants UR17ES22, Bp 676, Centre Urbain Nord, 1080 Charguia Cedex, Tunisia
- Tunis University, ENSIT, Avenue Taha Hussein, Montfleury, 1008 Tunis, Tunisia
| | - Juan Casanova-Chafer
- MINOS-EMaS, Universitat Rovira i Virgili, Avda. Països Catalans, 26, 43007 Tarragona, Spain
| | - Eduard Llobet
- MINOS-EMaS, Universitat Rovira i Virgili, Avda. Països Catalans, 26, 43007 Tarragona, Spain
| | - Adnane Abdelghani
- Carthage University, National Institute of Applied Science and Technology, Research Unit of Nanobiotechnology and Valorisation of Medicinal Plants UR17ES22, Bp 676, Centre Urbain Nord, 1080 Charguia Cedex, Tunisia
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8
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Enriquez Garcia A, Jalilehvand F, Niksirat P. Reactions of Rh 2(CH 3COO) 4 with thiols and thiolates: a structural study. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:450-461. [PMID: 30855255 PMCID: PMC6412178 DOI: 10.1107/s160057751900033x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
The structural differences between the aerobic reaction products of Rh2(AcO)4 (1; AcO- = CH3COO-) with thiols and thiolates in non-aqueous media are probed by X-ray absorption spectroscopy. For this study, ethanethiol, dihydrolipoic acid (DHLA; a dithiol) and their sodium thiolate salts were used. Coordination of simple thiols to the axial positions of Rh2(AcO)4 with Rh-SH bonds of 2.5-2.6 Å keeps the RhII-RhII bond intact (2.41 ± 0.02 Å) but leads to a colour change from emerald green to burgundy. Time-dependent density functional theory (TD-DFT) calculations were performed to explain the observed shifts in the electronic (UV-vis) absorption spectra. The corresponding sodium thiolates, however, break up the Rh2(AcO)4 framework in the presence of O2 to form an oligomeric chain of triply S-bridged Rh(III) ions, each with six Rh-S (2.36 ± 0.02 Å) bonds. The RhIII...RhIII distance, 3.18 ± 0.02 Å, in the chain is similar to that previously found for the aerobic reaction product from aqueous solutions of Rh2(AcO)4 and glutathione (H3A), {Na2[Rh2III(HA)4]·7H2O}n, in which each Rh(III) ion is surrounded by about four Rh-S (2.33 ± 0.02 Å) and about two Rh-O (2.08 ± 0.02 Å). The reaction products obtained in this study can be used to predict how dirhodium(II) tetracarboxylates would react with cysteine-rich proteins and peptides, such as metallothioneins.
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Affiliation(s)
- Alejandra Enriquez Garcia
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
| | - Farideh Jalilehvand
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
| | - Pantea Niksirat
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
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9
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Kankate L, Hamann T, Li S, Moskaleva LV, Gölzhäuser A, Turchanin A, Swiderek P. Tracking down the origin of peculiar vibrational spectra of aromatic self-assembled thiolate monolayers. Phys Chem Chem Phys 2018; 20:29918-29930. [PMID: 30475374 DOI: 10.1039/c8cp03651a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Several studies have previously observed surprisingly low frequencies for the C-H stretching modes of self-assembled monolayers (SAMs) prepared from aromatic thiols. The reason for this property has so far remained elusive. Therefore, we report a novel study of the vibrational spectra of SAMs prepared on Au from two different aromatic thiols, namely, 4'-nitro-1,1'-biphenyl-4-thiol (NBPT) and 4-aminothiophenol (ATP). The SAMs were prepared by vapor deposition (VD) in ultrahigh vacuum (UHV) as well as by the solution method (SM) and their quality was controlled by X-ray photoelectron spectroscopy (XPS). In addition, amino terminated SAMs were also obtained by electron irradiation and by chemical reduction of NBPT SAMs. Beside infrared reflection absorption spectroscopy (IRRAS), we have employed high resolution electron energy loss spectroscopy (HREELS), by which VD SAMs can be studied in situ, i.e. without exposing them to air. Hence, we can exclude possible contributions of solvent molecules to the vibrational spectra. Nonetheless, HREELS in fact reveals the same large red shift of the C-H stretching modes in the SAMs as also observed in ex situ IRRAS experiments. In contrast, HREELS for physisorbed ATP and ATP in a KBr pellet measured by transmission infrared spectroscopy exhibit the expected aromatic bands. Using a computational approach, we can exclude molecular packing effects as origin of this shift. Therefore, we propose chemical changes in the aromatic rings during SAM formation as an alternative explanation for the observed frequency shift. As another striking effect, the N-H stretching vibrational modes of the amino-terminated SAMs are extremely weak in both IRRAS and HREELS despite the fact that XPS confirms the presence of amino groups. A very weak signal is observed only in the case of an electron irradiated NBPT SAM. In contrast, an energy loss ascribed to the N-H stretching vibrations is clearly observed in HREELS of ATP physisorbed on an ATP SAM and on graphite as well as in the transmission infrared spectrum of ATP in KBr. The extremely low intensity of these vibrations in the SAM is traced back to the inherently low transition dipole moment for the excitation of N-H stretching modes in free N-H groups. Furthermore, the calculations suggest that the much stronger signals of N-H stretching modes involved in hydrogen-bonding with adjacent amino groups are suppressed because these vibrations are oriented parallel to the surface.
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Affiliation(s)
- Laxman Kankate
- University of Bremen, Faculty 2 (Chemistry/Biology), Institute of Applied and Physical Chemistry, Leobener Straße 5 (NW2), Postfach 330440, 28334 Bremen, Germany.
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10
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11
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Piotrowski P, Pawłowska J, Bilewicz R, Kaim A. Selective and reversible self-assembly of C 60fullerene on a 9,10-bis(S-acetylthiomethyl)anthracene modified gold surface. RSC Adv 2016. [DOI: 10.1039/c6ra04806d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synthesized di-S-acetyl anthracene derivative deposited on gold surface allows for selective multi-cycle capture of C60fullerene by reversible forming well-ordered monolayers of C60fullerene–anthracene adduct according to Diels–Alder reaction.
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Affiliation(s)
- P. Piotrowski
- Department of Chemistry
- University of Warsaw
- 02-093 Warsaw
- Poland
| | - J. Pawłowska
- Department of Chemistry
- University of Warsaw
- 02-093 Warsaw
- Poland
| | - R. Bilewicz
- Department of Chemistry
- University of Warsaw
- 02-093 Warsaw
- Poland
| | - A. Kaim
- Department of Chemistry
- University of Warsaw
- 02-093 Warsaw
- Poland
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12
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Forster-Tonigold K, Stammer X, Wöll C, Groß A. Temperature effects in the vibrational spectra of self-assembled monolayers. PHYSICAL REVIEW LETTERS 2013; 111:086102. [PMID: 24010456 DOI: 10.1103/physrevlett.111.086102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Indexed: 06/02/2023]
Abstract
The vibrational spectrum of a thiolate-based self-assembled monolayer fabricated by the adsorption of benzylmercaptan on a Au(111) substrate is studied using a combined experimental and theoretical approach employing infrared reflection absorption spectroscopy and density functional theory. The vibrational spectra are derived both using a finite differences approach and from ab initio molecular dynamics simulations at various temperatures. In addition, the possibility of adsorbate-induced reconstructions of the Au(111) substrate is taken into account. It turns out that the measured spectra can only be understood by taking finite temperatures into account.
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Affiliation(s)
- Katrin Forster-Tonigold
- Helmholtz Institute Ulm (HIU) Electrochemical Energy Storage, D-89069 Ulm, Germany and Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany
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13
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Characterization of hydroxyphenol-terminated alkanethiol self-assembled monolayers: Interactions with phosphates by chemical force spectrometry. J Colloid Interface Sci 2013; 393:352-60. [DOI: 10.1016/j.jcis.2012.10.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 10/09/2012] [Indexed: 11/19/2022]
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14
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Meyerbröker N, Zharnikov M. Modification of nitrile-terminated biphenylthiol self-assembled monolayers by electron irradiation and related applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9583-9592. [PMID: 22650608 DOI: 10.1021/la301399a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Here we describe the behavior of self-assembled monolayers (SAMs) of 4'-cyanobiphenyl-4-thiol (CBPT) on Au(111) upon electron irradiation. Under such a treatment, the aromatic framework of CBPT SAMs is laterally cross-linked while the nitrile groups, located at the SAM-ambience interface, are reduced to active amine moieties which can be used as docking sites for the coupling of other species. This makes CBPT monolayers as a promising system for conventional and chemical lithography as well as for nanofabrication. Along these lines, we demonstrate the preparation of complex polymer brushes, patterning of the underlying substrate, and fabrication of molecule-thin, free-standing membranes on the basis of CBPT SAMs. The balance between the application-favorable processes and defragmentation in these films is studied in detail, and comparison to the well-established (for the relevant applications) system of 4'-nitrobiphenyl-4-thiols is performed. Taking CBPT SAMs as a model system, the effect of the energy of the primary electrons on the extent of the chemical transformation and cross-linking in substituted aromatic SAMs is investigated.
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Affiliation(s)
- Nikolaus Meyerbröker
- Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
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15
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Ishitsuka M, Hiaki T, Osaka N. Coadsorption self-assembled monolayers of trithiocyanuric acid and 1,3,5-benzenetrithiol on an evaporated silver film. J Mol Struct 2011. [DOI: 10.1016/j.molstruc.2011.07.029] [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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16
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Ramin MA, Le Bourdon G, Daugey N, Bennetau B, Vellutini L, Buffeteau T. PM-IRRAS investigation of self-assembled monolayers grafted onto SiO2/Au substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:6076-6084. [PMID: 21486004 DOI: 10.1021/la2006293] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to characterize self-assembled monolayers (SAMs). Novel ester-terminated organosilicon coupling agents possessing a trialkoxysilyl headgroup and a urea group in the linear alkyl chains (4) were synthesized and grafted onto SiO(2)/Au substrates (SiO(2) film of 200 Å thickness deposited on gold mirror). This composite substrate allowed the anchoring of SAMs and preserved the high reflectivity for infrared radiation. PM-IRRAS spectra with very high signal-to-noise ratios have been obtained in the mid-infrared spectral range allowing monitoring of the grafted SAMs. Quantitative analysis of the measured signal is described to compare PM-IRRAS and conventional IRRAS spectra. This quantitative analysis has been validated since the band intensities in the corrected PM-IRRAS and conventional IRRAS spectra are identical. Orientation information on the different functional groups has been obtained comparing the corrected PM-IRRAS spectrum with the one calculated using isotropic optical constants of ester-terminated organosilicon coupling agents 4. The carbonyls of the urea groups are preferentially parallel to the substrate surface favoring intermolecular hydrogen bonding and consequently a close packing of the molecules attached to the surface. By contrast, the alkyl chains present gauche defects and are poorly oriented.
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Affiliation(s)
- Michaël A Ramin
- Institut des Sciences Moléculaires (UMR 5255-CNRS), Université Bordeaux 1, 351 Cours de la Libération, 33405 Talence, France
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