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Delley MF, Nichols EM, Mayer JM. Interfacial Acid-Base Equilibria and Electric Fields Concurrently Probed by In Situ Surface-Enhanced Infrared Spectroscopy. J Am Chem Soc 2021; 143:10778-10792. [PMID: 34253024 DOI: 10.1021/jacs.1c05419] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding how applied potentials and electrolyte solution conditions affect interfacial proton (charge) transfers at electrode surfaces is critical for electrochemical technologies. Herein, we examine mixed self-assembled monolayers (SAMs) of 4-mercaptobenzoic acid (4-MBA) and 4-mercaptobenzonitrile (4-MBN) on gold using in situ surface-enhanced infrared absorption spectroscopy (SEIRAS). Measurements as a function of the applied potential, the electrolyte pD, and the electrolyte concentration determined both the relative surface populations of acidic and basic forms of 4-MBA, as well as the local electric fields at the SAM-solution interface by following the Stark shifts of 4-MBN. The effective acidity of the SAM varied with the applied potential, requiring a 600 mV change to move the pKa by one unit. Since this is ca. 10× the Nernstian value of 59 mV/pKa, ∼90% of the applied potential dropped across the SAM layer. This emphasizes the importance of distinguishing applied potentials from the potential experienced at the interface. We use the measured interfacial electric fields to estimate the experienced potential at the SAM edge. The SAM pKa showed a roughly Nernstian dependence on this estimated experienced potential. An analysis of the combined acid-base equilibria and Stark shifts reveals that the interfacial charge density has significant contributions from both SAM carboxylate headgroups and electrolyte components. Ion pairing and ion penetration into the SAM also influence the observed surface acidity. To our knowledge, this study is the first concurrent examination of both effective acidity and electric fields, and highlights the relevance of experienced potentials and specific ion effects at functionalized electrode surfaces.
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Affiliation(s)
- Murielle F Delley
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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Hubin A, Doneux T. Preface to the Special Issue in the honour of Claudine Buess-Herman on the occasion of her 65th anniversary. J Electroanal Chem (Lausanne) 2020. [DOI: 10.1016/j.jelechem.2020.114319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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3
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Salvarezza R, Carro P. The electrochemical stability of thiols on gold surfaces. J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2017.10.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Electric field induced proton transfer at α,ω-mercaptoalkanecarboxylic acids self-assembled monolayers of different chain length. J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2018.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Martens I, Fisher EA, Bizzotto D. Direct Mapping of Heterogeneous Surface Coverage in DNA-Functionalized Gold Surfaces with Correlated Electron and Fluorescence Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2425-2431. [PMID: 29361826 DOI: 10.1021/acs.langmuir.7b03766] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The characterization of biofunctionalized surfaces such as alkanethiol self-assembled monolayers (SAMs) on gold modified with DNA or other biomolecules is a challenging analytical problem, and access to a routine method is desirable. Despite substantial investigation from structural and mechanistic perspectives, robust and high-throughput metrology tools for SAMs remain elusive but essential for the continued development of these devices. We demonstrate that scanning electron microscopy (SEM) can provide image contrast of the molecular interface during SAM functionalization. The high-speed, large magnification range, and ease of use make this widely available technique a powerful platform for measuring the structure and composition of SAM surfaces. This increased throughput allows for a better understanding of the nonideal spatial heterogeneity characteristic of SAMs utilized in real-world conditions. SEM image contrast is characterized through the use of fluorescently labeled DNA, which enables correlative SEM and fluorescence microscopy. This allows identification of the DNA-modified regions at resolutions that approach the size of the biomolecule. The effect of electron beam irradiation dose is explored, which leads to straightforward lithographic patterning of DNA SAMs with nanometer resolution and with control over the surface coverage of specifically adsorbed DNA.
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Affiliation(s)
- Isaac Martens
- Advanced Materials and Proceess Engineering Laboratory (AMPEL) and ‡Department of Chemistry, University of British Columbia , Vancouver V6T 1Z1, Canada
| | - Elizabeth A Fisher
- Advanced Materials and Proceess Engineering Laboratory (AMPEL) and ‡Department of Chemistry, University of British Columbia , Vancouver V6T 1Z1, Canada
| | - Dan Bizzotto
- Advanced Materials and Proceess Engineering Laboratory (AMPEL) and ‡Department of Chemistry, University of British Columbia , Vancouver V6T 1Z1, Canada
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Leung KK, Gaxiola AD, Yu HZ, Bizzotto D. Tailoring the DNA SAM surface density on different surface crystallographic features using potential assisted thiol exchange. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2017.12.114] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Fisher EA, Leung KK, Casanova-Moreno J, Masuda T, Young J, Bizzotto D. Quantifying the Selective Modification of Au(111) Facets via Electrochemical and Electroless Treatments for Manipulating Gold Nanorod Surface Composition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12887-12896. [PMID: 29058912 DOI: 10.1021/acs.langmuir.7b03021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Manipulating the composition of a mixed alkylthiol self-assembled monolayer (SAM) modified gold surface using both electrochemical and electroless methods is demonstrated. Through the use of fluorophore labeled thiolated DNA and in situ fluorescence microscopy with a gold single crystal bead electrode, a procedure was developed to study and quantify the selective desorption of an alkylthiolate SAM. This method enabled a self-consistent measurement of the removal of the SAM from the 111 surface compared to the 100 surface region at various potentials. A 20-fold increase in the electrochemical removal and replacement of the SAM from the 111 surface over the 100 surface was realized at -0.8 V/AgAgCl. A related procedure was developed for the solution-based electroless removal of the SAM using NaBH4 achieving a similar selectivity at the same potential. Unfortunately, in the electroless process fine control over the reducing potential was difficult to achieve. In addition, working in the presence of O2 complicates the solution potential measurement due to depolarization by the reduction of O2, resulting in a less clear relationship between selectivity and measured solution potential. Interestingly, the electrochemical method was not disturbed by the presence of O2. In preparation for work with Au nanorods, electrochemical measurements were performed in electrolyte that included 1 mM CTAB and was found to not interfere with this method. Preliminary results are promising for using this methodology for treatment of acid-terminated alkylthiol modified Au nanorods.
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Affiliation(s)
- Elizabeth A Fisher
- AMPEL, ‡Department of Chemistry, and §Department of Physics and Astronomy, University of British Columbia , Vancouver, BC V6T 1Z4, Canada
| | - Kaylyn K Leung
- AMPEL, ‡Department of Chemistry, and §Department of Physics and Astronomy, University of British Columbia , Vancouver, BC V6T 1Z4, Canada
| | - Jannu Casanova-Moreno
- AMPEL, ‡Department of Chemistry, and §Department of Physics and Astronomy, University of British Columbia , Vancouver, BC V6T 1Z4, Canada
| | - Tamiko Masuda
- AMPEL, ‡Department of Chemistry, and §Department of Physics and Astronomy, University of British Columbia , Vancouver, BC V6T 1Z4, Canada
| | - Jeff Young
- AMPEL, ‡Department of Chemistry, and §Department of Physics and Astronomy, University of British Columbia , Vancouver, BC V6T 1Z4, Canada
| | - Dan Bizzotto
- AMPEL, ‡Department of Chemistry, and §Department of Physics and Astronomy, University of British Columbia , Vancouver, BC V6T 1Z4, Canada
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Martínez-Romero N, Aguilar-Sánchez R, Fu YC, Homberger M, Simon U. Electrochemical stability and electron transfer across 4-methyl-4′-(n-mercaptoalkyl) biphenyl monolayers on Au(100)-(1×1) electrodes in 1-hexyl-3-methylimidazolium hexafluorophosphate ionic liquid. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Escalera-López D, Gómez E, Vallés E. Electrochemical growth of CoNi and Pt-CoNi soft magnetic composites on an alkanethiol monolayer-modified ITO substrate. Phys Chem Chem Phys 2015; 17:16575-86. [PMID: 26055346 DOI: 10.1039/c5cp02291f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CoNi and Pt-CoNi magnetic layers on indium-tin oxide (ITO) substrates modified by an alkanethiol self-assembled monolayer (SAM) have been electrochemically obtained as an initial stage to prepare semiconducting layer-SAM-magnetic layer hybrid structures. The best conditions to obtain the maximum compactness of adsorbed layers of dodecanethiol (C12-SH) on ITO substrate have been studied using contact angle, AFM, XPS and electrochemical tests. The electrochemical characterization (electrochemical probe or voltammetric response in blank solutions) is fundamental to ensure the maximum blocking of the substrate. Although the electrodeposition process on the SAM-modified ITO substrate is very slow if the blocking of the surface is significant, non-cracked metallic layers of CoNi, with or without a previously electrodeposited seed-layer of platinum, have been obtained by optimizing the deposition potentials. Initial nucleation is expected to take place at the pinhole defects of the C12-SH SAM, followed by a mushroom-like growth regime through the SAM interface that allows the formation of a continuous metallic layer electrically connected to the ITO surface. Due to the potential of the methodology, the preparation of patterned metallic deposits on ITO substrate using SAMs with different coverage as templates is feasible.
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Affiliation(s)
- D Escalera-López
- Grup d'Electrodeposició de Capes Primes i Nanoestructures (Ge-CPN), Departament de Química Física and Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
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Casanova-Moreno JR, Bizzotto D. What happens to the thiolates created by reductively desorbing SAMs? An in situ study using fluorescence microscopy and electrochemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2065-2074. [PMID: 23317370 DOI: 10.1021/la305170c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In situ examination of the reductive desorption process for Au microelectrodes modified with a thiol self-assembled monolayer (SAM) using fluorescence microscopy enabled the study of the fate of the desorbed thiolate species. The Bodipy labeled alkyl-thiol SAM, when adsorbed, is not fluorescent due to quenching by the Au surface. Once reductively desorbed, the thiolate molecules fluoresce and their direction and speed are monitored. At moderately negative reduction potentials, the thiolate species hemispherically diffuse away from the microelectrode. Also observed is the influence of a closely positioned counter electrode on the direction of the desorbed thiolate movement. As the potential becomes more negative, the molecules move in an upward direction, with a speed that depends on the amount of dissolved H(2) produced by water reduction. Shown is that this motion is controlled, in large part, by the change in the electrolyte density near the electrode due to dissolved H(2). These results should help in explaining the extent of readsorption at oxidative potentials observed in cyclic voltammetry (CV) reductive desorption measurements, as well as improving the general understanding of the SAM removal process by reductive desorption. The electrogenerated H(2) was also shown to be able to reductively remove the thiol SAM from the Pt/Ir particles that decorate the microelectrode glass sheath.
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Bougouma M, Van Elewyck A, Steichen M, Buess-Herman C, Doneux T. Selenium electrochemistry in choline chloride–urea deep eutectic electrolyte. J Solid State Electrochem 2012. [DOI: 10.1007/s10008-012-1955-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Liatard S, Chauvin J, Balestro F, Jouvenot D, Loiseau F, Deronzier A. An original electrochemical method for assembling multilayers of terpyridine-based metallic complexes on a gold surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10916-10924. [PMID: 22742072 DOI: 10.1021/la301709d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A new method based on the electrochemical oxidation of thiols was used to easily generate multilayer assemblies of coordination complexes on a gold surface. For this purpose, two complexes bearing two anchoring groups for surface attachment have been prepared: [Ru(tpySH)(2)](2+) (1) and [Fe(tpySH)(2)](2+) (2) (tpySH = 4'-(2-(p-phenoxy)ethanethiol)-2,2':6',2″-terpyridine). Cyclic voltammetry of 1 in CH(3)CN exhibits two successive oxidation processes. The first is irreversible and attributed to the oxidation of the thiol substituents, whereas the second is reversible and corresponds to the 1 e(-) metal-centered oxidation. In the case of 2 both processes are superimposed. Monolayers of 1 or 2 have been formed on gold electrodes by spontaneous adsorption from micromolar solutions of the complexes in CH(3)CN. SAMs (self-assembled monolayers) exhibit redox behavior similar to the complexes in solution. The high surface coverage value obtained (Γ = 6 × 10(-10) and 4 × 10(-10) mol cm(-2) for 1 and 2, respectively) is consistent with a vertical orientation for the complexes; thus, one thiol is bound to the gold electrode, with the second unreacted thiol moiety exposed to the outer surface. Successive cyclic voltammetry induced a layer-by-layer nanostructural growth at the surface of the SAMs, and this is presumably due to the electrochemical formation of disulfide bonds, where the thiol moieties play a double role of both an anchoring group and an electroactive coupling agent. The conditions of the deposition are studied in detail. Modified electrodes containing both 1 and 2 alternatively can be easily prepared following this new approach. The film proved to be stable, displaying a similar current/voltage response for more than 10 repeating cycles in oxidation up to 0.97 V vs Ag/AgNO(3) (10(-2) M).
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Affiliation(s)
- Sébastien Liatard
- Département de Chimie Moléculaire, UMR-5250, Laboratoire de Chimie Inorganique Rédox, Institut de Chimie Moléculaire de Grenoble FR- CNRS-2607, Université Joseph Fourier Grenoble 1/CNRS, BP-53, 38041 Grenoble Cedex 9, France
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Bouffier L, Lister K, Higgins S, Nichols R, Doneux T. Electrochemical investigations of dissolved and surface immobilised 2-amino-1,4-naphthoquinones in aqueous solutions. J Electroanal Chem (Lausanne) 2012. [DOI: 10.1016/j.jelechem.2011.10.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Kye J, Hwang S. In situ real time monitoring of kinetics of thiol adsorption on gold based on electrochemical steady-state current. Electrochem commun 2011. [DOI: 10.1016/j.elecom.2011.08.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Kissling GP, Miles DO, Fermín DJ. Electrochemical charge transfer mediated by metal nanoparticles and quantum dots. Phys Chem Chem Phys 2011; 13:21175-85. [DOI: 10.1039/c1cp21996k] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Doneux T, Steichen M, De Rache A, Buess-Herman C. Influence of the crystallographic orientation on the reductive desorption of self-assembled monolayers on gold electrodes. J Electroanal Chem (Lausanne) 2010. [DOI: 10.1016/j.jelechem.2010.02.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Uosaki K. Electrochemical oxidative formation of ordered monolayers of thiol molecules on Au(111) surface. CHEM REC 2009; 9:199-209. [DOI: 10.1002/tcr.200900002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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