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Pontoni D, DiMichiel M, Murphy BM, Honkimäki V, Deutsch M. Ordering of ionic liquids at a charged sapphire interface: Evolution with cationic chain length. J Colloid Interface Sci 2024; 661:33-45. [PMID: 38295701 DOI: 10.1016/j.jcis.2024.01.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/09/2024] [Accepted: 01/18/2024] [Indexed: 02/27/2024]
Abstract
HYPOTHESIS Room Temperature Ionic Liquids (RTILs) bulk's molecular layering dominates their structure also at the RTIL/sapphire interface, increasing the layer spacing with the cationic alkyl chain length n. However, the negatively-charged sapphire surface compresses the layers, increases the layering range, and affects the intra-layer structure in yet unknown ways. EXPERIMENTS X-ray reflectivity (XR) off the RTIL/sapphire interface, for a broad homologous RTIL series 1-alkyl-3-methylimidazolium bis(trifluoromethansulfonyl)imide, hitherto unavailable for any RTIL. FINDINGS RTIL layers against the sapphire, exhibit two spacings: da and db. da is n-varying, follows the behavior of the bulk spacing but exhibits a downshift, thus showing significant layer compression, and over twofold polar slab thinning. The latter suggests exclusion of anions from the interfacial region due to the negative sapphire charging by x-ray-released electrons. The layering range is larger than the bulk's. db is short and near n-independent, suggesting polar moieties' layering, the coexistence mode of which with the da-spaced layering is unclear. Comparing the present layering with the bulk's and the RTIL/air interface's provides insight into the Coulomb and dispersion interaction balance dominating the RTIL's structure and the impact thereon of the presence of a charged solid interface.
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Affiliation(s)
- Diego Pontoni
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Marco DiMichiel
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Bridget M Murphy
- Institute of Experimental and Applied Physics, Kiel University, Kiel D-24098, Germany; Ruprecht-Haensel Laboratory, Kiel University, Kiel D-24118, Germany
| | - Veijo Honkimäki
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Moshe Deutsch
- Physics Dept. & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel.
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2
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Montes-Campos H, Rivera-Pousa A, Méndez-Morales T. Density functional theory of alkali metals at the IL/graphene electrochemical interface. J Chem Phys 2022; 156:014706. [PMID: 34998333 DOI: 10.1063/5.0077449] [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] Open
Abstract
The mechanism of charge transfer between metal ions and graphene in the presence of an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) is investigated by means of density functional theory calculations. For that purpose, two different comparisons are established: (i) the behavior of Li+ and K+ when adsorbed onto the basal plane of graphene and (ii) the differences between Li+ approaching the carbon surface from the basal plane and being intercalated through the edge plane of trilayer graphene. In the first case, it is found that the metal ions must overcome high energy barriers due to their interaction with the ionic liquid before reaching an equilibrium position close to the interface. In addition, no significant charge transfer between any of the metals and graphene takes place until very close energetically unfavorable distances. The second configuration shows that Li+ has no equilibrium position in the proximity of the interface but instead has an equilibrium position when it is inside the electrode for which it has to cross an energy barrier. In this case, the formation of a LiC12 complex is observed since the charge transfer at the equilibrium distance is achieved to a considerable extent. Thus, the interfacial charge transfer resistance on the electrode in energy devices based on ionic liquids clearly depends not only on the binding of the ionic liquid to the metal cations and their ability to form a dense solvation shell around them but also on the surface topography and its effect on the ion packing on the surface.
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Affiliation(s)
- H Montes-Campos
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela, Spain
| | - A Rivera-Pousa
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela, Spain
| | - T Méndez-Morales
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela, Spain
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3
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Wang YL, Li B, Sarman S, Mocci F, Lu ZY, Yuan J, Laaksonen A, Fayer MD. Microstructural and Dynamical Heterogeneities in Ionic Liquids. Chem Rev 2020; 120:5798-5877. [PMID: 32292036 PMCID: PMC7349628 DOI: 10.1021/acs.chemrev.9b00693] [Citation(s) in RCA: 183] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 12/11/2022]
Abstract
Ionic liquids (ILs) are a special category of molten salts solely composed of ions with varied molecular symmetry and charge delocalization. The versatility in combining varied cation-anion moieties and in functionalizing ions with different atoms and molecular groups contributes to their peculiar interactions ranging from weak isotropic associations to strong, specific, and anisotropic forces. A delicate interplay among intra- and intermolecular interactions facilitates the formation of heterogeneous microstructures and liquid morphologies, which further contributes to their striking dynamical properties. Microstructural and dynamical heterogeneities of ILs lead to their multifaceted properties described by an inherent designer feature, which makes ILs important candidates for novel solvents, electrolytes, and functional materials in academia and industrial applications. Due to a massive number of combinations of ion pairs with ion species having distinct molecular structures and IL mixtures containing varied molecular solvents, a comprehensive understanding of their hierarchical structural and dynamical quantities is of great significance for a rational selection of ILs with appropriate properties and thereafter advancing their macroscopic functionalities in applications. In this review, we comprehensively trace recent advances in understanding delicate interplay of strong and weak interactions that underpin their complex phase behaviors with a particular emphasis on understanding heterogeneous microstructures and dynamics of ILs in bulk liquids, in mixtures with cosolvents, and in interfacial regions.
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Affiliation(s)
- Yong-Lei Wang
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bin Li
- School
of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, P. R. China
| | - Sten Sarman
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Francesca Mocci
- Department
of Chemical and Geological Sciences, University
of Cagliari, I-09042 Monserrato, Italy
| | - Zhong-Yuan Lu
- State
Key Laboratory of Supramolecular Structure and Materials, Institute
of Theoretical Chemistry, Jilin University, Changchun 130021, P. R. China
| | - Jiayin Yuan
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Aatto Laaksonen
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
- State
Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
- Centre of
Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry Aleea Grigore Ghica-Voda, 41A, 700487 Iasi, Romania
- Department
of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, SE-97187 Luleå, Sweden
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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4
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Yokota Y, Miyamoto H, Imanishi A, Takeya J, Inagaki K, Morikawa Y, Fukui KI. Microscopic properties of ionic liquid/organic semiconductor interfaces revealed by molecular dynamics simulations. Phys Chem Chem Phys 2018; 20:13075-13083. [DOI: 10.1039/c8cp01043a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Structural and dynamic properties of an ionic liquid are compared on several organic semiconductors.
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Affiliation(s)
- Yasuyuki Yokota
- Surface and Interface Science Laboratory
- RIKEN
- Wako
- Saitama 351-0198
- Japan
| | - Hiroo Miyamoto
- Department of Materials Engineering Science
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
| | - Akihito Imanishi
- Department of Materials Engineering Science
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
| | - Jun Takeya
- Department of Advanced Materials Science
- Graduate School of Frontier Sciences
- The University of Tokyo
- Kashiwa
- Japan
| | - Kouji Inagaki
- Department of Precision Science and Technology
- Graduate School of Engineering
- Osaka University
- Suita
- Japan
| | - Yoshitada Morikawa
- Department of Precision Science and Technology
- Graduate School of Engineering
- Osaka University
- Suita
- Japan
| | - Ken-ichi Fukui
- Department of Materials Engineering Science
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
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5
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Elfassy E, Mastai Y, Pontoni D, Deutsch M. Liquid-Mercury-Supported Langmuir Films of Ionic Liquids: Isotherms, Structure, and Time Evolution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:3164-3173. [PMID: 26963651 DOI: 10.1021/acs.langmuir.6b00196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ionic liquids have been intensively developed for the last few decades and are now used in a wide range of applications, from electrochemistry to catalysis and nanotechnology. Many of these applications involve ionic liquid interfaces with other liquids and solids, the subnanometric experimental study of which is highly demanding, and has been little studied to date. We present here a study of mercury-supported Langmuir films of imidazolium-based ionic liquids by surface tensiometry and X-ray reflectivity. The charge-delocalized ionic liquids studied here exhibit no 2D lateral order but show diffuse surface-normal electron density profiles exhibiting gradual mercury penetration into the ionic liquid film, and surface-normal structure evolution over a period of hours. The effect of increasing the nonpolar alkyl chain length was also investigated. The results obtained provide insights into the interactions between these ionic liquids and liquid mercury and about the time evolution of the structure and composition of their interface.
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Affiliation(s)
| | | | - Diego Pontoni
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, France
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6
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He X, Wu C, Rajagopal K, Punpongjareorn N, Yang DS. Ordered ionic liquid structure observed at terraced graphite interfaces. Phys Chem Chem Phys 2016; 18:3392-6. [DOI: 10.1039/c5cp07575k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reflection high-energy electron diffraction is presented as a contactless, surface-specific method to probe the ion organization and layering at the ionic liquid–solid interfaces.
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Affiliation(s)
- Xing He
- Department of Chemistry
- University of Houston
- Houston
- USA
| | - Chengyi Wu
- Department of Chemistry
- University of Houston
- Houston
- USA
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7
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Filipe EJM, Morgado P, Teixeira M, Shimizu K, Bonatout N, Goldmann M, Canongia Lopes JN. Crystalline-like structures and multilayering in Langmuir films of ionic liquids at the air–water interface. Chem Commun (Camb) 2016; 52:5585-8. [DOI: 10.1039/c6cc01368f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Langmuir films of [C18mim][NTf2] ionic liquid exhibited, for the first time, the reversible formation of crystalline-like structures at the surface of water, compatible with the formation of multilayers.
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Affiliation(s)
- Eduardo. J. M. Filipe
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Pedro Morgado
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Miguel Teixeira
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Karina Shimizu
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
| | - Nathalie Bonatout
- Sorbonne Universités
- UPMC Univ Paris 06
- CNRS-UMR 7588
- Institut des NanoSciences de Paris
- Paris
| | - Michel Goldmann
- Sorbonne Universités
- UPMC Univ Paris 06
- CNRS-UMR 7588
- Institut des NanoSciences de Paris
- Paris
| | - José Nuno Canongia Lopes
- Centro de Química Estrutural
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
- Portugal
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8
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Affiliation(s)
- Robert Hayes
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Gregory G. Warr
- School
of Chemistry, The University of Sydney, NSW 2006, Sydney, Australia
| | - Rob Atkin
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
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9
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Rouha M, Cummings PT. Thickness-dependent structural arrangement in nano-confined imidazolium-based ionic liquid films. Phys Chem Chem Phys 2015; 17:4152-9. [DOI: 10.1039/c4cp05138f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nano-confined ionic liquid interfacial layers showing lateral and perpendicular structural changes dependent on thickness of adsorbed film.
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Affiliation(s)
- Michael Rouha
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
- Institute for Nanomaterials
| | - Peter T. Cummings
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
- Center for Nanophase Materials Sciences
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10
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Steinrück HG, Magerl A, Deutsch M, Ocko BM. Pseudorotational epitaxy of self-assembled octadecyltrichlorosilane monolayers on sapphire (0001). PHYSICAL REVIEW LETTERS 2014; 113:156101. [PMID: 25375723 DOI: 10.1103/physrevlett.113.156101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Indexed: 06/04/2023]
Abstract
The structure of octadecyltrichlorosilane self-assembled monolayers (SAMs) on sapphire (0001) was studied by Å-resolution surface-specific x-ray scattering methods. The monolayer was found to consist of three sublayers where the outermost layer corresponds to vertically oriented, closely packed alkyl tails. Laterally, the monolayer is hexagonally packed and exhibits pseudorotational epitaxy to the sapphire, manifested by a broad scattering peak at zero relative azimuthal rotation, with long powderlike tails. The lattice mismatch of ∼ 1%-3% to the sapphire's and the different length scale introduced by the lateral Si-O-Si bonding prohibit positional epitaxy. However, the substrate induces an intriguing increase in the crystalline coherence length of the SAM's powderlike crystallites when rotationally aligned with the sapphire's lattice. The increase correlates well with the rotational dependence of the separation of corresponding substrate-monolayer lattice sites.
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Affiliation(s)
- H-G Steinrück
- Crystallography and Structural Physics, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - A Magerl
- Crystallography and Structural Physics, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - M Deutsch
- Physics Department and Institute of Nanotechnology, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - B M Ocko
- Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973, USA
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11
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Ariga K, Yamauchi Y, Mori T, Hill JP. 25th anniversary article: what can be done with the Langmuir-Blodgett method? Recent developments and its critical role in materials science. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:6477-512. [PMID: 24302266 DOI: 10.1002/adma.201302283] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Indexed: 05/18/2023]
Abstract
The Langmuir-Blodgett (LB) technique is known as an elegant method for fabrication of well-defined layered structures with molecular level precision. Since its discovery the LB method has made an indispensable contribution to surface science, physical chemistry, materials chemistry and nanotechnology. However, recent trends in research might suggest the decline of the LB method as alternate methods for film fabrication such as layer-by-layer (LbL) assembly have emerged. Is LB film technology obsolete? This review is presented in order to challenge this preposterous question. In this review, we summarize recent research on LB and related methods including (i) advanced design for LB films, (ii) LB film as a medium for supramolecular chemistry, (iii) LB technique for nanofabrication and (iv) LB involving advanced nanomaterials. Finally, a comparison between LB and LbL techniques is made. The latter reveals the crucial role played by LB techniques in basic surface science, current advanced material sciences and nanotechnologies.
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Affiliation(s)
- Katsuhiko Ariga
- World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS) PRESTO & CREST, JST, 1-1 Namiki, Tsukuba, 305-0044, Japan
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12
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Kirchner K, Kirchner T, Ivaništšev V, Fedorov M. Electrical double layer in ionic liquids: Structural transitions from multilayer to monolayer structure at the interface. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.05.049] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Elsen A, Festersen S, Runge B, Koops CT, Ocko BM, Deutsch M, Seeck OH, Murphy BM, Magnussen OM. In situ X-ray studies of adlayer-induced crystal nucleation at the liquid-liquid interface. Proc Natl Acad Sci U S A 2013; 110:6663-8. [PMID: 23553838 PMCID: PMC3637733 DOI: 10.1073/pnas.1301800110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Crystal nucleation and growth at a liquid-liquid interface is studied on the atomic scale by in situ Å-resolution X-ray scattering methods for the case of liquid Hg and an electrochemical dilute electrolyte containing Pb(2+), F(-), and Br(-) ions. In the regime negative of the Pb amalgamation potential Φ(rp) = -0.70 V, no change is observed from the surface-layered structure of pure Hg. Upon potential-induced release of Pb(2+) from the Hg bulk at Φ > Φ(rp), the formation of an intriguing interface structure is observed, comprising a well-defined 7.6-Å-thick adlayer, decorated with structurally related 3D crystallites. Both are identified by their diffraction peaks as PbFBr, preferentially aligned with their axis along the interface normal. X-ray reflectivity shows the adlayer to consist of a stack of five ionic layers, forming a single-unit-cell-thick crystalline PbFBr precursor film, which acts as a template for the subsequent quasiepitaxial 3D crystal growth. This growth behavior is assigned to the combined action of electrostatic and short-range chemical interactions.
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Affiliation(s)
- Annika Elsen
- Institute for Experimental and Applied Physics, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
| | - Sven Festersen
- Institute for Experimental and Applied Physics, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
| | - Benjamin Runge
- Institute for Experimental and Applied Physics, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
| | - Christian T. Koops
- Institute for Experimental and Applied Physics, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
| | - Benjamin M. Ocko
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Moshe Deutsch
- Physics Department, and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Oliver H. Seeck
- Deutsches Elektronensynchrotron DESY, 22607 Hamburg, Germany; and
| | - Bridget M. Murphy
- Institute for Experimental and Applied Physics, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
- Ruprecht Haensel Laboratory, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
| | - Olaf M. Magnussen
- Institute for Experimental and Applied Physics, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
- Ruprecht Haensel Laboratory, Christian-Albrechts-University Kiel, 24098 Kiel, Germany
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14
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Zhang X, Cai Y. Ultralow voltage electrowetting on a solidlike ionic-liquid dielectric layer. Angew Chem Int Ed Engl 2013; 52:2289-92. [PMID: 23325747 DOI: 10.1002/anie.201207857] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/18/2012] [Indexed: 11/07/2022]
Affiliation(s)
- Xiaoning Zhang
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY, USA
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15
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Zhang X, Cai Y. Ultralow Voltage Electrowetting on a Solidlike Ionic-Liquid Dielectric Layer. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201207857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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16
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Tamam L, Ocko BM, Deutsch M. Two-dimensional order in mercury-supported langmuir films of fatty diacids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15586-15597. [PMID: 23072520 DOI: 10.1021/la3034325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The structure of mercury-supported Langmuir films of dicarboxylic acid molecules with 13 ≤ n ≤ 22 carbons is studied by X-ray methods and surface tensiometry. The molecules lie surface-parallel, forming mono-, bi-, or trilayers, depending on coverage. All films exhibit a full 2D order of the same single-molecule oblique unit cell. In particular, the distinct odd-even structure difference of 3D crystals of the same molecules is not observed. The unit cell's width and angle show a small systematic decrease with n, while the length increases commensurately with the molecular length. These results show the films to consist of closely packed, extended, polymer-like chains of diacid molecules, bound by their carboxyl end groups. Evidence is presented for the inclusion of a single mercury atom in the carboxyl-carboxyl bond. The possible conformation of this bond and implications of the parity-independent structure are discussed.
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Affiliation(s)
- Lilach Tamam
- Physics Department, Bar-Ilan University, Ramat-Gan, Israel
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17
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Zhang X, Lu L, Cai Y. Surface properties of ionic liquid adsorbate layer are influenced by the dipole of the underneath substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9593-9600. [PMID: 22616784 DOI: 10.1021/la301452d] [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
Ionic liquids (ILs) form nonfluidic layers at the solid-liquid interface. The properties of the IL interfacial layer play important roles in IL-based applications. Since the liquid-phase IL directly contacts and interacts with the IL interfacial layer rather than the underneath substrate, the surface properties of the interfacial layer could influence how the IL behaves on a solid surface. We used scanning probe microscopy (SPM) and force spectroscopy to investigate how chemical patterns with different dipoles reacted with ionic liquids. We find that even without direct contact on chemical patterns, the IL can form an adsorbate layer on chemical patterns via vapor-phase condensation. The dipole of the chemical pattern can direct the adsorption and assembly of the IL adsorbate. The surface properties of the IL adsorbate layer depend on the dipole of the underneath chemical patterns. Our results indicate that the interfacial IL layer may exist before the IL contacts a solid surface. The charge and dipole of the substrate can influence the structures and properties of the IL interfacial layer. Characterization and measurements of the IL interfacial properties must be conducted under the pretext that the charge/dipole of the substrate is known.
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Affiliation(s)
- Xiaoning Zhang
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, Kentucky 40506, United States
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18
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Cremer T, Wibmer L, Calderón SK, Deyko A, Maier F, Steinrück HP. Interfaces of ionic liquids and transition metal surfaces—adsorption, growth, and thermal reactions of ultrathin [C1C1Im][Tf2N] films on metallic and oxidised Ni(111) surfaces. Phys Chem Chem Phys 2012; 14:5153-63. [DOI: 10.1039/c2cp40278e] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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