1
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Pérez Ramos Á, Zheng Y, Peng J, Ridruejo Á. Structure, Partitioning, and Transport behavior of Microemulsion Electrolytes: Molecular Dynamics and Electrochemical Study. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
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2
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Horváth RA, Fábián B, Szőri M, Jedlovszky P. Investigation of the liquid-vapour interface of aqueous methylamine solutions by computer simulation methods. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.110978] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Benjamin I. Chemical Reaction Dynamics at Liquid Interfaces: A Computational Approach. PROGRESS IN REACTION KINETICS AND MECHANISM 2019. [DOI: 10.3184/007967402103165360] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recent advances in experimental and theoretical studies of liquid interfaces provide remarkable evidence for the unique properties of these systems. In this review we examine how these properties affect the thermodynamics and kinetics of chemical reactions which take place at the liquid/vapor interface and at the liquid/liquid interface. We demonstrate how the rapidly varying density and viscosity, the marked changes in polarity and the surface roughness manifest themselves in isomerization, electron transfer and photodissociation reactions.
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Affiliation(s)
- Ilan Benjamin
- Department of Chemistry, University of California, Santa Cruz, California 95064, USA
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4
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Guo SX, Unwin PR, Whitworth AL, Zhang J. Microelectrochemical Techniques for Probing Kinetics at Liquid/Liquid Interfaces. PROGRESS IN REACTION KINETICS AND MECHANISM 2019. [DOI: 10.3184/0079674044037441] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We provide an overview of recent advances in microelectrochemical approaches to investigate the kinetics of various physicochemical processes that occur at the interface between two immiscible electrolyte solutions (ITIES). To place the advances in context, background material on the structure of the ITIES, derived from both experimental studies and computer simulation, is also provided. The main focus of the article is micro-ITIES techniques, single droplet measurements, microelectrochemical measurements at expanding droplets (MEMED) and scanning electrochemical microscopy (SECM). Recent developments in a combined SECM-Langmuir trough technique for probing diffusion processes across Langmuir monolayers at the water/air (W/A) interface are also highlighted, by considering an organic monolayer at a water surface as a special case of a liquid/liquid interface.
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Affiliation(s)
- Si-Xuan Guo
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Patrick R. Unwin
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Anna L. Whitworth
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Jie Zhang
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
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5
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Liu Z, Stecher T, Oberhofer H, Reuter K, Scheurer C. Response properties at the dynamic water/dichloroethane liquid–liquid interface. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1504132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Zhu Liu
- Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Garching, Germany
| | - Thomas Stecher
- Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Garching, Germany
| | - Harald Oberhofer
- Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Garching, Germany
| | - Karsten Reuter
- Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Garching, Germany
| | - Christoph Scheurer
- Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Garching, Germany
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6
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Voloshin VP, Kim AV, Shelepova EA, Medvedev NN. Determination of the Boundary Surface Between the Lipid Bilayer and Water. J STRUCT CHEM+ 2018. [DOI: 10.1134/s0022476618010146] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Braga C, Muscatello J, Lau G, Müller EA, Jackson G. Nonequilibrium study of the intrinsic free-energy profile across a liquid-vapour interface. J Chem Phys 2016; 144:044703. [DOI: 10.1063/1.4940137] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Carlos Braga
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Jordan Muscatello
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Gabriel Lau
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Erich A. Müller
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - George Jackson
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
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8
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Sonu S, Kumari S, Saha SK. Solvation dynamics and rotational relaxation of coumarin 153 in mixed micelles of Triton X-100 and cationic gemini surfactants: effect of composition and spacer chain length of gemini surfactants. Phys Chem Chem Phys 2016; 18:1551-63. [DOI: 10.1039/c5cp03835a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To demonstrate simultaneously how the solvation dynamics and rotational relaxation in nonionic micelles change with the composition of a gemini surfactant and how this change depends on spacer chain length of gemini surfactants.
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Affiliation(s)
- Sonu Sonu
- Department of Chemistry
- Birla Institute of Technology & Science (BITS)
- Pilani
- India
| | - Sunita Kumari
- Department of Chemistry
- Birla Institute of Technology & Science (BITS)
- Pilani
- India
| | - Subit K. Saha
- Department of Chemistry
- Birla Institute of Technology & Science (BITS)
- Pilani
- India
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9
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10
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Rey R, Hynes JT. Solvation Dynamics in Liquid Water. 1. Ultrafast Energy Fluxes. J Phys Chem B 2015; 119:7558-70. [DOI: 10.1021/jp5113922] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Rossend Rey
- Departament de Física
i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Campus
Nord B4-B5, Barcelona 08034, Spain
| | - James T. Hynes
- Department of Chemistry and
Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
- Chemistry Department, Ecole Normale
Supérieure,
UMR ENS-CNRS-UPMC 8640, 24 Rue Lhomond, 75005 Paris, France
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11
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Richert S, Mosquera Vazquez S, Grzybowski M, Gryko DT, Kyrychenko A, Vauthey E. Excited-State Dynamics of an Environment-Sensitive Push–Pull Diketopyrrolopyrrole: Major Differences between the Bulk Solution Phase and the Dodecane/Water Interface. J Phys Chem B 2014; 118:9952-63. [DOI: 10.1021/jp506062j] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Sabine Richert
- Department
of Physical Chemistry, University of Geneva, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Sandra Mosquera Vazquez
- Department
of Physical Chemistry, University of Geneva, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Marek Grzybowski
- Institute of Organic Chemistry of the Polish Academy of Sciences, 01-224 Warsaw, Poland
| | - Daniel T. Gryko
- Institute of Organic Chemistry of the Polish Academy of Sciences, 01-224 Warsaw, Poland
| | - Alexander Kyrychenko
- V. N. Karazin Kharkiv National University, 4 Svobody Square, Kharkiv 61022, Ukraine
| | - Eric Vauthey
- Department
of Physical Chemistry, University of Geneva, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
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12
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Holmberg N, Sammalkorpi M, Laasonen K. Ion Transport through a Water–Organic Solvent Liquid–Liquid Interface: A Simulation Study. J Phys Chem B 2014; 118:5957-70. [DOI: 10.1021/jp412162c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Nico Holmberg
- Department
of Chemistry, Aalto University, Aalto, Finland
| | | | - Kari Laasonen
- Department
of Chemistry, Aalto University, Aalto, Finland
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13
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Cooper JK, Benjamin I. Photoinduced Excited State Electron Transfer at Liquid/Liquid Interfaces. J Phys Chem B 2014; 118:7703-14. [DOI: 10.1021/jp409541u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jason K. Cooper
- Department
of Chemistry and
Biochemistry University of California Santa Cruz, California 95064, United States
| | - Ilan Benjamin
- Department
of Chemistry and
Biochemistry University of California Santa Cruz, California 95064, United States
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14
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Reprint of “Role of the fluidity of a liquid phase in determining the surface properties of the opposite phase”. J Mol Liq 2014. [DOI: 10.1016/j.molliq.2013.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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15
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Darvas M, Jorge M, Cordeiro MND, Jedlovszky P. Calculation of the intrinsic solvation free energy profile of methane across a liquid/liquid interface in computer simulations. J Mol Liq 2014. [DOI: 10.1016/j.molliq.2013.05.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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16
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Darvas M, Jorge M, Cordeiro MNDS, Kantorovich SS, Sega M, Jedlovszky P. Calculation of the intrinsic solvation free energy profile of an ionic penetrant across a liquid-liquid interface with computer simulations. J Phys Chem B 2013; 117:16148-56. [PMID: 24175995 PMCID: PMC3871283 DOI: 10.1021/jp404699t] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 10/10/2013] [Indexed: 11/29/2022]
Abstract
We introduce the novel concept of an intrinsic free energy profile, allowing one to remove the artificial smearing caused by thermal capillary waves, which renders difficulties for the calculation of free energy profiles across fluid interfaces in computer simulations. We apply this concept to the problem of a chloride ion crossing the interface between water and 1,2-dichloroethane and show that the present approach is able to reveal several important features of the free energy profile which are not detected with the usual, nonintrinsic calculations. Thus, in contrast to the nonintrinsic profile, a free energy barrier is found at the aqueous side of the (intrinsic) interface, which is attributed to the formation of a water "finger" the ion pulls with itself upon approaching the organic phase. Further, by the presence of a nonsampled region, the intrinsic free energy profile clearly indicates the coextraction of the first hydration shell water molecules of the ion when entering the organic phase.
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Affiliation(s)
- Mária Darvas
- Sector
of Molecular and Statistical Biophysics, SISSA, 265 via Bonomea, I-34136 Trieste, Italy
| | - Miguel Jorge
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose
Street, Glasgow G1 1XJ, United Kingdom
| | - M. Natalia D. S. Cordeiro
- Faculdade
de Ciências da Universidade do Porto, REQUIMTE, Rua do Campo
Alegre, 687, 4169-007 Porto, Portugal
| | - Sofia S. Kantorovich
- Faculty
of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Institute
of Mathematics and Computer Sciences, Ural
Federal University, 51
Lenin Avenue, R-620083 Ekaterinburg, Russia
- Department
of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Marcello Sega
- Department
of Physics, University of Rome “Tor
Vergata”, via
della Ricerca Scientifica 1, I-00133 Rome, Italy
- Institut
für Computergestützte Biologische Chemie, University of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
| | - Pál Jedlovszky
- Laboratory
of Interfaces and Nanosize Systems, Institute of Chemistry, Eötvös Loránd University, Pázmány P. Stny 1/A, H-1117 Budapest, Hungary
- MTA-BME
Research Group of Technical Analytical Chemistry, Szt. Gellért tér 4, H-1111 Budapest, Hungary
- Department
of Chemistry, EKF, Leányka utca 6, H-3300 Eger, Hungary
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17
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Role of the fluidity of a liquid phase in determining the surface properties of the opposite phase at the liquid–liquid interface. J Mol Liq 2013. [DOI: 10.1016/j.molliq.2013.04.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Nelson KV, Benjamin I. Electronic Absorption Line Shapes at the Water Liquid/Vapor Interface. J Phys Chem B 2012; 116:4286-91. [DOI: 10.1021/jp3010037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Katherine V. Nelson
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064,
United States
| | - Ilan Benjamin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064,
United States
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19
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Momotenko D, Pereira CM, Girault HH. Differential capacitance of liquid/liquid interfaces of finite thicknesses: a finite element study. Phys Chem Chem Phys 2012; 14:11268-72. [DOI: 10.1039/c2cp41437f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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20
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McFearin CL, Richmond GL. The unique molecular behavior of water at the chloroform-water interface. APPLIED SPECTROSCOPY 2010; 64:986-994. [PMID: 20828435 DOI: 10.1366/000370210792434288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The molecular bonding and orientation of water at the chloroform-water interface has been examined in this study using vibrational sum-frequency spectroscopy (VSFS). The results provide a key puzzle piece towards our understanding of the systematic changes in the interfacial bonding and orientation of water that occur with variations in the polarity of the organic phase, especially when compared with previous studies of different liquid-liquid interfacial systems. In these VSFS studies the OH spectral responses of interfacial water molecules are used to characterize the interactions between water and the organic phase. The spectral analysis, aided by isotopic dilution studies, shows that the moderate polarity of the chloroform phase results in a mixed interfacial region with stronger organic-water bonding and fewer bonding interactions between adjacent water molecules than was previously found for studies of non-polar organic liquid-water interfaces. Even with the more mixed interfacial region and stronger organic-water interactions, interfacial water retains a significant amount of orientational ordering. These results are compared with recent predictions from molecular dynamics simulations about how molecules behave at the chloroform-water interface.
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Affiliation(s)
- Cathryn L McFearin
- Department of Chemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
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21
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Wang H, Carlson E, Henderson D, Rowley RL. Molecular Dynamics Simulation of the Liquid–liquid Interface for Immiscible and Partially Miscible Mixtures. MOLECULAR SIMULATION 2010. [DOI: 10.1080/0892702031000121842] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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Shaytan AK, Ivanov VA, Shaitan KV, Khokhlov AR. Free energy profiles of amino acid side chain analogs near water-vapor interface obtained via MD simulations. J Comput Chem 2010; 31:204-16. [DOI: 10.1002/jcc.21267] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Goswami T, Kumar SKK, Dutta A, Goswami D. Probing the Ultrafast Solution Dynamics of a Cyanine Dye in an Organic Solvent Interfaced with Water. J Phys Chem B 2009; 113:16332-6. [DOI: 10.1021/jp903753u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Tapas Goswami
- Department of Chemistry and Centre for Laser Technology, Indian Institute of Technology, Kanpur, UP - 208016, India
| | - S. K. Karthick Kumar
- Department of Chemistry and Centre for Laser Technology, Indian Institute of Technology, Kanpur, UP - 208016, India
| | - Aveek Dutta
- Department of Chemistry and Centre for Laser Technology, Indian Institute of Technology, Kanpur, UP - 208016, India
| | - Debabrata Goswami
- Department of Chemistry and Centre for Laser Technology, Indian Institute of Technology, Kanpur, UP - 208016, India
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24
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25
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Dey S, Sasmal DK, Das DK, Bhattacharyya K. A Femtosecond Study of Solvation Dynamics and Anisotropy Decay in a Catanionic Vesicle: Excitation-Wavelength Dependence. Chemphyschem 2008; 9:2848-55. [DOI: 10.1002/cphc.200800658] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Adhikari A, Dey S, Mandal U, Das DK, Ghosh S, Bhattacharyya K. Femtosecond Solvation Dynamics in Different Regions of a Bile Salt Aggregate: Excitation Wavelength Dependence. J Phys Chem B 2008; 112:3575-80. [DOI: 10.1021/jp7106445] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Aniruddha Adhikari
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Shantanu Dey
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Ujjwal Mandal
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Dibyendu Kumar Das
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Subhadip Ghosh
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Kankan Bhattacharyya
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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27
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Pártay LB, Horvai G, Jedlovszky P. Molecular level structure of the liquid/liquid interface. Molecular dynamics simulation and ITIM analysis of the water-CCl4 system. Phys Chem Chem Phys 2008; 10:4754-64. [DOI: 10.1039/b807299j] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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28
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Denning EJ, Woolf TB. Chapter 14 Computational Models for Electrified Interfaces. CURRENT TOPICS IN MEMBRANES 2008. [DOI: 10.1016/s1063-5823(08)00014-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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29
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30
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Understanding how organic solvent polarity affects water structure and bonding at halocarbon–water interfaces. J Mol Liq 2007. [DOI: 10.1016/j.molliq.2007.08.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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31
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Benjamin I. Solute rotational dynamics at the water liquid/vapor interface. J Chem Phys 2007; 127:204712. [DOI: 10.1063/1.2803895] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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32
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Mottamal M, Shen S, Guembe C, Krilov G. Solvation of Transmembrane Proteins by Isotropic Membrane Mimetics: A Molecular Dynamics Study. J Phys Chem B 2007; 111:11285-96. [PMID: 17784746 DOI: 10.1021/jp0740245] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mixtures of organic solvents are often used as membrane mimetics in structure determination of transmembrane proteins by solution NMR; however, the mechanism through which these isotropic solvents mimic the anisotropic environment of cell membranes is not known. Here, we use molecular dynamics simulations to study the solvation thermodynamics of the c-subunit of Escherichia coli F1F0 ATP synthase in membrane mimetic mixtures of methanol, chloroform, and water with varying fractions of components as well as in lipid bilayers. We show that the protein induces a local phase separation of the solvent components into hydrophobic and hydrophilic layers, which provides the anisotropic solvation environment to stabilize the amphiphilic peptide. The extent of this effect varies with solvent composition and is most pronounced in the ternary methanol-chloroform-water mixtures. Analysis of the solvent structure, including the local mole fraction, density profiles, and pair distribution functions, reveals considerable variation among solvent mixtures in the solvation environment surrounding the hydrophobic transmembrane region of the protein. Hydrogen bond analysis indicates that this is primarily driven by the hydrogen-bonding propensity of the essential Asp(61) residue. The impact of the latter on the conformational stability of the solvated protein is discussed. Comparison with the simulations in explicit all-atom models of lipid bilayer indicates a higher flexibility and reduced structural integrity of the membrane mimetic solvated c-subunit. This was particularly true for the deprotonated form of the protein and found to be linked to solvent stabilization of the charged Asp(61).
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Affiliation(s)
- Madhusoodanan Mottamal
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, USA
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33
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Yamaguchi A, Amino Y, Shima K, Suzuki S, Yamashita T, Teramae N. Local environments of coumarin dyes within mesostructured silica-surfactant nanocomposites. J Phys Chem B 2007; 110:3910-6. [PMID: 16509675 DOI: 10.1021/jp0564086] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The local environments surrounding dye molecules were studied with use of coumarin dyes in a mesostructured silica-surfactant nanocomposite, which was formed in a porous alumina membrane by a surfactant-templated method and has an average pore diameter of 3.4 nm. Coumarin dyes, such as coumarin 480 (C480), coumarin 343 (C343), and propylamide coumarin 343 (PAC343), were extracted into the silica-surfactant nanocomposite and time-resolved fluorescence spectra of these dyes were examined. C480 and C343 show slow dynamic Stokes shifts and the decay curve can be fitted by a biexponential function. The decay-time constants obtained from the fitting are almost identical for C480 and C343: 0.87 and 7.5 ns for C480, and 0.86 and 7.6 ns for C343. In contrast to these two coumarin dyes, short decay-time constants (0.50 and 4.8 ns) were obtained for PAC343 in the silica-surfactant nanocomposite. These results indicate that the local environments of C480 and C343 are almost identical but different from that of PAC343. By considering the origin of the dynamic Stokes shift and the mesostructure of the silica-surfactant nanocomposite, the location and microenvironment of coumarin dyes within the silica-surfactant nanocomposite are discussed.
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Affiliation(s)
- Akira Yamaguchi
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
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34
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Ghosh S, Mandal U, Adhikari A, Dey S, Bhattacharyya K. Study of organized and biological systems using an ultrafast laser. INT REV PHYS CHEM 2007. [DOI: 10.1080/01442350701416888] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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35
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Sýkora J, Slavícek P, Jungwirth P, Barucha J, Hof M. Time-dependent stokes shifts of fluorescent dyes in the hydrophobic backbone region of a phospholipid bilayer: combination of fluorescence spectroscopy and ab initio calculations. J Phys Chem B 2007; 111:5869-77. [PMID: 17488002 DOI: 10.1021/jp0719255] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We explored the time-dependent Stokes shifts of fluorescent dyes containing an anthroyloxy chromophore (2-AS, 9-AS, and 16-AP) in bilayers composed of palmitoyl-oleoyl-phosphatidylcholine. The obtained data revealed a nontrivial solvation response of these dyes, which are located in the backbone region of the bilayer with a gradually increasing depth. For comparison, steady-state emission spectra in the neat solvents of various polarities and viscosities were also recorded. The results indicate that on the short picosecond time scale the AS dyes undergo complex photophysics including formation of states with a charge-transfer character. This observation is supported by ab initio calculations of the excited states of 9-methylanthroate. The slower nanosecond part of the relaxation process can be attributed to the solvation response of the dyes. A slowdown in solvent relaxation is observed upon moving toward the center of the bilayer. A mechanism similar to preferential solvation present in the mixture of a polar and nonpolar solvent is considered to explain the obtained data.
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Affiliation(s)
- Jan Sýkora
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, Prague 8, Czech Republic.
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36
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Chevrot G, Schurhammer R, Wipff G. Synergistic effect of dicarbollide anions in liquid-liquid extraction: a molecular dynamics study at the octanol-water interface. Phys Chem Chem Phys 2007; 9:1991-2003. [PMID: 17431527 DOI: 10.1039/b616753e] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a molecular dynamics study of chlorinated cobalt bis(dicarbollide) anions [(B(9)C(2)H(8)Cl(3))(2)Co](-)"CCD(-)" in octanol and at the octanol-water interface, with the main aim to understand why these hydrophobic species act as strong synergists in assisted liquid-liquid cation extraction. Neat octanol is quite heterogeneous and is found to display dual solvation properties, allowing to well solubilize CCD(-), Cs(+) salts in the form of diluted pairs or oligomers, without displaying aggregation. At the aqueous interface, octanol behaves as an amphiphile, forming either monolayers or bilayers, depending on the initial state and confinement conditions. In biphasic octanol-water systems, CCD(-) anions are found to mainly partition to the organic phase, thus attracting Cs(+) or even more hydrophilic counterions like Eu(3+) into that phase. The remaining CCD(-) anions adsorb at the interface, but are less surface active than at the chloroform interface. Finally, we compare the interfacial behavior of the Eu(BTP)(3)(3+) complex in the absence and in the presence of CCD(-) anions and extractant molecules. It is found that when the CCD(-)'s are concentrated enough, the complex is extracted to the octanol phase. Otherwise, it is trapped at the interface, attracted by water. These results are compared to those obtained with chloroform as organic phase and discussed in the context of synergistic effect of CCD(-) in liquid-liquid extraction, pointing to the importance of dual solvation properties of octanol and of the hydrophobic character of CCD(-) for synergistic extraction of cations.
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Affiliation(s)
- G Chevrot
- Laboratoire MSM, UMR CNRS 7177, Institut de Chimie, Université Louis Pasteur, 4 rue B., 67000 Strasbourg, France
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Frediani L, Cammi R, Corni S, Tomasi J. A polarizable continuum model for molecules at diffuse interfaces. J Chem Phys 2006; 120:3893-907. [PMID: 15268556 DOI: 10.1063/1.1643727] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In this work we illustrate an extension of the polarizable continuum model to describe solvation effects on molecules at the interface between two fluid phases (liquid/liquid, liquid/vapor). This extension goes beyond the naive picture of the interface as a plane dividing two distinct dielectrics, commonly employed in continuum models. The main feature of the model is the use of a diffuse interface with an electric permittivity depending on the position. This characteristic clearly allows the study of simple interfaces as well as more complex membrane or multilayer structures. Moreover the smooth variation of the permittivity in the diffuse interface, in contrast to the sharp boundary between two regions, overcomes the numerical divergences due to charges placed at the boundary. The implementation of the model relies on the integral equation formalism, which allows one to calculate the reaction field acting on a molecule immersed in a dielectric environment once the proper Green's function is known. In the present case, such a Green's function is obtained numerically, allowing a large flexibility in the choice of the dielectric permittivity profile. The applications have been selected with the aim of illustrating the capabilities of the model; its present limitations are also discussed.
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Affiliation(s)
- Luca Frediani
- Dipartimento di Chimica, Università di Parma, Viale delle Scienze 17/A, 43100, Italy
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38
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Sen P, Ghosh S, Sahu K, Mondal SK, Roy D, Bhattacharyya K. A femtosecond study of excitation wavelength dependence of solvation dynamics in a PEO-PPO-PEO triblock copolymer micelle. J Chem Phys 2006; 124:204905. [PMID: 16774382 DOI: 10.1063/1.2197495] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Excitation wavelength (lambdaex) dependence of solvation dynamics of coumarin 480 (C480) in the micellar core of a water soluble triblock copolymer, PEO20-PPO70-PEO20 (Pluronic P123), is studied by femtosecond and picosecond time resolved emission spectroscopies. In the P123 micelle, the width of the emission spectrum of C480 is found to be much larger than that in bulk water. This suggests that the P123 micelle is more heterogeneous than bulk water. The steady state emission maximum of C480 in P123 micelle shows a significant red edge excitation shift by 25 nm from 453 nm at lambdaex=345 nm to 478 nm at lambdaex=435 nm. The solvation dynamics in the interior of the triblock copolymer micelle is found to depend strongly on the excitation wavelength. The excitation wavelength dependence is ascribed to a wide distribution of locations of C480 molecules in the P123 micelle with two extreme environments-a bulklike peripheral region with very fast solvent response and a very slow core region. With increase in lambdaex, contribution of the bulklike region having an ultrafast component (< or =2 ps) increases from 7% at lambdaex=375 nm to 78% at lambda(ex)=425 nm while the contribution of the ultraslow component (4500 ps) decreases from 79% to 17%.
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Affiliation(s)
- Pratik Sen
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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Jurkiewicz P, Sýkora J, Olzyńska A, Humpolícková J, Hof M. Solvent relaxation in phospholipid bilayers: principles and recent applications. J Fluoresc 2006; 15:883-94. [PMID: 16328702 DOI: 10.1007/s10895-005-0013-4] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Although there exist a number of methods, such as NMR, X-ray, e.g., which explore the hydration of phospholipid bilayers, the solvent relaxation (SR) method has the advantage of simple instrumentation, easy data treatment and possibility of measuring fully hydrated samples. The main information gained from SR by the analysis of recorded "time-resolved emission spectra" (TRES) is micro-viscosity and micro-polarity of the dye microenvironment. Based on these parameters, one can draw conclusions about water structure in the bilayer. In this review, we focus on physical background of this method, on all the procedures that are needed in order to obtain relevant parameters, and on the requirements on the fluorescence dyes. Furthermore, a few recent applications (the effect of curvature, binding of antibacterial peptides and phase transition) illustrating the versatility of this method are mentioned. Moreover, limitations and potential problems are discussed.
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Affiliation(s)
- Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223, Prague 8, Czech Republic
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40
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Buhn JB, Bopp PA, Hampe MJ. Structural and dynamical properties of liquid–liquid interfaces: A systematic molecular dynamics study. J Mol Liq 2006. [DOI: 10.1016/j.molliq.2005.11.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Sahu K, Mondal SK, Ghosh S, Roy D, Bhattacharyya K. Temperature dependence of solvation dynamics and anisotropy decay in a protein: ANS in bovine serum albumin. J Chem Phys 2006; 124:124909. [PMID: 16599727 DOI: 10.1063/1.2178782] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Temperature dependence of solvation dynamics and fluorescence anisotropy decay of 8-anilino-1-naphthalenesulfonate (ANS) bound to a protein, bovine serum albumin (BSA), are studied. Solvation dynamics of ANS bound to BSA displays a component (300 ps) which is independent of temperature in the range of 278-318 K and a long component which decreases from 5800 ps at 278 K to 3600 ps at 318 K. The temperature independent part is ascribed to a dynamic exchange of bound to free water with a low barrier. The temperature variation of the long component of solvation dynamics corresponds to an activation energy of 2.1 kcal mol(-1). The activation energy is ascribed to local segmental motion of the protein along with the associated water molecules and polar residues. The time scale of solvation dynamics is found to be very different from the time scale of anisotropy decay. The anisotropy decays are analyzed in terms of the wobbling motion of the probe (ANS) and the overall tumbling of the protein.
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Affiliation(s)
- Kalyanasis Sahu
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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Affiliation(s)
- Ilan Benjamin
- Department of Chemistry, University of California, Santa Cruz, California 95064, USA
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Sen P, Roy D, Mondal SK, Sahu K, Ghosh S, Bhattacharyya K. Fluorescence Anisotropy Decay and Solvation Dynamics in a Nanocavity: Coumarin 153 in Methyl β-Cyclodextrins. J Phys Chem A 2005; 109:9716-22. [PMID: 16833284 DOI: 10.1021/jp051607a] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Fluorescence anisotropy decay and solvation dynamics of coumarin 153 (C153) are studied in dimethyl beta-cyclodextrin (DIMEB) and trimethyl beta-cyclodextrin (TRIMEB) nanocavity in water. C153 binds to DIMEB and TRIMEB to form both 1:1 and 1:2 (C153:cyclodextrin) complexes. The anisotropy decays of C153 in DIMEB and TRIMEB are found to be biexponential. The fast component of anisotropy decay (approximately 1000 ps) is attributed to the 1:1 complex and the slower one (approximately 2500 ps) to the 1:2 complex. From the components of the anisotropy decay, the length of the 1:1 and 1:2 complexes are estimated. Solvation dynamics of C153 in DIMEB exhibits a very fast (2.4 ps) component (41%) and two slower components of 50 ps (29%) and 1450 ps (30%). Solvation dynamics in TRIMEB is described by three slow components of 10.3 ps (24%), 240 ps (45%), and 2450 ps (31%). Possible origins of the ultraslow components are discussed.
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Affiliation(s)
- Pratik Sen
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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Keresztúri A, Jedlovszky P. Computer Simulation Investigation of the Water−Benzene Interface in a Broad Range of Thermodynamic States from Ambient to Supercritical Conditions. J Phys Chem B 2005; 109:16782-93. [PMID: 16853137 DOI: 10.1021/jp051343s] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The dependence of the properties of the water-benzene system on the thermodynamic conditions in a broad range of temperatures and pressures has been investigated by computer simulation methods. For this purpose, Monte Carlo simulations have been performed at 23 different thermodynamic states, ranging from ambient to supercritical conditions. The density profiles of the water and benzene molecules have been determined at each of the thermodynamic states investigated. Information on the dependence of the mutual solubility of the two components in each other as well as of the width of the interface on the temperature and pressure has been extracted from these profiles. The width of the interface has been found to increase with increasing temperature up to a certain point, where it diverges. The temperature of this divergence corresponds to the mixing of the two phases. The determination of the critical mixing temperature at various pressures allowed us to estimate the upper critical curve, separating the two-phase and one-phase liquid systems, of the phase diagram of the simulated water-benzene system. In analyzing the preferential orientation of the interfacial molecules relative to the interface, it has been found that the main orientational preference of the benzene molecules is to lie parallel with the plane of the interface, and the water molecules penetrated deepest into the benzene phase prefer to stay perpendicular to the interface, pointing by one of their O-H bonds almost straight toward the benzene phase, whereas the waters located at the aqueous side of the interface are preferentially aligned parallel with the interfacial plane. Although the strength of the observed orientational preferences decreases rapidly with increasing temperature, the preferred orientations themselves are found to be independent of the thermodynamic conditions. Remains of the orientational preferences of the molecules are found to be present up to temperatures as high as 650 K. The analysis of the relative orientation of the neighboring water-benzene pairs has revealed that the radius of the first hydration shell of the benzene molecules is independent of the thermodynamic conditions, even if the system consists of one single phase. It has been found that the nearest water neighbors of the benzene molecules are preferentially located above and below the benzene ring, whereas more distant water neighbors, belonging still to the first hydration shell, prefer to stay within the plane of the benzene molecule. In the two-phase systems the dipole vector of the nearest waters has been found to be preferentially perpendicular to the vector pointing from the center of the benzene molecule to the water O atom.
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Affiliation(s)
- Agnes Keresztúri
- Department of Colloid Chemistry, Eötvös Lorand University, Pazmany Péter stny. 1/a, H-1117 Budapest, Hungary
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Chorny I, Benjamin I. Hydration Shell Exchange Dynamics during Ion Transfer Across the Liquid/Liquid Interface. J Phys Chem B 2005; 109:16455-62. [PMID: 16853092 DOI: 10.1021/jp051836x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We examine using molecular dynamics simulations the rate and mechanism of water molecules exchange around the Li(+) and Na(+) ions during ion transfer across the interface between water and nitrobenzene. As the ions are transferred from the water to the organic phase, they keep their first hydration shell and an incomplete second shell. The rate of water exchange between the first shell and the rest of the interfacial water molecule decreases during the transfer, which is consistent with an increase in the barrier along the ion-water potential of mean force. While in bulk water the exchange of water molecules around the Li(+) follows an associative (A) or associative interchange (I(a)) type mechanism, the fraction of exchange events of type A increases at the interface. In contrast, while in bulk water the exchange of water molecules around the six coordinated Na(+) hydrated species mainly follows a dissociative mechanism, the situation at the interface involves an equilibrium interchange between the four- and five-coordinated hydrated ion. Simulation of the reversed process, in which the hydrated Li(+) ion is transferred to the aqueous phase, shows the same general behavior as a function of location from the interface.
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Affiliation(s)
- Ilya Chorny
- Department of Chemistry, University of California, Santa Cruz, California 95064, USA
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Winter N, Benjamin I. Nucleophilic Substitution Reactions at Liquid/Liquid Interfaces: Molecular Dynamics Simulation of a Model SN1 Dissociation Reaction at the Water/Carbon Tetrachloride Interface. J Phys Chem B 2005; 109:16421-8. [PMID: 16853087 DOI: 10.1021/jp052112o] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The ionic dissociation step of the nucleophilic substitution reaction t-BuCl --> t-Bu(+) + Cl(-) is studied at the water/carbon tetrachloride interface using molecular dynamics computer simulations. The empirical valence bond approach is used to couple two diabatic states, covalent and ionic, in the electronically adiabatic limit. The umbrella sampling technique is used to calculate the potential of mean force along the reaction coordinate (defined as the t-Bu to Cl distance) at several interface regions of varying distances from the Gibbs dividing surface. We find a significant increase of the ionic dissociation barrier height and of the reaction free energy at the interface relative to bulk water. This is shown to be due to the reduced polarity of the interface which causes a destabilization of the pure ionic state. However, deformation to the neat interface structure in the form of water protrusions into the organic phase may provide partial stabilization of the ionic species. The importance of these structural effects is examined by repeating the calculations with an artificially smooth interface. The destabilization of the ionic state at the interface also manifests itself with a rapid (picosecond time scale) recombination dynamics of the ions to form the parent molecule followed by a slow vibrational relaxation.
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Affiliation(s)
- Nicole Winter
- Department of Chemistry, University of California, Santa Cruz, California 95064, USA
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Roy D, Mondal SK, Sahu K, Ghosh S, Sen P, Bhattacharyya K. Temperature Dependence of Anisotropy Decay and Solvation Dynamics of Coumarin 153 in γ-Cyclodextrin Aggregates. J Phys Chem A 2005; 109:7359-64. [PMID: 16834102 DOI: 10.1021/jp0520143] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Effect of temperature on the fluorescence anisotropy decay and the ultraslow component of solvation dynamics of coumarin 153 (C153) in a gamma-cyclodextrin (gamma-CD) nanocavity are studied using a picosecond set up. The steady-state anisotropy (0.13 +/- 0.01) and residual anisotropy (0.14 +/- 0.01) in fluorescence anisotropy decay in an aqueous solution containing 7 microM C153 and 40 mM gamma-CD are found to be quite large. This indicates formation of large linear nanotube aggregates of gamma-CD linked by C153. It is estimated that >53 gamma-CD units are present in each aggregate. In these aggregates with rise in temperature, the average solvation time (<tau(s)>(obs)) decreases markedly from 680 ps at 278 K to 160 ps at 318 K. The dynamic Stokes shift is found to decrease from 800 cm(-1) at 278 K to 250 cm(-1) at 318 K. The fraction of dynamic Stokes shift (f(d)) detected in a picosecond set up is calculated using the Fee-Maroncelli procedure. The corrected solvation time (<tau(s)>(corr) = f(d)<(tau(s)>(obs)) displays an Arrhenius type temperature dependence. From the temperature variation, the activation energy and entropy of the solvation process are determined to be 12.5 kcal M(-1) and 28 cal M(-1) K(-1), respectively. The ultraslow component and its temperature dependence are ascribed to a dynamic exchange between bound and free water molecules.
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Affiliation(s)
- Durba Roy
- Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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Abstract
Hydrogen bond dynamics at the neat interface between water and a series of organic liquids are studied with molecular dynamics computer simulation. The organic liquids are nonpolar (carbon tetrachloride), weakly polar (1,2-dichloroethane), and polar (nitrobenzene). The effect of surface polarity and surface roughness is examined. The dynamics are expressed in terms of the hydrogen bond population autocorrelation functions and are found to be nonexponential and strongly dependent on the nature of the organic phase. In particular, at all interfaces, the dynamics are slower at the interface than in the bulk and sensitive to the location of the water molecules along the interface normal.
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Affiliation(s)
- Ilan Benjamin
- Department of Chemistry, University of California, Santa Cruz, California 95064, USA
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Guha S, Sahu K, Roy D, Mondal SK, Roy S, Bhattacharyya K. Slow Solvation Dynamics at the Active Site of an Enzyme: Implications for Catalysis. Biochemistry 2005; 44:8940-7. [PMID: 15966719 DOI: 10.1021/bi0473915] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Solvation dynamics at the active site of an enzyme, glutaminyl-tRNA synthetase (GlnRS), was studied using a fluorescence probe, acrylodan, site-specifically attached at cysteine residue C229, near the active site. The picosecond time-dependent fluorescence Stokes shift indicates slow solvation dynamics at the active site of the enzyme, in the absence of any substrate. The solvation dynamics becomes still slower when the substrate (glutamine or tRNA(Gln)) binds to the enzyme. A mutant Y211H-GlnRS was constructed in which the glutamine binding site is disrupted. The mutant Y211H-GlnRS labeled at C229 with acrylodan exhibited significantly different solvent relaxation, thus demonstrating that the slow dynamics is indeed associated with the active site. Implications for catalysis and specificity have been discussed.
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Affiliation(s)
- Soumi Guha
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VIIM, Kolkata 700 054, India
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Li S, Thompson WH. Proton Transfer in Nanoconfined Polar Solvents. 1. Free Energies and Solute Position. J Phys Chem B 2005; 109:4941-6. [PMID: 16863151 DOI: 10.1021/jp045036i] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction free energy curves for a model phenol-amine proton-transfer system in a confined CH3Cl solvent have been calculated by Monte Carlo simulations. The free energy curves, as a function of a collective solvent coordinate, have been obtained for several fixed reaction complex radial positions (based on the center-of-mass). A smooth, hydrophobic spherical cavity was used to confine the solvent, and radii of 10 and 15 A have been considered. Quantum effects associated with the transferring proton have been included by adding the proton zero-point energy to the classical free energy. The results indicate the reaction complex position can be an important component of the reaction coordinate for proton-transfer reactions in nanoconfined solvents.
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Affiliation(s)
- Shenmin Li
- Department of Chemistry and Chemical Engineering, Dalian University, Dalian 116622, PR China
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