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Trabelsi S, Tlili M, Abdelmoulahi H, Bouazizi S, Nasr S, González MA, Bellissent-Funel MC, Darpentigny J. Intermolecular interactions in an equimolar methanol-water mixture: Neutron scattering, DFT, NBO, AIM, and MD investigations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118131] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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2
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Zhai Y, Luo P, Waller J, Self JL, Harriger LW, Z Y, Faraone A. Dynamics of molecular associates in methanol/water mixtures. Phys Chem Chem Phys 2022; 24:2287-2299. [PMID: 35015001 DOI: 10.1039/d1cp04726d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dynamics of molecular associates in a methanol/water mixture was investigated using quasielastic neutron scattering. By measuring the signal from four methanol/water samples differing only by their isotopic composition, the relative motion of the water to methanol molecules, i.e. their mutual dynamics, was determined at the nanoscale. The thus obtained nanoscopic mutual diffusion coefficient signals a significantly slower process than the single particle diffusion of either methanol or water in the system as well as their macroscopic mutual diffusion. The data do not provide any indication of microsegregation in this preeminent alcohol/water mixture; however, they do indicate the existence of long lived but dynamic molecular associates of water and methanol molecules. Analysis of the structural relaxation shows that the lifetime of molecular association through hydrogen bonding determines the fact that viscosity of the mixtures at intermediate concentrations is higher than that of both pure components.
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Affiliation(s)
- Yanqin Zhai
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Peng Luo
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Jackson Waller
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Jeffrey L Self
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Leland W Harriger
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
| | - Y Z
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
| | - Antonio Faraone
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
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Dubey V, Daschakraborty S. Breakdown of the Stokes-Einstein Relation in Supercooled Water/Methanol Binary Mixtures: Explanation Using the Translational Jump-Diffusion Approach. J Phys Chem B 2020; 124:10398-10408. [PMID: 33153260 DOI: 10.1021/acs.jpcb.0c07318] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A recent experiment has directly checked the validity of the Stokes-Einstein (SE) relation for pure water, pure methanol, and their binary mixtures of three different compositions at different temperatures. The effect of composition on the nature of breakdown of the SE relation is interesting. While in the majority of the systems, an increasing SE breakdown is observed with decreasing temperature, the breakdown is already significant at higher temperatures for the equimolar mixture. Violations of the SE relation in pure supercooled water at different temperatures and pressures have been previously explained using the translational jump-diffusion (TJD) approach, which provides a fundamental molecular basis, by directly connecting the SE breakdown with jump-diffusion of the molecules. We have used the same TJD approach for explaining the SE breakdown for the methanol/water binary mixtures of compositions studied in the experiment over a wide range of temperatures between 220 K and 300 K. We have understood that the jump-diffusion is the key responsible factor for the SE breakdown. The maximum jump-diffusion contribution gives rise to the early SE breakdown observed for the equimolar mixture observed in the experiment. This study, therefore, provides molecular insight into the SE breakdown for the supercooled water/methanol binary mixture, as found in the experiment.
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Affiliation(s)
- Vikas Dubey
- Department of Chemistry, Indian Institute of Technology Patna, Patna, Bihar 801106, India
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Pethes I, Pusztai L, Ohara K, Kohara S, Darpentigny J, Temleitner L. Temperature-dependent structure of methanol-water mixtures on cooling: X-ray and neutron diffraction and molecular dynamics simulations. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113664] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Devlin JP, Balcı FM, Maşlakcı Z, Uras-Aytemiz N. CO2 and C2H2 in cold nanodroplets of oxygenated organic molecules and water. J Chem Phys 2014; 141:18C506. [PMID: 25399171 DOI: 10.1063/1.4895549] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recent demonstrations of subsecond and microsecond timescales for formation of clathrate hydrate nanocrystals hint at future methods of control of environmental and industrial gases such as CO2 and methane. Combined results from cold-chamber and supersonic-nozzle [A. S. Bhabhe, "Experimental study of condensation and freezing in a supersonic nozzle," Ph.D. thesis (Ohio State University, 2012), Chap. 7] experiments indicate extremely rapid encagement of components of all-vapor pre-mixtures. The extreme rates are derived from (a) the all-vapor premixing of the gas-hydrate components and (b) catalytic activity of certain oxygenated organic large-cage guests. Premixing presents no obvious barrier to large-scale conditions of formation. Further, from sequential efforts of the groups of Trout and Buch, a credible defect-based model of the catalysis mechanism exists for guidance. Since the catalyst-generated defects are both mobile and abundant, it is often unnecessary for a high percentage of the cages to be occupied by a molecular catalyst. Droplets represent the liquid phase that bridges the premixed vapor and clathrate hydrate phases but few data exist for the droplets themselves. Here we describe a focused computational and FTIR spectroscopic effort to characterize the aerosol droplets of the all-vapor cold-chamber methodology. Computational data for CO2 and C2H2, hetero-dimerized with each of the organic catalysts and water, closely match spectroscopic redshift patterns in both magnitude and direction. Though vibrational frequency shifts are an order of magnitude greater for the acetylene stretch mode, both CO2 and C2H2 experience redshift values that increase from that for an 80% water-methanol solvent through the solvent series to approximately doubled values for tetrahydrofuran and trimethylene oxide (TMO) droplets. The TMO solvent properties extend to a 50 mol.% solution of CO2, more than an order of magnitude greater than for the water-methanol solvent mixture. The impressive agreement between heterodimer and experimental shift values throughout the two series encourages speculation concerning local droplet structures while the stable shift patterns appear to be useful indicators of the gas solubilities.
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Affiliation(s)
- J Paul Devlin
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, USA
| | - F Mine Balcı
- Department of Chemistry, Suleyman Demirel University, 32260 Isparta, Turkey
| | - Zafer Maşlakcı
- Department of Polymer Engineering, Karabuk University, 78050 Karabuk, Turkey
| | - Nevin Uras-Aytemiz
- Department of Polymer Engineering, Karabuk University, 78050 Karabuk, Turkey
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