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Kozlova SG, Tkachev SV. 1H NMR spectra of triethylamine binary aqueous solutions as functions of concentration and temperature. The triethylamine rich phase. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Korotkevich AA, Bakker HJ. Confined Water Molecules in Binary Mixtures of Water and 2,6-Lutidine Near Lower Solution Critical Temperature. J Phys Chem B 2021; 125:287-296. [PMID: 33370126 PMCID: PMC7816194 DOI: 10.1021/acs.jpcb.0c09363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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We study the concentration and temperature dependence of the reorientation
dynamics of water molecules in binary mixtures of water and 2,6-lutidine
below the lower solution critical temperature (LSCT) with femtosecond
mid-infrared pump–probe spectroscopy. The measurements reveal
the presence of water molecules interacting with both the hydrophobic
groups of lutidine and forming
a hydrogen bond with the nitrogen atom of lutidine. Both types of
molecules show a strongly decreased rotational mobility in comparison
to bulk water. From the temperature dependence of the slow water fraction,
we conclude that the lutidine molecules form clusters that decrease
in size when the temperature is decreased further below the LSCT.
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Affiliation(s)
| | - Huib J Bakker
- AMOLF, Science Park 104, Amsterdam 1098 XG, The Netherlands
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Klimavicius V, Gdaniec Z, Balevicius V. Very short NMR relaxation times of anions in ionic liquids: new pulse sequence to eliminate the acoustic ringing. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 132:879-883. [PMID: 24938418 DOI: 10.1016/j.saa.2014.04.140] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 03/10/2014] [Accepted: 04/23/2014] [Indexed: 06/03/2023]
Abstract
NMR relaxation processes of anions were studied in two neat imidazolium-based room temperature ionic liquids (RTILs) 1-decyl-3-methyl-imidazolium bromide- and chloride. The spin-lattice and spin-spin relaxations of 81Br and 35Cl nuclei were found to be extremely fast due to very strong quadrupolar interactions. The determined relaxation rates are comparable with those observed in the solids or in some critical organic solute/water/salt systems. In order to eliminate the acoustic ringing of the probe-head during relaxation times measurements the novel pulse sequence has been devised. It is based on the conventional inversion recovery pulse sequence, however, instead of the last 90° pulse the subsequence of three 90° pulses applied along axes to fulfill the phase cycling condition is used. Using this pulse sequence it was possible to measure T1 for both studied nuclei. The viscosity measurements have been carried out and the rotational correlation times were calculated. The effective 35Cl quadrupolar coupling constant was found to be almost one order lower than that for 81Br, i.e. 1.8 MHz and 16.0 MHz, respectively. Taking into account the facts that the ratio of (Q(35Cl)/Q(81Br))2≈0.1 and EFG tensors on the anions are quite similar, analogous structural organizations are expected for both RTILs. The observed T1/T2 (1.27-1.44) ratios were found to be not sufficiently high to confirm the presence of long-living (on the time scale of ≥10(-8) s) mesoscopic structures or heterogeneities in the studied neat ionic liquids.
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Affiliation(s)
- Vytautas Klimavicius
- Department of General Physics and Spectroscopy, Vilnius University, Sauletekio 9-3, LT-10222 Vilnius, Lithuania.
| | - Zofia Gdaniec
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, PL-61704 Poznan, Poland.
| | - Vytautas Balevicius
- Department of General Physics and Spectroscopy, Vilnius University, Sauletekio 9-3, LT-10222 Vilnius, Lithuania.
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Balevicius V, Gdaniec Z, Aidas K, Tamuliene J. NMR and Quantum Chemistry Study of Mesoscopic Effects in Ionic Liquids. J Phys Chem A 2010; 114:5365-71. [DOI: 10.1021/jp909293b] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vytautas Balevicius
- Faculty of Physics, Vilnius University, Sauletekio 9-3, LT-10222 Vilnius, Lithuania, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, PL-61704 Poznan, Poland, Department of Chemistry, H. C. Ørsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, and Institute of Theoretical Physics and Astronomy, Vilnius University, Gostauto 12, LT-01108 Vilnius, Lithuania
| | - Zofia Gdaniec
- Faculty of Physics, Vilnius University, Sauletekio 9-3, LT-10222 Vilnius, Lithuania, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, PL-61704 Poznan, Poland, Department of Chemistry, H. C. Ørsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, and Institute of Theoretical Physics and Astronomy, Vilnius University, Gostauto 12, LT-01108 Vilnius, Lithuania
| | - Kestutis Aidas
- Faculty of Physics, Vilnius University, Sauletekio 9-3, LT-10222 Vilnius, Lithuania, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, PL-61704 Poznan, Poland, Department of Chemistry, H. C. Ørsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, and Institute of Theoretical Physics and Astronomy, Vilnius University, Gostauto 12, LT-01108 Vilnius, Lithuania
| | - Jelena Tamuliene
- Faculty of Physics, Vilnius University, Sauletekio 9-3, LT-10222 Vilnius, Lithuania, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, PL-61704 Poznan, Poland, Department of Chemistry, H. C. Ørsted Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark, and Institute of Theoretical Physics and Astronomy, Vilnius University, Gostauto 12, LT-01108 Vilnius, Lithuania
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Fonseca TL, Coutinho K, Canuto S. The isotropic nuclear magnetic shielding constants of acetone in supercritical water: A sequential Monte Carlo/quantum mechanics study including solute polarization. J Chem Phys 2008; 129:034502. [DOI: 10.1063/1.2951995] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Balevicius V, Balevicius VJ, Aidas K, Fuess H. Determination of Critical Indices by “Slow” Spectroscopy: NMR Shifts by Statistical Thermodynamics and Density Functional Theory Calculations. J Phys Chem B 2007; 111:2523-32. [PMID: 17309288 DOI: 10.1021/jp065477x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The temperature dependencies of NMR shifts in the critical region of two coexisting phases have been simulated using statistical thermodynamics and graph-theory consideration of equilibrium processes of molecular association. Microparameters of magnetic screening of various water and water/pyridine structures used in the statistical averaging have been evaluated by density functional theory calculations (PBE1PBE and B3PW91 functionals in the 6-311++G** basis set). The gauge-including atomic orbital (GIAO) approach has been applied to ensure gauge invariance of the results. Solvent effects were taken into account by a polarized continuum model (PCM). NMR shifts "order parameters" (Deltadelta = |delta+ - delta-|) and "diameters" (phidelta = |(delta+ + delta-)/2 - deltaC|, where delta+, delta-, and deltaC are the chemical shifts of coexisting phases and at the critical point respectively) have been calculated in each case close to the lower critical solution point (TL) and processed using linear regression analysis of Deltadelta approximately |T - TL| and phidelta approximately |T - TL| in the log-log plot. It has been shown that the critical index beta can be evaluated with high precision from the slope of Deltadelta = f(T - TL) at any realistic set of model input parameters. The slope of diameter has been found to depend on both input beta and alpha values. The obtained phidelta slopes (0.58-0.63) are very close to 2beta values. The results are discussed within the concept of complete scaling. Results of simulation are compared and supported by experimental NMR data for water/2,6-lutidine, acetic anhydride/n-heptane, and acetic anhydride/cyclohexane systems.
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Bagchi D, Kumar A, Menon R. Ion-induced multiply reentrant liquid-liquid transitions and the nature of criticality in ethanol-water mixture. J Chem Phys 2006; 125:34511. [PMID: 16863366 DOI: 10.1063/1.2212941] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report a quite unusual feature of four liquid-liquid reentrant transitions in ethanol (E)+water (W)+ammonium sulfate mixture by meticulous tuning of the ammonium sulfate concentration in a narrow range, as a function of temperature, at atmospheric pressure. Detailed exploration of the intricate phase behavior in terms of E/W sections shows that the range of triple reentrance shrinks with increasing E/W. The behavior of osmotic susceptibility is investigated by light scattering, near the critical point, in the one-phase region by varying the temperature at fixed concentration of the components, in a particular E/W section. The critical exponent of susceptibility (gamma) and correlation length (nu) are observed to have Fisher renormalized Ising values [Phys. Rev. 176, 237 (1968)], with gamma(r)=1.41 and nu(r)=0.718. The effective susceptibility exponent, gamma(eff), exhibits a sharp, nonmonotonic crossover from Ising to mean-field critical behavior, which is completed outside the critical regime. The amplitude of the correlation length, xi(o)(=21.2+/-0.4 A), deduced from light scattering experiment, is an order of magnitude larger than the typical values in usual aqueous electrolyte systems. This value of xi(o) is further verified from small-angle x-ray scattering (SAXS) experiments and found to be consistent. SAXS experiments on the critical sample reveal the presence of long-ranged intermolecular correlations, leading to supramolecular structuring, at a temperature far away from the critical point. These results convincingly demonstrate that the finite length scale arising due to the structuring competes with the diverging correlation length of critical concentration fluctuations, which influences the nonasymptotic critical behavior in this aqueous electrolyte system. The sulphate ions play a dominant role in both structuring and the complex phase behavior.
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Affiliation(s)
- Debjani Bagchi
- Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
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