Vibrational spectra of anhydrous lithium perchlorate in crystalline and molten states

1969 ◽  
Vol 22 (3) ◽  
pp. 499 ◽  
Author(s):  
WH Leong ◽  
DW James
Keyword(s):  
Molten Salts ◽  
Ion Pairs ◽  
Lithium Perchlorate ◽  
Frequency Region ◽  
Infrared And Raman Spectra ◽  
Molten State ◽  
Infrared And Raman Spectroscopy ◽  
Degenerate Modes ◽  
Contact Ion Pairs ◽  
Crystalline Symmetry

Anhydrous lithium perchlorate has been examined in the crystalline and molten state by infrared and Raman spectroscopy. In the crystalline phase all degenerate modes are split but the Raman and infrared spectra are essentially identical in the internal frequency region. In the molten state the spectra are more simple but no coincidences exist between infrared and Raman spectra. The spectra are interpreted in terms of a crystalline symmetry perturbation for both the solid and molten salts. The symmetry of the perturbing field is shown to change in going from the solid to the melt. An explanation of the melt spectra in terms of contact ion pairs is considered and dismissed. Observed vibrational frequencies and assignments are given.

Picosecond Dynamics of Molecular Entities in Lithium Salt Solutions in Dimethyl Sulfoxide, Propylene Carbonate, and Dimethyl Carbonate

2018 ◽  
Vol 63 (3) ◽  
pp. 245 ◽  
Author(s):  
M. I. Gorobets ◽  
S. A. Kirillov
Keyword(s):  
Dimethyl Sulfoxide ◽  
Propylene Carbonate ◽  
Molten Salts ◽  
Dimethyl Carbonate ◽  
Lithium Salt ◽  
Ion Pairs ◽  
Lithium Salts ◽  
Strong Interactions ◽  
Solvent Molecules ◽  
Contact Ion Pairs

An analysis of the Raman spectra of the solutions of lithium salts in dimethyl sulfoxide, propylene carbonate, and dimethyl carbonate in a concentration range from diluted solutions to the mixtures of molten solvates with salts has been performed in terms of the dynamics, specifically, the dephasing (тv) and modulation (тw) times of all molecular entities present in solutions are determined and analyzed. It has been found that, in the picosecond time domain, the dephasing and modulation in solvent molecules hydrogen-bonded with an anion and/or solvating a cation are slower than in free solvent molecules. In solvent separated ion pairs, both тv and тw are much longer than in solvated anions, thus indicating the strong interactions between anions and their surrounding. In contact ion pairs, тv are great, whereas тw appear close to those for free anions. This reflects that the structure of the liquid tends to the structure of molten salts.

scholarly journals Raman Spectroscopy for Understanding of Lithium Intercalation into Graphite in Propylene Carbonated-Based Solutions

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Yang-Soo Kim ◽  
Soon-Ki Jeong
Keyword(s):  
Spectroscopic Analysis ◽  
Ion Pairs ◽  
Solid Electrolyte Interphase ◽  
Lithium Ion ◽  
Lithium Perchlorate ◽  
Lithium Intercalation ◽  
Graphene Layers ◽  
Raman Spectroscopic ◽  
Contact Ion Pairs ◽  
Raman Spectroscopic Analysis

Electrochemical lithium intercalation within graphite was investigated in propylene carbonate (PC) containing different concentrations, 0.4, 0.9, 1.2, 2.2, 2.8, 3.8, and 4.7 mol dm−3, of lithium perchlorate, LiClO4. Lithium ion was reversibly intercalated into and deintercalated from graphite in 3.8 and 4.7 mol dm−3solutions despite the use of pure PC as the solvent. However, ceaseless solvent decomposition and intense exfoliation of the graphene layers occurred in other solutions. The results of the Raman spectroscopic analysis indicated that contact ion pairs are present in 3.8 and 4.7 mol dm−3solutions, which suggested that the presence of contact ion pairs is an important factor that determines the solid electrolyte interphase- (SEI-) forming ability in PC-based electrolytes.

Ion Pairing and Dielectric Decrement in Glycosaminoglycan Brushes

2020 ◽  
Author(s):  
James Sterling ◽  
Wenjuan Jiang ◽  
Wesley M. Botello-Smith ◽  
Yun L. Luo
Keyword(s):  
Molecular Dynamics ◽  
Ion Pairs ◽  
Mean Field ◽  
Salt Bridge ◽  
Ion Pairing ◽  
Donnan Potential ◽  
Mean Field Models ◽  
Ion Exclusion ◽  
Dynamics Simulations ◽  
Contact Ion Pairs

Molecular dynamics simulations of hyaluronic acid and heparin brushes are presented that show important effects of ion-pairing, water dielectric decrease, and co-ion exclusion. Results show equilibria with electroneutrality attained through screening and pairing of brush anionic charges by cations. Most surprising is the reversal of the Donnan potential that would be expected based on electrostatic Boltzmann partitioning alone. Water dielectric decrement within the brush domain is also associated with Born hydration-driven cation exclusion from the brush. We observe that the primary partition energy attracting cations to attain brush electroneutrality is the ion-pairing or salt-bridge energy associated with cation-sulfate and cation-carboxylate solvent-separated and contact ion pairs. Potassium and sodium pairing to glycosaminoglycan carboxylates and sulfates consistently show similar abundance of contact-pairing and solvent-separated pairing. In these crowded macromolecular brushes, ion-pairing, Born-hydration, and electrostatic potential energies all contribute to attain electroneutrality and should therefore contribute in mean-field models to accurately represent brush electrostatics.

Reversible fluorescent and colorimetric rhodamine based-chemosensor of Cu 2+ contact ion-pairs using a ditopic receptors

2015 ◽  
Vol 123 ◽  
pp. 204-211 ◽  
Author(s):  
Chatthai Kaewtong ◽  
Buncha Pulpoka ◽  
Thawatchai Tuntulani
Keyword(s):  
Ion Pairs ◽  
Ditopic Receptors ◽  
Contact Ion Pairs

scholarly journals Interactions of Na+ Cations with a Highly Charged Fatty Acid Langmuir Monolayer: Molecular Description of the Phase Transition

2019 ◽  
Author(s):  
Adrien Sthoer ◽  
Eric Tyrode
Keyword(s):  
Phase Transition ◽  
Surface Charge ◽  
Surface Potential ◽  
Arachidic Acid ◽  
Ion Pairs ◽  
Theoretical Models ◽  
Langmuir Monolayer ◽  
Vibrational Sum Frequency Spectroscopy ◽  
Ion Size ◽  
Contact Ion Pairs

Vibrational sum frequency spectroscopy has been used to study the molecular properties upon compression of a highly charged arachidic acid Langmuir monolayer, which displays a first order phase transition plateau in the surface pressure - molecular area (p-A) isotherm. By targeting vibrational modes from the carboxylic acid headgroup, alkyl chain, and interfacial water molecules, information regarding the surface charge, surface potential, type of ion pair formed, and conformational order of the monolayer could be extracted. The monolayer in the liquid expanded phase is found to be fully charged until reaching the 2D-phase transition plateau, where partial reprotonation, as well as the formation of COO⎺ Na<sup>+ </sup>contact-ion pairs, start to take place. In the condensed phase after the transition, three headgroup species, mainly hydrated COO⎺, COOH, and COO⎺ Na<sup>+ </sup>contact-ion pairs could be identified and their proportions quantified. Comparison with theoretical models shows that despite the low ionic strengths used (i.e. 10 mM), the predictions from the Gouy Chapman model are only adequate for the lowest surface densities, when the surface charge does not exceed -0.1 C/m<sup>2</sup>. In contrast, a modified Poisson-Boltzmann (MPB) model that accounts for the steric effects associated with the finite ion-size, captures many of the experimental observables, including the partial reprotonation, and surface potential changes upon compression. The agreement highlights the importance of hydronium ion – carboxylate interactions, as well as the layer of sodium ions packed at the steric limit, for explaining the phase transition behavior. The MPB model, however, does not explicitly consider the formation of contact ion pairs with the sodium counterion. The experimental results provide a quantitative molecular insight that could be used to test potential extensions to the theory.

Elektronentransfer und Ionenpaare, 15 [ 1– 3] Radikalanion und Radikal-Kontakt-Ionenpaare von Dimesityl-tetraketon / Electron Transfer and Ion Pairing, 15 [1-3] Radical Anion and Radical Ion Pairs of Dimesityl Tetraketone

1990 ◽  
Vol 45 (8) ◽  
pp. 1197-1204 ◽  
Author(s):  
H. Bock ◽  
P. Hänel ◽  
H.-F. Herrmann
Keyword(s):  
Electron Transfer ◽  
Radical Anion ◽  
Ion Pairs ◽  
Ion Pairing ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Temperature Dependent ◽  
Contact Ion Pairs

The radical anion of dimesityltetraketone (ERed, I = -0.40 V) is easily generated in THF by potassium mirror/[2.2.2]-cryptand reduction. Its contact ion pairs with Na⊕, Cs⊕ and Ba⊕⊕ counter cations, prepared in THF solution by single electron transfer from the respective metals, are characterized by their ESR/ENDOR spectra, which exhibit temperature-dependent metal couplings of aNa⊕ = 0.061 mT (190 K), aCs⊕ = 0.021 mT (190 K), and aBa⊕⊕ = 0.145 mT (295 K).

Sign in / Sign up

Export Citation Format

Share Document