Effect of Solventsand Temperature on O—H stretching Band of Methanol: Measure of van der Waals Interactions

1984 ◽  
Vol 39 (9) ◽  
pp. 888-892
Author(s):  
W. A. P. Luck ◽  
H. Y. Zheng
Keyword(s):  
Frequency Shift ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Frequency Shifts ◽  
Oh Groups ◽  
Nonpolar Solvents ◽  
Different Temperatures ◽  
Solvent Molecules

The frequency shift of methanolic OH stretching bands by different nonpolar solvents at different temperatures can be described quantitatively by an equation proposed recently relating it to the temperature dependence of van der Waals interactions. The method shows that methanolic OH groups are surrounded by about 40% more solvent molecules than t-butanol OH groups. Frequency shifts of CH3OH by binary solvent mixtures demonstrate an averaged potential with small preference of the solvent with higher interaction.

Crystal Structures of Two New Cyclosporin Clathrates

2000 ◽  
Vol 65 (12) ◽  
pp. 1950-1958 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Alexandr Jegorov
Keyword(s):  
Crystal Structures ◽  
Methyl Ether ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Solvent Molecules ◽  
Butyl Methyl Ether

Two isomorphous clathrates formed by dihydrocyclosporin A or cyclosporin V with tert-butyl methyl ether are reported and compared with the structures of related P21-symmetry cyclosporin clathrates. The cyclosporin molecules in both structures are associated via van der Waals interactions forming cavities occupied by solvent molecules (cyclosporin : tert-butyl methyl ether is 1 : 2).

scholarly journals Spectrophotometric and conductometric study of the complexation of N-salicylidene-2-aminophenol with Cu2+ in methanol + 1,4-dioxane binary solutions

2014 ◽  
Vol 79 (10) ◽  
pp. 1263-1277
Author(s):  
Rashmidipta Biswas ◽  
Dhiraj Brahman ◽  
Biswajit Sinha
Keyword(s):  
Stability Constants ◽  
Mixed Solvents ◽  
Molar Conductance ◽  
Binary Solvent ◽  
Complexation Reaction ◽  
Solvent Mixtures ◽  
Linear Behaviour ◽  
Different Temperatures ◽  
Conductometric Study ◽  
The Stability

The complexation reaction between N-salicylidene-2-aminophenol, abbreviated as SAP, with Cu2+ ion was studied in binary mixtures of methanol and 1,4-dioxane by using conductometric and spectrophotometric method at different temperatures. The stability constants (Kf) for the 1:1 complex, Cu2+-SAP, were calculated from computer fitting of absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM) in different binary solvent mixtures. A non-linear behaviour was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (?H, ?S and ?G) for the formation of Cu2+-SAP complex were determined from the temperature dependence of stability constants (Kf). The overall results showed that the complexation reaction is entropy driven and is affected by the nature and composition of the mixed solvents.

Effects of di-, tri-, and tetraethylene glycols on the thermodynamic and micellar properties of Triton X-100 in water

2004 ◽  
Vol 82 (12) ◽  
pp. 1774-1780 ◽  
Author(s):  
Gwen MacIsaac ◽  
Aiysha Al-Wardian ◽  
Karen Glenn ◽  
Rama M Palepu
Keyword(s):  
Surface Tension ◽  
Tetraethylene Glycol ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Fluorescence Studies ◽  
Gibbs Energies ◽  
Micellization Process ◽  
Solvent Systems ◽  
Solvent Molecules ◽  
Triton X

Micellar and surface thermodynamic properties of aggregation of Triton X-100 (TX-100) in mixed solvent systems containing di-, tri-, and tetraethylene glycol with water have been investigated by employing surface tension, density, and fluorescence methods. The differences in Gibbs energies of micellization between water and binary solvent mixtures were determined to evaluate the influence of the co-solvent on the micellization process. From the surface tension measurements, the effects of the co-solvent on parameters such as surface excess, minimum area per molecule, and surface pressure indicate that the surface activity of the surfactant decreases with increasing concentration of the glycol co-solvent. Partial specific volumes, obtained from density measurements, indicate that the fraction of solvent molecules interacting with the micelles by hydrogen bonding vary with the type of additive. Fluorescence studies reveal that quenching of the pyrene probe by cetyl pyridinum chloride in TX-100 micelles is accompanied by simultaneous static and dynamic processes.Key words: Triton X-100, glycols, thermodynamics, micelles, fluorescence quenching.

Preferential solvation of Co2+ and Ni2+ ions in mixed solvents: n.m.r. methods

1968 ◽  
Vol 46 (20) ◽  
pp. 3183-3187 ◽  
Author(s):  
L. S. Frankel ◽  
T. R. Stengle ◽  
C. H. Langford
Keyword(s):  
Preferential Solvation ◽  
Mixed Solvents ◽  
Alternative Methods ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Significant Information ◽  
Coordination Sites ◽  
Coordination Spheres ◽  
Solvent Molecules ◽  
Solvent Proton

A method for the study of preferential solvation in the outer coordination spheres from paramagnetic broadening of solvent proton n.m.r. signals was proposed by Frankel, Stengle, and Langford. It is now extended to determinations of the relative concentrations of water and dioxane, dimethylformamide, or dimethylsulfoxide in the inner coordination spheres of Co2+ and Ni2+ ions in the binary solvent mixtures. The assumptions of the analysis are cross-checked by a new method based on the contact shifts experienced by protons on solvent molecules in the coordination spheres of paramagnetic ions. The second method depends upon assumptions independent of the first. Three cases are presented as tests of these n.m.r. approaches. It is clear that highly precise solvation sphere populations will be difficult to obtain but that useful and significant information can be obtained in situations to which alternative methods are almost totally inapplicable.The results indicate that dimethylsulfoxide and dimethylformamide are good competitors for coordination sites but that dioxane is excluded by water.

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