scholarly journals Potential drug delivery system: study of the association of a model nitroimidazole drug with aggregates of amphiphilic polymers on aqueous solution

2011 ◽  
Vol 47 (4) ◽  
pp. 725-731 ◽  
Author(s):  
Constain Hugo Salamanca Mejia ◽  
Bruno Felipe Urbano ◽  
Andres Floreal Olea Carrasco
Keyword(s):  
Aqueous Solution ◽  
Alkyl Chain ◽  
Standard Free Energy ◽  
System Study ◽  
Varying Length ◽  
Free Energy Of Transfer ◽  
Hydrophobic Microdomains ◽  
Polymeric Solutions ◽  
Model Drug ◽  
Energy Of Transfer

This study evaluated the association of N-hexyl-2-methyl-4-nitroimidazol, a model drug, to aggregates formed by anionic polyelectrolytes on aqueous solution. The alternating copolymers of maleic anhydride and N-vinyl-2-pyrrolidone were synthesized and then modified by reaction of the anhydride groups with aliphatic amines and alcohols of varying length of the alkyl chain. The partition of the model drug between water and the hydrophobic microdomains provided by the copolymers was studied using the pseudo-phase model to determinate the distribution coefficient K S, and the standard free energy of transfer ∆µ°t. The results indicate that all copolymers assessed are potential pharmaceutical reservoirs of the model drug. Nevertheless, the solubility of N-hexyl-2-methyl-4-nitroimidazol on the polymeric solutions is independent from the length of the alkyl chain of the copolymer.

scholarly journals HYDROPHOBIC EFFECTS IN WATER AND WATER/UREA SOLUTIONS A COMPARISON

1994 ◽  
Vol 2 (2) ◽  
pp. 71-82
Author(s):  
E. A. Lissi ◽  
E. B. Abuin
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Alkyl Chain ◽  
Standard Free Energy ◽  
The Other ◽  
Standard Entropy ◽  
Simple Description ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Entropy Of Transfer

The partition of several n-alkanols, from methanol to n-nonanol, between n-hexane and water and between n-hexane and water containing 20 % (w/v) urea has been measured at temperatures ranging from 0 °C to 60 °C. The standard free energy of transfer from water to the urea-containing solution decreases with the length of the alkyl chain, being positive for the small alcohols and negative for the higher alkanols. The same tendency is observed upon all the temperature range considered. On the other hand, the standard entropy of transfer from water to the urea-containing solution increases with the length of the alkyl chain of the alkanol. These results are compatible with a simple description of the urea effect in terms of increasing the entropy of dissolution of the hydrophobic alkyl chain in the aqueous solution.

A vapor pressure method for the simultaneous determination of standard thermodynamic functions of both solutes in a ternary dilute solution

1978 ◽  
Vol 56 (6) ◽  
pp. 844-847 ◽  
Author(s):  
Claude Treiner ◽  
Pierre Tzias ◽  
Marius Chemla
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Vapor Pressure ◽  
Tetrabutylammonium Bromide ◽  
Ternary Mixtures ◽  
Binary Solvents ◽  
Volatile Components ◽  
Polar Group ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

It is shown that from vapor pressure measurements on dilute solutions of ternary mixtures with one nonvolatile component, the standard free energy of transfer (ΔGt0) of both solutes from water to aqueous binary solvents can be determined simultaneously. The method is most useful in the case of volatile components. ΔGt0 values are discussed in particular in the case of the transfer of tetrahydrofuran, acetone, and acetonitrile from water to aqueous tetrabutylammonium bromide and urea solutions and compared to the case of the transfer of nonpolar solutes to the same aqueous solution. In each case, the free energy of transfer from water to an aqueous solution of a nonpolar molecule was negative, and introduction in that molecule of a polar group caused the free energy of transfer to be considerably less negative.

A surface tension approach to the salting-out of nonpolar nonelectrolytes

1982 ◽  
Vol 60 (11) ◽  
pp. 1317-1326 ◽  
Author(s):  
Robert Aveyard
Keyword(s):  
Surface Tension ◽  
Salt Solution ◽  
Standard Free Energy ◽  
Scaled Particle Theory ◽  
Salt Effects ◽  
Salting Out ◽  
Polar Solutes ◽  
Order Of Magnitude ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

A simple approach is developed for the salting-out of nonpolar molecules by strongly solvated salts. The standard free energy of transfer of solute from pure solvent to salt solution, and hence the salting coefficient, k, is calculated in terms of the surface tension increment caused by the addition of salt to the solvent. In its simplest form the method gives k in terms of the molar volumes of solvent and solute, and the osmotic coefficient of the salt solution. It is more successful in the prediction of k than the McDevit and Long theory, and it also has advantages over the more complex scaled particle theory of salt effects. In addition to a range of nonpolar solutes, the salt effects on some alcohols are also considered but application to polar solutes generally requires a knowledge of experimentally determined surface tension increments which are not widely available. The correct order of magnitude for the temperature coefficient of k at room temperature for some alkanes and H2 in water is given, although minima in k as a function of temperature, which have sometimes been observed, are not reproduced.

scholarly journals Standard Free Energy of Transfer of Potassium Chloride from Light to Heavy Water from Solubilities of Sparingly Soluble Salts.

1971 ◽  
Vol 25 ◽  
pp. 361-363 ◽  
Author(s):  
Pentti Salomaa ◽  
Marja Mattsén ◽  
Hans Sievertsson ◽  
Inger Skånberg ◽  
Karl-Gustav Svensson ◽  
...  
Keyword(s):  
Free Energy ◽  
Potassium Chloride ◽  
Heavy Water ◽  
Standard Free Energy ◽  
Soluble Salts ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

Thermodynamic Properties of Aqueous Organic Solutes in Relation to Their Structure. Part I. Free Energy of Transfer from H2O to D2O for a Series of Isomeric Ketones

1973 ◽  
Vol 51 (18) ◽  
pp. 3051-3061 ◽  
Author(s):  
Carmel Jolicoeur ◽  
Ghislain Lacroix
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Scaled Particle Theory ◽  
Cavity Formation ◽  
Degree Of Branching ◽  
Structural Part ◽  
Hydrocarbon Chains ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Heats Of Transfer

The solubilities of 18 decanones have been measured in H2O and D2O at 25 °C from their u.v. absorption spectra. The data were used to calculate ΔGt0, the standard free energy of transfer of these solutes from H2O to D2O ΔGt0 was found negative for the saturated ketones, but positive for most of the unsaturated and polycyclic isomers. A rough correlation was observed between ΔGt0 and the degree of branching in the hydrocarbon chains of the ketones: ΔGt0 increases with the degree of branching. From the temperature dependence of ΔGt0 obtained at 10, 25, and 40 °C, heats of transfer ΔHt0 were determined for typical ketones, namely 2-decanone and adamantanone. ΔHt0 was found as −2.1 kcal mol−1 for 2-decanone and ~0 ± 0.5 kcal mol−1 for adamantanone.The results are discussed in terms of two main contributions: (1) an isotope effect in the free energy of cavity formation and (2) perturbation of solvent structure by the solutes, differing in H2O and D2O. Using the scaled-particle theory to evaluate the former, the variations in the observed ΔGt0 are assigned to the structural part of ΔGt0.

Use of the scaled-particle theory for the determination of single ion standard free energy of transfer between solvents

1977 ◽  
Vol 55 (4) ◽  
pp. 682-685 ◽  
Author(s):  
Claude Treiner
Keyword(s):  
Free Energy ◽  
Mixed Solvents ◽  
Standard Free Energy ◽  
General Rule ◽  
Scaled Particle Theory ◽  
Particle Theory ◽  
Solvent Interactions ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

The tetraphenylboron extrathermodynamic assumption is one of the methods most often used for the evaluation of single ion standard thermodynamic functions of transfer between two solvents. We show in this article that the scaled-particle theory may be useful for discriminating among those solvents for which this extrathermodynamic assumption may be questionable because of strong solute–solvent interactions. Although no general rule is proposed, the tetraphenylboron assumption seems valid in the case of the free energy of transfer between water and solvents like methanol, ethanol, acetonitrile, and formamide; it should not be used in the case of the transfer to solvents like propylene carbonate, dimethylsulfoxide or sulfolane. The scaled-particle theory may also be used to predict within 20% the standard free energy of transfer of the tetraphenylboron ion between water and aqueous mixed solvents; examples are given for water–methanol and water–ethanol mixtures.

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