Entropy enthalpy compensation

The relationship of thermodynamic functions of selective bonding of Hb to a series of carboxylic CP in the variation of the degree of ionization of carboxylic groups is expressed by the effect of enthalpy-entropy compensation (Fig. 18). The compensation effect of enthalpy and entropy components is the most wide-spread characteristic of many reactions in aqueous solutions for systems with a cooperative change in structure [78],... [Pg.30]

Guillaume et al. [69] presented a high performance liquid chromatographic method for an association study of miconazole and other imidazole derivatives in surfactant micellar using a hydrophilic reagent, Montanox DF 80. The thermodynamic results obtained showed that imidazole association in the surfactant micelles was effective over a concentration of surfactant equal to 0.4 pM. In addition, an enthalpy-entropy compensation study revealed that the type of interaction between the solute and the RP-18 stationary phase was independent of the molecular structure. The thermodynamic variations observed were considered the result of equilibrium displacement between the solute and free ethanol (respectively free surfactant) and its clusters (respective to micelles) created in the mobile phase. [Pg.49]

K. J. Breslauer, D. P. Remeta, W. Y Chou, R. Ferante, J Curry, D. Zauczkowski, J. G. Snyder, and L. A. Marky, Enthalpy-entropy compensations in drug-DNA binding studies, Proc. Natl. Acad. Aci. USA 84 892 (1987). [Pg.166]

Enthalpy-entropy compensation has been investigated in reversed-phase HPLC with octylsilica stationary phase [77]. The compensation temperatures were determined for this system, and the results show that their change with the composition of the mobile phase is almost similar to that with octadecylsilica stationary phase. It can be concluded that the retention mechanisms of the separation of alkyl benzenes is the same in both systems with the mobile phase exceeding 20% water content. [Pg.537]

The latter describes in essence a phenomenon more commonly known as enthalpy-entropy compensation. One way of stating this is that the free energy changes in similar processes are kept within a narrow interval because AH and AS vary in proportion, and thereby compensate each other, through the equation... [Pg.130]

Effusive beam technique, 157-158 Electron bombardment flow radiolysis, 238 Electrospray ionization and ionic clusters, 168 Enantiomers, separation techniques, 154-155 Enantioselectivity of enzymes, 148 Enthalpy-entropy compensation plots, 261 Enthalpy of activation, and quantum tunneling, 67, 70-71... [Pg.339]

Fig. 4.—Enthalpy-Entropy Compensation for Alpha Cyclodextrin Inclusion-Complexes. [The guest identification numbers are as given in Table II.]...

Enthalpy-entropy compensation, is expected to occur only if unity of mechanism exists. From the slope of the enthalpy vs entre y plot the so-called compensation temperature, which is chm teristic for the type of transformation under investigation, can be calculated. [Pg.308]

A. A. Edwards, J. M. Mason, K. Clinch, P. C. Tyler, G. B. Evans, and V. L. Schramm, Altered enthalpy-entropy compensation in picomolar transition state analogues of human nucleoside phosphorylase, Biochemistry, 48 (2009) 5226-5238. [Pg.288]

This temperature effect is the usual one for a regular or enthalpy-entropy compensated chromatographic separation, suggesting that the retention of each... [Pg.48]

MOLECULAR RECOGNITION IN CHEMISTRY AND BIOLOGY AS VIEWED FROM ENTHALPY-ENTROPY COMPENSATION EFFECT ... [Pg.55]

Enthalpy—Entropy Compensation Effect as Extrathermodynamic Relationship. 64... [Pg.55]

ENTHALPY-ENTROPY COMPENSATION EFFECT AS EXTRATHERMODYNAMIC RELATIONSHIP... [Pg.64]

It would be somewhat surprising that the enthalpy-entropy compensation, though never derived from the fundamental thermodynamic relationships, is found so abundantly in various reactions and equilibria and that the reaction rate and equilibrium are independent of any perturbing factors at the specific temperature. However, it seems natural at the same time that chemical events are not controlled exclusively by a single factor but are rather governed by multiple factors correlating each other. [Pg.66]

It is thus demonstrated that the inclusion behavior of cyclodextrins is similarly analyzed and interpreted in terms of the enthalpy-entropy compensation effect, although the major weak forces involved are quite different from those working in... [Pg.83]

One of the most intriguing biological supramolecular systems that should be examined by the enthalpy-entropy compensation theory is the duplex formation and intercalation of DNA and RNA. [Pg.89]

It is advised therefore that the extrathermodynamic analysis based on the enthalpy-entropy compensation effect should be restricted to the (suprajmolecular recognition phenomena governed by cooperative weak interactions. [Pg.91]

Bustamante, P., S. Romero, A. Pena, B. Escalera, and A. Reillo, Enthalpy-entropy compensation for the solubility of drugs in solvent mixtures Paracetamol, acetanilide, and nalidixic acid in dioxane-water , J. Pharrn. Sci., 87, 1590-1596 (1998). [Pg.1218]

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