Entropy driven

Eldridge M D, Madden P A and Frenkel D 1993 Entropy-driven formation of a superlattioe in a hard-sphere binary mixture Mol. Phys. 79 105-20... 

What distinguishes water from ordinary organic solvents and justifies the term hydrophobic interaction is the molecular origin of the effect, being entropy driven in pure water at room temperature and resulting primarily from the strong water-water interactions. 

If one would ask a chemist not burdened with any knowledge about the peculiar thermodynamics that characterise hydrophobic hydration, what would happen upon transfer of a nonpolar molecule from the gas phase to water, he or she would probably predict that this process is entropy driven and enthalpically highly unfavourable. This opinion, he or she wo ild support with the suggestion that in order to create room for the nonpolar solute in the aqueous solution, hydrogen bonds between water molecules would have to be sacrificed. 

M. Dijkstra, D. Frenkel. Evidence for entropy-driven demixing in hard-core fluids. Phys Rev Lett 72 298-300, 1994. 

We called this material the chameleon TPE. This material represents a new concept in material science entropy-driven TPE (ETPE). 

The main models are described in a review by Vrhovski and Weiss [8]. For ideal elastomers in the extended mode, all the energy resides on the backbone and can therefore be recovered upon relaxation [18]. Generally, it is believed that the mechanism of elasticity is entropy-driven, thus the stretching decreases the entropy of the system and the recoil is then induced by a spontaneous return to the maximal level of entropy [8]. 

Reactions that have positive AH° and positive A S ° are favored by entropy but dis-favored by enthalpy. Such reactions are spontaneous at high temperature, where the T AS° term dominates A G °, because matter becomes dispersed during the reaction. A reaction is entropy-driven under these conditions. These reactions are nonspontaneous at low temperature, where the A iiT ° term dominates A G °. 

A. Miklavc, D. Kocjan, J. Mavri, J. Roller and D. Hadzi, On the fundamental difference in thermodynamics of agonist and antagonist interactions with P-adrenergic receptors and the mechanism of entropy-driven binding. Biochem. Pharmacol., 40 (1990) 663-669. 

Figure 5.5 Comparing liposome-water to octanol-water partition coefficients of a series of uncharged substituted benzylalkylamines [387]. The membrane partitioning of the smaller members of the series (n — 0 3) is thought to be dominated by electrostatic and H-bonding effects (enthalpy-driven), whereas the partitioning of the larger members is thought to be directed by hydrophobic forces (entropy-driven) [387]. [Avdeef, A., Curr. Topics Med. Chem., 1, 277-351 (2001). Reproduced with permission from Bentham Science Publishers, Ltd.]...

The interaction between 4-(4-hydroxybut-2-ynyloxy)-3-(phenylsulfonyl)-l,2,5-oxadiazole-2-oxide 16 and bovine serum albumin (BSA) was studied by spectroscopic methods including fluorescence and UV-Vis absorption spectroscopy. The results indicate that molecules 16 bind with BSA forming 1 1 complex. Thermodynamic parameters, such as AH, AG, and A.Y, were calculated. The results indicate that the binding reaction is mainly entropy driven and hydrophobic forces play a major role in this reaction <2006CHJ1050>. 

Excellent reviews on micelles formed in organic solvents have been published by Hamley [2], Chu et al. [86], and Riess [14]. From these overviews it appears that a wide range of styrene-, (meth)acrylates-, and dienes-based block copolymers were investigated and that the formation of micelles in organic solvents can generally be considered as an entropy-driven process. AB diblock and ABA triblock architectures were systematically compared. All these previous investigations have been summarized by Hamley [2], We will therefore not perform an extensive review of all these systems, since this information has already been provided by others, but we will briefly outline some selected examples. 

As noted in table 11.1, the ability of THFTCA to separate LJO from trivalent lanthanide ions is mainly of enthalpic origin. Reaction 11.33 has a considerably more unfavorable enthalpic contribution than reaction 11.32. The complexation is, however, predominantly entropy driven because the T ArS° term dominates the ArH° contribution for all systems. The large positive entropy changes observed for reactions 11.32 and 11.33 result from the release of water molecules coordinated to the metal on complexation with the tridentate THFTCA2- ligand. Note that a negative entropy contribution would be expected if these reactions were truly 2 particle = 1 particle reactions [226]. 

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