Cycloamyloses as enzyme models. Effects of inclusion complex formation on intramolecular participation

The Stability of Cyclodextrin Complexes in Solution

“…In this model the "driving force" for association may appear as either a favorable enthalpy or entropy change, and it follows that to rely on the sign or magnitude of ∆H°or ∆S°a s a criterion of interaction mechanism or type of intermolecular force is risky in these systems. van der Jagt et al 481 reached a similar conclusion in 1971.…”

Towards an Understanding of the Molecular Mechanism of Solvation of Drug Molecules: A Thermodynamic Approach by Crystal Lattice Energy, Sublimation, and Solubility Exemplified by Hydroxybenzoic Acids

“…From Scheme follows, that 3‐ and 4‐hydroxybenzoic acids can be regarded as classical cases of a compensation effect for the transfer process, whereas for 2‐hydroxybenzoic acid—a “nonclassical” behavior with prevailing of hydrophobic effects20–22 is observed. Nevertheless, it should be noted, that for all the considered compounds the transfer process is enthalpy driven, which also is in accordance with partitioning experiments 24.…”

Complexation and Chiral Recognition Thermodynamics of 6-Amino-6-deoxy-β-cyclodextrin with Anionic, Cationic, and Neutral Chiral Guests: Counterbalance between van der Waals and Coulombic Interactions

“…In many cases, the hydrophobic and van der Waals interactions are the principal intermolecular weak forces responsible for the formation of stable supramolecular complexes, although it is difficult to rigorously separate the contributions of these two forces in general and particularly in the complexation of CDs . Furthermore, the intracavity interactions between CD and guest could be better described by a “nonclassical” hydrophobic model, where the enthalpy (Δ H °) and entropy changes (Δ S °) can be either positive or negative, ,, rather than by a “classical” one, where both Δ H ° and Δ S ° are positive. , Indeed, the degree of hydrophobicity is not uniform over the whole CD cavity but varies from point to point, and the cavity surrounded by several C−O dipoles should be considered moderately polar rather than totally nonpolar. 10a,b In view of the intermolecular forces involved, there are several significant differences between the classical hydrophobic process, i.e., the transfer of organic molecule from water to nonpolar organic media, and the inclusion complexation by CD which involves the insertion of a less-polar part of the guest into the CD cavity. First, the size and shape of the CD cavity are defined by the covalently bonded glucose units.…”