Interrelation of Entropic Contributors to $$\pi $$ π -Stacking in Solution

Abstract

The recently published most complete set of thermodynamical data on selfand hetero-complexation of aromatic molecules measured under comparable experimental conditions were analyzed. The main aim of this study is to get insights into contribution of various entropic factors to π -stacking in aqueous solution. It was found that the experimental entropy change on π -stacking is determined by counterbalancing effects of two principal factors, i.e., the hydrophobic interaction (positive contribution) and the loss of degrees of freedom (negative contribution) modulated by the electrostatic contribution. Other factors, including the mixing entropy contribution, were shown to be less important.

Entropy‐driven binding of octyl gallate in albumin: Failure in the application of temperature effect to distinguish dynamic and static fluorescence quenching

“…The physicochemical background for the application of temperature criterion to distinguish static and dynamic quenching is the formation or not of the ground‐state complex. As well established, the complexation of molecules is accompanied by a natural loss in the translational and rotational degrees of freedom, that is, negative Δ S . Hence, considering the Gibbs equation (Equation ), an augment in temperature will be unfavorable for complexation and the consequence is a decrease in the binding constant.…”

“…These results confirmed the entropy‐driven features of the interaction of G8 with BSA. Accordingly, the total entropy change for protein‐ligand interaction has been proposed as a sum of three components: (a) Δ S solv , which represents the solvent entropy change due to solvent release upon binding; (b) Δ S conf , which represents the conformational entropy change due to conformational freedom of both the protein and ligand upon binding, and (c) Δ S r/t , which represents the loss of translational and rotational degrees of freedom of the protein and ligand upon complex formation . In this sense, Δ S solv must be the major contributor to the total entropy change in the interaction with G8.…”