Linear hydrophobic congeneric groups of bile acid anion derivatives based on the self-association (micellization) process and the phenomenon of enthalpy–entropy compensation

Abstract

If anions of bile acids form primary micelles by means of hydrophobic effect and interaction, then these anions of bile acids in the lnk - lnCMC plane (k = RP-HPLC capacity factor and CMC = Critical Micellization Concentration) form linear hydrophobic congeneric groups (LCG). Bile salts that form H-bonds in the primary micelles hydrophobic domain are outliers concerning LCG from the plane lnk - lnCMC. In the manuscript, LCG is described using a thermodynamic approach (analytical theory). LCG resulting from enthalpy-entropy compensation (EEC) in the plane of enthalpy and entropy of bile salts micellization is connected with an LCG in the plane of lnk - lnCMC. Bile acid anion, an outliner in the plane of lnk – lnCMC, in the plane of enthalpy and entropy of micellization is included in LCG. This means that in the EEC phenomenon, the formation of LCG is not determined solely by the hydrophobic effect and interaction but also by the energy and the entropy changes of the hydrogen bonds in primary micelles.