Dependence of the cooperativity of hydrophobic interactions on the nature of functional groups. A microcalorimetric study of binary aqueous solutions of α,ω-difunctional compounds at 298.15 K

Enthalpies of dilution of binary aqueous solutions containing α,ω-amino acids, α,ω-dicarboxylic acids, α,ω-diamines and α,ω-diols have been determined at 298.15 K by flow microcalorimetry. The pairwise enthalpic coefficients of the virial expansion of the excess enthalpies were evaluated. These coefficients show that the investigated substances differ greatly in the cooperativity of their hydrophobic interactions, depending on the nature of the functional group. The diamines show the highest cooperativity among the solutes studied to date. The coefficients were interpreted using the 'preferential configuration' model and compared with the results obtained from a statistical approach.