Calorimetric determination of chiral interactions in aqueous solutions. Part 2. N-Acetyl-leucinamide at 298.15 K.

The heats of dilution in water of the binary and ternary solutions of the two enantioneric forms of N-acetyl-leucinamide have been determined at 298.15 K using a microcalorimetric procedure. The excess enthalpies obtained by these data, and expressed as varial expansion series, permit the evaluation of the pairwise homotactic and heterotactic enthalpic coefficients. As for the chiral forms of other N-acetyl-peptidoamides and of a few monosaccnarides, the etherotactic coefficient for the interactions between the D- and L- enantiomers is slightly but significantly different from the corresponding homotactic coefficients. A weak solvent-mediated chiral recognition can be assumed to still exist in a polar screening solvent, such as water.