Novel chiral monoaza-15-crown-5 ether derivatives 1 and 2 were prepared from l-phenylalaninol and l-leucinol, respectively. The effect of the substituent at the stereogenic center on chiralrecognition and enantioselectivity were investigated. Binding constant (K), free-energy changes (−ΔG0), enthalpy change (ΔH), and entropy change (ΔS) values were determined with enantiomers of organicammonium salts