The enantiomeric recognition of chiral monoaza-crown ethers for amino acids as their sodium and potassium salts has been investigated by UV–vis. The highest discrimination was observed for TrpK (d/l= 6.47). The reversed enantioselectivity of chiral monoaza-crown ether II was observed for TrpK.
[Aitken, R. Alan; Armstrong, David P.; Galt, Ronald H. B.; Mesher, Shaun T. E. Journal of the Chemical Society - Perkin Transactions 1, 1997 , # 14 p. 2139 - 2145]