C2 -Symmetric chiral diamine ligands for enantiomeric recognition of amino acid esters and mandelic acid by proton NMR titration method
C2 -Symmetric chiral diamine ligands for enantiomeric recognition of amino acid esters and mandelic acid by proton NMR titration method
Two novel C2 -symmetric chiral diamines containing α-phenylethyl and α-(1-naphthyl)ethyl chiral subunits were prepared with quantitative yields. Enantiomeric recognition properties of these simple structured diamine ligands towards D- and L-amino acid esters and D- and L-mandelic acid were examined by the 1 H NMR titration method. These ligands exhibited strong complexation (with Kf up to 2481 M−1 ) and good enantioselectivity (up to K L /K D = 4.08) towards the mandelic acid enantiomers.