Discrimination of the Chirality of α‐Amino Acids in ZnII Complexes of DPA‐Appended Binaphthyl Imine

Binaphthol aldehydes with appended dipicolylamine moieties, (R)‐1, and (R)‐2, were synthesized. The reaction of (R)‐1 with an amino acid together with the ZnII ion produces a monomeric complex that discriminates the chirality of the bound amino acid by 1H NMR spectroscopy. The same reaction of (R)‐2, which is different from (R)‐1 by only one nitrogen atom, generates a dimeric complex that is highly enantiospecific for the l‐form of amino acids such as Phe and Trp.