Chiral separation of racemic amino acids with novel polyamides having N-α-acetyl-l-glutamyl residue as a diacid component

Novel polyamides with asymmetric carbons in their main chains were obtained from aromatic diamines, 4,4′-diaminodiphenylmethane (DADPM) or 1,3-phenylenediamine (1,3-PDA), and N-α-protected l-glutamic acid, N-α-acetyl-l-glutamic acid (Ac-l-Glu-OH). Newly prepared polyamides showed optical rotation, implying that optically active polyamides were successfully obtained in the present study. These two types of chiral polyamides showed chiral recognition ability, which was studied by surface plasmon resonance (SPR) spectroscopy; they recognized d-glutamic acid in preference to the corresponding l-isomer. The adsorption selectivity was determined to be 1.66 for 1,3-PDA-Ac-l-Glu and 1.49 for DADPM-Ac-l-Glu. Enantioselective electrodialysis was studied adopting racemic N-α-acetyl-tryptophan (Ac-Trp) mixtures as model pairs of enantiomers. The membranes selectively transported Ac-d-Trp. Permselectivity toward the d-isomer reached 2.03.