Detection of the chirality of C α ‐methylated α‐amino acids with a dynamic helical poly(phenylacetylene) bearing aza‐18‐crown‐6 ether pendants

A stereoregular poly(phenylacetylene) bearing the aza‐18‐crown‐6 ether pendants (poly‐ 1 ) was found to form a predominantly one‐handed helix upon complexation with optically active C α ‐methylated α‐amino acids and their amide derivatives including typical meteoritic C α ‐methylated α‐amino acids such as C α ‐methyl norvaline and C α ‐methyl valine. The complexes exhibited an induced circular dichroism (ICD) in the UV‐visible region of the polymer backbone. Therefore, poly‐ 1 can be used as a novel probe for detection of the chirality of C α ‐methylated α‐amino acids. The effect of the enantiomeric excess (ee) of C α ‐methylated α‐amino acids on the helicity induction in poly‐ 1 was also investigated. Chirality, 2006. © 2006 Wiley‐Liss, Inc.