We have designed a novel stereoregular poly(phenylacetylene) bearing the bulky crown ether as the pendant (poly-1) for the amino acid binding site. The polymer forms a one-handed helix upon complexation with l-amino acid perchlorates, and the complexes exhibit an induced circular dichroism (ICD) with the same Cotton effect signs in the polymer backbone region through a significant cooperative interaction. Poly-1 is highly sensitive to the amino acid chirality and can detect an extremely small enantiomeric imbalance in alpha-amino acids (less than 0.005% enantiomeric excess of alanine, for example).

A novel stereoregular poly(phenylacetylene) with the bulky aza-15-crown-5 ether as the pendant was prepared by polymerization of the corresponding phenylacetylene monomer with a rhodium catalyst. The polymer was found to form a predominantly one-handed helical conformation upon complexation with various chiral compounds, such as amino acids, amines, and amino alcohols through noncovalent interaction in organic solvents and water. The complexes exhibited an induced circular dichroism (ICD) in the UV−vis region of the polymer backbone; in particular, the polymer showed high affinity to secondary amines, and the complexes exhibited relatively intense ICDs. The assay of 19 common free l-amino acids gave the same ICD sign in acetonitrile−5 N HClO4 (99.88/0.12, v/v). The effects of pH, temperature, and guest concentration on the ICD during the complexation of poly-1 with chiral compounds were also investigated.

A stereoregular poly(phenylacetylene) bearing the bulky aza-18-crown-6 ether as the pendant (poly-1) formed a predominantly one-handed helical conformation upon complexation with various chiral compounds, such as amino acids, peptides, aminosugars, amines, and amino alcohols in water. The complexes exhibited an induced circular dichroism (ICD) in the UV-visible region of the polymer main chain. Therefore, poly-1 can be used as a novel probe for determining the chirality of chiral compounds in water. The assay of 19 common free L-amino acids gave the same ICD sign at 0°C except for L-phenylalanine. The effects of pH, temperature, guest concentration, and organic solvent content on the ICD during the complexation of poly-1 with chiral compounds were also investigated.

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