Chiroptical study and conformation analysis of helical polymers surrounded by helical hydrogen-bonding strands

The chiroptical properties of poly((S)-N-(3-butynyl)-3-methylpentanamide) (poly(1)) were studied, and the conformation was analyzed. Poly(1) exhibited a large specific rotation and Cotton effect in CHCl3, indicating that it took a helical structure with predominantly one-handed screw sense. From liquid state IR spectroscopic analysis along with molecular mechanics and semiempirical molecular orbital calculations, it was concluded that the helix was stabilized by intramolecular hydrogen-bonding strands between the amide groups of nth and (n+3)th units.