Preparation and application of abietic acid-derived optically active helical polymers and their chiral hydrogels

Abstract

A novel chiral monomer N-propargyl abietamide, M1, was synthesized from abietic acid and catalytically polymerized with (nbd)Rh+B−(C6H5)4 (nbd=norbornadiene), providing polymer [poly(1)] with a molecular weight of 13,000–36,000 at a yield of 59–84%. Poly(1) did not form stable helices in tetrahydrofuran at room temperature whereas copolymerization of M1 and the achiral N-propargylamide monomer, M2, led to the formation of helical optically active copolymers as indicated by circular dichroism studies, UV–vis spectroscopy, and specific optical rotation measurements. Hydrogels were prepared based on an optically active helical copolymer, poly(M10.32-co-M20.68) that exhibited enantioselective recognition toward l-alanine. The novel chiral polymers derived from abietic acid are expected to find applications in such areas as chiral recognition, chiral resolution, and chiral catalysis.