Synthesis and properties of helical poly(phenylacetylene) derivatives. Effect of chirality combination on the helicity

Novel 4-ethynylphthaloyl amino acid esters carrying different terminal groups, 4-ethynylphthaloyl glycine (1S,2R,5S)-menthyl ester (1), 4-ethynylphthaloyl glycine (1R,2S,5R)-menthyl ester (2), 4-ethynylphthaloyl L-leucine methyl ester (3), 4-ethynylphthaloyl L-leucine (1S,2R,5S)-menthyl. ester (4), 4-ethynylphthaloyl L-leucine (1R,2S,5R)-menthyl ester (5) were synthesized and polymerized with a rhodium catalyst. Polymers with high molecular weights were obtained in 71-92% yields. The helical conformation of the polymers could be tuned by the chirality of the amino acid connected to the backbone, together with the chirality and bulkiness of the terminal pendent groups. (C) 2008 Wiley Periodicals, Inc.