Design and synthesis of semiflexible substituted polyacetylenes with helical conformation

In this review article, we summarize our recent efforts on the design and synthesis of helical polymers from propiolic esters. Stereoregular cis-transoidal poly(propiolic esters) prepared with Rh catalysts have proven to possess semiflexible main chain, which drives the main chain to the helical conformation with long persistence length. Based on the chiroptical properties of poly(propiolic esters) bearing various chiral pendants, we established the design strategy for the production of well-ordered helical poly(propiolic esters). NMR study of various poly(propiolic esters) enabled estimation of not only the activation energy of helix reversal, but also the free energy difference between the helical and disordered states. The helix sense of poly(propiolic esters) is determined by the configuration of the chiral center, structure of the pendant groups, temperature, and solvent. (C) 2002 Elsevier Science B.V. All rights reserved.