Abstract
Helical polyisocyanides have been precisely synthesized by living polymerization of aryl isocyanides with an acetylene-bridged Pd-Pt dinuclear complex. Polymerization of chiral aryl isocyanide monomers that had stereogenic carbons at α-position of ester bonds produced one-handed helical polymers selectively. Because these polymers had high regularity of the imino groups in the main chain, the selectivity of one-handed helix was much higher than that prepared by a Ni (II) salt. Helical-sense selective polymerization of bulky achiral monomer was achieved by using a helical oligomeric initiator that was prepared by oligomerization of chiral monomers. Isocyanide monomers with porphyrin groups were polymerized by the present polymerization system to give helical porphyrin arrays, and were applied for determination of helical sense by exciton coupled circular dichroism. Polyisocyanides possessing chiral ferrocenyl pendants exhibited a circular dichroic response with reversible conformational change on electrochemical stimulus.
