Long-Range Chiral Induction in Chemical Systems with Helical Organization. Promesogenic Monomers in the Formation of Poly(isocyanide)s and in the Organization of Liquid Crystals

Abstract

The preparation of optically active poly(isocyanide)s derived from chiral promesogenic monomers is reported. Remarkably, the stereogenic carbon atom in the monomer is able to pass its chiral “information” to the growing polymer backbone which is at least 14 atoms (approximately 16 A) remote from it. The sense of helical induction in these conformationally rigid polymers is compared to the helical sense of the cholesteric phases, as well as to the helical senses of chiral smectic C phases, induced by the monomers in nematic and smectic C phases, respectively. Both relate to the odd−even rules for chiral sense changes in liquid crystalline phases. The role of noncovalent interactions in the polymerization has been proven by performing the reactions at various concentrations and in different solventsthe chiral induction from monomer to polymer is greatest in most concentrated reactions and in solvents with a balance between high dipolarity−polarizability and low hydrogen bond accepting and cavitational terms...