Cationic Ring Opening Cyclopolymerization of Bis(oxazolines). Synthesis of Chiral Polymers Containing Pendent Heteromacrocycles

Abstract

Novel biphenyldiylbis(oxazoline) and both racemic and optically active and binaphthyldiylbis(oxazolines) (1−4) have been cationically cyclopolymerized to give polymers that contained pendent heteromacrocyclic metal receptors. The optically active cyclopolymers showed very high specific optical rotations per repeat unit that varied between [α −248° and [α −321° depending upon the solvent. Circular dichroism spectra and optical rotation showed dependence on molecular weight. The cyclopolymers are thermally robust with decomposition temperatures >400 °C and glass transition temperatures (Tg) between 200 and 302 °C. The polymers were reduced with AlH3 to give polymers with pendent nitrogen-containing heteromacrocycles. Dichloromethane solutions of the reduced polymers were used to extract Cu(NO3)2 from aqueous solutions to give complexes whose stoichiometry varied from 3−4 Cu2+ ions per five reduced repeating units. The Cu2+-containing cyclopolymers gave higher Tg (100−180 °C) than obtained for the reduced polymers (72−138 °C) which in turn gave much lower Tg than did the corresponding unreduced polymers