Synthesis of aromatic poly(ether ketone)s bearing optically active macrocycles through Suzuki coupling polymerization

Abstract

Palladium (Pd)-catalyzed Suzuki coupling polymerization of macrocycle-bearing monomers, obtained through two-step nucleophilic aromatic substitution reactions with three types of diboric acid pinacol esters, produced aromatic poly(ether ketone)s that have optically active macrocycles composed of two 2,2′-dioxy-1,1′-binaphthyl-6,6′-diyl units and two aromatic ether ketone linkers. The macrocycle-bearing aromatic poly(ether ketone)s have excellent thermal and optical properties, that is, high glass-transition temperatures (Tg: 220–257 °C) and large molar rotations ([Φ]D25: +1906–1976 deg). In addition, polyketones have excellent solubility in typical solvents such as CHCl3 and N,N-dimethylformamide (DMF). Pd-catalyzed Suzuki coupling polymerization of macrocycle-containing monomer with diboric acid pinacol esters afforded aromatic poly(ether ketone)s with optically active macrocycles. The resulting aromatic poly(ether ketone)s have high glass transition temperatures (Tg: 220–257°C), large molar rotations ([Φ]D25: +1906–1976 deg) and excellent solubility to typical solvents such as CHCl3 and DMF.