A chiral co-crystalline form of poly(2,6-dimethyl-1,4-phenylene)oxide (PPO)

Abstract

For an industrially relevant specialty polymer, poly(2,6-dimethyl-1,4-phenylene)oxide (PPO), for the first time, a crystalline structure is resolved. It is a co-crystalline structure of the polymer with a chiral guest molecule (α-pinene), exhibiting a 2/1 monomer-unit–guest molar ratio. The most relevant feature of this co-crystalline structure is its chirality. In fact, the unit cell includes all left- or right-handed polymer helices and (1S)-(−)- or (1R)-(+)-α-pinene guest molecules, respectively. The induction of non-racemic macromolecular helicity in the co-crystalline structure, clearly confirmed by VCD measurements, leads to amplification of chirality. Guest extraction procedures from the PPO–α-pinene co-crystalline form produce optically inactive nanoporous-crystalline modifications, which present high sorption ability toward organic compounds.