Synthesis and controlled radical polymerization of axially chiral monomers with a binaphthyl skeleton

Abstract

The synthesis of optically active polymers from monomers with chiral central centers is a well-established method, but reports on the synthesis of optically active polymers using axially chiral monomers are limited. In this study, we present the controlled radical polymerization of axially chiral monomers derived from the commercially available 1,1′-bi-2-naphthol (BINOL) structure. A series of optically active polymers based on the axially chiral structures were successfully polymerized using cumyl dithiobenzoate (CDB) as a chain transfer agent (CTA) for the reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization process resulted in polymers with high conversions and yield controlled molecular weights. The differences observed in the specific optical rotation and the circular dichroism (CD) signal intensity between the polymers and the monomers confirmed the synthesis of optically active polymers with specific structures. Owing to their unique molecular scaffold, these chiral polymers have promising applications in areas such as chiral separation and catalysis. The graphical abstract shows the controlled radical polymerization of axially chiral monomers bearing a 1,1′-bi-2-naphthol (BINOL) skeleton. The evident increase in magnitude and opposite deflection direction of the specific optical rotation between the synthesized polymer and the monomer confirms the synthesis of the chiral polymers with specific structures.