Synthesis of Well-Defined Chiral Oligopinanylsiloxane Graft Copoly(phenylacetylene)s Using the Macromonomer Method and Their Enantioselective Permeability

Abstract

As enantioselectively permeable membrane materials showing high permeability and good self-membrane forming ability, 24 well-defined chiral graft copolymers (PPA-graft-OMPS) consisting of flexible chiral oligomethylpinanylsiloxane (OMPS) grafts and a rigid poly­(phenylacetylene) (PPA) backbone were synthesized stepwise in a well-controlled manner. First, synthesized cyclic OMPS monomers containing one or two chiral pinanyl groups were used in living anion ring-opening polymerization to produce the precursors of the corresponding macromonomers whose degrees of polymerization were controlled. Then, by introducing a triple bond at one end of the precursors, the macromonomers were obtained. Finally, PPA-graft-OMPSs with controlled numbers of the grafts were synthesized by copolymerization of the macromonomers with phenylacetylene comonomers. The PPA-graft-OMPSs show good self-membrane forming abilities in spite of the very high content of the flexible OMPS unit because of the rigid conjugated backbone. They show stable enantioselective permeation with high permeability for around 1000 h based on solution selectivity.

Recent Advances in Separation and Analysis of Chiral Compounds

“…A series of chiral graft copolymers were prepared with flexible chiral oligomethylpinanylsiloxane grafts and a rigid poly­(phenylacetylene) backbone by Zang and Aoki et al (Figure ). The copolymer with the highest amount of grafts presented the highest selectivity value for the separation of racemic mandelic acid, and the permeability was 100 times higher than that of the chiral homopolymer. Triptycene-based polyimides are also popular materials with high porosity and intrinsic chirality.…”

Recognition in the Domain of Molecular Chirality: From Noncovalent Interactions to Separation of Enantiomers

“…875 In the last few years, functionalized one-handed helical polyacetylenes have been also used as enantioselective membranes for the enantioseparation of phenylethylamine 876,877 and mandelic acid. 878 4.4.2. Crystallization.…”

Preparation and Enantioselective Permeation of Polymer Membranes Containing One-Handed Helical Channels

“…On the other hand, separation by enantioselective permeation through membranes is a simple and continuous process and could treat a large amount of racemates. Therefore, we − and others , synthesized several chiral polymer membranes and reported their enantioselectivities. However, when a membrane showed high selectivity, its permeability was very low. − …”

“…Therefore, we − and others , synthesized several chiral polymer membranes and reported their enantioselectivities. However, when a membrane showed high selectivity, its permeability was very low. − …”