Cyclopolymerization through large ring formation

Large cyclic structures are capable of interacting with low-molecular weight molecules or ions, which fit to the rings. Such interactions play important roles in biological activities. Polymers bearing large ring structures can serve as hosts for supramolecular complexes, and their applications involve stationary phases for separation, (chiral) templates for reactions, and ligands. However, large ring formations are typically difficult, and as a result, polymerizations accompanied by consequtive formations of large rings are more difficult. Accordingly, we are trying to polymerize monomers designed for large ring formations.

Synthesis of polymers bearing 11-membered chiral rings

 Radical polymerization of a bisacrylamide prepared from a-pinene proceeds through 11-membered ring formation, and gave the corresponding polymer in quantitative yields. The MALDI-TOF mass spectroscopy analysis of the polymer demonstrated that the cyclopolymerization was not accompanied by undesired inter-polymer propagation.

(Optimized geometry of the monomer calculated by the HF3-21G* basis-set based on the conformation optimized by MMFF calculation)

Potential applications of this polymer are chiral resolution media and chiral templates。

Nagai, A.; Ochiai, B.; Endo, T. Macromolecules, 2005, 38, 2547-2549.

Controlled cyclopolymerization through 19-membered ring formation

 We designed a dimethacrylate whose conformation is fixed by the cyclohexane ring and the hydrogen-bonding urethane groups. The radical polymerization of this monomer procceds smoothly, and yields a soluble polymer in quantitative yield. The RAFT polymerization proceeds via controlled fashion.

Ochiai, B.; Ootani, Y.; Endo, T. J. Am. Chem. Soc. 2008, 130, 10832-10833.

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