Study on Molecular Recognition through the Inclusion Complex Formation of Helical Polymers

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Syndiotactic poly(methyl methacrylate) (st-PMMA), a stereoregular commodity plastic, can encapsulate fullerenes such as C_<60> and C_<70> within its helical cavity to form a crystalline inclusion complex. We found that the st-PMMA helical cavity formed in toluene recognizes the encapsulated fullerene size and changes its helical structure flexibly depending of the size of guest molecules. On the basis of the preferential encapsulation of st-PMMA, higher fullerenes (> C_<76>) were selectively obtained from carbon soot. Moreover, it was found that polycyclic aromatic hydrocarbons such as pyrene and phenanthrene can be encapsulated in the st-PMMA helical cavity, leading to novel crystalline inclusion complexes with unique characteristics based on the arrayed guest species. We also found C_<60> to be soluble in polar solvents when st-PMMA was used as a solubilizing agent ; C_<60> dissolves through inclusion complex formation. Furthermore, we developed a facile synthetic procedure of highly stereoregular polymethacrylates with various ester groups as pendants.