Received July 25, 2007

Abstract:

Poly-pseudo-rotaxanes CDs1 (CDs; cyclodextrins, 1; poly(-valerolactone) having single -CD at the end of the polymer chain) initiate polymerization of -valerolactone (-VL) in the solid state when CDs (-CD, -CD, and 2,6-di-O-methyl--CD) are threaded onto the polymer chain. 1 without threaded CDs did not show any polymerization ability for -VL. An adamantane molecule (Ad) inhibited the polymerization ability of CDs1 for -VL, indicating that -CD at the end of CDs1 could not bind -VL because the -CD cavity was occupied by Ad. It should be noted that the insertion reaction and the polymerization took place inside the -CD cavity at the end of CDs1 and that the formation of poly-pseudo-rotaxane is necessary for the initiation of -VL. The structures of -CD1 and 1 were characterized by powder X-ray diffraction measurements and solid-state NMR spectroscopies. The polymer chain of -CD1 was found to elongate in the solid state, whereas the polymer chain of 1 formed a random coil conformation. 1 was deactivated for the polymerization by blocking the active cavity of -CD with the polymer chain. CDs threaded onto 1 are immune to the initiation of -VL directly but have an essential role to fold the polymer chain in a proper way as an artificial chaperone.

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