Development of Novel Synthetic Method of Rotaxane by Utilizing Dynamic Property of SS Linkage and Its Application to Molecular Materials

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This work was to synthesize rotaxanes by utilizing reversible cleavage of disulfide linkage. During these three years, many important findings have been done. In the synthetic method, dumbbell-shaped disulfide reacts with thiol to give rise to the reversible cleavage of the disulfid bond during which wheel molecule slips into the disulfide bond to yield the corresponding rotaxane. One of the purposes of this work was to complete the synthetic method and the method was actually useful in the syntheses of many [2] and [3]rotaxanes in high yields. The highest yield reached 95% via precise thermodynamic control. We have named mis method "entering method".Meanwhile, in the case of [2]rotaxane obtained which has two annmonium groups one of which was covered with crown ether wheel, the wheel componet can move freely from one ammonium moiety to another one when some conditions are fulfilled, that is known as "shuttling". Effect of substituents on the crwon ether wheel was studied by ^1H NMR method, and the shuffling rate was enhanced as the electron-donating power of the substituents increased. As an application of the synthetic method to the synthesis of polyrotaxane, poly[3]rotaxane was synthesized with bifunctional ammonium salt and crwon ether. As a result, first ply[3]rotaxane with MW 30000 was obtained only by mixing the two bifunctional components in the presence of a catalytic amount of thiophenol. The poryrotaxane had topotogical lilnkages as the linking structure of the monomer units, while the poly[3]rotaxane thus prepared was the first topological polymer.The novel synthetic method "entering method" was completed through the work which enabled the high yield syntheses of [2] and [3] rotaxanes, and the first topological polymer was obtained by applying die method to the bifunctional monomers.