A dibenzoazacyclooctyne as a reactive chain stopper for [2]rotaxanes

A strained dibenzoazacyclooctyne (DIBAC) derivative was introduced for the preparation of a rotaxane by strain-promoted azide-alkyne cycloaddition (SPAAC), also referred to as a copper-free click reaction. The DIBAC can efficiently act as a bulky reactive chain stopper to transform a pseudorotaxane architecture consisting of a diazo-functionalized dialkoxy-naphthalene guest and a tetracationic cyclobis(paraquat-p-phenylene) (CBPQT(4+)) host into the corresponding [2]rotaxane. Furthermore, the use of the DIBAC is demonstrated to be limited to short rigid macrocycles, as it is unable to act as stopper for a rotaxane featuring a larger crown ether macrocyclic host.