Pillar [5]arene-based [2]rotaxanes have been prepared from the reactions of diacyl chloride reagents with various amine stoppers. The yields of the [2]rotaxanes are sensitive to the reaction conditions (solvent and stoichiometry) as well as to structural and electronic factors. In particular, the nature of the starting amine reagent has a dramatic influence on the yields of [2]rotaxanes; thus, the reaction outcome is not simply related to the binding constant of the diacyl chloride reagent with the pillar[5]arene. Indeed, the differences in the

The cover picture shows a pseudorotaxane intermediate bearing an acyl chloride unit ready to react with an amine stopper to afford a pillar[5]arene‐based [2]rotaxane. The yield of [2]rotaxane is sensitive to the reaction conditions but also to electronic and structural factors, in particular the nature of the amine reagent and the size of the peripheral groups on both rims of the pillar[5]arene building block. Details are discussed in the article by R. Deschenaux, J.‐F. Nierengarten et al. on .