Cyclobis(paraquat-p-phenylene)^1,2 (CBPQT⁴⁺, A in the Box) is a much exploited ring component in rotaxanes and catenanes. The sensitivity of this tetracationic ring to bases and nucleophiles dictates the sequence of steps in traditional preparations of (supra)molecular systems in as much as it necessitates 1) the prior formation of an acyclic (rotaxanes) or cyclic (catenanes) templates, followed by 2) the templated clipping³ of the CBPQT⁴⁺ ring around the templates. The latter reaction is often low-yielding and – on account of the fact that it is the very last step in synthesis – highly wasteful.

The advent⁴ of the mild and highly selective, Cu(I)-catalyzed, 1,3-cycloaddition (click reaction) of organic azides and alkynes opens up the possibility to invert the above mentioned sequence of steps. This alternative methodology would be the synthetic complement of the one described above and should lead to a significant increase in the yields of the desired compounds. Indeed, subjecting the suitably end-functionalized pseudorotaxane B (formed by complexation of CBPQT⁴⁺ and the naphthalene-based guest) to the click reaction afforded the catenane C, which was characterized by ¹H and ¹³C NMR spectroscopy and mass spectrometry. The results of additional synthetic forays will be described in the poster.