[2]Catenanes and inclusion complexes derived from self-assembled rectangular PdII and PtII metallocycles

New inclusion complexes and [2]catenanes were self-assembled from a fluorescent diazapyrenium based ligand, a Pd-II or Pt-II complex, and cyclic or acyclic electron rich aromatic guests in aqueous and organic media. The molecular rectangles display a pi-deficient cavity suitable to incorporate pi-donor aromatic systems. The inclusion complexes between the metallocycles and phenylenic (2a,b) and naphthalenic (3a,b-5a,b) derivatives were studied by NMR, UV-vis and fluorescence spectroscopy. The crystal structure of (3b) subset of 1a center dot 6PF(6) confirmed the insertion of the guest into the cavity of the metallocycle. Following the same self-assembly strategy, the use of polyethers 6,7 as pi-donors resulted in the self-assembly of the [2]catenanes 1a(6,7)center dot 6PF(6). Single-crystal X-ray analysis of 1a(7)center dot 6PF(6) revealed the [2]catenane structure being stabilized by p-stacking and [C-H center dot center dot center dot O] interactions.