New self-assembled dinuclear Pd(II) and Pt(II) metallomacrocycles of a 4,4′-bipyridin-1-ium ligand with an inner cavity

New dinuclear Pd(II) and Pt(II) metallocycles of 1-(pyridin-4-ylmethyl)-4,4′-bipyridin-1-ium ligand with an inner cavity were prepared and its inclusion complexes in solution studied. The cavity of macrocycle 6b presents a nearly optimal size to form supramolecular complexes through π-stacking interactions with electron-rich aromatic units. On the contrary, the distance between the two pseudoparallel bipyridinium units in 3b is too short to allow the insertion of aromatic guests.