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,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 pi-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. (c) 2006 Elsevier Ltd. All rights reserved.