Self-assembly with postmodification: Kinetically stabilized metalla-supramolecular rectangles

Interaction of a predesigned molecular "clip" (4) with rigid dipyridyl brid ging ligands, in acetone/ water mixtures, leads to the formation of molecul ar rectangles (5-8) in 92-97% isolated yields via spontaneous self-assembly . Characterization was accomplished with multinuclear NMR and UV-vis spectr oscopy, FAB mass spectrometry, and X-ray crystallography. The length of the se metallamacrocycles ranges from 2 to 3 nm. Postmodification via non-nucle ophilic counterion exchange results in enhanced structural integrity for th e assemblies.