Discrete Stacking of Large Aromatic Molecules within Organic-Pillared Coordination Cages


  • This work was supported by a CREST (Core Research for Evolution Science and Technology) project from the Japan Science and Technology Agency. We thank Prof. S. Adachi (KEK) for performing the X-ray crystallographic measurements.


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Metal-hinged, organic-pillared cages accommodate a limited number (n) of π-stacked molecules in the cavity (see scheme): Discrete n+2 aromatic stacking occurs by the accommodation of n large aromatic guests (n=1–3). Owing to efficient donor–acceptor (D–A) interactions, A–D–A (n=1), A–D–D–A (n=2), and A–D–A–D–A (n=3) stacks are observed, which bring about even–odd-number effects in the UV/Vis absorption spectra.