Discrete stacking of large aromatic molecules within organic-pillared coordination cages.

Introduction Aromatic stacking of π-conjugated planar molecules leads to the exhibition of unique chemical and physical properties. Discotic liquid crystals are, for example, columnar assembly of aromatic compounds with long alkyl chains. Organic electroconductive materials involve alternative charge-transfer stacking of electron-donating and -accepting π-conjugated compounds. Whereas such infinite assemblies have been thoroughly studied, precisely controlled discrete assemblies composed of more than two π-conjugated molecules are much less explored. Here we report the self-assembly of a metalhinged organic-pillared cage 1 with a large cavity which can accommodate two large π-conjugated molecules. The cage consists of two large organic panels 2, three rod-like pillars 3, and six metal-hinges 4 (Figure1a). The large box-shaped cavity accommodates π-conjugated molecules in limited numbers.