The synthesis of C4- and C2-symmetrical cycloparaphenylene (CPP)-octacarboxylates has been achieved via macrocyclization by the rhodium-catalyzed intermolecular stepwise cross-cyclotrimerization and subsequent reductive aromatization. The C4-symmetrical octa-tert-butyl CPP-octacarboxylate forms a dimer in which eight ester moieties face each other. The dimers are aligned so as to make a one-dimensional column with a channel structure inside. Both absorption and fluorescence maxima of CPP-octacarboxylates in CHCl3 were significantly blue-shifted compared to those of CPP due to the presence of eight electron-withdrawing ester moieties.
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