The synthesis of C2-symmetrical cycloparaphenylene (CPP) tetracarboxylates has been achieved via macrocyclization by the rhodium-catalyzed intermolecular stepwise cross-alkyne cyclotrimerization and subsequent reductive aromatization. The 1H NMR spectra of the thus-obtained C2-symmetrical CPP-tetracarboxylates revealed that the rotation of unsubstituted benzene rings is slow at room temperature. These CPPs formed columnar packing structures, and their absorption maxima were significantly blue-shifted compared to that of nonsubstituted CPP due to the presence of four electron-withdrawing ester moieties.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry