Synthesis, Structures, and Photophysical Properties of Alternating Donor-Acceptor Cycloparaphenylenes

The synthesis of alternating donor-acceptor [12] and [16] cycloparaphenylenes (CPPs) has been achieved by the rhodium-catalyzed intermolecular cross-cyclotrimerization followed by imidation and/or aromatization. These alternating donor-acceptor CPPs showed positive solvato-fluorochromic properties and smaller HOMO-LUMO gaps compared with nonfunctionalized CPPs, which was confirmed by the theoretical study.