Bottom-Up Synthesis of Multiply Fused Pd^II Anthriporphyrinoids

Anthriporphyrinoid and its dimeric homologues were synthesized by Suzuki-Miyaura coupling and subsequent oxidation. Both porphyrinoids were smoothly converted to their Pd^II complexes and were further decorated by Suzuki-Miyaura coupling with thiophene derivatives and subsequent oxidative fusion reaction to provide multiply fused compounds. Most Pd^II anthriporphyrinoids have been structurally well characterized to be planar for monomeric and helically twisted for dimeric species. The dimeric anthriporphyrinoids show paratropic ring currents due to their global antiaromatic networks, the extent of which increases with an increase of conjugated network. Multiply fused dimeric anthriporphyrinoids show helical structures, fully reversible six redox potentials, small HOMO-LUMO gaps, and absorption tails reaching in the near-infrared region, suggesting the high potential of this approach to explore molecular graphene. Optical separations of the dimeric helical species were accomplished, and racemization barrier heights were determined.