Synthesis of Direct β-to-β Linked Porphyrin Arrays with Large Electronic Interactions: Branched and Cyclic Oligomers.

Direct β-to-β linked branched and cyclic porphyrin trimers and pentamers have been synthesized by the Suzuki-Miyaura coupling of β-borylporphyrins and β-bromoporphyrins. The cyclic porphyrin trimer, the smallest directly linked cyclic porphyrin wheel to date, and its twined pentamer, exhibit small electrochemical HOMO-LUMO gaps, broad nonsplit Soret bands, and red-shifted Q-bands, thus indicating large electronic interactions between the constituent porphyrin units. [ABSTRACT FROM AUTHOR]