A meso-meso β-β β-β Triply Linked Subporphyrin Dimer.

A meso-meso β-β β-β triply linked subporphyrin dimer 6 was synthesized by stepwise reductive elimination of β-to-β doubly Pt -bridged subporphyrin dimer 9. Dimer 6 was characterized by spectroscopic and electrochemical measurements, theoretical calculations, and picosecond time-resolved transient absorption spectroscopy. X-ray diffraction analysis reveals that 6 has a bowl-shaped structure with a positive Gaussian curvature. Despite the curved structure, 6 exhibits a remarkably red-shifted absorption band at 942 nm and a small electrochemical HOMO-LUMO gap (1.35 eV), indicating an effectively conjugated π-electronic network.