A meso–meso β‐β β‐β Triply Linked Subporphyrin Dimer

• Published in: Angewandte Chemie International Edition 2017-09, Vol.56 (40), p.12317-12321
• Main Authors: Okuda, Yasuhiro, Fukui, Norihito, Kim, Jinseok, Kim, Taeyeon, Jiang, Hua‐Wei, Copley, Graeme, Kitano, Masaaki, Kim, Dongho, Osuka, Atsuhiro
• Format: Article
• Language: English
• Subjects: curved structures; fused porphyrinoids; near-IR absorption; positive Gaussian curvature; subporphyrin
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201707123

A meso–meso β‐β β‐β triply linked subporphyrin dimer 6 was synthesized by stepwise reductive elimination of β‐to‐β doubly PtII‐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. A triply linked subporphyrin dimer was synthesized by stepwise reductive elimination of a β‐to‐β doubly PtII‐bridged subporphyrin dimer with the concurrent formation of the meso–meso bond. Despite the curved structure, the triply linked dimer displayed a remarkably red‐shifted absorption spectrum and narrow electrochemical HOMO–LUMO gap because of the effectively conjugated π‐electronic network.