A 1, 5‐Naphthyridine‐Fused Porphyrin Dimer: Intense NIR Absorption and Facile Redox Interconversion with Its Reduced Congener. Issue 25 (16th April 2018) - Fujimoto, Keisuke
Abstract: Pt II ‐catalyzed cyclization of β‐to‐β ethynylene‐bridged meso ‐amino Ni II porphyrin dimer4 followed by oxidation with PbO2 afforded 1, 5‐naphthyridine‐fused porphyrin dimer5 in good yield. This dimer possesses a redox‐active 1, 4‐diazabutadiene linkage that is interconvertible with its reduced 1, 2‐diaminoethene linkage upon treatments with NaBH4 or PbO2 . The dimer5 exhibits an intense NIR absorption and a narrow HOMO–LUMO gap with a remarkably low reduction potential mainly due to effective bonding interactions in the LUMO through the 1, 4‐diazabutadiene linkage. In contrast, the reduced dimer7 is fairly electron‐rich with high HOMO energy and shows a relatively large HOMO–LUMO gap compared to that of5 . Abstract : 1, 5‐Naphthyridine‐fused Ni II porphyrin dimer was effectively synthesized by Pt II ‐catalyzed cyclization of β‐to‐β ethynylene‐bridged meso ‐amino Ni II porphyrin dimer followed by oxidation with PbO2 . The 1, 4‐diazabutadiene linkage is interconvertible with the 1, 2‐diaminoethene linkage with large changes in the optical and electrochemical properties.