title: Covalently linked 5,15-diazaporphyrin dimers: promising scaffolds for a highly conjugated azaporphyrin π system.
abstract: The first examples of β-β directly linked, acetylene-bridged, and butadiyne-bridged 5,15-diazaporphyrin dimers have been prepared by palladium-catalyzed coupling reactions of nickel(II) and copper(II) complexes of 3-bromo-10,20-dimesityl-5,15-diazaporphyrin (mesityl=2,4,6-trimethylphenyl). The effects of the linking modes and meso-nitrogen atoms on the structural, optical, electrochemical, and magnetic properties of the distributed π systems were investigated by using X-ray crystallography, UV/Vis absorption spectroscopy, DFT calculations, cyclic voltammetry, and ESR spectroscopy. Both the electronic and steric effects of the meso-nitrogen atoms play an important role in the highly coplanar geometry of the directly linked dimers. The direct β-β linkage produces enhanced π conjugation and electron-spin coupling between the two diazaporphyrin units.
authors: Department of Chemistry, Faculty of Science, Niigata University, Niigata 950-2181 (Japan). matano@chem.sc.niigata-u.ac.jp.
authors: Yoshihiro
authors: Y
authors: Matano
authors: Daisuke
authors: D
authors: Fujii
authors: Tarou
authors: T
authors: Shibano
authors: Ko
authors: K
authors: Furukawa
authors: Tomohiro
authors: T
authors: Higashino
authors: Haruyuki
authors: H
authors: Nakano
authors: Hiroshi
authors: H
authors: Imahori
keywords: EPR spectroscopy; electrochemistry; macrocycles; porphyrinoids; transition metals