title: Efficient Synthesis of Tris-Heteroleptic Iridium(III) Complexes Based on the Zn2+-Promoted Degradation of Tris-Cyclometalated Iridium(III) Complexes and Their Photophysical Properties.
abstract: We report on the efficient synthesis of tris-heteroleptic iridium (Ir) complexes based on the degradation of tris-cyclometalated Ir complexes (IrL3, L: cyclometalating ligand) in the presence of Brønsted and Lewis acids such as HCl (in 1,4-dioxane), AlCl3, TMSCl, and ZnX2(X = Br or Cl), which affords the corresponding halogen-bridged Ir dimers (μ-complexes). Tris-cyclometalated Ir complexes containing electron-withdrawing groups such as fluorine, nitro, or CF3moieties on the ligands were less reactive. This different reactivity was applied to the selective degradation of heteroleptic Ir complexes such as fac-Ir(tpy)2(F2ppy) (fac-12) (tpy: 2-(4'-tolyl)pyridine and F2ppy: 2-(4',6'-difluorophenyl)pyridine), mer-Ir(tpy)2(F2ppy) (mer-12), and mer-Ir(mpiq)2(F2ppy) (mer-15) (mpiq: 1-(4'-methylphenyl)isoquinoline). For example, the reaction of mer-12 with ZnBr2gave the heteroleptic μ-complex [{Ir(tpy)(F2ppy)(μ-Br)}2] 27b as a major product, resulting from the selective elimination of the tpy ligand of mer-12, and treatment of 27b with acetylacetone (acacH) afforded the corresponding tris-heteroleptic Ir complex Ir(tpy)(F2ppy)(acac)18. In addition, another tris-heteroleptic Ir complex 35a having 8-benzenesulfonylamidoquinoline (8BSQ) ligand was synthesized. Mechanistic studies of this degradation reaction and the photochemical properties, especially a dual emission, of these newly synthesized tris-heteroleptic Ir complexes are also reported.
authors.affiliation: Faculty of Pharmaceutical Science and §Division of Medical-Science-Engineering Cooperation, ∥Imaging Frontier Center, ‡Research Institute for Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tamura
authors.affiliation: Faculty of Pharmaceutical Science and §Division of Medical-Science-Engineering Cooperation, ∥Imaging Frontier Center, ‡Research Institute for Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Hisamatsu
authors.affiliation: Faculty of Pharmaceutical Science and §Division of Medical-Science-Engineering Cooperation, ∥Imaging Frontier Center, ‡Research Institute for Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Sarvendra
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Faculty of Pharmaceutical Science and §Division of Medical-Science-Engineering Cooperation, ∥Imaging Frontier Center, ‡Research Institute for Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Taiki
authors.initials: T
authors.lastname: Itoh
authors.affiliation: Faculty of Pharmaceutical Science and §Division of Medical-Science-Engineering Cooperation, ∥Imaging Frontier Center, ‡Research Institute for Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Kyouhei
authors.initials: K
authors.lastname: Sato
authors.affiliation: Faculty of Pharmaceutical Science and §Division of Medical-Science-Engineering Cooperation, ∥Imaging Frontier Center, ‡Research Institute for Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Kuroda
authors.affiliation: Faculty of Pharmaceutical Science and §Division of Medical-Science-Engineering Cooperation, ∥Imaging Frontier Center, ‡Research Institute for Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Shin
authors.identifier: http://orcid.org/0000-0002-4287-6487
authors.initials: S
authors.lastname: Aoki