1. Synthesis of Pendant-Type Anthraquinone-Bridged Cofacial Dinuclear Platinum(II) Complexes and Their Emission Properties.
- Author
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Utsuno, Mitsuya, Yutaka, Tomona, Murata, Masaki, Kurihara, Masato, Tamai, Naoto, and Nishihara, Hiroshi
- Subjects
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ORGANOPLATINUM compounds , *ORGANIC synthesis , *ANTHRAQUINONES , *EMISSION spectroscopy , *LIGANDS (Chemistry) , *CHARGE transfer - Abstract
Anthraquinone-bridged mononuclear and dinuclear complexes, [PtCl(AQ-amide-tpy)](PF6) (1), (Pt2Cl2(AQ-amide-tpy2)](PF6)2 (2), and [Pt2Cl2(AQ-eth-tpy2)](PF6)2 (3), were synthesized and their photochemical properties were investigated. Amide-bound mononuclear complex 1 exhibited only metal-to-ligand charge transfer (MLCT) absorption and emission, whereas dinuclear complex 2 exhibited a low-energy emission around 700 nm at room temperature. Emission lifetime analysis indicated that this emission was originated from the metal-metal-to-ligand charge transfer (MMLCT) excited state, implying the existence of an intramolecular Pt-Pt interaction at the photoexcited state. 3 with rigid ethynylene linkers showed a low-energy absorption around 520 nm (ϵ = ~1100 M-1 cm-1) in addition to an ¹MLCT absorption, which was ascribed to a ³MLCT absorption from the consideration of the Pt-Pt distance on a geometry-optimized structure. The emission of 3 appeared at 600 nm, which is higher in energy compared with the emission of 2. It is postulated that the restriction of the Pt-Pt distance flexibility in the rigid structure of 3 prevents the significant increase of the Pt-Pt interaction at the excited state. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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