Synthesis of pendant-type anthraquinone-bridged cofacial dinuclear platinum(II) complexes and their emission properties.
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 (epsilon = approximately 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.
Utsuno
Mitsuya
M
Department of Chemistry, School of Science, The University of Tokyo, Hongo, Tokyo, Japan.
Yutaka
Tomona
T
Murata
Masaki
M
Kurihara
Masato
M
Tamai
Naoto
N
Nishihara
Hiroshi
H
D000880:Anthraquinones / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D015394:Molecular Structure; D017671:Platinum Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013053:Spectrophotometry; D013997:Time Factors
D000880:Anthraquinones; D003432:Cross-Linking Reagents; D017671:Platinum Compounds