Switch of the Lowest Excited-States of Terpyridylplatinum(II) Acetylide Complexes Bearing Amino or Azacrown Moieties by Proton and Cations
✍ Scribed by Qing-Zheng Yang; Qing-Xiao Tong; Li-Zhu Wu; Zi-Xin Wu; Li-Ping Zhang; Chen-Ho Tung
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 172 KB
- Volume
- 2004
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
The investigation of the synthesis and unique photophysical properties of two terpyridylplatinum(II) acetylide complexes [Pt(terpy)(C≡CC~6~H~4~‐4‐R)] where terpy is 2,2′:6′,2′′‐terpyridyl and R = N(CH~3~)~2~ (1) or N‐15‐monoazacrown‐5 (2) has been carried out. These complexes exhibit an absorption band in the region of 460−650 nm in neutral or basic solution that corresponds to a ligand‐to‐ligand charge transfer (LLCT) transition from the amino‐substituted acetylide to the terpyridyl acceptor. In acidic solutions the complexes show the lowest‐energy absorption band at 380−500 nm, which is assignable to a dπ(Pt)→π*(terpy) metal‐to‐ligand charge transfer (MLCT) transition. In acidic media the complexes are emissive with quantum yields of 1 × 10^−3^ to 2 × 10^−3^, and lifetimes of 20−50 ns. Compound 2 may complex metal cations through its azacrown ether moiety. For Na^+^, Ba^2+^, Ca^2+^ and Mg^2+^, a 1:1 binding mode with log __K__s of 2.52 to 4.18 was observed. As in the case of acidic solution, the cation‐bound complex also features the lowest‐lying MLCT excited state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)