Cantuel Martine, Gumy Frédéric, Bünzli Jean-Claude G, Piguet Claude
Department of Inorganic, Analytical and Applied Chemistry, University of Geneva, 30 quai E. Ansermet, CH-1211, Geneva 4, Switzerland.
Dalton Trans. 2006 Jun 14(22):2647-60. doi: 10.1039/b602392d. Epub 2006 Apr 4.
The segmental bidentate-tridentate-bidentate ligand L2 reacts with M(II) (M = Cr, Zn) and Ln(III) (Ln = La, Eu, Gd, Tb, Lu) to give the heterotrimetallic triple-stranded helicates [MLnM(L2)3]7+. For M = Zn(II), the isolated complexes ZnLnZn(L2)37 (Ln = Eu, Tb) display only lanthanide-centred luminescence arising from the pseudo-tricapped trigonal prismatic LnN9 coordination site. For M = Cr(II), rapid air oxidation provides Cr(III) and leads to the isolation of inert CrLnCr(L2)39 (Ln = Eu, Tb) complexes, in which divergent intramolecular Ln --> Cr energy transfers can be evidenced. Taking [ZnEuZn(L2)3]7+ as a luminescent standard for Eu-centred emission, a quantitative treatment of the energy migration processes indicates that the rate constant characterizing the Eu --> Cr energy transfer is more efficient in the trimetallic system, than in the analogous simple bimetallic edifice. Particular attention is focused on potential control of directional energy transfer processes in Cr-Ln pairs.
分段双齿-三齿-双齿配体L2与M(II)（M = Cr、Zn）和Ln(III)（Ln = La、Eu、Gd、Tb、Lu）反应，生成异三金属三链螺旋配合物[MLnM(L2)3]7+。对于M = Zn(II)，分离得到的配合物ZnLnZn(L2)37（Ln = Eu、Tb）仅显示出源于伪三帽三棱柱LnN9配位位点的以镧系元素为中心的发光。对于M = Cr(II)，快速空气氧化生成Cr(III)，并导致惰性配合物CrLnCr(L2)39（Ln = Eu、Tb）的分离，其中可以证明存在不同的分子内Ln→Cr能量转移。以[ZnEuZn(L2)3]7+作为以Eu为中心发射的发光标准，对能量迁移过程的定量处理表明，表征Eu→Cr能量转移的速率常数在三金属体系中比在类似的简单双金属结构中更有效。特别关注Cr-Ln对中定向能量转移过程的潜在控制。
