Dendritic bipyridine ligands and their tris(bipyridine)ruthenium(II) chelates - Syntheses, absorption spectra, and photophysical properties
Dendritic bipyridine ligands and their tris(bipyridine)ruthenium(II) chelates - Syntheses, absorption spectra, and photophysical properties
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DOI：
10.1002/chem.19970030509
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发表时间：
1997-05-01
影响因子：
4.3
通讯作者：
Balzani, V
中科院分区：
文献类型：
--
作者：
Issberner, J;Vogtle, F;Balzani, V
已经探索了几种合成策略来制备以[Ru(bpy)(3)](2+)络合物为核心的树枝状聚合物(bpy = 2,2'-联吡啶)。树枝状配体是通过在 bpy 的 4,4'-位置连接分支来合成的。最大的树枝状联吡啶配体含有54个外围甲基酯单元，制备了四个Ru-II树枝状配合物，它们的吸收和发射光谱与未取代的母体Ru-II-联吡啶配合物非常相似，然而，大的树枝状配合物在充气溶液中表现出比[Ru(bpy)(3)](2+)更强烈的发射和更长的激发态寿命，这是由于Ru(bpy)(3)](2+)的屏蔽效应Ru-联吡啶核上有树枝状大分子分支，限制了分子氧的猝灭作用。最大的树枝状配合物包含54个外围甲基酯单元，在充气乙腈溶液中的激发态寿命长于1μs，双氧猝灭的速率常数比[Ru(bpy)(3)](2+)小12倍。
Several synthetic strategies have been explored to prepare dendrimers having the [Ru(bpy)(3)](2+) complex as their core (bpy = 2,2'-bipyridine). Dendritic ligands have been synthesized by attaching branches in the 4,4'-positions of bpy. The largest dendritic bipyridine ligand contains 54 peripherical methylester units, Four Ru-II dendritic complexes have been prepared, Their absorption and emission spectra are very similar to those of the unsubstituted parent Ru-II-bipyridine complexes, The large dendritic complexes, however, exhibit a more intense emission and a longer excited-state lifetime than [Ru(bpy)(3)](2+) in aerated solutions, This is due to the shielding effect oi-the dendrimer branches on the Ru-bipyridine core, which limits the quenching effect of molecular oxygen, For the largest dendritic complex, which contains 54 peripherical methylester units, the excited-state lifetime in aerated acetonitrile solution is longer than 1 mu s, and the rate constant for dioxygen quenching is twelve times smaller than for [Ru(bpy)(3)](2+).