Solid-state and solution properties of the lanthanide complexes of a new nonadentate tripodal ligand derived from 1,4,7-triazacyclononane
Solid-state and solution properties of the lanthanide complexes of a new nonadentate tripodal ligand derived from 1,4,7-triazacyclononane
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1,4,7-三氮杂环壬烷衍生的新型九齿三足配体的镧系元素配合物的固态和溶液性质
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
L. Helm
中科院分区：
文献类型：
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作者：
C. Gateau;M. Mazzanti;J. Pécaut;F. Dunand;L. Helm
本文报道了一种新的1，4，7-三[（6-羧基吡啶-2-基）甲基]-1，4，7-三氮杂环壬烷（H_3tpatcn）的N-功能化衍生物的合成。制备了该配体的四种镧系离子（Nd，Eu，Gd，Lu）的配合物，并对其结构进行了表征。这些配合物具有高的水溶性，表现出高度刚性的C3对称溶液结构。所有配合物均为单核九配位固态结构。配位多面体是一个略微扭曲的三帽三棱柱。对[Gd（tpatcn）]配合物测量的NMR（核磁弛豫色散）曲线表明，由与配合物表面上的羧酸根部分紧密氢键结合的水分子的存在引起的第二球贡献不足以解释先前报道的[Gd（tpaa）（H2O）2]配合物（H3 tpaa = 1.02mol/L）的非常高的弛豫率。
α，α′，α″-次氮基三（6-甲基-2-吡啶甲酸））。事实上，[Gd（tpatcn）]的低场弛豫率更可能指向有利的电子弛豫速率。
The synthesis of the potentially nonadentate ligand 1,4,7-tris[(6-carboxypyridin-2-yl)methyl]-1,4,7-triazacyclononane (H3tpatcn), a new derivative of 1,4,7-triazacyclononane N-functionalised with three pyridinecarboxylate arms, is described. The complexes of four lanthanide ions (Nd, Eu, Gd, Lu) of this ligand have been prepared and structurally characterised. These complexes, which have high water solubility, show highly rigid C3 symmetric solution structures. All the complexes present mononuclear nine-coordinated solid-state structures. The coordination polyhedron is a slightly distorted tricapped trigonal prism. The NMRD (Nuclear Magnetic Relaxation Dispersion) profiles measured for the [Gd(tpatcn)] complex indicate that the second-sphere contribution arising from the presence of water molecules tightly hydrogen-bonded to the carboxylate moieties on the surface of the complex are not large enough to explain the very high relaxivity of the previously reported [Gd(tpaa)(H2O)2] complex (H3tpaa =
α,α′,α″-nitrilotri(6-methyl-2-pyridinecarboxylic acid)). In fact the low-field relaxivity of [Gd(tpatcn)] more likely points to a favorable electronic relaxation rate.
影响因子：
4.9
作者：
Castro-Rodriguez, I;Olsen, K;Meyer, K
通讯作者：
Meyer, K