Nuclear magnetic resonance, luminescence and structural studies of lanthanide complexes with octadentate macrocyclic ligands bearing benzylphosphinate groups
Nuclear magnetic resonance, luminescence and structural studies of lanthanide complexes with octadentate macrocyclic ligands bearing benzylphosphinate groups
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DOI：
10.1039/a703065g
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发表时间：
1997-10-07
期刊：
影响因子：
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通讯作者：
Williams, JAG
中科院分区：
文献类型：
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作者：
Aime, S;Batsanov, AS;Williams, JAG
本文用核磁共振、弛豫、晶体学和电子物理等方法研究了1，4，7，10-四氮杂环十二烷-1，4，7，10-四甲基四亚甲基四（苄基次膦酸酯）镧系配合物L-1a及其邻、间、对甲氧基苄基类似物L-2、L-3、L-4的溶液和固态结构。结果表明，配合物[LaL 1a]（-）是9配位的，具有一个束缚水分子的扭曲正方形反棱柱结构。类似的[YL 1a]（-）、[YbL 1a]（-）、[GdL 1a]（-）和[EuL 1a]（-）配合物也采用扭曲的正方形反棱柱几何构型，但是是八配位的，没有金属结合水。用钆络合物的弛豫研究表明，它们是纯粹的“外层”造影剂，但它们与蛋白质强烈相关，导致明显的弛豫增强。[GdL 1a]（-）的详细生物分布研究显示，在低剂量下，胆汁摄取旺盛，复合物从肿瘤组织中清除的趋势明确，允许组织分化。
The solution and solid-state structures of lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetryltetramethylenetetra(benzylphosphinate), L-1a, and of its o-, m- and p-methoxybenzyl analogues (L-2, L-3, L-4) have been investigated by NMR, relaxometry, crystallographic and photophysical methods. It has been shown that the number of proximate water molecules is dependent on the size of the bound lanthanide ion: the complex [LaL1a](-) is nine-co-ordinate and adopts a twisted square-antiprismatic structure with one bound water molecule. The analogous [YL1a](-), [YbL1a](-), [GdL1a](-) and [EuL1a](-) complexes also adopt a twisted square-antiprismatic geometry, but are eight-co-ordinate, with no metal-bound water. Relaxivity studies with the gadolinium complexes showed that they are purely 'outer-sphere' contrast agents, but they associate strongly with proteins leading to a pronounced relaxivity enhancement. Detailed biodistribution studies with [GdL1a](-) revealed avid biliary uptake at low doses and a well defined tendency for the complex to be cleared more slowly from tumour tissue, allowing tissue differentiation.