Metal-switching and self-inclusion of functional cavitands.
Metal-switching and self-inclusion of functional cavitands.
复制标题
功能性空配体的金属转换和自包含。
DOI：
10.1021/ja0204269
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发表时间：
2002
影响因子：
15
通讯作者：
J. Rebek
中科院分区：
文献类型：
--
作者：
P. Amrhein;A. Shivanyuk;Darren W. Johnson;J. Rebek
通过相应的溴乙酰胺空配体与亚磷酸三烷基酯的Arbuzov反应合成了在其边缘上带有八(5)和两个(13)金属配位羧甲基膦酸酯基团的空配体。它们以CDCl(3) 中的花瓶构象存在，并通过氢键的环状接缝稳定。通过单晶 X 射线分析，八溴乙酰胺 4a 和二膦酸空穴配体 13 的固态也发现了这种结构。空穴配体 5 和 13 在 CDCl(3)、CD(2)Cl(2) 和醇溶液中与金刚烷衍生物 15a,b、奎宁环 15d、铵盐和鏻盐 14 以及布洛芬 15c 等药物形成空穴复合物，所有这些物质在 295 K 的 NMR 时间尺度上都是稳定的。NMR 光谱表明在 223 K 存在八膦酸 5b有两种形式：主要的 C(4)-对称化合物充满溶剂，而次要的物质则显示出分子内包含二烷氧基磷酰基。在甲醇-d(4) 中，5 和 13 以自包含一个烷基的较低对称性花瓶构象存在。这些配合物与 La(OTf)(3) 的相互作用导致空配体从花瓶到风筝的构象发生变化，并伴随着封装客体的定量释放。每当量空穴配体 5a-d 需要两到三当量的镧系元素盐才能完全解络所包含的客体。风筝和花瓶构象异构体在 295 K 的 NMR 时标上缓慢平衡。添加金属阳离子（硝酸根或 CMPO 杯芳烃 16）的良好配体将平衡转移到花瓶形腔复合体，并允许定量控制客体的结合和释放。甲醇-d(4) 中的八磷酸盐 5 的镧系元素配合物是由四个金属阳离子结合在一起的类似 velcraplex 的二聚体。
Cavitands bearing both eight (5) and two (13) metal-ligating carboxymethylphosphonate groups on their rims were synthesized by Arbuzov reaction of the corresponding bromoacetamido cavitands with trialkyl phosphites. These exist in the vase conformation in CDCl(3) and are stabilized by a cyclic seam of hydrogen bonds. This structure was also found in the solid state for the octabromoacetamide 4a and diphosphonate cavitand 13 by single-crystal X-ray analysis. Cavitands 5 and 13 form caviplexes in CDCl(3), CD(2)Cl(2), and alcohol solutions with adamantane derivatives 15a,b, quinuclidine 15d, ammonium and phosphonium salts 14, and drugs like ibuprofen 15c, all of which are stable on the NMR time scale at 295 K. NMR spectroscopy reveals that at 223 K octaphosphonate 5b exists in two forms: the major C(4)-symmetrical compound is filled with solvent while the minor species shows intramolecular inclusion of a dialkoxyphosphoryl group. In methanol-d(4) 5 and 13 exist in a lower symmetry vase conformation with self-inclusion of one alkyl group. Interaction of these complexes with La(OTf)(3) results in a change in the conformation of the cavitand from vase to kite with concomitant and quantitative release of the encapsulated guests. Two to three equivalents of the lanthanide salt per equivalent of cavitand 5a-d is necessary for the complete decomplexation of the included guest. The kite and the vase conformers equilibrate slowly on the NMR time scale at 295 K. The addition of good ligands for metal cations (nitrate or CMPO calixarene 16) shifts the equilibrium to the vase-shaped caviplex and allows quantitative control of the binding and release of the guest. The lanthanide complexes of octaphosphonates 5 in methanol-d(4) are velcraplex-like dimers held together by four metal cations.