Supramolecular Control of Hetero-multinuclear Polytopic Binding of Metal Ions (ZnII, CuI) at a Single Calix[6]arene-Based Scaffold

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• 作者：Jean-No毛l Rebilly ; Olivia Bistri ; Benoit Colasson ; Olivia Reinaud
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：May 21, 2012
• 年：2012
• 卷：51
• 期：10
• 页码：5965-5974
• 全文大小：751K
• 年卷期：v.51,no.10(May 21, 2012)
• ISSN：1520-510X

文摘

A Calix[6]arene scaffold was functionalized to provide a tridentate binding site at the small rim and three bidentate chelate sites at the large rim of the cone to generate a heteropolytopic ligand. Its complexation to one equivalent of Zn^II at the small rim yields a funnel complex displaying both host鈥揼uest properties and preorganization of the three chelate groups at the large rim. These two aspects allowed the full control of the binding events to regioselectively form dinuclear Zn^II and heteropolynuclear Zn^II/Cu^I complexes. The heteropolynuclear systems all rely on the host鈥揼uest relationship thanks to the induced-fit behavior of the calix cavity. With the short guest MeCN, the large rim is preorganized into a trigonal tris-triazole core and accommodates a single Cu^I ion. A long guest breaks this spatial arrangement, and three Cu^I ions can then be bound at the tris-bidentate triazole-dimethylamine site at the large rim. In a noncoordinating solvent however, the tetranuclear complex is submitted to scrambling and the addition of exogenous 蟺-acceptor ligands is required to control the binding of Cu^I in a well-defined environment. Hindrance selectivity was then induced by the accessibility at the small rim site. Indeed, while CO can stabilize Cu^I at both coordination sites, PPh₃ cannot fit into the cavity and forces Cu^I to relocate at the large rim. The resulting well-defined symmetrical tetranuclear complex thus arises from the quite remarkable selective supramolecular assembly of nine partners (1 Zn^II, 3 Cu^I, 1 calixarene, 1 guest alkylamine, 3 PPh₃).