Supramolecular Recognition. Terpyridyl Palladium and Platinum Molecular Clefts and Their Association with Planar Platinum Complexes

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• 作者：Andrew J. Goshe ; Ian M. Steele ; and B. Bosnich
• 刊名：Journal of the American Chemical Society
• 出版年：2003
• 出版时间：January 15, 2003
• 年：2003
• 卷：125
• 期：2
• 页码：444 - 451
• 全文大小：232K
• 年卷期：v.125,no.2(January 15, 2003)
• ISSN：1520-5126

文摘

Molecular receptors, consisting of either two parallel cofacially disposed terpyridyl-Pd-Cl⁺ orterpyridyl-Pt-Cl⁺ units, are described. Concerted rotation of these units about the molecular spacer canalter their separation between 6.4 and 7.2 Å to accommodate the dimensions of molecular guests. Neutraland anionic planar complexes of platinum(II) were investigated as guests to determine if metal-metalinteraction between the host and guest metals could stabilize host-guest association. With a neutral guest,it was found that host-guest formation is signaled by a color change from light yellow to deep red. For oneof the anionic guests, a visible absorption band appears upon host-guest formation with the platinumreceptor that is ascribed to transitions associated with a Pt-Pt interaction. The association constants foundfor the neutral guest with the palladium and platinum receptors are large, suggesting that metal-metalinteraction contributes to the molecular recognition. The structures of the host-(neutral)guest complexesin solution have been determined by ¹H NOESY spectra. A crystal structure of the platinum host-(neutral)guest complex is the same as that found in solution and confirms the presence of a Pt-Pt interaction.Temperature-dependent ¹⁹⁵Pt NMR spectra in solution provide a quantitative estimate of the conformationalinterconversions of the free platinum receptor.