Exploring the Programmable Assembly of a Polyoxometalate鈥揙rganic Hybrid via Metal Ion Coordination

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• 作者：Panchao Yin ; Tao Li ; Ross S. Forgan ; Claire Lydon ; Xiaobing Zuo ; Zhaoxiong Norm Zheng ; Byeongdu Lee ; Deliang Long ; Leroy Cronin ; Tianbo Liu
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：September 11, 2013
• 年：2013
• 卷：135
• 期：36
• 页码：13425-13432
• 全文大小：512K
• 年卷期：v.135,no.36(September 11, 2013)
• ISSN：1520-5126

文摘

The conformational flexibility and programmed assembly of a dumbbell-shaped polyoxometalate鈥搊rganic hybrid molecule comprising two Dawson-type polyoxometalates linked by a 2,2鈥?bipyridine unit, which can be coordinate to metal ions, in this case of Zn²⁺, are described. SAXS, UV/vis, and NMR spectroscopic techniques confirm that the hybrid molecules exist as the trans dumbbell in metal-ion-free solutions and can be reversibly transformed into the cis dumbbell through coordination upon the addition of ZnCl₂ into a DMSO solution containing the hybrid. Subsequent addition of EDTA reverses the switching process by extracting the Zn²⁺ cations from the hybrid. During the interchange process between trans and cis dumbbells, a further reorganization of the hybrid molecules occurs through bond rotation to minimize steric clashes between the polyoxometalate subunits, in order to stabilize the corresponding dumbbell conformation. The Zn²⁺-controlled conformational transformation of the hybrid can be further utilized to manipulate the hybrid鈥檚 solvophobic interaction-driven self-assembly behavior in the metal-ion driven reversible formation of 140 nm sized vesicles, studied by laser light scattering techniques.