Cross-Linked Supramolecular Polymer Gels Constructed from Discrete Multi-pillar[5]arene Metallacycles and Their Multiple Stimuli-Responsive Behavior

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• 作者：Zhong-Yu Li ; Yanyan Zhang ; Chang-Wei Zhang ; Li-Jun Chen ; Chao Wang ; Hongwei Tan ; Yihua Yu ; Xiaopeng Li ; Hai-Bo Yang
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：June 18, 2014
• 年：2014
• 卷：136
• 期：24
• 页码：8577-8589
• 全文大小：797K
• 年卷期：v.136,no.24(June 18, 2014)
• ISSN：1520-5126

文摘

A new family of discrete hexakis-pillar[5]arene metallacycles with different sizes have been successfully prepared via coordination-driven self-assembly, which presented very few successful examples of preparation of discrete multiple pillar[n]arene derivatives. These newly designed hexakis-pillar[5]arene metallacycles were well characterized with one-dimensional (1-D) multinuclear NMR (¹H and ³¹ P NMR), two-dimensional (2-D) ¹H鈥?sup>1H COSY and NOESY, ESI-TOF-MS, elemental analysis, and PM6 semiempirical molecular orbital methods. Furthermore, the host鈥揼uest complexation of such hexakis-pillar[5]arene hosts with a series of different neutral ditopic guests G1鈥?b>6 were well investigated. Through host鈥揼uest interactions of hexakis-pillar[5]arene metallacycles H2 or H3 with the neutral dinitrile guest G5, the cross-linked supramolecular polymers H2(G5)₃ or H3(G5)₃ were successfully constructed at the high-concentration region, respectively. Interestingly, these cross-linked supramolecular polymers transformed into the stable supramolecular gels upon increasing the concentrations to a relatively high level. More importantly, by taking advantage of the dynamic nature of metal鈥搇igand bonds and host鈥揼uest interactions, the reversible multiple stimuli-responsive gel鈥搒ol phase transitions of such polymer gels were successfully realized under different stimuli, such as temperature, halide, and competitive guest, etc. The mechanism of such multiple stimuli-responsive processes was well illustrated by in situ multinuclear NMR investigation. This research not only provides a highly efficient approach to the preparation of discrete multiple pillar[n]arene derivatives but also presents a new family of multiple stimuli-responsive 鈥渟mart鈥?soft matters.