Supramolecular Gelation of Rigid Triangular Macrocycles through Rings of Multiple C–H···O Interactions Acting Cooperatively

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• 作者：Zhichang Liu ; Junling Sun ; Yu Zhou ; Yu Zhang ; Yilei Wu ; Siva Krishna Mohan Nalluri ; Yuping Wang ; Avik Samanta ; Chad A. Mirkin ; George C. Schatz ; J. Fraser Stoddart
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：March 18, 2016
• 年：2016
• 卷：81
• 期：6
• 页码：2581-2588
• 全文大小：598K
• ISSN：1520-6904

文摘

When equimolar solutions of the enantiomeric naphthalenediimide-based highly rigid triangles R-Δ and S-Δ in ClCH₂CH₂Cl are mixed, the racemate rac-Δ forms an organogel that is composed of interwoven fibers, resulting from the columnar stacking of the triangles in an alternating R-Δ/S-Δ fashion. Under identical conditions, the pure enantiomers do not form organogels. Density functional theory calculations reveal that the racemic RS dimer is more stable than the RR dimer as a result of the enantiomeric relationship between R-Δ and S-Δ, allowing them to act as two complementary rings comprised of 12 [C–H···O] interactions with an unprecedented and uninterrupted circular ADDAADDAADDA·DAADDAADDAAD alignment of hydrogen bond donors (D) and acceptors (A), in contrast with the square-wave manner in which the RR dimer forms a complementary yet interrupted ADADAD·DADADA circular sequence of six longer [C–H···O] hydrogen bonds. It follows that gelation is favored by weak interactions acting cooperatively in rings under precise stereoelectronic control.