Achieving Strong Positive Cooperativity through Activating Weak Non‐Covalent Interactions. Issue 3 (23rd November 2017)

• Record Type: Journal Article
• Authors: Ma, Yan‐Long; Ke, Hua; Valkonen, Arto; Rissanen, Kari; Jiang, Wei
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 3(2018)
• Page Start: 709
• Page End: 713
• Publication Date: 2017-11-23
• Subjects: cooperativity -- host–guest chemistry -- macrocycles -- self-assembly -- supramolecular chemistry; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201711077
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Positive cooperativity achieved through activating weak non‐covalent interactions is common in biological assemblies but is rarely observed in synthetic complexes. Two new molecular tubes have been synthesized and the syn isomer binds DABCO‐based organic cations with high orientational selectivity. Surprisingly, the ternary complex with two hosts and one guest shows a high cooperativity factor ( α =580), which is the highest reported for synthetic systems without involving ion‐pairing interactions. The X‐ray single‐crystal structure revealed that the strong positive cooperativity likely originates from eight C−H⋅⋅⋅O hydrogen bonds between the two head‐to‐head‐arranged syn tube molecules. These relatively weak hydrogen bonds were not observed in the free hosts and only emerged in the complex. Furthermore, this complex was used as a basic motif to construct a robust [2+2] cyclic assembly, thus demonstrating its potential in molecular self‐assembly. Abstract : A high level of complexity : Strong positive allosteric cooperativity in a ternary complex involving two molecular tubes was revealed to be caused by the formation of relatively weak C−H⋅⋅⋅O hydrogen bonds. This robust binding motif was further applied to the construction of a large [2+2] cyclic complex.