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Toward High‐Generation Rotaxane Dendrimers That Incorporate a Ring Component on Every Branch: Noncovalent Synthesis of a Dendritic [10]Pseudorotaxane with 13 Molecular Components
Author(s) -
Kim SooYoung,
Ko Young Ho,
Lee Jae Wook,
Sakamoto Shigeru,
Yamaguchi Kentaro,
Kim Kimoon
Publication year - 2007
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200700043
Subject(s) - dendrimer , rotaxane , chemistry , protonation , molecule , non covalent interactions , ring (chemistry) , nuclear magnetic resonance spectroscopy , stereochemistry , molecular switch , crystallography , supramolecular chemistry , polymer chemistry , hydrogen bond , organic chemistry , ion
By taking advantage of the fact that cucurbit[6]uril (CB[6]) forms exceptionally stable host–guest complexes with protonated amines, and that its homologue CB[8] can encapsulate a pair of electron‐rich and electron‐deficient guest molecules to form a stable 1:1:1 complex, we synthesized a novel dendritic [10]pseudorotaxane, or second‐generation rotaxane dendrimer (from a topological point of view), in which 13 molecular components are held together by noncovalent interactions. A triply branched molecule containing an electron‐deficient bipyridinium unit on each branch formed a branched [4]pseudorotaxane with 3 equivalents of CB[8]. Addition of 3 equivalents of 2,6‐dihydroxynaphthalene produced a first‐generation rotaxane dendrimer, which was characterized by NMR spectroscopy and CSI‐MS. The reaction of the branched [4]pseudorotaxane with 3 equivalents of a triply branched molecule that has an electron‐donor unit at one arm and CB[6]‐containing units at the other two gave the dendritic [10]pseudorotaxane, the structure of which was confirmed by NMR spectroscopy, UV/Vis titration experiments, and CSI‐MS.