Toward high-generation rotaxane dendrimers that incorporate a ring component on every branch: noncovalent synthesis of a dendritic [10]pseudorotaxane with 13 molecular components.
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.
Kim
Soo-Young
SY
National Creative Research Initiative Center for Smart Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784, Republic of Korea.
Ko
Young Ho
YH
Lee
Jae Wook
JW
Sakamoto
Shigeru
S
Yamaguchi
Kentaro
K
Kim
Kimoon
K
D001952:Bridged-Ring Compounds; D050091:Dendrimers / Q000138:chemical synthesis*; D007093:Imidazoles; D009682:Magnetic Resonance Spectroscopy; D011726:Pyridinium Compounds; D043862:Rotaxanes / Q000138:chemical synthesis*; D013057:Spectrum Analysis; D017186:Titrimetry; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
D001952:Bridged-Ring Compounds; D050091:Dendrimers; D007093:Imidazoles; D011726:Pyridinium Compounds; D043862:Rotaxanes; C454805:cucurbit(6)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils