期刊
LANGMUIR
卷 27, 期 22, 页码 13847-13853出版社
AMER CHEMICAL SOC
DOI: 10.1021/la203110z
关键词
-
资金
- Basic Research Development Program [2010CB833305]
- National Natural Science Foundation of China [20803084, 91027042]
- Chinese Academy of Sciences
Self-assembly of several low-molecular-weight L-glutamic acid-based gelators, which individually formed helical nanotube or nanofiber structures, was investigated in the presence of Cu2+ ion. It was found that, when Cu2+ was added into the system, the self-assembly manner changed significantly. Only in the case of bolaamphiphilic glutamic acid, N,N'-hexadecanedioyl-di-L-glutamic acid (L-HDGA), were the hydrogel formation as well as the nanotube structures maintained. The addition of Cu2+ ion caused a transition from monolayer nanotube of L-HDGA to a multilayer nanotube with the thickness of the tubular wall about 10 rim. For the other amphiphiles, the gel was destroyed and nanofiber structures were mainly formed. The formed Cu2+-containing nanostructures can function as an asymmetric catalyst for Diels-Alder cycloaddition between cyclopentadiene and aza-chalcone. In comparison with the other Cu2+-containing nanostructures, the Cu2+-mediated nanotube structure showed not only accelerated reaction rate, but enhanced enantiomeric selectivity. It was suggested that, through the Cu2+ mediated nanotube formation, the substrate molecules could be anchored on the nanotube surfaces and produced a stereochemically favored alignment. When adducts reacted with the substrate, both the enantiomeric selectivity and the reaction rate were increased. Since the Cu2+-mediated nanotube can be fabricated easily and in large amount, the work opened a new way to perform efficient chiral catalysis through the supramolecular gel.
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