Hydrogels composed of organic amphiphiles and alpha-cyclodextrin: supramolecular networks of their pseudorotaxanes in aqueous media.
Hydrogels composed of organic amphiphiles and alpha-cyclodextrin: supramolecular networks of their pseudorotaxanes in aqueous media.
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DOI：
10.1002/chem.200903315
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发表时间：
2010-06
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影响因子：
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通讯作者：
T. Taira;Yuji Suzaki;K. Osakada
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文献类型：
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作者：
T. Taira;Yuji Suzaki;K. Osakada
n -烷基吡啶化合物[py-N-(CH(2))(n)OC(6)H(3)-3,5-(OMe)(2)](+)(X(-)) （1bCl: n = 10, X = Cl; 1cBr: n = 12, X = Br）和-环糊精（- cd）的混合物在水介质中形成超分子水凝胶。两种组分的浓度影响溶胶-凝胶转变温度，其范围为7 ~ 67℃，用丙酮洗涤或蒸发留下的水凝胶，（13）C CP/MAS NMR测量，粉末x射线衍射（XRD）和扫描电镜（SEM）表明，1bCl（或1cBr）和α - cd的干凝胶是由高结晶度的假环紫杉烷组成的。（13）凝胶的C{(1)H}和(1)H NMR谱揭示了组分的详细组成。来自1bCl和α - cd的凝胶含有相应的[2]-和[3]伪环紫杉烷[1b x (α - cd)]Br和[1b x (α - cd)(2)]Br，而来自1cBr和α - cd的凝胶主要由[3]伪环紫杉烷[1c x (α - cd)(2)]Br组成。二维ROESY (1)H NMR测量表明轴组分的3,5-二甲氧基和吡啶基端基分子间接触。[3]伪烷的存在对于凝胶的形成是不可缺少的。因此，轴组分端基之间的分子间相互作用和[3]伪烷α - cds之间的相互作用有助于网络的形成。通过加入尿素、C(6)H(3)-1,3,5-(OH)(3)和[py-N-nBu](+)（Cl(-)）等变性剂将超分子凝胶转化为溶胶。
Mixtures of N-alkyl pyridinium compounds [py-N-(CH(2))(n)OC(6)H(3)-3,5-(OMe)(2)](+)(X(-)) (1bCl: n = 10, X = Cl; 1cBr: n = 12, X = Br) and alpha-cyclodextrin (alpha-CD) form supramolecular hydrogels in aqueous media. The concentrations of the two components influences the sol-gel transition temperature, which ranges from 7 to 67 degrees C. Washing the hydrogel with acetone or evaporation of water left the xerogel, and (13)C CP/MAS NMR measurements, powder X-ray diffraction (XRD), and scanning electron microscopy (SEM) revealed that the xerogel of 1bCl (or 1cBr) and alpha-CD was composed of pseudorotaxanes with high crystallinity. (13)C{(1)H} and (1)H NMR spectra of the gel revealed the detailed composition of the components. The gel from 1bCl and alpha-CD contains the corresponding [2]- and [3]pseudorotaxanes, [1b x (alpha-CD)]Br and [1b x (alpha-CD)(2)]Br, while that from 1cBr and alpha-CD consists mainly of [3]pseudorotaxane [1c x (alpha-CD)(2)]Br. 2D ROESY (1)H NMR measurements suggested intermolecular contact of 3,5-dimethoxyphenyl and pyridyl end groups of the axle component. The presence of the [3]pseudorotaxane is indispensable for gel formation. Thus, intermolecular interaction between the end groups of the axle component and that between alpha-CDs of the [3]pseudorotaxane contribute to formation of the network. The supramolecular gels were transformed into sols by adding denaturing agents such as urea, C(6)H(3)-1,3,5-(OH)(3), and [py-N-nBu](+)(Cl(-)).