枝杈状Bola型两亲分子包覆的层状近晶相多金属氧簇液晶

我们利用离子自组装的方法以含苯甲酸基团的两亲分子A6包覆了含铕的无机多金属氧簇Na9EuW10O36]。利用红外光谱、热重分析、元素分析等方法对所得有机无机杂化复合物A6Eu进行了详细的结构表征。苯甲酸基团通过分子间氢键相互作用发生的二聚使有机组分形成了枝杈状的Bola型结构,这种结构导致外围的介晶基元以侧向方式连接在无机簇上。我们通过差示扫描量热法、偏光显微镜和变温X射线衍射对A6Eu的热致液晶性质进行了表征。虽然单独的两亲分子A6组装成了简单的近晶结构,但是复合物A6Eu表现出新颖的层状近晶相液晶结构。层状近晶相液晶结构中介晶基元是平行于层面的。由此可见,介晶基元的侧向连接方式对复合物的热致组装结构具有重要影响。多金属氧簇的荧光性质在液晶材料中得到了很好的保持。

Lamellar-Smectic Polyoxometalate Liquid Crystal Encapsulated by Branched Bola-Form Amphiphiles

The quaternary ammonium amphiphile A6 with carboxylic acid group was employed to encapsulate the europium-containing inorganic polyoxometalate Na₉EuW₁₀O₃₆] through ionic self-assembly strategy. The resultant surfactant-encapsulated polyoxometalate complex A6Eu was characterized by FT-IR spectra, thermogravimetric analysis and elemental analysis in detail. The dimerization of the carboxylic acid groups through intermolecular hydrogen bonding gives rise to a branched bola-form structure of the organic moieties, which leads to a lateral attachement of the peripheral mesogen to the inorganic cluster. The thermotropic liquid crystalline properties of polyoxometalate complex were characterized by differential scanning calorimetry, polarized optical microscopy, and temperature-dependent X-ray diffraction. A6Eu exhibited novel lamellar-smectic mesophase in which the mesogen is organized parallel to the layer planes, while the amphiphile A6 alone was found to form simple smectic structures. The lateral attachment of the mesogen was demonstrated to have an important influence on the thermotropic organized structures of the complex. The luminescence of polyoxometalate is well retained in the liquid crystalline mesophase.