Liquid-crystalline, polycatenar complexes of silver(I): dependence of the mesomorphism on the ligand and the anion
作者:Bertrand Donnio、Duncan W. Bruce
DOI:10.1039/a809320b
日期:——
We have synthesised several series of poly(alkoxy)stilbazole ligands, and investigated the thermal behaviour of their complexes with some silver salts. Most of the complexes, with the general formula [AgL2][X], where X=dodecyl sulfate (DOS) or trifluoromethanesulfonate (OTf), and L=poly(alkoxy)stilbazole, were found to be liquid-crystalline over a wide-temperature range, the vast majority of them being low-melting. The mesomorphic properties were mainly dominated by the formation of hexagonal columnar (Colh) phases and to a lesser extent, of bicontinuous Iad cubic phases; monotropic nematic and smectic C phases were also seen for one structural type of compound only. The mesophases were assigned on the basis of their optical textures under polarised optical microscope (POM) prior to being identified by X-ray diffraction (XRD). The temperatures and enthalpies of the transitions were determined by differential scanning calorimetry (DSC). The mesomorphism was found to be strongly dependent on the substitution pattern of the ligand, that is on the number, position and length of alkoxy chains, as well as on the type of the counter anion. We explain the mesomorphism in terms of ionic interactions and in terms of mean interfacial curvature between the hydrophobic, aliphatic chains and the rigid, aromatic, central core, by analogy to lyotropic systems.
我们合成了几系列聚(烷氧基)斯蒂尔巴索配体,并研究了它们与一些银盐形成的复合物的热行为。大多数复合物的通用公式为[AgL2][X],其中X为十二烷基硫酸盐(DOS)或三氟甲磺酸盐(OTf),L为聚(烷氧基)斯蒂尔巴索,发现在较宽的温度范围内,这些复合物呈现液晶状态,绝大多数具有低熔点。相态主要由六角柱状(Colh)相的形成主导,在小程度上也有双连续Iad立方相;单调型向列相和层状C相仅在一种结构类型的化合物中被观察到。通过在偏振光学显微镜(POM)下观察其光学纹理,先对这些中间相进行赋名,然后通过X射线衍射(XRD)进行确认。通过差示扫描量热法(DSC)确定了转变的温度和焓。发现中间相的形成强烈依赖于配体的取代模式,即烷氧基链的数量、位置和长度,以及对离子的类型。我们从离子相互作用和疏水性的脂肪链与刚性芳香性中央核心之间的平均界面曲率解释了中间相的形成,这与液晶系统相类比。