DWI an der RWTH Aachen e.V. and Institut für Technische und Makromolekulare Chemie der RWTH Aachen, Pauwelsstr. 8, 52056 Aachen, Germany.
Chemphyschem. 2010 Dec 3;11(17):3638-44. doi: 10.1002/cphc.201000567.
Herein, we describe the synthesis of a low-symmetry monodendron, 3,4-bis(dodecyloxy)-5-[3,4,5-tris(dodecyloxy)benzyloxy]benzoic acid, following a simple route which starts from gallic acid ethyl ester and does not require any protecting groups. The self-assembled structures formed by the compound in 3D and 2D were investigated by synchrotron X-ray scattering and scanning force microscopy (SFM). In 3D, the compound forms a stable crystalline phase with an orthorhombic lattice in which the alkyl chains connected to different benzene rings form crystalline and amorphous domains. Upon cooling from the isotropic melt the compound exhibits a monotropic smectic mesophase. In 100-nm-thick films on a neutral substrate the structure loses its biaxiality, adopting a hexagonal columnar structure with the columns oriented parallel to the substrate. By contrast, in ultrathin films on graphite the SFM likely reveals two crystal orientations, which can develop due to the epitaxial adsorption on the substrate of the alkyl chains pertinent to different benzene rings.
在此，我们描述了一种低对称性单树突的合成，3,4-双（十二烷氧基）-5-[3,4,5-三（十二烷氧基）苯甲酰氧基]苯甲酸，该方法路线简单，起始原料为没食子酸乙酯，且无需使用任何保护基团。通过同步辐射 X 射线散射和扫描力显微镜（SFM）研究了化合物在 3D 和 2D 中形成的自组装结构。在 3D 中，化合物形成了具有正交晶格的稳定结晶相，其中连接到不同苯环的烷基链形成结晶和非晶畴。在各向同性熔体冷却过程中，化合物表现出单各向异性的近晶相。在中性基底上的 100nm 厚薄膜中，结构失去了双轴性，采用了与基底平行的六方柱状结构，其中柱状物沿基底取向。相比之下，在石墨上的超薄膜中，SFM 可能揭示了两种晶体取向，这可能是由于与不同苯环相关的烷基链在基底上的外延吸附所致。
