Tahara Kazukuni, Kaneko Kyohei, Katayama Keisuke, Itano Shintaro, Nguyen Chi Huan, Amorim Deborah D D, De Feyter Steven, Tobe Yoshito
†Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
‡Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Celestijnenlaan 200 F, 3001 Leuven, Belgium.
Langmuir. 2015 Jun 30;31(25):7032-40. doi: 10.1021/acs.langmuir.5b01507. Epub 2015 Jun 19.
To demonstrate key roles of multiple interactions between multiple components and multiple phases in the formation of an uncommon self-assembling pattern, we present here the construction of a porous hexagonal star (h-star) structure using a trigonal molecular building block at the liquid/solid interface. For this purpose, self-assembly of hexaalkoxy-substituted dehydrobenzo[12]annulene derivatives DBA-OCns was investigated at the tetradecane/graphite interface by means of scanning tunneling microscopy (STM). Monolayer structures were significantly influenced by coadsorbed tetradecane molecules depending on the alkyl chains length (C13-C16) of DBA-OCn. However, none of DBA-OCn molecules formed the expected trigonal complexes, indicating that an additional driving force is necessary for the formation of the trigonal complex and its assembly into the h-star structure. As a first approach, we employed the "guest induced structural change" for the formation of the h-star structure. In the presence of two guest molecules, nonsubstituted DBA and hexakis(phenylethynyl)benzene which fit the respective pores, an h-star structure was formed by DBA-OC15 at the tetradecane/graphite interface. Moreover, a tetradecane molecule was coadsorbed between a pair of alkyl chains of DBA-OC15, thereby blocking the interdigitation of the alkyl chain pairs. Therefore, the h-star structure results from the self-assembly of the four molecular components including the solvent molecule. The second approach is based on aggregation of perfluoroalkyl chains via fluorophilicity of DBA-F, in which the perfluoroalkyl groups are substituted at the end of three alkyl chains of DBA-OCn via p-phenylene linkers. A trigonal complex consisting of DBA-F and three tetradecane molecules formed an h-star structure, in which the perfluoroalkyl groups that orient into the alkane solution phase aggregated at the hexagonal pore via fluorophilicity. The present result provides useful insight into the design and control of complex molecular self-assembly at the liquid/solid interface.
为了证明多个组分和多个相之间的多重相互作用在形成罕见的自组装图案中的关键作用，我们在此展示了在液/固界面使用三角分子构建块构建多孔六边形星状（h-star）结构。为此，通过扫描隧道显微镜（STM）研究了六烷氧基取代的脱氢苯并[12]环烯衍生物DBA-OCns在十四烷/石墨界面的自组装。取决于DBA-OCn的烷基链长度（C13 - C16），共吸附的十四烷分子对单层结构有显著影响。然而，没有一个DBA-OCn分子形成预期的三角配合物，这表明形成三角配合物并将其组装成h-star结构需要额外的驱动力。作为第一种方法，我们采用“客体诱导结构变化”来形成h-star结构。在存在两个适合各自孔的客体分子、未取代的DBA和六（苯乙炔基）苯的情况下，DBA-OC15在十四烷/石墨界面形成了h-star结构。此外，一个十四烷分子共吸附在DBA-OC15的一对烷基链之间，从而阻止了烷基链对的相互交错。因此，h-star结构是由包括溶剂分子在内的四个分子组分的自组装形成的。第二种方法基于DBA-F的亲氟性使全氟烷基链聚集，其中全氟烷基通过对亚苯基连接体取代在DBA-OCn的三个烷基链末端。由DBA-F和三个十四烷分子组成的三角配合物形成了h-star结构，其中取向进入烷烃溶液相的全氟烷基通过亲氟性在六边形孔处聚集。目前的结果为液/固界面复杂分子自组装的设计和控制提供了有用的见解。
