Formation of Multicomponent Star Structures at the Liquid/Solid Interface

Abstract

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.

Separation of Arylenevinylene Macrocycles with a Surface‐Confined Two‐Dimensional Covalent Organic Framework

“…Nevertheless, covalently linked two‐dimensional (2D) nanoporous networks confined on a surface, known as surface covalent organic frameworks (surface COFs), are more robust than supramolecular networks. Surface COFs, having nanometer‐sized cavities within a periodic pattern, are of significant importance and great interest to act as host networks and nanofilters, and can lead to applications in various domains of nanotechnology …”

Chalice‐Type Tridentate Silicon Lewis Acids of C3 Symmetry in a Single Step Starting from Hexadehydrotribenzo[12]annulene

“…Their rigid framework was basis for the synthesis of multiple‐component covalent organic frameworks (COFs), [10, 11] and planar carbon networks [1, 8, 12] . The addition of hydrophilic side chains opened the access to liquid‐crystalline materials [13, 14] …”

Formation of multicomponent 2D assemblies of C2v-symmetric terphenyl tetracarboxylic acid at the solid/liquid interface: recognition, selection, and transformation

“…5,15,26 The incorporation of guest molecules into the nanoporous network on the basis of shape matching has been widely exploited to obtain multicomponent pattern at the solid/liquid interface. [27][28][29][30][31] On the other hand, the structure transformation between different assemblies, or so-call adaptive assembly, has also been observed. For example, the isophthalic acid can form assembled structure stabilized by dimer hydrogen bonds.…”