Macroscopically Oriented Porous Materials with Periodic Ordered Structures: From Zeolites and Metal–Organic Frameworks to Liquid‐Crystal‐Templated Mesoporous Materials

Abstract

Porous materials with molecular‐sized periodic structures, as exemplified by zeolites, metal–organic frameworks, or mesoporous silica, have attracted increasing attention due to their range of applications in storage, sensing, separation, and transformation of small molecules. Although the components of such porous materials have a tendency to pack in unidirectionally oriented periodic structures, such ideal types of packing cannot continue indefinitely, generally ceasing when they reach a micrometer scale. Consequently, most porous materials are composed of multiple randomly oriented domains, and overall behave as isotropic materials from a macroscopic viewpoint. However, if their channels could be unidirectionally oriented over a macroscopic scale, the resultant porous materials might serve as powerful tools for manipulating molecules. Guest molecules captured in macroscopically oriented channels would have their positions and directions well‐defined, so that molecular events in the channels would proceed in a highly controlled manner. To realize such an ideal situation, numerous efforts have been made to develop various porous materials with macroscopically oriented channels. An overview of recent studies on the synthesis, properties, and applications of macroscopically oriented porous materials is presented.

Supramolecular Organization in Confined Nanospaces

“…Such organization of the guests can then be extended to the macroscale using assembly approaches in the case of colloidal particles/microcrystals ,. Other strategies imply the attachment of the microcrystal on a support. In this case, a key role is played by the terminations of the porous crystals, still little explored at atomistic detail .…”

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures

“…When placed in an external magnetic field, these multidimensional nanomaterials become magnetized due to magnetism-responsive electrons that are present in the nano-objects. [51] This phenomenon results in long-range ordered structuring of nano-objects in a uniform and static magnetic field. Then, during the hydrogelation process, such a well-ordered nanocomposite structure can be fixed by a 3D hydrogel matrix.…”

GO-guided direct growth of highly oriented metal–organic framework nanosheet membranes for H2/CO2 separation

“…Generally, without any GO layer, the ZnO NP layer coated on a porous substrate can act as seeds for the formation of a corresponding Zn-MOF membrane, but the achieved membrane is usually composed of neither nanosheets nor oriented structure. 28 , 29 , 43 With a thin layer of GO coated on the top of the ZnO NP layer, the nucleation of Zn 2 (bIm) 4 nanosheets should start from the interface between GO and the top of the ZnO NP layer because the C–O/C O groups of the GO surface easily react with Zn 2+ from ZnO NPs in the ligand solution. The ZnO NPs coming into contact with GO will preferentially react with the ligands to generate Zn 2 (bIm) 4 nanosheets.…”