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

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.

Oriented Chiral DNA-Silica Film Guided by a Natural Mica Substrate

The formation of highly ordered chiral organic/inorganic films with high density and long-range orientation is important in constructing chiral devices, such as broadband polarization devices, liquid-crystal displays, or negative-reflection materials. A feasible strategy is presented to fabricate three-dimensional mesostructured chiral DNA-silica assemblies into large-scale oriented arrangements. The highly ordered film was aligned by a mica crystal substrate with the bridging effect of suitable divalent metal ions, followed by the growth of the DNA-silica composite by bottom-up assembly with a "quartet templating" method. This simple and effective route would perform well in the alignment and arrangement of highly charged biomolecules, such as polypeptides, proteins, viruses, and their inorganic assemblies, and furthermore could allow the fabrication of chiral optical materials with long-range ordering.