Macrocycle-Based Hierarchically Porous Hydrogen-Bonded Organic Frameworks

Hydrogen-bonded organic frameworks (HOFs) are porous crystalline materials. The pores in HOFs are usually non-covalent extrinsic pores constructed through the formation of the framework. Supramolecular macrocycles with intrinsic pores in their structures are good candidates for constructing HOFs with intrinsic pores from the macrocycles themselves, thus leading to hierarchically porous structures. Combining the macrocycle and HOFs will endow these hierarchically porous materials with enhanced properties and special functionalities. This review summarizes recent advances in macrocycle-based HOFs, including the macrocycles used for constructing HOFs, the hierarchically porous structures of the HOFs, and the applications induced by the hierarchically HOFs porous structures. This review provides insights for future research on macrocycle-based hierarchically porous HOFs and the appropriate applications of the unique structures.

Beyond Microporosity in Porous Organic Molecular Materials (POMMs)

Porous organic molecular materials (POMMs) are a novel class of porous materials that cover a wide range of organic-based molecular building blocks connected through weak supramolecular interactions, such as hydrogen bonds, π-π stacking, van der Waals and electrostatic interactions. Despite of their diverse chemical and structural nature, common features to POMMs include solution processability, crystallinity and microporosity. Herein, we focus, for the first time, on the advance of the field of POMMs beyond the archetypical microporosity. In particular, we highlight relevant examples of meso- and macroporous POMMs, as well as hierchachical ones (micro-/meso-, micro-/macro- and meso-/macroporous). We also remark some of their unique properties, and how they can be key in many applications.

One-Step Method for Fabricating Porous Copper with Hierarchical Porosities by Dealloying Multi-Phase Cu–Mn–Al Alloy

The bulk porous copper structures with three levels of pore size from macro- to micro- to nano-scale were prepared from Cu–Mn–Al alloy through a facile one-step dealloying process. The excellent performances, such as hierarchical porosity, ultralow density (theoretical density at 0.53 g/cm3), and stable mechanical properties, were obtained in these copper structures which could be widely applied in many potential industrial applications. In addition, the process and mechanism of the pore formation was well investigated by SEM and EDX in this paper. The experimental results showed that the hierarchical multi-scale porosities in bulk copper structures were successfully fabricated by the one-step dealloying method. The macro-pores (up to 70 μm in major axis) and the micro-pores (about 2˜5 μm in diameter) in this sample were obtained from the removed high-purity Al phase of the precursor alloy, while the nano-pores (about 70˜100 nm in diameter) were generated from the dealloyed intermetallic compounds of Al2Cu and Al11Cu5Mn3, respectively.