Self‐Assembly of Metal–Organic Frameworks into Monolithic Materials with Highly Controlled Trimodal Pore Structures

Abstract

We present at wo-step template-free approach towardm onolithic materials with controlled trimodal porous structures with macro-, meso-, and micropores.O ur method relies on two ordering processes in discrete length scales: 1) Spontaneous formation of macroporous structures in monolithic materials by the sol-gel process through the short-range ordered self-assembly of metal-organic frameworks (MOFs), and 2) reorganization of the framework structures in am ediator solution. The Zr-terephthalate-based MOF (UiO-66-NH 2 ) was adopted as aproof of concept. The self-assembly-induced phase separation process offered interconnected macropores with diameters ranging from 0.9 to 1.8 mm. The subsequent reorganization process converted the microporous structure from low crystalline framework to crystalline UiO-66. The resultant mesopore sizew ithin the skeletons was controlled in the range from 9to21 nm. This approach provides anovel way of designing spaces from nano-to micrometer scale in network-forming materials.

Monolithic metal–organic frameworks for carbon dioxide separation

“…So far, there have only been a limited number of reports on selfshaping MOFs. [44][45][46][47][48][49][50][51][52] In early self-shaping MOFs, researchers utilised precursor MOF gels to form selfshaped materials via syneresis when the MOF gel was dried under ambient conditions, while elevated drying temperatures gave way to powder formation. 53 These materials displayed similar properties to xerogels, displaying large volumes of hierarchical porosity and low bulk densities.…”

Metal–organic frameworks as a therapeutic strategy for lung diseases

“…132,133 Although the ideal ligand coordination number of UiO-66 is 12, there are certain ligand defects in its actual structure, which are not common to any other MOFs. 134 The defective ligands in the UiO-66 structure influence directly its surface area. Defective ligands are controlled via synthetic conditions (e.g., crystallization duration or temperature) or the addition of different types of regulators.…”

A resistant and stable HKUST@MC composite for highly efficient gas adsorptive desulfurization

“…The most representative MOF shaping methods are: pressing, 15,16 granulation, 17,18 extrusion, 19,20 spray drying 21,22 and the sol-gel method. 23,24 An efficient shaping method should reduce the powdered form limitations and preserve the intrinsic properties of the pristine material. 12 The extrusion method of forming viscous pastes prepared from a powdered MOF and a binder material is technically feasible and low in cost, and has shown satisfactory results in the preparation of resistant beads without compromising the MOF crystallinity and porosity.…”