MOFS

Metal-organic frameworks (MOFs) are crystalline materials composed of metal ions or metal-containing clusters, called nodes, connected by organic molecules known as linkers to form extended porous networks. The combination creates high surface areas and tunable pore structures, enabling selective adsorption and catalysis. MOFs exhibit structural diversity and can be designed by selecting different metal nodes and organic linkers, allowing control over porosity and functionality.

Design and classification: MOFs are often described by topology; isoreticular MOFs (IRMOFs) demonstrate that the same network can be realized with linkers of varying length. Common metals include zinc, copper, zirconium and iron; linkers are typically carboxylates, azolates, or phosphonates. Synthesis methods include solvothermal or hydrothermal routes, often in polar solvents with modulators to steer crystallization.

Properties and measurements: MOFs have high surface areas, often exceeding 1000 m2/g, and pore sizes ranging from microporous to mesoporous. Stability varies; zirconium- and aluminum-based frameworks tend to be more hydrolytically stable than some copper or iron variants. Characterization typically uses X-ray diffraction, nitrogen adsorption (BET) for surface area, thermogravimetric analysis, and electron microscopy.

Applications: gas storage and separation (hydrogen, methane, CO2), catalysis, sensing, drug delivery, and energy storage. They can capture greenhouse gases, serve as heterogeneous catalysts, or function as hosts for reactive species. Limitations include moisture sensitivity, batch-to-batch variability, and challenges in scalable synthesis.

Outlook: research aims to develop robust, scalable MOFs with high stability and conductivity, deepen understanding of structure-property relationships, and integrate MOFs into devices for separations, catalysis, and energy applications.