Metal-Organic Frameworks
New materials with spaces full of possibilities
Imagine a material so porous that a single gram can contain an internal surface area equivalent to several football fields.
The Universe in a Gram of Material
These extraordinary materials have revolutionized materials chemistry to such an extent that their creators, Susumu Kitagawa, Richard Robson, and Omar Yaghi, were awarded the Nobel Prize in Chemistry 2025 2 .
The Royal Swedish Academy of Sciences emphasized that "metal-organic frameworks have enormous potential, providing previously unthinkable opportunities for customized materials with new functions" 2 .
The magic of MOFs lies in their design: like molecular LEGO pieces, scientists can combine them to create structures with specific properties, opening a universe of possibilities to address some of humanity's greatest challenges 5 .
Carbon Capture
Extracting CO₂ from the atmosphere
Water Harvesting
Extracting water from desert air
Energy Storage
Hydrogen storage for fuel cells
What Are Metal-Organic Frameworks?
Molecular Architecture
Metal-organic frameworks are porous polymers formed by metal groups (known as secondary building units or SBUs) coordinated with organic ligands to form one-, two-, or three-dimensional structures 1 .
In simpler terms, they are molecular constructions where metal ions function as corners joined by long organic molecules (carbon-based) 2 .
Together, the metal ions and molecules organize to form crystals containing large cavities, creating extraordinarily efficient porous materials 2 .
An Architectural Analogy
Think of MOFs as molecular skyscrapers:
Metal Nodes
The steel beams that form the basic structure
Organic Ligands
The connectors that join these beams
Porous Spaces
The rooms where molecules can be stored and manipulated
This molecular architecture is not random; it follows precise design principles that allow chemists to control the size, shape, and functionality of the internal spaces 8 .
Brief History: From Concept to Nobel
The development of MOFs is a story of scientific vision and persistence.
1989
Richard Robson began testing the utilization of the inherent properties of atoms in a new way 2 . He combined positively charged copper ions with a four-armed molecule, creating a well-ordered, spacious crystal, like "a diamond filled with countless cavities" 2 .
1992-2003
Susumu Kitagawa and Omar Yaghi separately made a series of revolutionary discoveries:
1999
A crucial breakthrough came with the development of MOF-5, the first MOF to exhibit ultra-high porosity 1 . Built from zinc oxide groups and terephthalate linkers, MOF-5 illustrated unique properties such as high surface area, structural robustness, and versatility, establishing MOFs as a platform technology 1 .
2025
Nobel Prize in Chemistry awarded to Susumu Kitagawa, Richard Robson, and Omar Yaghi for their pioneering work on metal-organic frameworks 2 .
- Susumu Kitagawa
- Richard Robson
- Omar Yaghi
The Crucial Experiment: Creation of MOF-5
The development of MOF-5 by Omar Yaghi and his team marked a turning point, demonstrating for the first time that materials with exceptional porosity and stability could be created.
Step-by-Step Methodology
Zinc nitrate [Zn(NO₃)₂] and terephthalic acid (H₂BDC) were dissolved in dimethylformamide (DMF), an organic solvent 3 . The DMF acts as a medium for the reaction and also fills the initial pores of the material.
During this process, zinc ions and terephthalic acid molecules self-assembled forming an ordered three-dimensional structure with zinc oxide clusters as nodes and terephthalate as connectors.
Once the crystals formed, the crucial step was to activate the MOF by removing solvent molecules from the pores through heating and vacuum, thus revealing the material's enormous surface area 6 .
Results and Analysis
The results were extraordinary and paved the way for a new class of materials:
- MOF-5 exhibited a record surface area ~3000 m²/g
- Thermal stability ~300°C
- Perfectly ordered crystalline structure Confirmed
- Permanent porosity Demonstrated
The scientific importance of MOF-5 lies in the fact that it proved that it was possible to design and synthesize crystalline porous materials with atomic precision, establishing the foundations of what Yaghi would later call "reticular chemistry" - the chemistry of linking molecular units through strong bonds to create open structures 1 .
| Material | Surface Area (m²/g) | Pore Volume (cm³/g) | Thermal Stability (°C) |
|---|---|---|---|
| MOF-5 | ~3000 | ~1.5 | ~300 |
| Typical Zeolite | ~500 | ~0.3 | >600 |
| Activated Carbon | ~1500 | ~0.8 | ~500 |
The Scientist's Toolkit: Essential Materials in MOF Research
The synthesis of MOFs requires specific components whose design determines the properties of the resulting material.
| Component | Function | Common Examples |
|---|---|---|
| Metal Nodes | Act as structural connection points; their geometry defines the basic architecture | Zinc, copper, zirconium, iron ions; clusters like Zr₆O₄(OH)₄ 1 3 |
| Organic Ligands | Connect the metal nodes; define the size and chemistry of the pores | Terephthalic acid (BDC), trimesic acid, imidazoles, bipyridines 1 3 |
| Modulators | Control crystallization; enhance crystallinity and control particle size | Acetic acid, trifluoroacetic acid, pyridine 6 |
| Solvents | Reaction medium; influences thermodynamics and activation energy | DMF, water, ethanol, acetonitrile 3 6 |
Metal nodes form the structural foundation of MOFs. Different metals impart different properties:
Zinc
Stable structures
Copper
Flexible frameworks
Zirconium
High stability
Organic linkers determine pore size and functionality:
Linear
1D channels
Planar
2D layers
3D
Complex pores
Synthesis Methods: Creating Molecular Architecture
Chemists have developed multiple techniques to assemble these molecular components, each with specific advantages depending on the desired application.
| Method | Advantages | Disadvantages |
|---|---|---|
| Solvothermal/Hydrothermal | One-step synthesis, access to single crystals, moderate temperature | Long reaction time (hours/days), requires more solvent 3 6 |
| Microwave-Assisted | Fast (minutes), high purity, uniform morphology, eco-friendly | Difficult to obtain single crystals, not yet scalable 6 |
| Electrochemical | Doesn't need metal salts, mild conditions, fast (hours) | Requires N₂ atmosphere, variable structure, lower yield 6 |
| Mechanochemical | Room temperature, fewer hazardous byproducts, fast (minutes), eco-friendly | Decreased pore volume, lower crystallinity, lower yield 6 |
Solvothermal
Uses heat and pressure in sealed containers
Microwave
Rapid heating for faster synthesis
Electrochemical
Uses electrical current for synthesis
Mechanochemical
Grinding solids without solvents
Applications: From Laboratories to the Real World
Following the pioneering discoveries awarded the Nobel Prize, chemists have built tens of thousands of different MOFs 2 . Some of them can contribute to solving some of humanity's greatest challenges:
Carbon Capture
MOFs show exceptional potential for carbon dioxide capture, thanks to their high selectivity for CO₂, cyclic stability, and low energy requirements for regeneration 4 .
Companies like Svante and Nuada are developing MOF-based technologies that offer the potential for significant reductions in operating costs compared to current amine scrubbing technology 4 .
Water Harvesting
One of the most fascinating applications is the ability of some MOFs to extract water from the atmosphere, even in desert air 2 .
These materials can capture water molecules at night and release them when heated with sunlight, providing a potential source of drinking water in arid regions.
Energy Storage
In the energy field, MOFs are being researched for hydrogen storage in fuel cell vehicles and as advanced materials for batteries and supercapacitors 4 .
Their high surface area and tunable pore sizes make them ideal for storing gases and improving energy density in storage devices.
Gas Storage
Carbon Capture
Drug Delivery
Water Harvesting
Development stage of various MOF applications (estimated)
Conclusion: The Future Built Molecule by Molecule
The Nobel Prize in Chemistry 2025 not only celebrates the past: it charts the course for the future 5 . Metal-organic frameworks represent a fundamental transformation in how we design and create materials. We are no longer slaves to what nature offers us; now we can build custom substances, atom by atom, with specific properties for specific challenges.
From academic laboratories to industrial applications, MOFs illustrate the power of basic science to generate concrete solutions. As researcher Jeremy Feldblyum reflects, who has dedicated two decades to studying these materials: "The future of MOFs is as limitless as the future of chemistry itself. I am constantly surprised by the new and innovative ways scientists implement these materials" 8 .
The story of MOFs — from the Nobel-winning pioneers to new generations of light-activated materials — is also the story of a powerful idea: that molecular design can transform how we face the challenges of the 21st century 5 .