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New Covalent Organic Frameworks Show Promise for Carbon Dioxide Capture
An international research collaboration led by Heinrich Heine University Düsseldorf (HHU) and the University of Siegen has successfully created a novel compound that forms a covalent organic framework (COF). This innovative compound, derived from condensed phosphonic acids, demonstrates remarkable stability and could potentially serve as a method for capturing carbon dioxide (CO2), as detailed in their findings published in the journal Nature Communications.
Covalent organic frameworks are a particular category of porous crystalline materials that have a scaffold-like architecture. The term “covalent” refers to the type of bonding present, where chemical connections between the framework’s components are made through shared electron pairs.
The project, spearheaded by Dr. Gündoğ Yücesan, a Heisenberg Junior Research Group Leader in the Section for Nanoporous and Nanoscale Materials at HHU, and Professor Dr. Jörn Schmedt auf der Günne, head of the Inorganic Materials Chemistry group at the University of Siegen, showcases a straightforward method for creating these frameworks. The team included researchers from various institutions across Berlin, Bremen, Saarbrücken, Turkey, and the United Kingdom, highlighting the collaborative nature of this scientific endeavor.
This particular class of polyphosphonate covalent organic frameworks is distinguished by phosphorus-oxygen-phosphorus bonds formed from elementary organic phosphonic acid units. These building blocks can be assembled akin to Lego bricks through a heating process at around 200 degrees Celsius.
According to Dr. Yücesan, “A key advantage of these COFs is their stability in water and water vapor, which allows for their application in aqueous environments and electrolytes unlike previous compounds.”
The researchers also made strides in establishing a sustainable synthesis process. Dr. Yücesan pointed out, “For the first time, we have developed a solid-state synthesis method for COFs that is entirely solvent-free. This advancement facilitates economical production on a large scale—ranging from kilograms to tonnes—making it a more viable alternative to existing microporous materials.”
One notable challenge faced by the research team was the amorphous nature of the compounds, which presented difficulties in crystallization. However, they utilized nuclear magnetic resonance to provide evidence of the bonding structure. Professor Schmedt auf der Günne remarked, “Without employing the common states of neighboring phosphorus atom nuclei, understanding the molecular bonding structure would have remained elusive.”
The application potential for these polyphosphonate frameworks is substantial. The structures are capable of capturing harmful greenhouse gases such as CO2, with the ability to release them through minor pressure changes. The study’s authors emphasized, “Such materials are essential for gas purification and in efforts to mitigate greenhouse gas emissions.”
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