Researchers have created a new compound that forms a covalent organic framework. This compound, based on condensed phosphonic acids, is stable and can be utilized for capturing carbon dioxide.
An international team of researchers led by Heinrich Heine University Düsseldorf (HHU) and the University of Siegen has developed a novel compound that establishes a covalent organic framework. This stable compound, which is founded on condensed phosphonic acids, has the potential to capture carbon dioxide (CO2), as detailed in their publication in the scientific journal Nature Communications.
Covalent organic frameworks, or COFs, are a unique class of porous crystalline materials that form supportive structures. The term “covalent” indicates that the chemical connections between the framework’s building blocks arise from shared electron pairs.
The research team, led by Dr. Gündoğ Yücesan, a Heisenberg Junior Research Group Leader at HHU, along with Professor Dr. Jörn Schmedt auf der Günne, who directs the Inorganic Materials Chemistry group at the University of Siegen, introduces a straightforward method for creating these stable frameworks, which hold significant promise for various applications. Collaborating researchers from Berlin, Bremen, Saarbrücken, Turkey, and the UK also contributed to this publication in Nature Communications.
The family of polyphosphonate covalent organic frameworks is characterized by phosphorus-oxygen-phosphorus bonds, which can be formed from simple organic phosphonic acid components and joined together at temperatures of about 200 degrees Celsius, much like assembling Lego bricks.
According to Dr. Yücesan, “What sets these COFs apart is that, despite the gentle synthesis conditions, they show strong stability in water and water vapor. This is a key advantage compared to previously developed compounds, as it allows for use in aquatic environments and electrolytes.”
A significant breakthrough was achieving a sustainable synthesis method. Yücesan explains, “For the first time, we have established a solid-state synthesis process for COFs that entirely eliminates the need for solvents. This technique allows for the cost-effective and scalable production, ranging from kilograms to tonnes, making it much more economical than other microporous materials.”
One hurdle the researchers faced was the poor crystallization of the compounds, resulting in an amorphous structure. They managed to demonstrate the bonds using nuclear magnetic resonance techniques. Professor Schmedt auf der Günne stated, “Without the ability to utilize the common states of neighboring phosphorus atom nuclei, the bonding structure of the compound would have remained unclear, preventing a thorough understanding of its properties.”
These types of polyphosphonates present tremendous opportunities for application. The framework structures can effectively capture the harmful greenhouse gas CO2, which can be released with minor changes in pressure. The study’s authors emphasize, “Such materials are essential for cleaning waste gases and reducing greenhouse gas emissions.”
