Organometallic framework films improve isomer separation control

Researchers have developed a method to enhance the separation of chemical isomers by controlling molecular diffusion. They utilized metal-organic framework thin films and applied dynamic chemical interactions to tune pore dynamics and anti-isomer diffusion priorities. Their research is published in Nature Communications.

Separation technology for chemicals (gases, hydrocarbons, isotopes, isomers) is essential to our daily life. A global effort is underway to simplify separation and purification processes using chemical engineering techniques and new materials.

Porous materials acting as membranes can achieve these separations with minimal energy input and reduced carbon emissions, making the process both economically and environmentally sustainable.

However, improving efficiency remains a challenge. Achieving this requires a better understanding and control of molecular interactions and diffusion (movement of molecules within pores) processes.

A research team led by Ritesh Halder from the Tata Institute of Fundamental Research in Hyderabad has devised a strategy to increase control over chemical diffusion processes.

Isomers are molecules that have the same chemical composition but different geometric shapes and, as a result, different chemical properties.

Separation of chemical isomers requires fine control of pore size and chemical functionality. Due to the small dimensions of the molecules, pores with dimensions of 10-10 μm are required. Because the isomers differ in size by small amounts (sometimes by a few angstroms), it is difficult to come up with a molecular sieve that can effectively separate isomers based on size.

To perform the controlled diffusion experiments, the researchers used nanoporous ordered materials known as organometallic frameworks.

Using a combination of experiments and molecular simulations, researchers were able to devise a new chemical strategy that allows them to fine-tune the diffusion of chemical isomers: dynamic chemical interactions.

In this methodology, the chemistry and mechanics of narrow pores work together. They were able to show that by implementing this strategy, the preference for isomer diffusion can even be reversed.

The research group of Jagannath Mondal and Soumya Ghosh at TIFR Hyderabad has predicted how chemical interactions and pore dynamics affect the movement of molecules.

Based on the research results, Ritesh Haldar’s team created the ideal porous material to demonstrate this unique dynamic interaction. Using the new method, they successfully separated aliphatic halogen isomers and even showed that the separation priorities could be reversed if necessary.