MIT scientists produce 'ultrastable' materials using new computing method
MIT researchers have used a computational model to identify about 10,000 possible metal-organic framework MOF structures that they classify as “ultrastable.” These states make them good candidates for applications such as converting methane gas to methanol.
“When people come up with hypothetical MOF materials, they don’t necessarily know beforehand how stable that material is,” said in a statement published on Tuesday Heather Kulik, an MIT associate professor of chemistry and chemical engineering and the senior author of the study.
“We used data and our machine-learning models to come up with building blocks that were expected to have high stability, and when we recombined those in ways that were considerably more diverse, our dataset was enriched with materials with higher stability than any previous set of hypothetical materials people had come up with.”
The scientists have also begun to explore using MOFs to deliver drugs or imaging agents within the body. MOFs consist of two secondary building units: organic molecules that incorporate metal atoms such as zinc or copper and organic molecules called linkers, which connect the secondary building units. These parts can be combined together just like LEGO building blocks.
“Because there are so many different types of LEGO blocks and ways you can assemble them, it gives rise to a combinatorial explosion of different possible metal-organic framework materials,” Kulik said.
“You can really control the overall structure of the metal-organic framework by picking and choosing how you assemble different components.”
Today, the most common way to design MOFs is through trial and error. Computational approaches offer a new and better approach to engineering these materials, especially if they take into account the stability of the resulting material.
An open structure
“A really good MOF material for catalysis or for gas storage would have a very open structure, but once you have this open structure, it may be really hard to make sure that that material is also stable under long-term use,” Kulik said.
In a 2021 study, Kulik reported a new model that she created by mining a few thousand papers on MOFs. In the new research, Kulik and her students used that same model to identify about 500 MOFs with very high stability.
Then, they broke those MOFs down to 120 secondary building units and 16 linkers and recombined them using about 750 different types of architectures. The researchers produced about 50,000 new MOF structures.
“One of the things that was unique about our set was that we looked at a lot more diverse crystal symmetries than had ever been looked at before, but [we did so] using these building blocks that had only come from experimentally synthesized highly stable MOFs,” Kulik concluded in the press release.