New large-scale screening method for hypothetical MOFs accelerates discovery of gas storage solutions by identifying materials with promise
A Northwestern University research team has developed a computational method that automatically generates and tests hypothetical metal-organic frameworks (MOFs), rapidly zeroing in on the most promising structures. These MOFs then can be synthesized and tested in the lab. A paper on their work is published in the journal Nature Chemistry.
Metal–organic frameworks (MOFs) are porous materials constructed from modular molecular building blocks, typically metal clusters and organic linkers. (Earlier post.) These can, in principle, be assembled to form an almost unlimited number of MOFs, yet materials reported to date represent only a tiny fraction of the possible combinations, the authors note in their paper.
Using their method, the researchers quickly identified more than 300 different MOFs that are predicted to be better than any known material for methane (natural gas) storage. The researchers then synthesized one of the promising materials and found it featured an adsorption of 213cm3/cm3, beating the US Department of Energy (DOE) storage target of 180cm3/cm3.
From a library of 102 building blocks we generated 137,953 hypothetical MOFs and for each one calculated the pore-size distribution, surface area and methane-storage capacity. We identified over 300 MOFs with a predicted methane-storage capacity better than that of any known material, and this approach also revealed structure–property relationships. Methyl-functionalized MOFs were frequently top performers, so we selected one such promising MOF and experimentally confirmed its predicted capacity.—Wilmer et al.
The team generated the 137,953 hypothetical MOF structures—much larger than the total number of MOFs reported to date by all researchers combined (approximately 10,000 MOFs)—in just 72 hours.
The new algorithm combines the chemical “intuition” that chemists use to imagine novel MOFs with sophisticated molecular simulations to evaluate MOFs for their efficacy in different applications. The algorithm could help remove the bottleneck in the discovery process, the researchers said.
When our understanding of materials synthesis approaches the point where we are able to make almost any material, the question arises: Which materials should we synthesize? This paper presents a powerful method for answering this question for metal-organic frameworks, a new class of highly versatile materials.—Randall Q. Snurr, professor of chemical and biological engineering in the McCormick School of Engineering and Applied Science, who led the research.
In addition to gas storage and vehicles that burn cleaner fuel, MOFs may lead to better drug-delivery, chemical sensors, carbon capture materials and catalysts. MOF candidates for these applications could be analyzed efficiently using the Northwestern method.
Christopher E. Wilmer, a graduate student in Snurr’s lab and first author of the paper, developed the new algorithm; Omar K. Farha, research associate professor of chemistry in the Weinberg College of Arts and Sciences, and Joseph T. Hupp, professor of chemistry, led the synthesis efforts.
Currently, researchers choose to create new materials based on their imagining how the atomic structures might look. The algorithm greatly accelerates this process by carrying out such “thought experiments” on supercomputers.—Chris Wilmer
Christopher E. Wilmer, Michael Leaf, Chang Yeon Lee, Omar K. Farha, Brad G. Hauser, Joseph T. Hupp & Randall Q. Snurr (2011) Large-scale screening of hypothetical metal–organic frameworks. Nature Chemistry DOI: 10.1038/nchem.1192