Crystals for Carbon Dioxide Capture

UCLA chemists have created three-dimensional synthetic DNA-like crystals that have a sequence of information which is believed to code for carbon capture. The discovery could result in a new way to capture heat-trapping carbon dioxide emissions and could lead to cleaner energy.

"We created three-dimensional, synthetic DNA-like crystals," said UCLA chemistry and biochemistry professor Omar M. Yaghi. "We have taken organic and inorganic units and combined them into a synthetic crystal which codes information in a DNA-like manner. It is by no means as sophisticated as DNA, but it is certainly new in chemistry and materials science."

"What we think this will be important for is potentially getting to a viable carbon dioxide–capture material with ultra-high selectivity," said Yaghi. "Potentially, we could create a material that can convert carbon dioxide into a fuel, or a material that can separate carbon dioxide with greater efficiency."

Yaghi worked with Hexiang "DJ" Deng, a UCLA graduate student of chemistry and biochemistry.

"DNA is a beautiful molecule that has a way to code for information," Yaghi said. "How do you code information in a crystal in the same way that DNA does? DJ and I figured out a way to do this. The sequence of organic functionalities that decorates the pores of the crystals is most certainly a unique code. DJ has illustrated that one member of a series of materials he has made has 400 percent better performance in carbon dioxide capture than one that does not have the same code."

In the early 1990s, Yaghi invented a class of materials called metal-organic frameworks (MOFs), sometimes described as crystal sponges, in which he can change the components nearly at will. MOFs have pores — openings on the nanoscale in which Yaghi and his colleagues can store gases that are usually difficult to store and transport. Molecules can go in and out of the pores unobstructed.

"We have created crystals of metal-organic frameworks in which the sequence of multiple functionalities of varying kind and ratios acts as a synthetic 'gene,'" Yaghi said. "With these multivariate MOFs, we have figured out a way to incorporate controlled complexity, which biology operates on, in a synthetic crystal — taking synthetic crystals to a new level of performance. This can be a boon for energy-related and other industrial applications, such as conversion of gases and liquids like carbon dioxide to fuel, or water to hydrogen, among many others."

Yaghi has been collaborating with his former UCLA chemistry colleague Sir J. Fraser Stoddart on how to take concepts from biology and incorporate them into a synthetic material.

"We hope the materials we are creating will introduce a new class of structures that have controlled complexity," Yaghi said. "Chemists and materials scientists are now able to ask new questions we have never asked before. Also, new tools for characterizing the sequences and deciphering the codes within the crystals will have to be developed."

(UCLA) 

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