In an article recently published in the Journal of the American Chemical Society (and featured on the Dec 26, 2019 journal cover), Prof. Scott Auerbach and collaborators from UMass Amherst and WPI have discovered new building blocks that they call "tricyclic bridges," which help to explain structures and vibrations of zeolites.
Zeolites are the most used catalysts by weight on planet earth, but the synthetic pathways leading to their crystallization remain poorly known. Raman spectroscopy of zeolites has been useful for shedding light on structures that exist in zeolite crystals and during crystallization. Despite the importance of understanding Raman spectra of zeolites, it is often assumed with little evidence that Raman bands can be assigned to individual zeolite rings. Auerbach and co-workers tested this assumption through an integrated synthesis, spectroscopy, and modeling study, finding the critical role of new building blocks they call "tricyclic bridges" -- collections of three zeolite rings connected together. Using this new concept, Auerbach and coworkers discovered a precise relationship between zeolite bond angle and Raman frequency that can be used to pinpoint structures that form during zeolite crystallization.
"This breakthrough is important because it gives us a way to see the invisible -- precise structures that lead to zeolite crystals," says Auerbach. "We hope such structural insights will help us to synthesize new, tailor-made zeolites for advanced applications in clean energy and carbon capture."
Auerbach and his colleagues are funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Award No. DE-SC0019170. In future work supported by this grant, Auerbach and his team plan to measure and model Raman spectra during the zeolite crystallization process, to determine which tricyclic bridges are present and become inherited by the resulting zeolites.