Today's paper summary comes from David Sholl.
Far more is known about defects in zeolites than about defects in MOFs, although the structural similarities between ZIFs and zeolites strongly hint that defects should be common in ZIFs and, by extension, other kinds of MOFs. Defects are typically thought of as introducing disorder or randomness into crystals, but this does not always have to be the case. Baerlocher and colleagues give a nice example of a high silica zeolite structure that includes an ordered set of defects in the crystal structure of the zeolite SSZ-74 (Baerlocher et al. Nature Materials, DOI: 10.1038/nmat2228) . Much of their paper deals with the technical details of solving the crystal structure of this complicated zeolite, but the main conclusion is that the structure includes a set of ordered Si vacancies in each unit cell. It is important to note that a perfectly plausible model of a defect-free silica material with the same framework could be constructed, so the existence of the ordered vacancies is a consequence of the complex crystallization process that generates SSZ-74.
This paper doesn't give a direct example of how the Si vacancies in the structure affect the performance or properties of the material. There are examples, however, of point defects such as oxygen vacancies giving zeolites properties such as luminescence that are not possible with defect-free materials (Bai et al., J. Luminesence, DOI:10.1016/j.jlumin.2013.08.01) .
Far more is known about defects in zeolites than about defects in MOFs, although the structural similarities between ZIFs and zeolites strongly hint that defects should be common in ZIFs and, by extension, other kinds of MOFs. Defects are typically thought of as introducing disorder or randomness into crystals, but this does not always have to be the case. Baerlocher and colleagues give a nice example of a high silica zeolite structure that includes an ordered set of defects in the crystal structure of the zeolite SSZ-74 (Baerlocher et al. Nature Materials, DOI: 10.1038/nmat2228) . Much of their paper deals with the technical details of solving the crystal structure of this complicated zeolite, but the main conclusion is that the structure includes a set of ordered Si vacancies in each unit cell. It is important to note that a perfectly plausible model of a defect-free silica material with the same framework could be constructed, so the existence of the ordered vacancies is a consequence of the complex crystallization process that generates SSZ-74.
This paper doesn't give a direct example of how the Si vacancies in the structure affect the performance or properties of the material. There are examples, however, of point defects such as oxygen vacancies giving zeolites properties such as luminescence that are not possible with defect-free materials (Bai et al., J. Luminesence, DOI:
