Understanding the breathing phenomena in nano-ZIF-7 upon gas adsorption

Abstract

Synchrotron X-ray diffraction and inelastic neutron scattering measurements have been applied to evaluate the breathing phenomena in small nanocrystals of ZIF-7 upon gas adsorption.

Flexible ZIFs: probing guest‐induced flexibility with CO2, N2 and Ar adsorption

“…We should note that the synthesis of ZIF‐7, ZIF‐9 and ZIF‐11 was carried out with ethanol, and ZIF‐12 was synthesized with methanol, and no DMF was used for the synthesis. As noted in the same paper by Cuadrado‐Collados et al, an extended solvent exchange process with methanol is essential for a solvent‐free structure …”

“…The small differences in the biggest pore window are unlikely to explain the large differences seen for Ar and N 2 uptake between ZIF‐11 and ZIF‐12. As noted above, the differences in uptake are more likely because of the fact that ZIF‐11 was exchanged with ethanol and ZIF‐12 was exchanged with methanol, which, as noted by Cuadrado‐Collados et al, is essential for obtaining a solvent‐free structure. Our results further confirm this observation.…”

“…As noted in the same paper by Cuadrado-Collados et al, an extended solvent exchange process with methanol is essential for a solvent-free structure. 36 ZIF-11 and ZIF-12 show CO 2 adsorption isotherms increasing progressively ( Figs 5 and 6), indicating adsorption in the cavity that occurs without the limitation of the pore window size. The small differences in the biggest pore window are unlikely to explain the large differences seen for Ar and N 2 uptake between ZIF-11 and ZIF-12.…”

“…As seen for ZIF-7, this gate-opening is consistent with a rotation of the benzimidazole linkers which increases the diameter of the cavities and allows for increased adsorption of CO 2 . A recent study by Cuadrado-Collados et al 36 highlighted the importance of complete solvent removal and equilibration times, and showed CO 2 to be less sensitive to the blocking effect of DMF. In that paper, N 2 was shown to be adsorbed by ZIF-7 under long equilibration times of 15 days.…”

Direct probe of the nuclear modes limiting charge mobility in molecular semiconductors

“…To measure the phonons that lead to dynamic disorder, we use inelastic neutron scattering (INS), a technique that probes the atomic dynamics of a material. INS has been used to infer a variety of materials properties including the local structure of polymers, 19,20 binding interactions in porous materials, 21,22 and protein folding in response to a stimulus. INS is particularly well suited for studying dynamic disorder in OSCs because spectroscopy with neutrons does not have any selection rules (every phonon mode in the Brillouin zone is observable) and neutrons interact with atomic nuclei only (not the free charge carriers).…”