Guest-dependent bond flexibility in UiO-66, a “stable” MOF

Abstract

We report “flexibility constants”—a conceptual analog to metal–ligand stability constants—of UiO-66, the prototypical “stable” MOF, across a wide temperature range in both vacuum and in the presence of typical guest solvents.

Ultrafast Water H-Bond Rearrangement in a Metal–Organic Framework Probed by Femtosecond Time-Resolved Infrared Spectroscopy

“…These trends indicate the following filling mechanism: initial water binding occurs at the highly charged open metal and triazolate sites shown in Figure . Evidence for this initial binding site is found in large shifts to the triazolate band, which may be due to either direct water–triazolate interactions or changes in the ligand–metal interactions that result from water binding. , Additional water molecules then bind to the waters at these charged sites, forming H-bond chains that include most of the pore water at humidities above 15%. The fact that the absorbance of the strongly bound peak increases with water loading indicates strong water–water H-bonds as well.…”

Dynamic metal-linker bonds in metal–organic frameworks

“…Guest molecules also influence the dynamic equilibria of MOF ML bonding. Whereas the above report studied MOFs under vacuum, VT-DRIFTS spectra were reported for UiO-66 (Zr 6 O 4 (OH) 4 (1,4-benzenedicarboxylate)6)—a MOF known for its unusual stability, 21 in the presence of solvent vapour, air, and dry N 2 . For comparison, analysis of VT-DRIFTS data yielded ln K tl ( K tl = [tight]/[loose]) values of 1.84 under vacuum.…”

“…While many early reports of MOFs document phase-change behaviour, soft mode behaviour was only introduced into the MOF literature recently. [17][18][19][20][21] In this Frontier article we will highlight recent studies of dynamic ML bonds and their implications for the future of the MOF field.…”

Dynamic metal-linker bonds in metal-organic frameworks

“…Guest molecules also influence the dynamic equilibria of MOF ML bonding. Whereas the above report studied MOFs under vacuum, VT-DRIFTS spectra were reported for UiO-66 (Zr6O4OH4(1,4-benzenedicarboxylate)6)-a MOF known for its unusual stability, 21 in the presence of solvent vapour, air, and dry N2. For comparison, analysis of VT-DRIFTS data yielded ln Ktl (Ktl = [tight]/[loose]) values of 1.84 under vacuum.…”

“…While many early reports of MOFs document phase-change behaviour, soft mode behaviour was only introduced into the MOF literature recently. [17][18][19][20][21] In this Frontier article we will highlight recent studies of dynamic ML bonds and their implications for the future of the MOF field. The tension between enthalpically and entropically favoured ML bond conformations gives rise to a generic one-dimensional configurational coordinate diagram shown in Fig.…”