Dear community, I'm analyzing metal-organic frameworks where orientational disorder of linkers induces a framework distortion due to local ordering. Moreover, this disorder is also involved in a disorder-order phase transition of the MOF at high temperature, which makes diffraction data better (as opposed to the common case where diffraction gets worse at increasing T due to Debye-Waller effects on structure factors)
Do you know of analogous cases that provide insightful comparisons to my case?
For instance, I am aware of the work by Lee et al. (J. Am. Chem. Soc. 2018, 140, 28, 8958–8964) where this effect is linked to disordering of solvent molecules in the cavities, resulting in overall higher periodicity of the MOF crystal; another interesting work is this by Pallach et al. (Nat Commun 2021, 12, 4097) showing MOF-5 crystals where functional groups on the linkers cause increased crystallinity at higher temperatures as they lose their mutual dispersive interactions.
Different, but still relevant, this work by Ehrling et al. (Nat. Chem. 2021, 568–574) shows a case where linker orientation has a direct influence on framework geometry within an overall aperiodic MOF.
Of course, any cases involving other materials such as zeolites or other systems are very useful.
Thanks in advance!
Stefano
I work with intercalated materials. In some cases, a covalent complex is formed around the intercalated atom due to its association with the host lattice. Such complexes are ordered due to the fact that the charge is localized on them. However, the formation of the complex is accompanied by lattice distortion. Therefore, the rigidity of the lattice prevents the formation of the complex. Heating leads to a softening of the lattice and allows the complexes to form. And then they sort themselves out. Naturally, with further heating, their disordering occurs. And at an even higher temperature, the complexes are completely thermally destroyed.
One such case is described in the attached article.
Thank you Alexander. Very different system, yet interesting analogies: that's very useful.
Stefano Canossa
All your examples refer to a phase transition in an ensemble of small systems. Water (substance) in the pores of MOF, zeolites belongs to small systems. I work with micellar surfactant solutions. In the region of micellization, the formation of micelles is accompanied by a phase transition with a change in the state of water. This is the opposite of yours. A special structure of water is formed around the surfactant molecules. Hill's theory is generally suitable for such a phase transition. It is statistical-thermodynamic and says little about the specifics of the transition. But it confirms the the great length of the transition, the fluctuation of the small system, and the state of the system, or state A or B.
Article Liquid Polyamorphous Transition and Self-Organization in Aqu...
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