Adaptive response of a metal–organic framework through reversible disorder–disorder transitions

Abstract

A highly porous metal-organic framework (DUT-8(Ni), DUT = Dresden University of Technology) is found to adopt a configurationally-degenerate family of disordered states that respond adaptively to specific guest stimuli. This disorder originates from non-linear carboxylate linkers arranging paddlewheels in closed loops of different local symmetries that in turn propagate as tilings of characteristic complex superstructures. Solvent exchange stimulates the formation of distinct disordered superstructures for specific guest molecules. Electron diffraction by desolvated DUT-8(Ni) nanoparticles demonstrates these superstructures to persist on the nanodomain level. Remarkably, guest exchange stimulates reversible and repeatable switching transitions between distinct disorder states. Deuterium NMR spectroscopy and in situ PXRD studies identify the transformation mechanism as an adaptive singular transformation event.

Dynamic Full‐Color Tuning of Organic Chromophore in a Multi‐Stimuli‐Responsive 2D Flexible MOF

“…Secondly, some 2D network architectures (e.g., sql , fes ) afford good resilience against external stimuli that enables the transformed structures not only to maintain their crystallinity and regularity, but also to reverse back without the aid of a second force. Thirdly, 2D MOFs usually possess 1D open channels such that various types of guest molecules can easily come into contact with the confined space decorated with the organic chromophore and affect the output luminescence signals in a responsive manner [37] . Finally, the relatively simple 2D structures allow for the facile structural characterization of flexible MOFs, the geometric identification of the grafted organic chromophores and the entrapped guest molecules, which will provide a quantum leap in understanding the intricate stimuli‐responsive luminescence mechanisms [46, 47] …”

Isotope-selective pore opening in a flexible metal-organic framework

“…1A). Crystal size, morphology, and conformation are used to effectively tune the responsivity of DUT-8(Ni) ( 35 , 36 ). While macrosized DUT-8(Ni) crystals show selective guest responsivity associated with a pronounced cell volume change (~250%) upon gate opening [an adsorption-induced transition from a closed-pore (cp) to an open-pore (op) phase triggered by nitrogen, carbon dioxide, or C2-C4 hydrocarbons at their standard boiling points ( 37 )], nanocrystals of DUT-8(Ni) are rigid instead and show reversible uptake of gasses after desolvation.…”

Coordination modulated on-off switching of flexibility in a metal–organic framework

“…We attribute this phenomena to the presence of residual solvent molecules trapped within the collapsed framework upon activation that can lower the activation energy for phase transitions. 40 This hypothesis is supported by TGA-MS measurements performed on activated samples of 1 ·[CuCl] showing residual solvent (Fig. S5 and S6 † ).…”