The Zeolitic Imidazolate Framework ZIF‐4 under Low Hydrostatic Pressures

Abstract

The zeolitic imidazolate framework ZIF‐4 has recently been shown to exhibit large structural flexibility as a response to hydrostatic pressures, going from an open pore phase (ZIF‐4(Zn)‐op) to a closed pore phase (ZIF‐4(Zn)‐cp). The use of diamond anvil cell (DAC) setups has so far restricted thorough experimental insight into the evolution of lattice parameters at pressures below p < 0.1 GPa. Here we revisit the high‐pressure properties of ZIF‐4(Zn) by applying a new high‐pressure powder X‐ray diffraction setup that allows for tracking the evolution of lattice parameters in pressure increments as small as Δp = 0.005 GPa in the pressure range p = ambient – 0.4 GPa; a pressure resolution that cannot be achieved by using traditional DACs. We find ZIF‐4(Zn) has a bulk modulus of K(ZIF‐4(Zn)‐op) = 2.01 ± 0.05 GPa and K(ZIF‐4(Zn)‐cp) = 4.39 ± 0.20 GPa, clarifying and confirming some ambiguous results that have been reported previously.

Abstimmung des Hochdruckphasenverhaltens hochkomprimierbarer zeolithischer Imidazolatgerüstverbindungen: Vom diskontinuierlichen zum kontinuierlichen Porenverschluss durch Linkersubstitution

“…Bei letzterem liegt der Phasenübergangsdruck, abhängig von dem verwendeten druckübertragenden Medium (Pressure Transmitting Medium, PTM), der Kompressionsrate und dem gewählten Metallion (Zn 2 + oder Co 2 + ), zwischen 280 und 5000 bar. [19,39,40] Die Netzwerkkonnektivität bleibt vollständig erhalten, während sich das Material nahezu isotrop um etwa 23% zusammenzieht. Die starke Kontraktion wird durch erhebliche Rotationen der im À -Linker (bis zu 69.3°) um die M-N-Bindungen erreicht, was zu einer Ineinanderfaltung des Netzwerks führt.…”

Configurational Entropy Driven High‐Pressure Behaviour of a Flexible Metal–Organic Framework (MOF)

“…Whilst recognizing the increasing number of high-pressure studies that have appeared in recent years, it can be observed that the overall number of such studies is still limited, arguably due to experimental limitations. [37][38][39][40] One class of flexible MOFs of which the high-pressure properties still remain entirely unknown is the series of pillared-layer MOFs with the general formula M 2 (fu-bdc [41,42] Here we use the abbreviation fu-MOFs, emphasising the possibility of linker functionalisation (fu) in this MOF series. In general, fu-MOFs are built from paddlewheel metal nodes which together with linear bdc 2À linkers form 2D sheets with sql topology, see Figure 1 a.…”

Structural phase transitions in flexible DUT-8(Ni) under high hydrostatic pressure

“…18,22 Structural transformations and reversible pressure-induced amorphisation were discovered in ZIF-4. 13,23 Under pressure, the flexible MOF CUK-1 undergoes fully reversible compression, similar to nanosprings. This could open a new direction in the creation of metamaterials capable of instantaneous energy storage.…”