Single particle Raman spectroscopy analysis of the metal–organic framework DUT-8(Ni) switching transition under hydrostatic pressure

Крылов, А. С.; Senkovska, Irena; Ehrling, Sebastian; Maliuta, Mariia; Krylova, S. N.; Slyusareva, E. A.; Vtyurin, A. N.; Kaskel, Stefan

doi:10.1039/d0cc02491k

Cited by 16 publications

(26 citation statements)

References 40 publications

(42 reference statements)

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“…The reason here is that some of the crystallites cannot be stimulated to open at a particular pressure because of the high activation barrier for opening. Higher pressures (Krylov et al, 2020 ) or adsorption enthalpies (Bon et al, 2015a ) would enable the stimulation of these crystals, exhibiting higher activation energy, forcing additional crystallites to transform, but the maximum pressure in the adsorption experiments is limited to the saturation pressure of the chosen adsorptive (1 atm at 77 K).…”

Section: Resultsmentioning

confidence: 99%

Impact of Crystal Size and Morphology on Switchability Characteristics in Pillared-Layer Metal-Organic Framework DUT-8(Ni)

et al. 2021

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Variation of the crystallite size in flexible porous coordination polymers can significantly influence or even drastically change the flexibility characteristics. The impact of crystal morphology, however, on the dynamic properties of flexible metal-organic frameworks (MOFs) is poorly investigated so far. In the present work, we systematically modulated the particle size of a model gate pressure MOF (DUT-8(Ni), Ni2(2,6-ndc)2(dabco), 2,6-ndc−2,6-naphthalenedicarboxylate, dabco−1,4-diazabicyclo[2.2.2]octane) and investigated the influence of the aspect ratio, length, and width of anisotropically shaped crystals on the gate opening characteristics. DUT-8 is a member of the pillared-layer MOF family, showing reversible structural transition, i.e., upon nitrogen physisorption at 77 K. The framework crystalizes as rod-like shaped crystals in conventional synthesis. To understand which particular crystal surfaces dominate the phenomena observed, crystals similar in size and differing in morphology were involved in a systematic study. The analysis of the data shows that the width of the rods (corresponding to the crystallographic directions along the layer) represents a critical parameter governing the dynamic properties upon adsorption of nitrogen at 77 K. This observation is related to the anisotropy of the channel-like pore system and the nucleation mechanism of the solid-solid phase transition triggered by gas adsorption.

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Section: Resultsmentioning

confidence: 99%

Impact of Crystal Size and Morphology on Switchability Characteristics in Pillared-Layer Metal-Organic Framework DUT-8(Ni)

et al. 2021

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“…Subsequent embedding of this crystallite in a medium will then allow to apply an external pressure to the crystal in a very natural manner (Figure 6). Experimentally, both mercury as well as silicone oil have been used as effective pressure transducers in order to detect pressureinduced structural transitions in several winerack frameworks (Beurroies et al, 2010;Yot et al, 2012;Yot et al, 2014Yot et al, , 2016Ramaswamy et al, 2017;Henke et al, 2018;Krause et al, 2018;Wahiduzzaman et al, 2018;Wieme et al, 2019;Yot et al, 2019) and other flexible frameworks such as ZIF-4 or DUT-8 (Kavoosi et al, 2017;Krylov et al, 2020); the simulation setup as described in Figure 6B would mirror such experiments.…”

Section: Discussionmentioning

confidence: 99%

Large-Scale Molecular Dynamics Simulations Reveal New Insights Into the Phase Transition Mechanisms in MIL-53(Al)

2021

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Soft porous crystals have the ability to undergo large structural transformations upon exposure to external stimuli while maintaining their long-range structural order, and the size of the crystal plays an important role in this flexible behavior. Computational modeling has the potential to unravel mechanistic details of these phase transitions, provided that the models are representative for experimental crystal sizes and allow for spatially disordered phenomena to occur. Here, we take a major step forward and enable simulations of metal-organic frameworks containing more than a million atoms. This is achieved by exploiting the massive parallelism of state-of-the-art GPUs using the OpenMM software package, for which we developed a new pressure control algorithm that allows for fully anisotropic unit cell fluctuations. As a proof of concept, we study the transition mechanism in MIL-53(Al) under various external pressures. In the lower pressure regime, a layer-by-layer mechanism is observed, while at higher pressures, the transition is initiated at discrete nucleation points and temporarily induces various domains in both the open and closed pore phases. The presented workflow opens the possibility to deduce transition mechanism diagrams for soft porous crystals in terms of the crystal size and the strength of the external stimulus.

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“…A cooperative mechanism is frequently assumed in thermodynamic models [90,91]. However, recently the cooperative character of adsorption-induced phase transitions in MOFs has been debated [92,93]. An earlier work suggested a layer-by-layer transformation mechanism for MIL-53 taking a variation of interfacial coupling into account [94].…”

Section: Cooperativitymentioning

confidence: 99%

“…For strong effective coupling, an avalanche and cooperative switching of all unit cells and distinct adsorption hysteresis are predicted. However, examples suggesting phase coexistence were reported [79,92,93]. Large strain may also lead to partial bond breaking or even full breakage of all bonds along a grain boundary.…”

Section: Cooperativitymentioning

confidence: 99%

From Macro- to Nanoscale: Finite Size Effects on Metal–Organic Framework Switchability

Ehrling

Miura

Senkovska

et al. 2021

Trends in Chemistry

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Switchable metal-organic frameworks (MOFs) standt out for potential applications in energy storage, separation, sensing, and catalysis. The understanding of MOF switchability mechanisms has progressed significantly over the past two decades. Nanostructuring is essential for the integration of such materials into thin films, hierarchical composites, and membranes and for biological applications. However, downsizing below critical dimensions causes dramatic changes in the dynamic behavior and responsiveness towards external stimuli. We discuss the most important experimental findings and derive general guidelines and hypotheses of relevance for the impact of crystal size on switchability. Understanding nanostructure thermodynamics and implications for the tailoring of dynamic porous systems requires an interdisciplinary approach, advanced physical characterization techniques, and new modeling strategies to cover a wider range of time and length scales. MOF Switchability and FunctionalityMOFs are among the most porous systems, with great potential in diverse applications such as energy storage, separation, air purification, and many more [1,2]. An outstanding feature, compared with other, traditional porous materials, is their ability to transform (switch) between different phases with well-defined crystalline structures triggered by external stimuli, often by guest inclusion [3,4]. The latter leads, in some cases, to important improvements in gas separation or storage due to ultrahigh selectivity [5] or high deliverable capacity [6]. The terms 'flexible MOF', 'soft porous crystals', and 'switchable MOF' are used synonymously [7,8]. An important aspect indicated by the term 'switchability' is the stepwise (first order) character of the structural transition between two phases (bistability). Recently, even multistable systems have emerged, leading to remarkable recognition effects [9,10]. These phase transitions induced by external stimuli (e.g., changes in temperature, external pressure, gas pressure, vapor pressure, or electromagnetic radiation) are associated with a latent heat of transformation, L, governing the energetics of the bulk phase transition. An activation barrier (E A or ΔG ǂ ) governs the kinetics and potential windows for metastable states. Nucleation (for nucleation theory see Glossary and see supplemental information online for additional Glossary terms) of the new solid phase is an important characteristic of the solid-solid phase transition. Nevertheless, the fluid kinetics of adsorption and, potentially, fluid nucleation kinetics may also play a role. HighlightsSwitchable metal-organic frameworks (MOFs) conquer advanced applications in energy storage, sensing, gas separation, catalysis, and biomedicine. They benefit from unique adsorption characteristics and responsive behavior leading to anomalously high separation selectivity and deliverable storage capacity.Nanostructuring provides an effective means to tailor the responsive behavior of switchable MOFs. The characteristic switching pressure d...

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Single particle Raman spectroscopy analysis of the metal–organic framework DUT-8(Ni) switching transition under hydrostatic pressure

Abstract: According to in situ Raman experiments, in certain pressure ranges open (op) and closed pore (cp) phases coexist in DUT-8(Ni) crystals.

Cited by 16 publications

References 40 publications

Impact of Crystal Size and Morphology on Switchability Characteristics in Pillared-Layer Metal-Organic Framework DUT-8(Ni)

Impact of Crystal Size and Morphology on Switchability Characteristics in Pillared-Layer Metal-Organic Framework DUT-8(Ni)

Large-Scale Molecular Dynamics Simulations Reveal New Insights Into the Phase Transition Mechanisms in MIL-53(Al)

From Macro- to Nanoscale: Finite Size Effects on Metal–Organic Framework Switchability

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