Zeolitic imidazole frameworks: structural and energetics trends compared with their zeolite analogues

Lewis, Dewi W.; Ruiz‐Salvador, A. Rabdel; Gómez, Ariel; Rodríguez‐Albelo, L. Marleny; Coudert, François‐Xavier; Slater, Ben; Cheetham, Anthony K.; Mellot‐Draznieks, Caroline

doi:10.1039/b912997a

Cited by 233 publications

(249 citation statements)

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“…If dia-Zn(MeIm) 2 is set as a reference point, kat-Zn(MeIm) 2 is less stable by 0.16 kcal mol À 1 (7 meV per atom) and ZIF-8 by 0.29 kcal mol À 1 (12.7 meV per atom). The reaction course can also be more qualitatively rationalized by considering the number of tetrahedra (T) per volume (V) for each involved framework 38 . The T/V value of 3.8 nm À 3 places kat-Zn(MeIm) 2 between ZIF-8 (T/V ¼ 2.4 nm À 3 ) and dia-Zn(MeIm) 2 (T/V ¼ 4.2 nm À 3 ).…”

Section: Discussionmentioning

confidence: 99%

In situ X-ray diffraction monitoring of a mechanochemical reaction reveals a unique topology metal-organic framework

et al. 2015

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Chemical and physical transformations by milling are attracting enormous interest for their ability to access new materials and clean reactivity, and are central to a number of core industries, from mineral processing to pharmaceutical manufacturing. While continuous mechanical stress during milling is thought to create an environment supporting nonconventional reactivity and exotic intermediates, such speculations have remained without proof. Here we use in situ, real-time powder X-ray diffraction monitoring to discover and capture a metastable, novel-topology intermediate of a mechanochemical transformation. Monitoring the mechanochemical synthesis of an archetypal metal-organic framework ZIF-8 by in situ powder X-ray diffraction reveals unexpected amorphization, and on further milling recrystallization into a non-porous material via a metastable intermediate based on a previously unreported topology, herein named katsenite (kat). The discovery of this phase and topology provides direct evidence that milling transformations can involve short-lived, structurally unusual phases not yet accessed by conventional chemistry.

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Section: Discussionmentioning

confidence: 99%

In situ X-ray diffraction monitoring of a mechanochemical reaction reveals a unique topology metal-organic framework

et al. 2015

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“…By now, the coi phase was disregarded in theoretical calculations and the zni phase was assumed to be the most stable phase. 7,8,11,12 In this Communication, we address the question of the 'ground state' in the Zn(im) 2 system from both an experimental and computational point of view.Variable-temperature X-ray diffraction (XRD) patterns taken from coi powder samples at ambient pressure reveal that a phase transition to zni takes place at #360 uC (Fig. 2a).…”

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confidence: 99%

Subtle polymorphism of zinc imidazolate frameworks: temperature-dependent ground states in the energy landscape revealed by experiment and theory

et al. 2013

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We show by variable-temperature X-ray diffraction and differential scanning calorimetry experiments that zinc imidazolates with coi and zni framework topology, respectively represent the thermodynamically stable phase below and above a transition temperature of #360 uC at ambient pressure. The relative stability of the two polymorphs and the experimentally observed strong negative thermal expansion of the coi phase at high temperatures close to the phase transition were successfully modelled using density functional theory calculations. A novel metastable zinc imidazolate with neb framework topology was detected by in situ X-ray diffraction experiments as a transient crystalline phase during solvothermal crystallisation of the stable coi phase.Zeolitic imidazolate frameworks (ZIFs) represent a new class of technology relevant microporous materials that are at the focus of current research efforts. 1,2 Important characteristics of ZIFs are comparatively high thermal and chemical stabilities and the ability to crystallise in a large variety of topologically different frameworks which may be tailored for a specific application in gas storage, separation, sensing or catalysis. ZIFs consist of tetrahedral cationic centres (Zn II , Co II , Fe II , Cd II , and also Li I /B III ) connected by imidazolate-based bridging ligands. Because of the local tetrahedral geometry of metal connectors and the metal-imidazolatemetal bridging angle of #145u ZIFs adopt network topologies common for microporous silica polymorphs and zeolites. Recent studies have revealed that ZIFs may undergo thermally-and/or pressure-induced amorphisation that reinforces the similarity between ZIFs and silica. [3][4][5] However, important differences between ZIFs and silica systems are still ignored in the literature. For example, it is well known that the thermodynamic 'ground state' of the silica system at ambient conditions corresponds to the a-quartz phase (qtz net) 6 , whereas the quartz-like topology is hardly accessible in the Zn(im) 2 (im = imidazolate) system as was shown in our previous ab initio study. 7,8 By considering only unsubstituted imidazolate bridging ligands, nine topologically different Zn(im) 2 frameworks have been experimentally realised to date (zni, coi, cag, mer, gis, dft, crb, zec, nog) 1,2,9 and even more are predicted to be synthetically accessible. 7 However, up to now there was no experimental study which addressed the important question about the thermodynamically most stable phase(s) ('ground state(s)') in the Zn(im) 2 system, which might be either of the two most dense phases zni or coi. Recently, an irreversible single-crystal-to-single-crystal pressureinduced phase transition from the zni to the coi phase was observed at room temperature by Spencer et al. 10 revealing that coi is stable at high pressures (>0.55 GPa). The polymorphs with zni and coi underlying nets crystallise in the tetragonal space groups I4 1 cd and I4 1 , respectively, and are closely related to each other since both frameworks may be considered ...

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“…Figure 1: Experimental and hypothetical zeolitic imidazolate frameworks (ZIF) generated by decoration of zeolite topologies by Lewis et al, [30] along with a plot of their relative energy (compared to dense ZIF of zni topology) versus density. Adapted from ref.…”

Section: Sio2mentioning

confidence: 99%

“…Zeolitic Imidazolate Frameworks (ZIF), [39,30] or more recently of porous zinc cyanide polymorphs; [40] • hypothetical covalent organic frameworks (COF). [41] The structures generated through this decoration process then need to be "relaxed" through energy minimization, relying on classical force field-based simulations or quantum chemistry calculations, in order to confirm their stability and evaluate their Figure 2: Depiction of the linker replacement strategy for computational prediction of isoreticular MOF structures, exemplified on the MIL-88 family.…”

Section: Crystal Structure Predictionmentioning

confidence: 99%

“…This process is exemplified on Figure 1, in the case of hypothetical ZIFs. [39,30] Starting with a given composition (in this case, Zn 2+ cations and unsubstituted imidazolate anions), zeolitic nets from the IZA database [34] are decorated with the metal centers (replacing the silicon atoms) and organic linkers (replacing the oxygen atoms). These "ideal" starting structures are energy-minimized through DFT calculations.…”

Section: Crystal Structure Predictionmentioning

confidence: 99%

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Computational characterization and prediction of metal–organic framework properties

Coudert

Fuchs

2016

Coordination Chemistry Reviews

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240

203

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In this introductory review, we give an overview of the computational chemistry methods commonly used in the field of metal-organic frameworks (MOFs), to describe or predict the structures themselves and characterize their various properties, either at the quantum chemical level or through classical molecular simulation. We discuss the methods for the prediction of crystal structures, geometrical properties and large-scale screening of hypothetical MOFs, as well as their thermal and mechanical properties. A separate section deals with the simulation of adsorption of fluids and fluid mixtures in MOFs.

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Zeolitic imidazole frameworks: structural and energetics trends compared with their zeolite analogues

Abstract: DFT calculations suggest many nanoporous Zinc Imidazole Frameworks (ZIFs) are viable synthesis targets and reveal a more complex energy landscape than their zeolite counterparts.

Cited by 233 publications

References 34 publications

In situ X-ray diffraction monitoring of a mechanochemical reaction reveals a unique topology metal-organic framework

In situ X-ray diffraction monitoring of a mechanochemical reaction reveals a unique topology metal-organic framework

Subtle polymorphism of zinc imidazolate frameworks: temperature-dependent ground states in the energy landscape revealed by experiment and theory

Computational characterization and prediction of metal–organic framework properties

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