Assessing Crystallisation Kinetics of Zr Metal–Organic Frameworks through Turbidity Measurements to Inform Rapid Microwave‐Assisted Synthesis

Griffin, Sarah L.; Briuglia, Maria L.; Horst, Joop H. ter; Forgan, Ross S.

doi:10.1002/chem.202000993

Cited by 26 publications

(26 citation statements)

References 55 publications

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“…12 Models based on monomer addition also do not apply to MOFs, as studies suggest MOF formation involves transiently metastable "primary" phases, aggregative growth, and other non-classical events. [13][14][15][16] Although these existing models can be modied to account for non-classical events, nanoMOF research requires a general model based on the acid-base and coordination chemistry of MOFs to reliably predict and control particle sizes.…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence for a general model of modulated MOF nanoparticle growth

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Experimental evidence for a general model of modulated MOF nanoparticle growth

et al. 2020

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“…This suggests a complex mixture of mechanisms underpin modulation rather than simple coordinative competition. 42 The importance of water addition in these syntheses is underlined by an in situ pair distribution function analysis of cluster formation, which showed that the [Zr 6 O 4 (OH) 4 (RCO 2 ) 12 ] SBU that underpins most Zr MOFs can form in solution prior to ligand incorporation. 43 Any additional modulator or ligand source that enhances this pre-clustering will likely increase reaction rates and modify particle sizes.…”

Section: Mechanistic Investigationsmentioning

confidence: 99%

Modulated self-assembly of metal–organic frameworks

2020

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Exercising fine control over the synthesis of metal-organic frameworks (MOFs) is key to ensuring reproducibility of physical properties such as crystallinity, particle size, morphology, porosity, defectivity, and surface chemistry. The principle of modulated self-assemblyincorporation of modulator molecules into synthetic mixtureshas emerged as the primary means to this end. This perspective article will detail the development of modulated synthesis, focusing primarily on coordination modulation, from a technique initially intended to cap the growth of MOF crystals to one that is now used regularly to enhance crystallinity, control particle size, induce defectivity and select specific phases.The various mechanistic driving forces will be discussed, as well as the influence of modulation on physical properties and how this can facilitate potential applications. Modulation is also increasingly being used to exert kinetic control over self-assembly; examples of phase selection and the development of new protocols to induce this will be provided. Finally, the application of modulated selfassembly to alternative materials will be discussed, and future perspectives on the area given. Fig. 18 Solid-state structures of different topologies accessible within the phase space of Zr MOFs linked by linear dicarboxylate ligands. (a) UiO-67 in the fcu topology. (b) The Zr-bdc MOF which is a polymorph of UiO-66 but has hex topology, viewed down the b (left) and c (right) crystallographic axes. (c) The hcp phase formed by Hf and bpdc. (d) The hxl phase formed by Hf and bpdc, which can spontaneously arise from the hcp phase by loss of bpdc. (e) The hns phase of Hf and bpdc, which is a delaminated version of the hxl phase. 4558 | Chem. Sci., 2020, 11, 4546-4562 This journal isFig. 20 (a) Schematic of aniline-modulated self-assembly of imine COFs to modify kinetics. (b) Selected SEM and optical images of COF-300 samples illustrating the particle size control offered by modulation. Reprinted in part (adapted) with permission from ref. 110.

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“…[1][2][3] Since the majority of MOF syntheses is carried out starting from liquid reaction mixtures, the formation of the solid product can be followed in situ employing scattering techniquessuch as X-ray diffraction (XRD), [4][5][6][7][8] small angle X-ray scattering (SAXS), [9][10][11] static/dynamic light scattering (SLS/DLS), [12][13] -or turbidity measurements. [14][15] SAXS, SLS/DLS and turbidity are especially suited to study the earliest stages of crystallisation because they can detect particles with subnanometric size, but they provide no information about the crystal structure of the scattering objects. 1 On the other hand, XRD is limited to crystallites having size at least in the nanometre range and is blind to amorphous matter, making it not suitable for studying the earliest stages of crystallisation.…”

Section: Introductionmentioning

confidence: 99%

In situ X-ray Diffraction Investigation of the Crystallisation of Perfluorinated Ce(IV)-based Metal-Organic Frameworks with UiO-66 and MIL-140 architectures

Shearan¹,

Jacobsen²,

Costantino³

et al. 2021

Preprint

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We report on the results of a thorough in situ synchrotron powder X-ray diffraction study of the crystallisation in aqueous medium of two recently discovered perfluorinated Ce(IV)-based metal-organic frameworks (MOFs), analogues of the already well investigated Zr(IV)-based UiO-66 and MIL-140A, namely, F4_UiO-66(Ce) and F4_MIL-140A(Ce). The two MOFs were originally obtained in pure form in similar conditions, using ammonium cerium nitrate and tetrafluoroterephthalic acid as building blocks, and small variations of the reaction parameters were found to yield mixed phases. Here, we investigate the crystallisation of these compounds in situ in a wide range of conditions, varying parameters such as temperature, amount of the protonation modulator nitric acid (HNO3) and amount of the coordination modulator acetic acid (AcOH). When only HNO3 is present in the reaction environment, F4_MIL-140A(Ce) is obtained as a pure phase. Heating preferentially accelerates nucleation, which becomes rate determining below 57 °C, whereas the modulator influences nucleation and crystal growth to a similar extent. Upon addition of AcOH to the system, alongside HNO3, mixed-phased products, consisting of F4_MIL-140A(Ce) and F4_UiO-66(Ce), are obtained. In these conditions, F4_UiO-66(Ce) is always formed faster and no interconversion between the two phases occurs. In the case of F4_UiO-66(Ce), crystal growth is always the rate determining step. An increase in the amount of HNO3 slows down both nucleation and growth rates for F4_MIL-140A(Ce), whereas nucleation is mainly affected for F4_UiO-66(Ce). In addition, a higher amount HNO3 favours the formation of F4_MIL-140A(Ce). Similarly, increasing the amount of AcOH leads to slowing down of the nucleation and growth rate, but favours the formation of F4_UiO-66(Ce). The pure F4_UiO-66(Ce) phase could also be obtained when using larger amounts of AcOH in the presence of minimal HNO3. Based on these in situ results, a new optimised route to achieving a pure, high quality F4_MIL-140A(Ce) phase in mild conditions (60 °C, 1 h) is also identified.

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Assessing Crystallisation Kinetics of Zr Metal–Organic Frameworks through Turbidity Measurements to Inform Rapid Microwave‐Assisted Synthesis

Cited by 26 publications

References 55 publications

Experimental evidence for a general model of modulated MOF nanoparticle growth

Experimental evidence for a general model of modulated MOF nanoparticle growth

Modulated self-assembly of metal–organic frameworks

In situ X-ray Diffraction Investigation of the Crystallisation of Perfluorinated Ce(IV)-based Metal-Organic Frameworks with UiO-66 and MIL-140 architectures

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