Direct Imaging of Correlated Defect Nanodomains in a Metal-Organic Framework

Defect engineering can enhance key properties of metal-organic frameworks (MOFs). Tailoring the distribution of defects, for example in correlated nanodomains, requires characterization across length scales. However, a critical nanoscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the sub-nanometre imaging used to observe individual defects. Here, we demonstrate that the emerging technique of scanning electron diffraction (SED) can bridge this gap. We directly image defect nanodomains in the MOF UiO-66(Hf) over an area of ca. 1 000 nm and with a spatial resolution ca. 5 nm to reveal domain morphology and distribution. Based on these observations, we suggest possible crystal growth processes underpinning synthetic control of defect nanodomains. We also identify likely dislocations and small angle grain boundaries, illustrating that SED could be a key technique in developing the potential for engineering the distribution of defects, or “microstructure”, in functional MOF design.

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Engineering Porosity Through Defects in a Giant Pore Metal–Organic Framework

10.26434/chemrxiv.12847574.v1 ◽

2020 ◽

Author(s):

Adam Sapnik ◽

Duncan Johnstone ◽

Sean M. Collins ◽

Giorgio Divitini ◽

Alice Bumstead ◽

...

Keyword(s):

Distribution Function ◽

Ball Milling ◽

Local Structure ◽

Pair Distribution Function ◽

Function Analysis ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Defect Engineering ◽

Metal Organic ◽

Unsaturated Metal Sites

Defect engineering is a powerful tool that can be used to tailor the properties of metal–organic frameworks (MOFs). Here, we incorporate defects through ball milling to systematically vary the porosity of the giant pore MOF, MIL-100 (Fe). We show that milling leads to the breaking of metal–linker bonds, generating more coordinatively unsaturated metal sites, and ultimately causes amorphisation. Pair distribution function analysis shows the hierarchical local structure is partiallyretained, even in the amorphised material. We find that the solvent toluene stabilises the MIL-100 (Fe) framework against collapse and leads to a substantial rentention of porosity over the non-stabilised material.

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Crystal growth of the core and rotated epitaxial shell of a heterometallic metal-organic framework revealed with atomic force microscopy

Faraday Discussions ◽

10.1039/d1fd00033k ◽

2021 ◽

Author(s):

Fajar Inggit Pambudi ◽

Michael William Anderson ◽

Martin Attfield

Keyword(s):

Atomic Force Microscopy ◽

Crystal Growth ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Force Microscopy ◽

The Core ◽

Atomic Force ◽

Metal Organic ◽

Surface Crystal ◽

Organic Framework

Atomic force microscopy has been used to determine the surface crystal growth of two isostructural metal-organic frameworks, [Zn2(ndc)2(dabco)] (ndc = 1,4-naphthalene dicarboxylate, dabco = 4-diazabicyclo[2.2.2]octane) (1) and [Cu2(ndc)2(dabco)] (2) from...

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Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

10.26434/chemrxiv.8143319 ◽

2019 ◽

Author(s):

Marco Taddei ◽

Giulia M. Schukraft ◽

Michael E. A. Warwick ◽

Davide Tiana ◽

Matthew McPherson ◽

...

Keyword(s):

Band Gap ◽

Gas Phase ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Benzoic Acids ◽

Defect Engineering ◽

Metal Organic ◽

Band Gap Modulation ◽

Valence Band Energy ◽

Defective Sites

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO2 reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

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Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

10.26434/chemrxiv.8143319.v2 ◽

2019 ◽

Author(s):

Marco Taddei ◽

Giulia M. Schukraft ◽

Michael E. A. Warwick ◽

Davide Tiana ◽

Matthew McPherson ◽

...

Keyword(s):

Band Gap ◽

Gas Phase ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Benzoic Acids ◽

Defect Engineering ◽

Metal Organic ◽

Band Gap Modulation ◽

Valence Band Energy ◽

Defective Sites

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO2 reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

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Band gap modulation in zirconium-based metal–organic frameworks by defect engineering

Journal of Materials Chemistry A ◽

10.1039/c9ta05216j ◽

2019 ◽

Vol 7 (41) ◽

pp. 23781-23786 ◽

Cited By ~ 12

Author(s):

Marco Taddei ◽

Giulia M. Schukraft ◽

Michael E. A. Warwick ◽

Davide Tiana ◽

Matthew J. McPherson ◽

...

Keyword(s):

Photocatalytic Activity ◽

Band Gap ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Defect Engineering ◽

Engineering Approach ◽

Metal Organic ◽

Engineered Materials ◽

Band Gap Modulation ◽

Organic Framework

A simple defect engineering approach to systematically tune the band gap of the prototypical zirconium-based metal–organic framework UiO-66 is reported. Defect engineered materials display enhanced photocatalytic activity.

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Low temperature synthesis study of metal–organic framework CPO-27: investigating metal, solvent and base effects down to −78 °C

Dalton Transactions ◽

10.1039/c7dt01223c ◽

2017 ◽

Vol 46 (25) ◽

pp. 8298-8303 ◽

Cited By ~ 1

Author(s):

Simon M. Vornholt ◽

Susan E. Henkelis ◽

Russell E. Morris

Keyword(s):

Metal Organic Framework ◽

Metal Organic Frameworks ◽

X Ray Diffraction ◽

Low Temperature Synthesis ◽

Temperature Synthesis ◽

X Ray ◽

Metal Organic ◽

Solvent Systems ◽

Metal Solvent ◽

Scanning Electron

CPO-27-M (M = Co, Mg, Ni, Zn) metal–organic frameworks have been successfully synthesized at temperatures down to −78 °C in a range of solvent systems and their crystallinity and morphology analyzed by powder X-ray diffraction and scanning electron microscopy.

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Band Gap Modulation in Zirconium-Based Metal-Organic Frameworks by Defect Engineering

10.26434/chemrxiv.8143319.v1 ◽

2019 ◽

Author(s):

Marco Taddei ◽

Giulia M. Schukraft ◽

Michael E. A. Warwick ◽

Davide Tiana ◽

Matthew McPherson ◽

...

Keyword(s):

Band Gap ◽

Gas Phase ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Benzoic Acids ◽

Defect Engineering ◽

Metal Organic ◽

Band Gap Modulation ◽

Valence Band Energy ◽

Defective Sites

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO2 reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

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Engineering New Defective Phases of UiO Family Metal-Organic Frameworks with Water

10.26434/chemrxiv.7301951 ◽

2018 ◽

Author(s):

Francesca Firth ◽

Matthew Cliffe ◽

Diana Vulpe ◽

Peyman Moghadam ◽

David Fairen-jimenez ◽

...

Keyword(s):

Mechanical Properties ◽

Rational Design ◽

Metal Organic Frameworks ◽

Synthesis Temperature ◽

Synthetic Control ◽

Critical Factors ◽

Defect Engineering ◽

Metal Organic

As defects significantly affect the properties of metal-organic frameworks (MOFs)–from changing their mechanical properties to enhancing their catalytic ability–obtaining synthetic control over defects is essential to tuning the effects on the properties of the MOF. Previous work has shown that synthesis temperature and the identity and concentration of modulating acid are critical factors in determining the nature and distribution of defects in the UiO family of MOFs. In this paper we demonstrate that the amount of water in the reaction mixture in the synthesis of UiO family MOFs is an equally important factor, as it controls the phase which forms for both UiO-67(Hf) and UiO-66(Hf) (F4BDC). We use this new understanding of the importance of water to develop a new route to the stable defect-ordered hcp UiO-66(Hf) phase, demonstrating the effectiveness of this method of defect-engineering in the rational design of MOFs. The insights provided by this investigation open up the possibility of harnessing defects to produce new phases and dimensionalities of other MOFs, including nanosheets, for a variety of applications such as MOF-based membranes.

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Engineering New Defective Phases of UiO Family Metal-Organic Frameworks with Water

10.26434/chemrxiv.7301951.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Francesca Firth ◽

Matthew Cliffe ◽

Diana Vulpe ◽

Peyman Moghadam ◽

David Fairen-jimenez ◽

...

Keyword(s):

Mechanical Properties ◽

Rational Design ◽

Metal Organic Frameworks ◽

Synthesis Temperature ◽

Synthetic Control ◽

Critical Factors ◽

Defect Engineering ◽

Metal Organic

As defects significantly affect the properties of metal-organic frameworks (MOFs)–from changing their mechanical properties to enhancing their catalytic ability–obtaining synthetic control over defects is essential to tuning the effects on the properties of the MOF. Previous work has shown that synthesis temperature and the identity and concentration of modulating acid are critical factors in determining the nature and distribution of defects in the UiO family of MOFs. In this paper we demonstrate that the amount of water in the reaction mixture in the synthesis of UiO family MOFs is an equally important factor, as it controls the phase which forms for both UiO-67(Hf) and UiO-66(Hf) (F4BDC). We use this new understanding of the importance of water to develop a new route to the stable defect-ordered hcp UiO-66(Hf) phase, demonstrating the effectiveness of this method of defect-engineering in the rational design of MOFs. The insights provided by this investigation open up the possibility of harnessing defects to produce new phases and dimensionalities of other MOFs, including nanosheets, for a variety of applications such as MOF-based membranes.

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