7 results on '"Post-Synthetic Exchange"'
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2. Post‐Synthetic Ligand Exchange in Zirconium‐Based Metal–Organic Frameworks: Beware of The Defects!
- Author
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Taddei, Marco, Wakeham, Russell J., Koutsianos, Athanasios, Andreoli, Enrico, and Barron, Andrew R.
- Subjects
- *
LIGAND exchange reactions , *ZIRCONIUM , *ORGANOMETALLIC compounds , *NUCLEAR magnetic resonance spectroscopy , *TEREPHTHALIC acid - Abstract
Abstract: Post‐synthetic ligand exchange in the prototypical zirconium‐based metal–organic framework (MOF) UiO‐66 was investigated by in situ solution 1H NMR spectroscopy. Samples of UiO‐66 having different degrees of defectivity were exchanged using solutions of several terephthalic acid analogues in a range of conditions. Linker exchange only occurred in defect‐free UiO‐66, whereas monocarboxylates grafted at defect sites were found to be preferentially exchanged with respect to terephthalic acid over the whole range of conditions investigated. A 1:1 exchange ratio between the terephthalic acid analogue and modulator was observed, providing evidence that the defects had missing‐cluster nature. Ex situ characterisation of the MOF powders after exchange corroborated these findings and showed that the physical‐chemical properties of the MOF depend on whether the functionalisation occurs at defective sites or on the framework. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
3. Immobilisation of Ru-Based Molecular Catalysts for Electrochemical Water Oxidation
- Author
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Howe, Andrew and Howe, Andrew
- Abstract
Artificial photosynthesis requires catalysts for efficient and selective conversions of small molecules. Molecular catalysts are advantageous to use in these instances as they offer precise control over chemical reactivity. They are synthetically tuneable, and their catalytic mechanisms are often well documented and more readily understood than those of solid-state catalysts. In this thesis, the synthetic incorporation of molecular catalysts into heterogenised molecular anodes for water oxidation are evaluated. The catalysts are incorporated as structural linkers into porous metal-organic framework (MOF) structures, and as coordination oligomers stacked onto graphitic surfaces. The preparation of MOF/molecular catalyst hybrid materials of two topologies, UiO (UiO = Universitet i Oslo) and NU-1000 (NU = Northwestern University), were investigated. Multiple synthetic methods for the incorporation of molecular ruthenium-based catalysts into MOFs were examined in papers I and II. In paper III of this thesis, a Ru-bda type molecular complex was successfully used in the solvothermal synthesis of a new MOF. The resulting material is the first of its kind that is built exclusively from molecular water oxidation catalyst linkers. It is shown that MOF incorporation greatly enhances the structural stability of the catalyst linker in chemical water oxidation experiments, giving rise to higher turnover numbers compared to that of a homogenous reference system. Finally, paper IV describes a stable and inert molecular ruthenium complex, which possesses a flexible adaptative multidentate equatorial (FAME) type equatorial ligand with a carbanion on the equatorial ligand that forms a C-Ru bond. This molecular complex is studied in homogeneous phase, and subsequently incorporated into a coordination oligomer, which can be activated for water oxidation catalysis. This finding broadens the field of molecular catalysis significantly, and proves that supramolecular interactions can be us
- Published
- 2022
4. Recent progress in the synthesis of metal–organic frameworks
- Author
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Yujia Sun and Hong-Cai Zhou
- Subjects
metal–organic frameworks ,solvothermal synthesis ,microwave-assisted synthesis ,electrochemical synthesis ,post-synthetic modification ,post-synthetic exchange ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Biotechnology ,TP248.13-248.65 - Abstract
Metal–organic frameworks (MOFs) have attracted considerable attention for various applications due to their tunable structure, porosity and functionality. In general, MOFs have been synthesized from isolated metal ions and organic linkers under hydrothermal or solvothermal conditions via one-spot reactions. The emerging precursor approach and kinetically tuned dimensional augmentation strategy add more diversity to this field. In addition, to speed up the crystallization process and create uniform crystals with reduced size, many alternative synthesis routes have been explored. Recent advances in microwave-assisted synthesis and electrochemical synthesis are presented in this review. In recent years, post-synthetic approaches have been shown to be powerful tools to synthesize MOFs with modified functionality, which cannot be attained via de novo synthesis. In this review, some current accomplishments of post-synthetic modification (PSM) based on covalent transformations and coordinative interactions as well as post-synthetic exchange (PSE) in robust MOFs are provided.
- Published
- 2015
- Full Text
- View/download PDF
5. Facile Synthesis of Various ZrO2 Phases and ZrO2-MO2 (M = Ti, Hf) by Thermal Decomposition of a Single UiO-66 Precursor for Photodegradation of Methyl Orange
- Author
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Ira Nur Arba’atul Jannah, Hanu Fiorena Sekarsari, Sri Mulijani, Karna Wijaya, Arief Cahyo Wibowo, and Aep Patah
- Subjects
Physical and Theoretical Chemistry ,Catalysis ,photodegradation ,methyl orange ,UiO-66 ,post-synthetic exchange ,thermal decomposition - Abstract
A zirconia-based catalyst with controlled crystalline phases is synthesized through a simple thermal decomposition of a parent UiO-66 single precursor. The introduction of Ti(IV) and Hf(IV) cation into the Zr(IV) framework has been successfully obtained to tune the photocatalytic activity over methyl orange (MO) solution. Their resulting crystalline phases, morphologies, elemental analysis, band gap values, surface area, and photocatalytic degradation study over MO dye are presented and discussed. The tetragonal zirconia (t-ZrO2) catalyst exhibits the highest photocatalytic activity with 89% decoloration efficiency under UV irradiation (λ = 254 nm) for 300 min compared to m-ZrO2 (67%), the mixed phases (t-ZrO2 and m-ZrO2), as well as the synthesized mixed oxides ZrO2-MO2 (M = Ti or Hf), where the photocatalytic activities are 74% and 63%, respectively. This result is on par with commercially available anatase TiO2 and other reported t-ZrO2 catalysts.
- Published
- 2022
- Full Text
- View/download PDF
6. Post-synthetic ligand exchange in zirconium-based metal-organic frameworks: beware of the defects!
- Author
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Russell J. Wakeham, Marco Taddei, Athanasios Koutsianos, Andrew R. Barron, and Enrico Andreoli
- Subjects
In situ ,metal–organic frameworks (MOFs) ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Catalysis ,chemistry.chemical_compound ,NMR spectroscopy ,defects ,post-synthetic exchange ,Polymer chemistry ,Terephthalic acid ,Zirconium ,010405 organic chemistry ,Ligand ,General Medicine ,General Chemistry ,Nuclear magnetic resonance spectroscopy ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Proton NMR ,Metal-organic framework ,0210 nano-technology ,Linker - Abstract
Post-synthetic ligand exchange in the prototypical zirconium-based metal-organic framework UiO-66 was investigated by in situ solution 1H nuclear magnetic resonance. Samples of UiO-66 having different degrees of defectivity were exchanged using solutions of several terephthalic acid analogues in a range of conditions. Linker exchange only occurred in defect-free UiO-66, whereas monocarboxylates grafted at defective sites were found to be preferentially exchanged with respect to terephthalic acid over the whole range of conditions investigated. A 1:1 exchange ratio between the terephthalic acid analogue and modulator was observed, providing evidence that the defects had missing-cluster nature. Ex situ characterisation of the MOF powders after exchange corroborated these findings and evidenced that the physical-chemical properties of the MOF depend on whether the functionalisation occurs at defective sites or on the framework. N2 sorption analysis showed that, upon exchange, defective samples underwent significant decrease of surface area and disappearance of large pores, associated with the presence of missing-cluster defects in the starting material. CO2 sorption studies displayed the different impact of pure defect functionalisation and pure framework functionalisation on isosteric heat of adsorption and CO2/N2 selectivity.
- Published
- 2018
- Full Text
- View/download PDF
7. Recent progress in the synthesis of metal–organic frameworks.
- Author
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Sun, Yujia and Zhou, Hong-Cai
- Subjects
- *
METAL-organic frameworks , *CHEMICAL synthesis , *CRYSTALLIZATION - Abstract
Metal–organic frameworks (MOFs) have attracted considerable attention for various applications due to their tunable structure, porosity and functionality. In general, MOFs have been synthesized from isolated metal ions and organic linkers under hydrothermal or solvothermal conditions via one-spot reactions. The emerging precursor approach and kinetically tuned dimensional augmentation strategy add more diversity to this field. In addition, to speed up the crystallization process and create uniform crystals with reduced size, many alternative synthesis routes have been explored. Recent advances in microwave-assisted synthesis and electrochemical synthesis are presented in this review. In recent years, post-synthetic approaches have been shown to be powerful tools to synthesize MOFs with modified functionality, which cannot be attained via de novo synthesis. In this review, some current accomplishments of post-synthetic modification (PSM) based on covalent transformations and coordinative interactions as well as post-synthetic exchange (PSE) in robust MOFs are provided. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
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