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Highly mesoporous metal-organic framework assembled in a switchable solvent.

Peng L, Zhang J, Xue Z, Han B, Sang X, Liu C, Yang G - Nat Commun (2014)

Bottom Line: The preparation of mesoporous metal-organic frameworks usually needs the supramolecular or cooperative template strategy.Moreover, the use of CO2 can accelerate the reaction for metal-organic framework formation from metal salt and organic linker due to the viscosity-lowering effect of CO2, and the product can be recovered through CO2 extraction.The as-synthesized mesocellular metal-organic frameworks are highly active in catalysing the aerobic oxidation of benzylic alcohols under mild temperature at atmospheric pressure.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
The mesoporous metal-organic frameworks are a family of materials that have pore sizes ranging from 2 to 50 nm, which have shown promising applications in catalysis, adsorption, chemical sensing and so on. The preparation of mesoporous metal-organic frameworks usually needs the supramolecular or cooperative template strategy. Here we report the template-free assembly of mesoporous metal-organic frameworks by using CO2-expanded liquids as switchable solvents. The mesocellular metal-organic frameworks with large mesopores (13-23 nm) are formed, and their porosity properties can be easily adjusted by controlling CO2 pressure. Moreover, the use of CO2 can accelerate the reaction for metal-organic framework formation from metal salt and organic linker due to the viscosity-lowering effect of CO2, and the product can be recovered through CO2 extraction. The as-synthesized mesocellular metal-organic frameworks are highly active in catalysing the aerobic oxidation of benzylic alcohols under mild temperature at atmospheric pressure.

No MeSH data available.


Related in: MedlinePlus

Schematic illustration for mesocellular MOF formation.The Cu2+ ions react with the deprotonated BTC3− in the CXL and the nanosized framework building blocks are produced. Then the MOF building blocks assemble to form the mesocellular MOFs with large mesopores and thin mesopore walls.
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f4: Schematic illustration for mesocellular MOF formation.The Cu2+ ions react with the deprotonated BTC3− in the CXL and the nanosized framework building blocks are produced. Then the MOF building blocks assemble to form the mesocellular MOFs with large mesopores and thin mesopore walls.

Mentions: On the basis of the experimental results, a possible mechanism for the CO2-directed formation of mesocellular MOF is proposed (Fig. 4). First, the Cu2+ ions react with the deprotonated BTC3− to structure the nanosized framework building blocks3945. Owing to the reduced solvency and viscosity of solvent by CO2 expansion, the microporous MOF building blocks produced in the CO2-expanded solvent are expected to be smaller than those yielded in CO2-free solvent3945, and higher pressure favours the formation of smaller building blocks323334. In a second step, the nanosized MOF building blocks assemble to form the network because smaller particles have higher surface energy46, and the assembly of MOF nanocrystals is looser at higher pressure due to the greater expansion of the solvent. Therefore, after removing the solvent and releasing CO2, the mesocellular MOFs with large mesopores and thin mesopore walls are formed. The structural parameters of the MOFs are dependent on CO2 pressure, that is, the higher the CO2 pressure is, the more porous MOF with larger mesopores is formed.


Highly mesoporous metal-organic framework assembled in a switchable solvent.

Peng L, Zhang J, Xue Z, Han B, Sang X, Liu C, Yang G - Nat Commun (2014)

Schematic illustration for mesocellular MOF formation.The Cu2+ ions react with the deprotonated BTC3− in the CXL and the nanosized framework building blocks are produced. Then the MOF building blocks assemble to form the mesocellular MOFs with large mesopores and thin mesopore walls.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109014&req=5

f4: Schematic illustration for mesocellular MOF formation.The Cu2+ ions react with the deprotonated BTC3− in the CXL and the nanosized framework building blocks are produced. Then the MOF building blocks assemble to form the mesocellular MOFs with large mesopores and thin mesopore walls.
Mentions: On the basis of the experimental results, a possible mechanism for the CO2-directed formation of mesocellular MOF is proposed (Fig. 4). First, the Cu2+ ions react with the deprotonated BTC3− to structure the nanosized framework building blocks3945. Owing to the reduced solvency and viscosity of solvent by CO2 expansion, the microporous MOF building blocks produced in the CO2-expanded solvent are expected to be smaller than those yielded in CO2-free solvent3945, and higher pressure favours the formation of smaller building blocks323334. In a second step, the nanosized MOF building blocks assemble to form the network because smaller particles have higher surface energy46, and the assembly of MOF nanocrystals is looser at higher pressure due to the greater expansion of the solvent. Therefore, after removing the solvent and releasing CO2, the mesocellular MOFs with large mesopores and thin mesopore walls are formed. The structural parameters of the MOFs are dependent on CO2 pressure, that is, the higher the CO2 pressure is, the more porous MOF with larger mesopores is formed.

Bottom Line: The preparation of mesoporous metal-organic frameworks usually needs the supramolecular or cooperative template strategy.Moreover, the use of CO2 can accelerate the reaction for metal-organic framework formation from metal salt and organic linker due to the viscosity-lowering effect of CO2, and the product can be recovered through CO2 extraction.The as-synthesized mesocellular metal-organic frameworks are highly active in catalysing the aerobic oxidation of benzylic alcohols under mild temperature at atmospheric pressure.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
The mesoporous metal-organic frameworks are a family of materials that have pore sizes ranging from 2 to 50 nm, which have shown promising applications in catalysis, adsorption, chemical sensing and so on. The preparation of mesoporous metal-organic frameworks usually needs the supramolecular or cooperative template strategy. Here we report the template-free assembly of mesoporous metal-organic frameworks by using CO2-expanded liquids as switchable solvents. The mesocellular metal-organic frameworks with large mesopores (13-23 nm) are formed, and their porosity properties can be easily adjusted by controlling CO2 pressure. Moreover, the use of CO2 can accelerate the reaction for metal-organic framework formation from metal salt and organic linker due to the viscosity-lowering effect of CO2, and the product can be recovered through CO2 extraction. The as-synthesized mesocellular metal-organic frameworks are highly active in catalysing the aerobic oxidation of benzylic alcohols under mild temperature at atmospheric pressure.

No MeSH data available.


Related in: MedlinePlus