A new covalent organic framework (COF) based on imine bonds was assembled from 2-(4-formylphenyl)-5-formylpyridine and 1,3,6,8-tetrakis(4-aminophenyl)pyrene, which showed an interesting dual-pore structure with high crystallinity. Postmetallation of the COF with Pt occurred selectively at the N donor (imine and pyridyl) in the larger pores. The metallated COF served as an excellent recyclable heterogeneous photocatalyst for decarboxylative difluoroalkylation and oxidative cyclization reactions.
Two-dimensional urea- and thiourea-containing covalent organic
frameworks (COFs) were synthesized at ambient conditions at large
scale within 1 h in the absence of an acid catalyst. The site-isolated
urea and thiourea in the COF showed enhanced catalytic efficiency
as a hydrogen-bond-donating organocatalyst compared to the molecular
counterparts in epoxide ring-opening reaction, aldehyde acetalization,
and Friedel–Crafts reaction. The COF catalysts also had excellent
recyclability.
The customisability of metal–-organic frameworks (MOFs) has attracted exponentially growing interest in the realm of materials science. Because of their porous nature, MOF research has been primarily focused on gas...
Zr-oxide secondary building units construct metal–organic
framework (MOF) materials with excellent gas adsorption properties
and high mechanical, thermal, and chemical stability. These attributes
have led Zr-oxide MOFs to be well-recognized for a wide range of applications,
including gas storage and separation, catalysis, as well as healthcare
domain. Here, we report structure search methods within the Cambridge
Structural Database (CSD) to create a curated subset of 102 Zr-oxide
MOFs synthesized to date, bringing a unique record for all researchers
working in this area. For the identified structures, we manually corrected
the proton topology of hydroxyl and water molecules on the Zr-oxide
nodes and characterized their textural properties, Brunauer–Emmett–Teller
(BET) area, and topology. Importantly, we performed systematic periodic
density functional theory (DFT) calculations comparing 25 different
combinations of basis sets and functionals to calculate framework
partial atomic charges for use in gas adsorption simulations. Through
experimental verification of CO2 adsorption in selected
Zr-oxide MOFs, we demonstrate the sensitivity of CO2 adsorption
predictions at the Henry’s regime to the choice of the DFT
method for partial charge calculations. We characterized Zr-MOFs for
their CO2 adsorption performance via high-throughput grand
canonical Monte Carlo (GCMC) simulations and revealed how the chemistry
of the Zr-oxide node could have a significant impact on CO2 uptake predictions. We found that the maximum CO2 uptake
is obtained for structures with the heat of adsorption values >25
kJ/mol and the largest cavity diameters of ca. 6–7 Å.
Finally, we introduced augmented reality (AR) visualizations as a
means to bring adsorption phenomena alive in porous adsorbents and
to dynamically explore gas adsorption sites in MOFs.
New
linkages for covalent organic frameworks (COFs) have been continuously
pursued by chemists as they serve as the structure and property foundation
for the materials. Developing new reaction types or modifying known
linkages have been the only two methods to create new COF linkages.
Herein, we report a novel strategy that uses H3PO3 as a bifunctional catalyst to achieve amine-linked COFs from readily
available amine and aldehyde linkers. The acidic proton of H3PO3 catalyzes the imine framework formation, which is
then in situ reduced to the amine COF by the reductive
P–H moiety. The amine-linked COF outperforms its imine analogue
in promoting Knoevenagel condensation because of the more basic sites
and higher stability.
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