Photochemistry of extended polyimine COF structures with laminar, spherical and 3D architectures has been examined. We show that these materials, composed by undecorated phenyl rings and imine ...fragments, can act as photocatalyts in oxidative transformations, being the crystalline laminar material the most active photocatalyst. The sulfoxidation reaction proceeds with good yields for a large variety of different sulfides. This process was carried out under visible light conditions (20 W), ethanol/H2O as solvent, and the heterogeneous porous material can be recycled up to 9 times. The crystallinity favours the behavior as photocatalyst of laminar and spherical COFs whereas any particular effect on the 3D material activity was observed. Sulfoxidation reaction mainly proceeds through an energy transfer mechanism using crystalline laminar material. In addition, these materials as photocatalysts were used for the oxidation of phenyl boronic acid into phenol.
Keep it simple! Undecorated imine‐based COF structures are able to perform as photocatalysts for oxidation of organic sulfides without the need of further structural design.
Delamination of Layered Covalent Organic Frameworks Berlanga, Isadora; Ruiz-González, Maria Luisa; González-Calbet, José María ...
Small (Weinheim an der Bergstrasse, Germany),
May 9, 2011, Letnik:
7, Številka:
9
Journal Article
Recenzirano
The isolation of nanostructures consisting of 10–25 layers of a covalent organic framework is confirmed by AFM carried out on several surfaces. This is achieved by means of selective ultrasound ...exfoliation on the bulk layered material. TEM demonstrates the porous nature of the free‐standing layers on a carbon gird. The chemical composition of this novel 2D polymer is determined by infrared, X‐ray photoelectron, and electron‐energy‐loss spectroscopy.
The activity of catalytic nanoparticles is strongly dependent on their surface chemistry, which controls colloidal stability and substrate diffusion toward catalytic sites. In this work, we studied ...how the outer surface chemistry of nanostructured Rh(II)‐based metal‐organic cages or polyhedra (Rh‐MOPs) impacts their performance in homogeneous catalysis. Specifically, through post‐synthetic coordination of aliphatic imidazole ligands onto the exohedral Rh(II) axial sites of Rh‐MOPs, we solubilized a cuboctahedral Rh‐MOP in dichloromethane, thereby enabling its use as a homogeneous catalyst. We demonstrated that the presence of the coordinating ligand on the surface of the Rh‐MOP does not hinder its catalytic activity in styrene aziridination and cyclopropanation reactions, thanks to the dynamic Rh‐imidazole coordination bond. Finally, we used similar ligand exchange post‐synthetic reactions to develop a ligand‐mediated approach for precipitating the Rh‐MOP catalyst, facilitating the recovery and reuse of Rh‐MOPs as homogeneous catalysts.
The post‐synthetic coordinative functionalization of Rh(II)‐based metal‐organic polyhedra (Rh‐MOPs) is employed to engineer homogeneous catalysts for styrene aziridination and cyclopropanation reactions. This dynamic coordinative functionalization does not hinder the catalytic activity of the Rh(II) sites and it can be coupled to ligand‐exchange reactions to precipitate the Rh‐MOP catalyst, facilitating its recovery and reuse.
2D materials: to graphene and beyond Mas-Ballesté, Rubén; Gómez-Navarro, Cristina; Gómez-Herrero, Julio ...
Nanoscale,
01/2011, Letnik:
3, Številka:
1
Journal Article
Recenzirano
This review is an attempt to illustrate the different alternatives in the field of 2D materials. Graphene seems to be just the tip of the iceberg and we show how the discovery of alternative 2D ...materials is starting to show the rest of this iceberg. The review comprises the current state-of-the-art of the vast literature in concepts and methods already known for isolation and characterization of graphene, and rationalizes the quite disperse literature in other 2D materials such as metal oxides, hydroxides and chalcogenides, and metal-organic frameworks.
Exfoliation of a family of polyacetylenic porous layered covalent organic frameworks by means of a simple sonication procedure results in the obtention of nanolayer structures as observed by AFM and ...TEM measurements. Systematic AFM analysis of the isolated nanostructures reveals that the degree of exfoliation depends on the polymer architecture, thinner layers being observed when the pore size decreases.
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