Dalton Transactions

doi: 10.1039/c8dt90072hpmid: N/A

doi: 10.1039/C8DT90072Hpmid: N/A

doi: 10.1039/C8DT90073Fpmid: N/A

doi: 10.1039/c8dt90073fpmid: N/A

doi: 10.1039/c8dt90074dpmid: N/A

doi: 10.1039/C8DT90074Dpmid: N/A

doi: 10.1039/c8dt90063apmid: N/A

Rossi, Liane M.; Fiorio, Jhonatan L.; Garcia, Marco A. S.; Ferraz, Camila P.

doi: 10.1039/c7dt04728bpmid: 29509204

Metal nanoparticles have received intense scientific attention in the field of catalysis. Precise engineering of nanomaterials’ size, shape and surface composition, including adsorbed capping ligands, is of utmost importance to control activity and selectivity, and distinguish colloidally prepared metal nanoparticle catalysts from traditional heterogeneous catalysts. The interface between the material and the reaction medium is where the key interactions occur; therefore, catalysis occurs under the influence of capping ligands. In this Perspective review, we focus on the choice of capping ligands (or stabilizing agents), and their role and fate in different steps from preparation to catalysis. Evaluating the influence of the ligands on the catalytic response is not trivial, but the literature provides examples where the ligands adsorbed on the nanoparticle surface dramatically change the activity and selectivity for a particular reaction, while acting either as a dynamic shell or a passivation coating. Steric and electronic effects resulting from the presence of adsorbed ligands have been proposed to influence the catalytic properties. Attempts to remove the capping ligands are discussed, even though they are not always successful or even necessary. Finally, we outline our personal understanding and perspectives on the use of ligands or functionalized supports to tune the activity and selectivity of supported metal nanoparticles.

Burns, Peter C.; Nyman, May

doi: 10.1039/c7dt04245kpmid: 29560974

Uranyl peroxide clusters containing from 16 to 124 uranyl ions self-assemble in aqueous solution and exhibit tremendous topological complexity. Most of these clusters are cages, with the inside and outside surfaces passivated by oxygen atoms that are triply bonded to U(vi) cations (yl oxygen). It has become increasing apparent that the counter cations associated with these anionic cage clusters impact their assembly, topologies, and behavior in solution, including aggregation and aqueous solubility. Here we review the chemical compositions and topologies of uranyl peroxide clusters. We focus attention on the role of counter cations in cluster assembly, the properties of clusters in solution including supramolecular assembly, thermodynamic studies, and endohedral encapsulation. We also review the most useful solution characterization techniques of the counter cations and counter cation-capsule interactions. Potential applications in nuclear fuel cycles are discussed, including exerting nanoscale control of actinides to revolutionize separation technologies and provide novel pathways to nuclear materials including fuels, and an improved understanding of the transport of uranium in various systems. Finally, we elucidate some future directions.

Markad, Datta; Mandal, Sanjay K.

doi: 10.1039/c8dt00708jpmid: 29675542

We describe the synthesis and structural characterization of a novel dinuclear Cu(ii) complex containing a new flexible mixed pyridine-carboxylate ligand. Single crystal X-ray diffraction reveals its uniqueness with two coordinated water molecules and four uncoordinated pyridyl groups. Utilizing the bifunctional catalytic sites, it has been found to be an efficient, robust and recyclable heterogeneous catalyst for the diastereoselective Henry (nitroaldol) reaction of aldehydes with nitroethane.