Electron- and Hydride-Reservoir Organometallics as Precursors of Catalytically Efficient Transition Metal Nanoparticles in Water

Cobalt sandwich-stabilized rhodium nanocatalysts for ammonia borane and tetrahydroxydiboron hydrolysis

A bulky organocobalt sandwich-supported Rh nanoparticle is an efficient, stable and recyclable nanocatalyst for hydrolysis of both ammonia borane and tetrahydroxydiboron to H2.

The supramolecular redox functions of metallomacromolecules

Abstract

Metallomacromolecules are frequently encountered in redox proteins including metal-tanned hide collagen and play crucial roles involving supramolecular properties in biological electron-transfer processes. They are also currently found in non-natural families, such as: metallopolymers, metallodendrimers and metallodendronic polymers. This mini-review discusses the supramolecular redox functions of such nanomaterials developed in our research group. Electron-transfer processes are first examined in mono-, bis- and hexa-nuclear ferrocenes and other electron-reservoir organoiron systems showing the influence of supramolecular and reorganization aspects on their mechanism. Then applications of electron-transfer processes using these same organoiron redox systems in metallomacromolecules and their supramolecular functions are discussed including redox recognition/sensing, catalysis templates, electrocatalysis, redox catalysis, molecular machines, electrochromes, drug delivery device and nanobatteries.

Graphical Abstract

Transition metal complex/gold nanoparticle hybrid materials

Gold nanoparticles (AuNPs) are of considerable interest for diverse applications in areas such as medicine, catalysis, and sensing. AuNPs are generally surface-stabilized by organic matrices and coatings, and while the resultant organic compound (OC)/AuNP hybrids have been explored extensively, they are not suitable for certain applications (e.g. those necessitating reversible redox behaviour and/or long excited-state lifetimes), and they often suffer from low photo- and/or thermal stability. Transition metal complex (TMC)/AuNP hybrids have recently come to the fore as they circumvent some of the aforementioned shortcomings with OC/AuNP hybrids. This review summarizes progress thus far in the nascent field of TMC/AuNP hybrids. The structure and composition of extant TMC/AuNP hybrids are briefly reviewed and the range of TMCs employed in the shell of the hybrids are summarized, the one-phase, two-phase, and post-nanoparticle-synthesis synthetic methods to TMC/AuNP hybrids are discussed and contrasted, highlighting the advantages of variants of the last-mentioned procedure, and the utility of the various characterization techniques is discussed, emphasizing the need to employ multiple techniques in concert. Applications of TMC/AuNP hybrids in luminescence, electrochemical, and electro-optical sensing are described and critiqued, and their uses and potential in imaging, photo-dynamic therapy, nonlinear optics, and catalysis are assessed.

Stabilization of a new nanocomposite family by reduction of gold nanoclusters with electron-reservoir complexes

Four stable 19-electron Fe and Co sandwich electron-reservoirs and three hydride reservoir complexes reduce the prototypal nanocluster Au25(SR)18 (R = CH2CH2Ph) leading to a largely increased kinetic stabilization of the anionic nanocluster form compared to previously known nanocluster anion salts; these salts represent new and robust nanocomposite anionic gold clusters with 18-electron sandwich complexes as counter cations.

High catalytic activity of Rh nanoparticles generated from cobaltocene and RhCl3 in aqueous solution

Cobalticinium chloride-stabilized RhNPs are very efficient catalysts for hydrolysis of H₃N-BH₃, reduction of 4-NP, hydrogenation of benzene and transfer hydrogenation.