Entrapment of an Organometallic Complex within a Metal: A Concept for Heterogeneous Catalysis

Abstract

A novel family of composite materials, organically doped metals, has been recently introduced. Here, we demonstrate their use as a new platform for heterogeneous catalysis, namely the doping of a metal with a catalytic organometallic complex. Specifically, a rhodium(I) catalyst, (RhCl(COD)(Ph2P(C6H4SO3Na))), ([Rh]), was physically entrapped within silver, thus creating a new type of catalytic material: [Rh]@Ag. Several aspects were demonstrated with the development of this heterogeneous catalyst: a metal can be used as a support for heterogenizing a homogeneous catalyst; the homogeneous catalyst is stabilized by the entrapment within the metal; the products of the composite catalyst are different compared to those obtained from the homogeneous one; and the adsorption of [Rh] on the surface of Ag and its entrapment are very different processes only the latter provided appreciable catalytic activity. Thus, while homogeneous [Rh] was entirely destroyed after converting styrene to ethylbenzne at 50%, [Rh]@Ag remained active after effecting the same reaction to a yield of 85% (compared to only 7% for [Rh] adsorbed on Ag), and while homogeneous [Rh] hydrogenated diphenylacetylene to bibenzyl (and was completely deactivated after one cycle) with no trace of cis-stilbene, [Rh]@Ag afforded that compound as the main product and could be reused.

Sustained release from a metal - Analgesics entrapped within biocidal silver

“…The water solubility of these drugs did not allow the standard mechanism of entrapment to operate. That mechanism (described in detail in previous publications) requires that the adsorptive residence time of the molecule to be entrapped on the surface of the growing metal crystallites, will be long enough to allow their entrapment in this state by further reductive precipitation of the metal 21, 22, 30 . However, the good water solubility of the two drugs, favored dissolution over adsorption.…”

“…What has enabled the developments described in this report is the advent of a new, powerful materials methodology, which enables the doping of metals with molecules, polymers and enzymes 18–21 . Many applications, all across chemistry, have been demonstrated with these new composites, and these are summarized in a recent review 22 .…”

Optical Properties of Hybrid Organic‐Inorganic Materials and their Applications

“…Avnir and co-workers have introduced original ways to entrap molecular dyes into different metals (Ag, Au, Cu, Fe). [152,[488][489][490][491][492][493][494][495] Indeed they generate the metal nanoparticles in the presence of the molecular guest and induce nanoaggregations entrapping the guests (Figure 43). They also developed electroless based deposition to grow hybrid films of metal aggregates entrapping molecular guests.…”

A Concept in Bactericidal Materials: The Entrapment of Chlorhexidine within Silver

“…The doping of silver employs, as mentioned above, a recent and general methodology for entrapping organic molecules and polymers within metals, which has already found various useful applications in catalysis [28][29][30] and bio-catalysis, [31] in alteration of metallic properties such as their reactivity, [2] in the induction of new and not necessarily related properties to metals such as chirality [32] or acidity/basicity, [33] and more. [34] The entrapment process involves a room temperature metal synthesis by chemical reduction of the metal cation, in either aqueous [2] or organic phases, [35] with either a homogenous [2] (solvent-soluble) or heterogeneous [3] (solvent-insoluble) reducing agent, carried out in the presence of the desired organic molecule.…”