The Reactivity of the Metal Oxide‐Water and Mineral‐Water Interfaces – An Inorganic/Coordination Viewpoint

Abstract

The reactivity of the metal oxide-water interface and that of the mineral-water interface can be understood from the viewpoint of coordination chemistry, comparing the reactivity of a metal ion belonging to the surface of a solid with the reactivity of the same metal ion dissolved in an aqueous solution. Ligand substitution reactions are key reactions for metal complexes in solution and metal complexes at the surface. At the surface, these processes lead to the formation of adsorbed species, which can be identified by different surface spectroscopic techniques. Surface reactions, such as proton adsorptiondesorption and anion and cation adsorption-desorption, are easily understood in this context. With the aid of kinetic measurements performed by ATR-FTIR, it is shown that adsorption-desorption reactions should take place through dissociative (D), associative (A), or interchange mechanisms (I d , I a ), as they also occur in solution. www.eurjic.org Minireviews

Nanometer-Thick Carbon Coatings with Covalent Chemical Functionalization of Metal Oxide Nanoparticles for Environmental and Biological Applications

“…A key challenge to even more widespread use of metal oxide nanoparticles is the inherent hydrolytic instability of the surface bonds involved in commonly used surface functionalization schemes, , limiting applicability in aqueous media for biological and environmental studies . For example, nearly all metal–oxygen–carbon bonds are hydrolytically unstable with respect to M–O–C + H 2 O → M–OH + C–OH. − One strategy for overcoming these instabilities is to form surface cross-links such that removal of the molecular layers requires hydrolysis of multiple bonds . Among widely used methods, silane monolayers and phosphonic acid layers are stabilized by the formation of Si–O–Si and P–O–P cross-links, respectively. − While effective for many applications, even these layers are ultimately susceptible to chemical degradation, limiting their overall utility in applications that require layers that are stable over longer periods of time, especially in harsh media such as those found in biological and/or environmental systems. − Carboxylic acids have been used extensively as modifiers on metal oxides but are also reported to degrade rapidly under conditions relevant to biological studies .…”