Inorganic Deuterium Effects Upon Aggregates Synthesis

Brown University, Providence RI

Investigators

Abstract

A fundamental, but yet unrecognized property of hydrogen isotopes, namely the deuterium-induced generation of new and/or morphologically different inorganic materials will be investigated. This effect manifests itself in the aqueous assembly of supramolecular structures. An aggregate exhibiting a structurally rigid, magnetic core, and interacting, hydrated diamagnetic ions at its periphery will be developed as a model. The initial demonstration of a link between isotope composition and supramolecular topology will be used to explore the nature of chemical and physical factors responsible for the deuterium effect. Technical issues to be investigated will focus on varying independently the hydrogen isotope, and several parameters viewed as potentially significant for tuning the assembly of large aggregates. Variable parameters include: (i) the ionic strength of the solution; (ii) ionic radii of ions linking aggregates into supramolecular structures; (iii) concentration of sodium chloride in water, a salt that is incorporated to a higher extent when deuterium is the solvent. The aggregates formed in water behave magnetically like molecules, while their deuterium counterparts exhibit solid-state, Neel-like points. This difference could be due to a bona fide formation of a solid, in case the magnetic ions oxidation states in the two aggregates are identical, or the deuterium complex may be a molecular magnet, in case the oxidation states are different. This question will be answered, inter alia, by x-ray absorption spectroscopy determinations of valence states. The answer will also shed light, if warranted, on the sensitivity of oxidation states to an isotope change. The hydrogen isotopomer - chemical parameters relationships will be used to rationally design new solids with predictable structural and, perhaps, magnetic features. Mixing two chemicals in water can give a predictive result, for example, compound A. Surprisingly, when A is a large molecule, using heavy water results in a related, but not identical product, B. The structural differences, especially in the way A and B assemble to form large "supramolecules", also result in magnetic differences of the type expected to distinguish a molecule from a solid. Elucidating the chemical factors responsible for these differences, and ways to rationally design new solids based upon an understanding of deuterium effects may well give rise to new synthetic paths to novel materials exhibiting new physical and chemical properties of high interest to the commercial sector.