A solved structure: The hydrated Ga(13) cluster, [Ga(13)(μ(3)-OH)(6)(μ-OH)(18)(H(2)O)(24)](NO(3))(15)], persists as a discrete nanoscale structure in an aqueous polar solvent at millimolar concentration. SAXS data confirm the presence of Ga(13) in dimethyl sulfoxide (DMSO). In aqueous [D(6)]DMSO (1)H NMR signals for the hydroxo and aquo ligands of Ga(13) were detected, thus showing a cluster with a hydrodynamic radius of (11.2±0.8) Å (see picture).

Herein, we report a new salt of a pyrophosphate-functionalized uranyl peroxide nanocluster {UPp} (1) exhibiting O molecular symmetry both in the solid and solution. Study of the system yielding 1 across a wide range of pH by single-crystal X-ray diffraction, small-angle X-ray scattering, and a combination of traditional P and diffusion-ordered spectroscopy (DOSY) NMR affords unprecedented insight into the amphoteric chemistry of this uranyl peroxide system. Key results include formation of a rare binary {U}·{UPp} (3) system observed under alkaline conditions, and evidence of acid-promoted decomposition of {UPp} (1) followed by spatial rearrangement and condensation of {U} building blocks into the {UPp} (2) cluster. Furthermore, P DOSY NMR measurements performed on saturated solutions containing crystalline {UPp} show only trace amounts (∼2% relative abundance) of the intact form of this cluster, suggesting a complex interconversion of {UPp}, {UPp}, and {UPp} ions.

The challenge of defining a length on the nanoscale is non-trivial. For a well-defined inorganic nanoscale species, a size measurement can describe a number of different dimensions (core, shell, solvation sphere). Often size is reported out of context or even inadvertently misrepresented. Since many of the techniques used to measure size depend on significant and sometimes destructive sample preparation, an additional challenge is defining "what size means" for a nanoscale species in solution. In this Concept, the distinction is made between complementary techniques that can be used together to unveil more information about the material in question, and corroborative techniques, which are used to make multiple measurements of the same property. Additionally, corroborative techniques can be used to measure the same property in and out-of solution so as to reveal details about solution behaviour. We highlight various approaches to this characterization challenge in the context of three case studies that demonstrate the use of both complementary and corroborative techniques to elucidate the various functional dimensions of different types of inorganic nanoscale species in solution.

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Electrochemical reduction is used to synthesize indium-gallium-hydroxide-nitrate nanoclusters which are shown to be promising precursors for thin-film transistors.

Multimeric oxo-hydroxo Al clusters function as models for common mineral structures and reactions. Cluster research, however, is often slowed by a lack of methods to prepare clusters in pure form and in large amounts. Herein, we report a facile synthesis of the little known cluster Al (OH) (H O) (SO ) (Al ) through a simple dissolution method. We confirm its structure by single-crystal X-ray diffraction and show by Al NMR spectroscopy, electrospray-ionization mass spectrometry, and small- and wide-angle X-ray scattering that it also exists in solution. We speculate that Al may form in natural water systems through the dissolution of aluminum-containing minerals in acidic sulfate solutions, such as those that could result from acid rain or mine drainage. Additionally, the dissolution method produces a discrete Al cluster on a scale suitable for studies and applications in materials science.

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The solution chemistry of aluminum has long interested scientists due to its relevance to materials chemistry and geochemistry. The dynamic behavior of large aluminum-oxo-hydroxo clusters, specifically [Al O (OH) (H O) ] (Al ), is the focus of this paper. Al NMR, H NMR, and H DOSY techniques were used to follow the isomerization of the ϵ-Al in the presence of glycine and Ca at 90 °C. Although the conversion of ϵ-Al to new clusters and/or Baker-Figgis-Keggin isomers has been studied previously, new H NMR and H DOSY analyses provided information about the role of glycine, the ligated intermediates, and the mechanism of isomerization. New H NMR data suggest that glycine plays a critical role in the isomerization. Surprisingly, glycine does not bind to Al clusters, which were previously proposed as an intermediate in the isomerization. Additionally, a highly symmetric tetrahedral signal (δ=72 ppm) appeared during the isomerization process, which evidence suggests corresponds to the long-sought α-Al isomer in solution.