Elucidating Inorganic Nanoscale Species in Solution: Complementary and Corroborative Approaches

Abstract

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.

Dynamic Phosphonic Bridges in Aqueous Uranyl Clusters

“…10 26-clusters were synthesized according to literature procedures. [6] All 1 H and 31 P NMR experiments were performed on Varian 600 MHz and Bruker 500 MHz spectrometers.…”

“…By using the calculated viscosities and the measured diffusion coefficient of each cluster, the hydrodynamic radii were calculated and complement the previous single crystal X-ray diffraction (XRD) and small angle X-ray scattering (SAXS) size analyses of the cluster's core dimensions (Table 1). [6,10] On the basis of the crystal structures of these two clusters, every hydrogen atom of the phosphonic bridges in U 22 points into the cage and away from the bulk solution. In contrast, U 28 has 14 inward-pointing and 10 outward-pointing phosphonic bridges.…”

An overview of selected current approaches to the characterization of aqueous inorganic clusters

“…8 In addition to studying pre-nucleation clusters to inform metal ion speciation in water, there is much motivation to investigate any persistent, discrete aqueous clusters that may exist under certain hydrolysis or dissolution conditions. [9][10][11][12] Furthermore, the simple discovery of new cluster geometries and chemistries inspires us in their elegance and advances the field of inorganic synthesis. [9][10][11][12] Furthermore, the simple discovery of new cluster geometries and chemistries inspires us in their elegance and advances the field of inorganic synthesis.…”

“…10,86,87 More so, advancements in DLS have allowed for relatively facile and routine detection of species as small as ∼1 nm and lower in radius [R h of 0.1 M Al(NO 3 ) 3 = 0.35 nm ± 0.11 nm]. 10,86,87 More so, advancements in DLS have allowed for relatively facile and routine detection of species as small as ∼1 nm and lower in radius [R h of 0.1 M Al(NO 3 ) 3 = 0.35 nm ± 0.11 nm].…”

Polyoxoniobates and Polyoxotantalates as Ligands—Revisited

“…techniques for determination of stoichiometry and solution dynamics, an approach both promising and highly recommendable to trace unambiguously the identity of large inorganic systems [74].…”