How Counterions Affect the Solution Structure of Polyoxoaurates: Insights from UV/Vis Spectral Simulations and Electrospray Mass Spectrometry

Abstract

The solution structure of the two presently known polyoxoaurates, [ (Au 4 Se 4 ), was elucidated by a combination of time-dependent density-functional-theory (TD-DFT) calculations, experimental UV/Vis spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). The TD-DFT-predicted electronic spectra for molecular models including different numbers of counterions, along with the main Au 4 As 4 and Au 4 Se 4 structural motifs, were analyzed and compared with the experimental UV/Vis spectra of the two polyanions. The performed analysis revealed important structural differences between the arsenate and the selenite derivatives in aqueous solution. For the selenite oxoaurate, the bare Au 4 Se 4 polyanion itself shows very good agreement between predicted

Capillary Zone Electrophoresis as a Tool to Monitor the Stability and Hydrolytic Equilibria of Strandberg‐Type Polyoxometalates in Aqueous Solution

“…On the other hand, it is rather a challenging task to determine the exact species involved in the equilibria; therefore, it is unlikely that the predominant species and the properties of POMs can be checked quickly. Spectroscopic techniques, such as UV/Vis and NMR spectroscopy, can be used to determine roughly the species and stabilities of POMs in solution. However, the sensitivities of these techniques are poor, and large amounts of samples are required.…”

“…Electrospray ionization mass spectrometry (ESI‐MS) is an alternative method. However, it is difficult to determine the dynamic equilibria of POMs in solution . Therefore, the development of a simple and efficient method that can be used to monitor the solution behavior of POMs in real time is urgently demanded.…”

Ion‐Directed Coordinative Polymerization of Copper(II) Pyridyl‐Alcohol Complexes Through Thiane Functionalities

“…We demonstrated that the ability of copper to adopt distinct coordination arrangements [35] and the sterics of small monodentate ligand anions play a crucial role in the construction of monomeric vs. extended structures in the presence of the sulfur source. In contrast to the situation in the cubane-like complexes of Co II and Ni II featuring "free" thiane tails, [21] the thiane unit of HL·S can effectively coordinate to the trigonalbipyramidal Cu II ions with higher affinity to sulfur in 2 to afford 1D polymeric chains with weak antiferromagnetic exchange interactions between the central copper atoms.…”

Breaking the Gordian Knot in the Structural Chemistry of Polyoxometalates: Copper(II)–Oxo/Hydroxo Clusters

“…The observed {Cu 4 O 4 (PO 4 ) 4 } constituents are isostructural to the arsenate‐capped polyoxoaurate (POAu) with the formula [Au III 4 O 4 (AsO 4 ) 4 ] 8− (Figure c). As shown in Figure d, two [Au III 4 O 4 (AsO 4 ) 4 ] 8− polyoxoanions intercalate five Na + ions to afford the [Na 5 Au III 8 O 8 (AsO 4 ) 8 ] 11− composition present in solution and in the solid state . A recent synthetic report demonstrates that similar compounds comprising {Cu 4 O 4 } rings that are capped by heterogroups can also be produced by a solvothermal reaction at a significantly lower temperature.…”