Investigating Cation Binding in the Polyoxometalate‐Super‐Crown [P8W48O184]40−

Protein crystallography is the most widely used method for determining the molecular structure of proteins and obtaining structural information on protein–ligand complexes at the atomic level. As the structure determines the functions and properties of a protein, crystallography is of immense importance for nearly all research fields related to biochemistry. However, protein crystallography suffers from some major drawbacks, whereby the unpredictability of the crystallization process represents the main bottleneck. Crystallization is still more or less a ‘trial and error’ based procedure, and therefore, very time and resource consuming. Many strategies have been developed in the past decades to improve or enable the crystallization of proteins, whereby the use of so-called additives, which are mostly small molecules that make proteins more amenable to crystallization, is one of the most convenient and successful methods. Most of the commonly used additives are, however, restricted to particular crystallization conditions or groups of proteins. Therefore, a more universal additive addressing a wider range of proteins and being applicable to a broad spectrum of crystallization conditions would represent a significant advance in the field of protein crystallography. In recent years, polyoxometalates (POMs) emerged as a promising group of crystallization additives due to their unique structures and properties. In this regard, the tellurium-centered Anderson–Evans polyoxotungstate [TeW6O24]6− (TEW) showed its high potential as crystallization additive. In this lecture text, the development of POMs as tools in protein crystallography are discussed with a special focus on the so far most successful cluster TEW.Electronic supplementary materialThe online version of this article (10.1007/s40828-018-0064-1) contains supplementary material, which is available to authorized users.

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“…In general, the solubility of POMs in aqueous solutions can be tuned by the choice of the counter-cation (e.g., H + , Na + , K + , etc.) [ 125 ].…”

Section: The Potential Of Hexatungstotellurate As a Powerful Crystallmentioning

confidence: 99%

Polyoxometalates: more than a phasing tool in protein crystallography

Bijelic

Rompel

2018

ChemTexts

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“…However, in contrast to the preparation of compound 1 , the synthesis of compound 2 utilized the Li 17 (NH 4 ) 21 H 2 [P 8 W 48 O 184 ]·85H 2 O starting material instead of K 28 Li 5 H 7 [P 8 W 48 O 184 ]·92H 2 O. The influence of specific alkali metal cations on the assembly of {P 8 W 48 }-based frameworks has previously been discussed; however, until the recent preparation of a potassium-deficient salt of {P 8 W 48 }, 49 this effect could not be directly investigated.…”

Section: Resultsmentioning

confidence: 99%

“…48,49 All other starting materials were commercially available and used without further purification.…”

Section: Experimental Methodsmentioning

confidence: 99%

POMzites: A Family of Zeolitic Polyoxometalate Frameworks from a Minimal Building Block Library

et al. 2017

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We describe why the cyclic heteropolyanion [P8W48O184]40– (abbreviated as {P8W48}) is an ideal building block for the construction of intrinsically porous framework materials by classifying and analyzing >30 coordination polymers incorporating this polyoxometalate (POM) ligand. This analysis shows that the exocyclic coordination of first-row transition metals (TMs) to {P8W48} typically yields frameworks which extend through {W–O–TM–O–W} bridges in one, two, or three dimensions. However, despite the rich structural diversity of such compounds, the coordination of TMs to the {P8W48} ring is poorly understood, and therefore largely unpredictable, and had not until now been present with any structural classification that could allow rational design. Herein, not only do we present a new approach to understand and classify this new class of materials, we also present three {P8W48}-based frameworks which complement those frameworks which have previously been described. These new compounds help us postulate a new taxonomy of these materials. This is possible because the TM coordination sites of the {P8W48} ring are found, once fully mapped, to lead to well-defined classes of connectivity. Together, analysis provides insight into the nature of the building block connectivity within each framework, to facilitate comparisons between related structures, and to fundamentally unite this family of compounds. Hence we have tentatively named these compounds as “POMzites” to reflect the POM-based composition and zeolitic nature of each family member, although crucially, POMzites differ from zeolites in the modular manner of their preparation. As the synthesis of further POMzites is anticipated, the classification system and terminology introduced here will allow new compounds to be categorized and understood in the context of the established materials. A better understanding of TM coordination to the {P8W48} ring may allow the targeted synthesis of new frameworks rather than the reliance on serendipity apparent in current methods.

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“…In contrast, homogeneous ion binding and sensing in POMs is still challenging and mainly focused on cation binding, for which favorable electrostatic interactions with the anionic POMs are possible. A series of ring‐shaped, inorganic crown‐ether analogues capable of binding inorganic and organic cations have recently been reported. Furthermore, uptake of carboxylates in giant Keplerate capsules was observed …”

Section: Introductionmentioning

confidence: 99%

Homogeneous and Heterogeneous Anion Sensing by a Molecular Cobalt–Vanadium Oxide

Heiland

Seliverstov

Schwarz

et al. 2017

Chemistry A European J

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Spectroscopic anion sensing is a vital non-invasive tool in chemistry and biology. Here, a molecular cobalt-vanadium-oxide cluster was shown to be capable of selectively binding and detecting various mono-anions in solution and immobilized on a solid support. The cluster anion [Co(X)V O ] (X=mono-anion, for example, halide, pseudohalide, carboxylate, etc.) was formed spontaneously upon anion addition by self-assembly in solution. The cluster showed distinct spectral changes upon anion binding that could be followed spectroscopically and visually owing to a significant change of the solution color. DFT computations showed that the anion binding observed experimentally was correlated to the relative cluster stabilities. Competitive-binding studies showed that selective anion binding was possible from a mixture of anions. Immobilization of the anion sensor on silica strips provided access to single-use dip-stick sensors for the facile detection of anions in solution. The system presented enables the development of homogeneous or heterogeneous molecular anion sensors with possible applications in chemistry, bio-medical scenarios, and under harsh environmental conditions.

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Investigating Cation Binding in the Polyoxometalate‐Super‐Crown [P₈W₄₈O₁₈₄]⁴⁰⁻

Cited by 26 publications

References 59 publications

Polyoxometalates: more than a phasing tool in protein crystallography

Polyoxometalates: more than a phasing tool in protein crystallography

POMzites: A Family of Zeolitic Polyoxometalate Frameworks from a Minimal Building Block Library

Homogeneous and Heterogeneous Anion Sensing by a Molecular Cobalt–Vanadium Oxide

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