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Cover Feature: Peroxo-Zr/Hf-Containing Wells-Dawson Polyoxometalates for H₂O₂-based Homogeneous, Heterogeneous, and Biphasic Oxidation Catalysis

Dr. Anusree Sundar, Dr. Nataliya V. Maksimchuk, Dr. Irina D. Ivanchikova, Dr. Olga V. Zalomaeva, Dr. Danica Bajuk-Bogdanović, Prof. Oxana A. Kholdeeva, Prof. Gordana Ćirić-Marjanović, Dr. Bassem S. Bassil, Prof. Ulrich Kortz

DOI: 10.1002/ceur.202300066

Peroxo-zirconium/hafnium-containing polyoxometalates as 3-in-1 catalysts were prepared and studied for homogeneous, heterogeneous, and biphasic oxidation catalysis with H₂O₂ as oxidant. The catalysts were evaluated in terms of activity and product selectivity and exhibited unique profiles. Most interestingly, the catalytic results proved highly relevant for applications in the chemical industry, possibly paving the way for green chemical processes.

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Front Cover: Special issue on Polyoxometalates
Guest Editors: José Ramón Galán-Mascarós (Institute of Chemical Research of Catalonia (ICIQ), Spain) and Ulrich Kortz (Jacobs University, Germany),  Acta Cryst. (2018). C74, 1180–1181.

DOI: 10.1107/S2053229618015188

The development of polyoxometalate (POM) chemistry during the last half-century or so has benefitted tremendously from single-crystal X-ray diffraction. Besides structural aspects, the study of the physicochemical properties of POMs has developed tremendously in recent decades. The multitude of attractive properties includes controllable size, composition, charge density, redox potential, acid strength, high thermal stability in the solid state, solubility in polar/nonpolar solvents and reversible electron/proton storage. Such versatility renders POMs of interest for academic and industrial applications, especially in catalysis. The contributions to this special issue on POMs provide an excellent overview of the current state of the subject, as well as providing updates to current reseach.

Guest Editors: José Ramón Galán-Mascarós (Institute of Chemical Research of Catalonia (ICIQ), Spain) and Ulrich Kortz (Jacobs University, Germany).

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Front Cover: Palladium(II) Incorporation in the All‐Inorganic Cryptand [As₄W₄₀O₁₄₀]^28–: Synthesis and Structural Characterization of [Pd₂Na₂KAs₄W₄₀O₁₄₀(H₂O)]^21– (Z. Anorg. Allg. Chem. 644(22)/2018) (p 1379)
Zhengguo Lin, Natalya V. Izarova, Fitsumbirhan T. Mehari, and Ulrich Kortz, 
DOI: 10.1002/zaac.201800327
Published Online: September 19, 2018

The cover picture, created by Dr. Rami Al‐Oweini, shows the careful insertion of palladium(II) ions into the polyoxometalate (POM) host [As₄W₄₀O₁₄₀]^28– (As₄W₄₀). In total two Pd²⁺ ions have been incorporated, resulting in the novel polyanion [Pd₂Na₂KAs₄W₄₀O₁₄₀(H₂O)]^21– (Pd₂As₄W₄₀). The insertion of noble metals (e.g. Pd, Pt, Au) into POMs is rather difficult and hence the proper reaction conditions must be carefully identified. Pd₂As₄W₄₀ represents the first structurally characterized noble metal derivative of As₄W₄₀. This work paves the way for the insertion of other d8 noble metal ions into As₄W₄₀. More details can be found in the article by Zhengguo Lin, Natalya V. Izarova, Fitsumbirhan T. Mehari, and Ulrich Kortz on page 1379 ff. 

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Cover Picture: Photocatalytic Water Oxidation by a Mixed-Valent Mn^IIIMn^IVO₃ Manganese Oxo Core that Mimics the Natural Oxygen-Evolving Center (Angew. Chem. Int. Ed. 53(42)/2014) (p 11182)
Rami Al-Oweini, Andrea Sartorel, Bassem S. Bassil, Mirco Natali, Serena Berardi, Franco Scandola, Ulrich Kortz, Marcella Bonchio
Published Online: July 27 2014
DOI: 10.1002/anie.201404664

The engine of aerobic life on earth is a tetramanganese oxo cluster at the very heart of Photosystem II (PS II) in green plants, algae, and photosynthetic bacteria. In their Communication on page 11182 ff, F. Scandola, U. Kortz, M. Bonchio et al. have identified a unique hybrid set of ligands to provide the first functional analogue of the PS II oxygen-evolving center that works in an artificial environment (Cover picture: Rami Al-Oweini).

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Inside Front Cover: Polyoxometalates Made of Gold: The Polyoxoaurate [Au^III₄As^V₄O₂₀]^8- (Angew. Chem. Int. Ed. 49(10)/2010) (p 1698)
Natalya V. Izarova, Nina Vankova, Thomas Heine, Rosa Ngo Biboum, Bineta Keita, Louis Nadjo, Ulrich Kortz
Published Online: Feb 19 2010 12:15PM
DOI: 10.1002/anie.200905566

A brand new line of gold jewelry has been designed in the world of polyoxometalate chemistry. In their Communication on page 1886 ff, U. Kortz et al. identify the first discrete inorganic polyoxoaurate [Au^III₄As^V₄O₂₀]^8- with a tetrameric structure and square-planar coordinated Au^III ions linked by oxo and arsenate bridging ligands (see structure; Au yellow, As blue, O red). The facile open-beaker synthetic procedure appears to be a convenient and general method for making a variety of gold-based inorganic oxo complexes. Mr. Rami Al-Oweini (PhD Student, Jacobs University) is thanked for his creative design.

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Cover Picture: Composite Cover Picture with Contributions from Five Authors (Eur. J. Inorg. Chem. 34/2009) (p NA)
Marcella Bonchio, Oxana A. Kholdeeva, Josep M. Poblet, Michael T. Pope, Toshihiro Yamase
Published Online: Nov 17 2009 10:01AM
DOI: 10.1002/ejic.200990093
Volume 2009 Issue 34 , Pages 5055 – 5276 (December 2009)
Special Issue: Polyoxometalates
Issue Edited by Ulrich Kortz
The cover picture depicts not only the internationality of the polyoxometalate community, well-reflected at the International Polyoxometalate Symposium (Jacobs University, Bremen July 28-August 1, 2009) on which this cluster issue is based, but also the huge scope of these compounds. The diversity of aspects in this issue is highlighted on the cover by a selection of graphics placed over the country of origin of the authors. Structural features (M. T. Pope et al.), mechanisms of formation (J. Poblet et al.), homogeneous oxidation catalysis (O. Kholdeeva et al.), design of enantioselective catalysts (M. Bonchio et al.) and photochemistry based analytical techniques (T. Yamase et al.) are some of the topics you will find. Mr Rami Al-Oweini (Jacobs University) is thanked for his creative design.

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Editorials
The Fascination of Polyoxometalates (p 5055)
Karen Hindson
Published Online: Nov 20 2009 9:19AM
DOI: 10.1002/ejic.200990097
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Cover Picture: The Tungstogermanate [Ce₂₀Ge₁₀W₁₀₀O₃₇₆(OH)₄(H₂O)₃₀]^56-: A Polyoxometalate Containing 20 Cerium(III) Atoms (Angew. Chem. Int. Ed. 46(32)/2007) (p 5985)
Bassem S. Bassil, Michael H. Dickman, Isabella Römer, Bernd von der Kammer, Ulrich Kortz
Published Online: Aug 3 2007 3:37AM
DOI: 10.1002/anie.200790155

A gigantic polyoxometalate [Ce₂₀Ge₁₀W₁₀₀O₃₇₆(OH)₄(H₂O)₃₀]^56- (1) was obtained in a classic one-pot synthesis from Ce^III ions and the trilacunary precursor [α-GeW₉O₃₄]^10- in water, as described by U. Kortz and co-workers in their Communication on page 6192 ff. The cover picture shows a possible mechanism of formation by stepwise self-assembly, beginning with the formation of Ce₂GeW₁₀ Keggin units, followed by arrangement of five such units into chiral, enantiomeric {Ce₂GeW₁₀}₅ species, and then dimerization of the R and S forms to give 1.

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Inside Front Cover: Organoruthenium derivative of the cyclic [H₇P₈W₄₈O₁₈₄]^33– anion: [{K(H₂O)}₃{Ru(p-cymene)(H₂O)}₄P₈W₄₉O₁₈₆(H₂O)₂]^27–
Sib Sankar Mal, Nadeen H. Nsouli, Michael H. Dickman and Ulrich Kortz,  Dalton Trans., 2007, 2627
DOI: 10.1039/b706762n

[{K(H₂O)}₃{Ru(p-cymene)(H₂O)}₄P₈W₄₉O₁₈₆(H₂O)₂]^27– ( 1) represents the first organometallic derivative of the large, crown-shaped tungstophosphate [H₇P₈W₄₈O₁₈₄]^33– (P₈W₄₈), and an unusual WO₆ group with four equatorial, terminal ligands is also grafted to P₈W₄₈.

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