Dalton Transactions Blog

Superior de(hydrogenation)

26 Mar 2012

As the world’s reserves of fossil fuels are fast diminishing, the need for alternative efficient fuels is increasing. Using hydrogen as an energy carrier is attractive for the future since when hydrogen fuel is used in a fuel cell to generate electricity, the only waste product is water. To realise a hydrogen economy, the barriers that need to be overcome are producing hydrogen more efficiently, hydrogen transport and a suitable means of hydrogen storage.

Finding new methods of storing hydrogen is a thriving area of research. The problem we face is that hydrogen storage at ambient pressure and temperature has been a challenge. Xingguo Li and his team are one of the few groups to investigate Mg-Pd films with a transition metal interlayer for hydrogen storage applications. The team have used a technique called magnetron spluttering which is a surface coating technique to produce Mg-Ti-Pd trilayer films.

Most magnesium-based materials for hydrogen storage that have been studied so far have high operating temperatures and so new systems need to be developed that operate at ambient conditions. Xingguo Li and his group have now shown that this is possible by discovering that the trilayer films could be reversibly (de)hydrogenated at ambient temperature – a great improvement on the kinetics of previous magnesium based systems for hydrogen storage.

To learn more about the role that the titanium interlayer plays in the enhancement of Mg-Pd films for hydrogen storage, read the full Dalton Transactions article:

Superior (de)hydrogenation properties of Mg-Ti-Pd trilayer films at room temperature
Gongbiao Xin, Junzhi Yang, Chongyun Wang, Jie Zheng and Xingguo Li
DOI: 10.1039/C2DT30253E

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Themed Issue: Coordination chemistry in the solid state

23 Mar 2012

By Matthew Cude, Development Editor.

This themed issue Guest Edited by Russell Morris showcases the breadth of inorganic chemistry research in coordination chemistry in the solid state, from unusual synthesis to advanced applications.

You can read the Editorial for a full overview of the themed issue which includes:

Highly oriented surface-growth and covalent dye labeling of mesoporous metal–organic
frameworks
Florian M. Hinterholzinger, Stefan Wuttke, Pascal Roy, Thomas Preuße, Andreas Schaate,
Peter Behrens, Adelheid Godt and Thomas Bein

Supramolecular isomers of metal–organic frameworks: the role of a new mixed donor
imidazolate-carboxylate tetradentate ligand
Victoria J. Richards, Stephen P. Argent, Adam Kewley, Alexander J. Blake, William Lewis and
Neil R. Champness

Hydrogen adsorption in the metal–organic frameworks Fe₂(dobdc) and Fe₂(O₂)(dobdc)
Wendy L. Queen, Eric D. Bloch, Craig M. Brown, Matthew R. Hudson, Jarad A. Mason, Leslie
J. Murray, Anibal Javier Ramirez-Cuesta, Vanessa K. Peterson and Jeffrey R. Long

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Vapour sorption with no loss of crystallinity

23 Mar 2012

By Fiona McKenzie, Executive Editor.

A recent article from John Field and his team at the University of KwaZulu-Natal, South Africa, describes the sorption and sensing properties of a porous material with an unusual crystal structure. The platinum based material has an open framework made up from repeating 2D stacks of [Pt{4′-(Ph)trpy}(NCS)]⁺ cations (where trpy is 2,2′:6′,2″-terpyridine) that are stabilised by extended π-π interactions. This is somewhat different to the usual coordination compounds that are formed from metal ions linked by bridging organic molecules.

Unlike it’s parent material ([Pt(trpy)(NCS)]SbF₆), this compound can reversibly sorb and desorb organic vapours with no disruption of the framework structure which the team attribute to the 4′-phenyl substituent which participates in stabilising π-π interactions with pyridines on the nearby cations.

The solvent accessible voids in [Pt{4′-(Ph)trpy}(NCS)]SbF₆

Read this HOT article now:
Sorption of small molecule vapours by single crystals of [Pt{4′-(Ph)trpy}(NCS)]SbF₆ where trpy = 2,2′:6′,2′′-terpyridine: a porous material with a structure stabilised by extended π–π interactions
John S. Field, Orde Q. Munro and Bradley P. Waldron

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Linking up with Mercury

14 Mar 2012

By Matthew Cude, Development Editor.

Species featuring group 12 to group 12 bonds have lately become the subject of much interest and discussion, as have species containing homo-nuclear metal to metal bonds. This Hot Communication from Paul Weiss, Shiv Khanna, Ayusman Sen and colleagues details the discovery of a dimeric zintl anion featuring an Hg-Hg bond.

Molecular orbital diagram of the dimeric zintl ion

The new zintl phase contains [As₇HgHgAs₇]⁴⁻ ions with an unsupported Hg-Hg bond, as characterized by cyclic voltammetry, molecular orbital diagram, band gap energy and Raman spectra. To find out more about the group’s findings you can download there paper below, which is free to access for 4 weeks.

On the stability of an unsupported mercury–mercury bond linking group 15 Zintl clusters
Sukhendu Mandal, Arthur C. Reber, Meichun Qian, Ran Liu, Hector M. Saavedra, Saikat Sen, Paul S. Weiss, Shiv N. Khanna and Ayusman Sen
Dalton Trans., 2012, Advance Article
DOI: 10.1039/C2DT30083D

You can also keep to date with latest news in inorganic chemistry by following us on twitter or siging up to our e-alert service.

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Hot Article: Iron Chelators for Iron Overload

14 Mar 2012

By Matthew Cude, Development Editor.

Iron is a biological necessity and the amount we take-in must be carefully controlled – normally this isn’t a problem as eating a varied, healthy diet provides us with the nutrients we need. Once we have an adequate concentration of iron our intestines then stop absorbing it, preventing a surplus building up.

Fe chelating ligand

This absorption control is usually very effective as eating and drinking is our main source of iron, however after a blood transfusion excess iron can be introduced into the body and there is no natural mechanism to remove the unwanted metal ions. Some diseases such as Diamond–Blackfan anemia or β-thalassemia can require regular treatment by blood transfusion, which can lead to acute iron overload. This can be very harmful as iron can build up in vital organs such as the heart and liver and cause irreversible organ damage.

Iron chelating agents offer a treatment for Fe overload by binding to the excess iron ions, allowing them to be safely excreted before they build up and cause damage to the body. This Hot Article by Professor Des Richardson and Professor Paul Bernhardt et al. details the synthesis and characterisation of a series of dithiocarbazate Schiff base analogues for their suitability as iron chelators. Schiff bases are previously known as chelation ligands, but the derivatives detailed here show some interesting biological activities…

Heterocyclic dithiocarbazate iron chelators: Fe coordination chemistry and biological activity
Maram T. Basha, Jy D. Chartres, Namfon Pantarat, Mohammad Akbar Ali, Aminul Huq Mirza, Danuta S. Kalinowski, Des R. Richardson and Paul V. Bernhardt
Dalton Trans., 2012, Advance Article
DOI: 10.1039/C2DT12387H

This article will be part of our upcoming themed issue on Metals in Medicine: Non-Cancer Therapeutics – other hot papers due to be published in this special themed issue include the HOT Article: Anti-microbials that target destabilised DNA and the Hot Perspective: Treating Wilsons Disease.

You can also keep up to date with the latest news in inorganic chemistry by following us on twitter or signing up to our e-alert service.

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Cerium cation behaviour could change water splitting studies

13 Mar 2012

By Matthew Cude, Development Editor.

Scientists in Germany and Japan have shown that cerium(IV) predominantly forms a dinuclear complex in aqueous solution. Until now, scientists had thought that tetravalent cerium was a monomeric species in aqueous solution. The finding could have important implications for scientists studying water oxidation.

Atsushi Ikeda-Ohno from the Helmholtz-Zentrum Dresden Rossendorf, Dresden, and colleagues used a combination of extended X-ray absorption fine structure and density functional theory calculations to study the cerium(IV) cation. ‘In an aqueous solution, the primary form of metal cations is generally a simple mononuclear hydrate complex or a mononuclear oxo-cation,’ says Ikeda-Ohno, ‘but cerium(IV) forms a unique oxo- or/and hydroxo-bridging dinuclear complex.’

A combined X-ray absorption spectroscopy and density functional calculation study has revealed that a single oxo-bridging dinuclear complex is the dominant form of soluble Ce(IV) species in an aqueous perchloric acid solution.

‘We have always assumed that any reaction between a catalyst and a cerium salt is a one electron transfer reaction,’ says Curtis Berlinguette from the University of Calgary, Canada, who studies the mechanistic behaviour of homogeneous water oxidation catalysts using cerium salts as the terminal oxidant. ‘But if cerium(IV) does exist as a dimer and has an oxo bridge, then it really does question these assumptions and, more importantly, the nature of the oxygen-oxygen bond formation step.’

Berlinguette explains that the current assumption is that you make a catalyst with the metal oxo unit and that reacts with water. But, if the cerium salt that exists in solution contains an oxo, then you could potentially have a combination between the cerium(IV) oxo and the metal oxo, producing oxygen. Therefore, what might appear to be a water oxidation catalyst is in fact just forming dioxygen through reaction with the cerium salt.

‘It would be really interesting if Ikeda-Ohno’s team could extend this study to the acidic conditions and concentrations that are more widely used by the homogeneous catalytic water oxidation community. Then we will have much more insight into what species we are actually studying in solution,’ says Berlinguette.

Ikeda-Ohno says that developing time-resolved systems for X-ray techniques to probe the reactions of the cerium(IV) is the team’s next challenge.

Written by Rachel Cooper

Dinuclear complexes of tetravalent cerium in an aqueous perchloric acid solution
Atsushi Ikeda-Ohno, Satoru Tsushima, Christoph Hennig, Tsuyoshi Yaita and Gert Bernhard
Dalton Trans., 2012, Advance Article
DOI: 10.1039/C2DT12406H

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Keeping it crystalline

08 Mar 2012

By Leah Morris, Web Writer.

When designing new chemical sensors and switches, it is desirable to synthesise materials that are able to retain their structural features even after the uptake of a small molecule. Usually to achieve this, polymeric materials are used with extensive strong bonding that are able to withstand structural changes.

Wojciech Grochala and his team began investigating macrocyclic nickel complexes and discovered a complex that could absorb, then desorb water with retention of its crystallinity. The molecular crystal consists of an almost square planar coordination of nickel(II) supported by a 10 membered, tetradentate sulfur macrocycle. During their investigations, the team discovered that the uptake and release of water vapour was reversible and was accompanied by a change in colour and magnetic susceptibility. The flexible nature of the macrocyclic ligand allows for Ni(12aneS₄)(BF₄)₂ to keep its crystallinity upon water uptake which is rare for molecular crystals and a stark contrast to previously studied coordination polymers.

This exciting finding opens up the possibility of nickel molecular crystals being used as moisture sensors in the future.

To find out more, download the full Dalton Transactions paper:
Chemo-switched chromatic, magnetic and structural changes with retention of molecular crystallinity, Ni(12aneS₄)(BF₄)₂
Andrew J. Churchard, Mariana Derzsi, Zvonko Jagličić, Arndt Remhof and Wojciech Grochala

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A deeper understanding of Pt-guanine complexes

28 Feb 2012

By Fiona McKenzie, Executive Editor.

N7-substituted guanine intermolecular hydrogen bonding Bernhard Lippert and colleagues have followed up on their previous Dalton Transactions article with further insights into the coordination of guanine to a platinum centre.

The team’s goal is to create platinated nucleobase analogues capable of recognising natural DNA. However, due to the many potential tautomeric forms of guanine, more questions on the hydrogen bonding of these Pt-guanine complexes need to be answered.

In their latest Dalton Transactions article, Lippert and co-workers discuss the solution and solid state behaviour of 7-methylguanine and determine if the Pt complex is able to recognise 1-methylcytosine through Watson–Crick base pairing.

See what they found out by downloading the HOT article now – it’s free to access until 26^th March.
7-Methylguanine: protonation, formation of linkage isomers with trans-(NH₃)₂Pt^II, and base pairing properties
Ágnes Kozma, Susana Ibáñez, Radu Silaghi-Dumitrescu, Pablo J. Sanz Miguel, Deepali Gupta and Bernhard Lippert

To read their previous article…
Pt(II) complexes of unsubstituted guanine and 7-methylguanine
Deepali Gupta, Ralf Nowak and Bernhard Lippert, Dalton Trans., 2010, 39, 73–84

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Hot Paper: Schiff base-cobalt(II) coordination polymer with anti-cancer activity

27 Feb 2012

By Jennifer Newton, Publishing Editor.

The ligand, 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (isonicotinic) hydrazone, is coordinated through the ONO donor atoms to one Co(II) metal center and bridged through the pyridine nitrogen atom to another similar Co(II) center to form a 1D polymeric unit.

Karuppannan Natarajan and colleagues have synthesised and characterised the Co(II) complex, {[Co(H₂L)(H₂O)₂](NO₃)₂·3H₂O}_n. Human cancer cytotoxicity studies have shown the complex is very specific for cancer cells and less toxic in comparison to the well-know cancer drug, cisplatin.

To find out more you can download this article now, which is free to access for 4 weeks!

A novel water soluble ligand bridged cobalt(II) coordination polymer of 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (isonicotinic) hydrazone: evaluation of the DNA binding, protein interaction, radical scavenging and anticancer activity
Duraisamy Senthil Raja, Nattamai S. P. Bhuvanesh and Karuppannan Natarajan
Dalton Trans., 2012
DOI: 10.1039/C2DT12274J

Take a look at some of the other papers published recently in Dalton Transactions on Schiff base complexes of transition metal ions…

Structural and luminescence studies of nickel(II) and copper(II) complexes with (1R,2R)-cyclohexanediamine derived unsymmetric Schiff base
Magdalena Barwiolek, Edward Szlyk, Tadeusz M. Muzioł and Tadeusz Lis
Dalton Trans., 2011, 40, 11012-11022
DOI: 10.1039/C1DT10882D

The unprecedented preparation of dinuclear zinc(II) complexes from 4-halido-2-[(3-cyclohexylaminopropylimino)methyl]phenol
Zhong-Lu You, Mei Zhang and Dong-Mei Xian
Dalton Trans., 2012, 41, 2515-2524
DOI: 10.1039/C1DT11566A

Heterocyclic dithiocarbazate iron chelators: Fe coordination chemistry and biological activity
Maram T. Basha, Jy D. Chartres, Namfon Pantarat, Mohammad Akbar Ali, Aminul Huq Mirza, Danuta S. Kalinowski, Des R. Richardson and Paul V. Bernhardt
Dalton Trans., 2012
DOI: 10.1039/C2DT12387H

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Dalton Transactions Blog

Superior de(hydrogenation)

Themed Issue: Coordination chemistry in the solid state

Vapour sorption with no loss of crystallinity

Linking up with Mercury

Hot Article: Iron Chelators for Iron Overload

Cerium cation behaviour could change water splitting studies

Keeping it crystalline

Top ten most accessed articles in January

A deeper understanding of Pt-guanine complexes

Hot Paper: Schiff base-cobalt(II) coordination polymer with anti-cancer activity

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