Archive for March, 2012

Exchanging ligands on semiconducting nanocrystals

Semiconductors are at the heart of nearly all things computerised, and with nearly all things computerised that makes semiconductors important. Semiconducting nanocrystals have become an interesting area of research because as colloidal inks they can potentially be used to easily print onto substrates to create photo-voltaic devices or a broad range of electronic devices.

CdSe nanocrystals undergoing ligand exchange and thermolysis

CdSe nanocrystals undergoing ligand exchange and thermolysis

This Hot Communication from the Brutchey group details the use of a ligand which exchanges with the capping ligand of semiconducting CdSe nanocrystals making them highly dispersible in a range of polar solvents (in DMF a stable colloid forms for > 2 weeks). Under mild conditions thermolysis transforms the surface bound ligands to thiocyanate in situ, producing nanocrystal films of CdSe(SCN). There are also indications of improved inter-particle coupling…

Nanocrystal ligand exchange with 1,2,3,4-thiatriazole-5-thiolate and its facile in situ conversion to thiocyanate
David H. Webber and Richard L. Brutchey

This Hot Article is part of our up-coming themed issue ‘New Talent Americas’, Guest Edited by Dan Mindiola and John Arnold, other articles due to be published in this special issue include:

Perceiving Molecular Themes in the Structures and Bonding of Intermetallic Phases: The Role of Hückel Theory in an Ab Initio Era
Timothy E. Stacey and Daniel Fredrickson

Splitting water with rust: hematite photoelectrochemistry
Thomas W. Hamann

A heterobimetallic metal–organic framework with tunable reactive metal sites: synthesis, characterization, and reactivity
Nathan C. Smythe, Derek P. Butler, Curtis E. Moore, William R. McGowan, Arnold L. Rheingold and Laurance G. Beauvais

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Nanocatalyst for hydrogen release

hydrogen release from the dimethlyamine-borane complexAmine borane complexes are a promising solution for storing hydrogen, particularly as we move towards a hydrogen economy. Whilst focusing on developing the dehydrogenation of such complexes (namely dimethylamine-borane), scientists from Turkey have shown that you need to think small to think big by preparing a nanoparticle catalyst for the reaction.

By adding ruthenium (III) chloride to the hydrogen storing dimethlyamine-borane complex, the team found that ruthenium nanoparticles are generated in-situ which further work to catalyse the release of hydrogen from the complex.

Nanosizing the catalyst means a higher proportion of surface atoms are available for the hydrogen-storage complex – the result is greater catalytic activity and faster hydrogen generation.

Read the HOT article now for free… Hydrogen liberation from the hydrolytic dehydrogenation of dimethylamine–borane at room temperature by using a novel ruthenium nanocatalyst
Salim Caliskan, Mehmet Zahmakiran, Feyyaz Durap and Saim Özkar

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Top ten most accessed articles in February

This month sees the following articles in Dalton Transactions that are in the top ten most accessed:-

The end of iodide? Cobalt complex redox shuttles in DSSCs 
Thomas W. Hamann  
Dalton Trans., 2012, 41, 3111-3115 DOI: 10.1039/C2DT12362B  
   
Enhanced cytotoxicity of silver complexes bearing bidentate N-heterocyclic carbene ligands 
Diana C. F. Monteiro ,  Roger M. Phillips ,  Benjamin D. Crossley ,  Jake Fielden and Charlotte E. Willans  
Dalton Trans., 2012, 41, 3720-3725 DOI: 10.1039/C2DT12399A  
   

A series of isostructural mesoporous metal–organic frameworks obtained by ion-exchange induced single-crystal to single-crystal transformation 
Qingxia Yao ,  Junliang Sun ,  Kuo Li ,  Jie Su ,  Maxim V. Peskov and Xiaodong Zou  
Dalton Trans., 2012, 41, 3953-3955 DOI: 10.1039/C2DT12088G     

Highly-connected, porous coordination polymers based on [M4(µ3-OH)2] (M = CoII and NiII) clusters: different networks, adsorption and magnetic properties 
Qing Chen ,  Wei Xue ,  Jian-Bin Lin ,  Rui-Biao Lin ,  Ming-Hua Zeng and Xiao-Ming Chen  
Dalton Trans., 2012, 41, 4199-4206 DOI: 10.1039/C2DT12022D     

Functional porphyrinic metal–organic frameworks: crystal engineering and applications 
Chao Zou and Chuan-De Wu  
Dalton Trans., 2012, 41, 3879-3888 DOI: 10.1039/C2DT11989G     

Synthesis and characterization of a new porphyrin–polyoxometalate hybrid material and investigation of its catalytic activity 
Mehdi Araghi ,  Valiollah Mirkhani ,  Majid Moghadam ,  Shahram Tangestaninejad and Iraj Mohammdpoor-Baltork  
Dalton Trans., 2012, 41, 3087-3094 DOI: 10.1039/C2DT11865C     

A copper thiolate centre for electron transfer: mononuclear vs. dinuclear complexes 
Marcello Gennari ,  Jacques Pécaut ,  Marie-Noëlle Collomb and Carole Duboc  
Dalton Trans., 2012, 41, 3130-3133 DOI: 10.1039/C2DT12355J   
 
Sequential self-assembly in metal–organic frameworks 
Brandon J. Burnett and Wonyoung Choe  
Dalton Trans., 2012, 41, 3889-3894 DOI: 10.1039/C2DT12103D  
   

Synthesis of porous aromatic framework with tuning porosity via ionothermal reaction 
Wei Wang ,  Hao Ren ,  Fuxing Sun ,  Kun Cai ,  Heping Ma ,  Jianshi Du ,  Huijun Zhao and Guangshan Zhu  
Dalton Trans., 2012, 41, 3933-3936 DOI: 10.1039/C2DT11996J     

A fluorescence “turn-on” chemodosimeter for Cu2+ in aqueous solution based on the ion promoted oxidation 
Junbo Li ,  Yang Zeng ,  Qihui Hu ,  Xianglin Yu ,  Jia Guo and Zhiquan Pan  
Dalton Trans., 2012, 41, 3623-3626 DOI: 10.1039/C2DT12497A     

Why not take a look at the articles today and blog your thoughts and comments below.

Fancy submitting an article to Dalton Transactions? Then why not submit to us today or alternatively email us your suggestions.

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Ion Uptake and Solid Solution Formation

The study of ion-mineral interactions is a fascinating topic which spans many disciplines from inorganic chemistry to geology and ancient history. The driving forces behind the interaction of an ion and a mineral are complex, and whether or not an ion becomes incorporated into the solid phase is determined by many factors.

celestite strontianite Eu3+ Cm3+ Eu Cm solid solution solid-solution

 This Hot paper by Kiel Holliday et al. looks at the coordination of Eu and Cm to investigate what role local symmetry, ligand strength and a range of other parameters have in solid solution formation in both Eu- and Cm-doped strontianite and celestite.

So what is solid solution formation dependent on and what factors influence it?

Discriminating factors affecting incorporation: comparison of the fate of Eu3+–Cm3+ in the Sr carbonate–sulfate system
Kiel Holliday, Aurélie Chagneau, Moritz Schmidt, Francis Claret, Thorsten Schäfer and Thorsten Stumpf
Journal Article
Dalton Trans., 2012, 41, 3642-3647
DOI: 10.1039/C2DT12425D

You can also keep up to date with the latest information by following us on twitter or siging up to our e-alert service.

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Superior de(hydrogenation)

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.

Mg-Ti-Pd films for hydrogen storage

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

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:

Coordination chemistry in the solid state MOFs CP coordination polymersHighly 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

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.

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

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

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

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

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Hot Article: Iron Chelators for Iron Overload

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…

l

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

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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