Archive for August, 2012

Organometallics in catalysis: an article collection

Perhaps the most well-known applications of organometallics in catalysis are the Ziegler–Natta catalysts which are used to generate polymers, the catalysts are made up of mixtures of transition metal halides and organo-aluminium complexes. Karl Ziegler and Giulio Natta were awarded the 1963 Nobel Prize in Chemistry for their discovery and development of the catalysts, which today are the most commonly used for the manufacture of polythene.

The esteemed history of organometallics are not to be under-estimated and include Grignard’s reagents, the Heck reaction, Schrock catalysts, Grubbs’ catalysts and the Suzuki Coupling to name just a few. Organometallic compounds have revolutionised science and industry and to keep you up to date with the latest break-through research being made across all areas of organometallics in catalysis, we have made this cross-journal article collection free until the 26th September.

Click here for the full list of free articles

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Versatile Copper Ensemble for Cyanide Detection

Cyanide compounds can be highly toxic as the cyanide anion inhibits an enzyme in the electron transport chain, cytochrome c oxidase. The inhibition of this enzyme means that cells in the body can no longer produce ATP aerobically for energy which can eventually affect the heart and the central nervous system.

Some  industrial processes such as gold mining make use of cyanide ions and the accidental release of these ions can cause serious problems. The potassium salt of cyanide is also used as a terror chemical agent. As such, there is a need for more efficicent detection of cyanide ions with lower detection limits than methods which have been used previously.

Manoj Kumar and his team at Guru Nanak Dev University, India have synthesized a triazole ( five membered ring with 3 nitrogen and 2 carbon atoms) modified triphenylene (four fused benzene rings) which can selectively complex copper2+ ions.

The triphenylene based copper ensemble was shown using UV-vis and fluorescence spectroscopy to give a selective response for cyanide ions, even in the presence of blood serum and bovine serum albumin. This paper highlights the potential versatility of the copper ensemble for cyanide detection in different environments.

To read more about the detection of sodium cyanide in tap water and solid state detection of cyanide using the copper ensemble read the full article.

Triphenylene based copper ensemble for the detection of cyanide ions
Vandana Bhalla ,  Hardev Singh and Manoj Kumar
Dalton Trans., 2012

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Inspiring inorganic chemists to make their mark in medicine

Declan Gaynor and Darren Griffith discuss how medicinal inorganic chemistry is currently flourishing in this Dalton Transactions Perspective.  Understanding the role of metals in biological systems is very important for drug design; the predictability and control of inorganic complexes make fine-tuning the properties of drugs incorporating such complexes a real possibility.  Metal-based compounds are already routinely administered on a regular basis and this Perspective encourages chemists to further investigate inorganic therapeutic and diagnostic medicine by looking at previous successes, e.g. MRI contrast agents, then moving onto current challenges such as antibacterial compounds for tackling hospital acquired infections.Key areas of applied medicinal inorganic chemistryKey areas of applied medicinal inorganic chemistry

To find out more, you can download the Perspective now – which is free to access for 4 weeks!

The prevalence of metal-based drugs as therapeutic or diagnostic agents: beyond platinum
Declan Gaynor and Darren M. Griffith
Dalton Trans., 2012
DOI: 10.1039/C2DT31601C, Perspective

Also of interest…

Mn(II) complexes of novel hexadentate AAZTA-like chelators: a solution thermodynamics and relaxometric study
Lorenzo Tei, Giuseppe Gugliotta, Marianna Fekete, Ferenc K. Kálmán and Mauro Botta
Dalton Trans., 2011, 40, 2025-2032
DOI: 10.1039/C0DT01114B, Paper

Metallic radionuclides in the development of diagnostic and therapeutic radiopharmaceuticals
Sibaprasad Bhattacharyya and Manish Dixit
Dalton Trans., 2011, 40, 6112-6128
DOI: 10.1039/C1DT10379B, Perspective
From themed issue Radiopharmaceuticals for imaging and therapy

The status of platinum anticancer drugs in the clinic and in clinical trials
Nial J. Wheate, Shonagh Walker, Gemma E. Craig and Rabbab Oun
Dalton Trans., 2010, 39, 8113-8127
DOI: 10.1039/C0DT00292E, Perspective

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Stronger crystal field interactions give actinides advantage over lanthanides in single-molecule magnet construction at high temperatures.

Slow magnetic relaxation in homoleptic trispyrazolylborate complexes of neodymium(III) and uranium(III)Jeffrey Rinehart and Jeffrey Long compare the dynamic properties of the 4f3 complex, NdTp3 (Tp = trispyrazolylborate), and its isostructural 5f3 congener, UTp3. This is the first direct comparison of slow magnetic relaxation behaviour for isostructural and valence isoelectronic lanthanide and actinide complexes.

Download the manuscript which is free to access for 4 weeks to find out more.

Slow magnetic relaxation in homoleptic trispyrazolylborate complexes of neodymium(III) and uranium(III)
Jeffrey D. Rinehart and Jeffrey R. Long
Dalton Trans., 2012
DOI: 10.1039/C2DT31352A, Communication

This manuscript is part of a themed issue titled Frontier and Perspectives in Molecule-Based Quantum Magnets which is due to be published later in the year. Below is a selection of papers also due to be included in this themed issue:

Single-ion magnet behaviour in [U(TpMe2)2I]
Joana T. Coutinho,  Maria A. Antunes,  Laura C. J. Pereira,  Hélène Bolvin,  Joaquim Marçalo,  Marinella Mazzanti and Manuel Almeida
Dalton Trans., 2012
DOI: 10.1039/C2DT31421E, Communication

Controlling magnetic communication through aromatic bridges by variation in torsion angle
Thomas B. Faust,  Floriana Tuna,  Grigore A. Timco,  Marco Affronte,  Valerio Bellini,  Wolfgang Wernsdorfer and Richard E. P. Winpenny
Dalton Trans., 2012
DOI: 10.1039/C2DT31292A, Paper

A oximato-bridged linear trinuclear [MnIVMnIIIMnIV] single-molecule magnet
Chang-Long Zhou,  Zhe-Ming Wang,  Bing-Wu Wang and Song Gao
Dalton Trans., 2012
DOI: 10.1039/C2DT31039B, Paper

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Ball milling oxides

Mechanochemistry has been used for centuries – according to some, as early as 371 B.C. The pestle and mortar still has a place in many chemistry labs but nowadays mechanically-induced chemistry is  performed with the help of a high-energy ball mill.

In their latest Dalton Transactions Perspective, Vladimir Šepelák, Sylvie Bégin-Colin and Gérard Le Caër describe how ball milling is used to effect transformations in oxides. Whilst understanding of the mechanochemical processes involved in ball-milling metalllic compounds is growing, for the more-complex oxide materials, the field is still relatively immature.

The authors explain the various uses of ball milling oxides which can be grouped into either homogeneous or heterogeneous processes (determined by whether there is a net exchange of atoms across boundaries or not). Homogeneous processes encompass polymorphic transformations and titania phase transformations; heterogeneous processes involve compound formations, decompositions and redox reactions.

To read more about the interesting nanocrystalline characteristics that ball milling offers, read the Perspective article now.

Transformations in oxides induced by high-energy ball-milling
Vladimir Šepelák, Sylvie Bégin-Colin and Gérard Le Caër

Interested in other mechanochemistry articles? Read the growing number of articles being added to the ChemComm web theme in mechanochemistry – guest edited by Stuart James and Tomislav Friščić.

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A solid solution for MOF stabilisation

Research in metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) has exploded lately due to their potential applications in diverse areas from gas storage to drug delivery, but the Kitagawa group has been looking at yet another application that has rarely been considered: proton conductivity.  This process would work in a similar way to Nafion, a DuPont product produced since the 1960s in which protons on SO3H groups hop between acid sites that extend from a Teflon backbone.  Modified Nafion’s excellent mechanical and thermal stability allow it to be used as a proton conductor for proton exchange membrane (PEM) fuel cells.

Foo et al. have synthesised a framework containing sulphonic acid groups, where sodium cations were exchanged in situ for protons.  The resultant framework proved to be unstable to loss of guest molecules and, as such, its use in most future applications is limited.

However, through a solid solution approach, where a mixture of ligands was used in differing proportions, mixed MOFs were produced.  The stand-out product was a framework in which 18% of the linkers contained sulphonic acid groups, which retained crystallinity and porosity following evacuation of guest molecules.  The incorporation of this small proportion of acidic groups increased both the total uptake and the heat of adsorption of CO2 at 288 K.

Read about a solid solution approach as an alternative route to stabilising MOFs in this HOT article.

Ligand-based solid solution approach to stabilisation of sulphonic acid groups in porous coordination polymer Zr6O4(OH)4(BDC)6 (UiO-66)
Maw Lin Foo, Satoshi Horike, Tomohiro Fukushima, Yuh Hijikata, Yoshiki Kubota, Masaki Takata and Susumu Kitagawa

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Top ten most accessed articles in June

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

Copper (I) complexes with bipyridyl and phosphine ligands: a systematic study
Inmaculada Andrés-Tomé ,  John Fyson ,  Fernando Baiao Dias ,  Andy P. Monkman ,  Giuliano Iacobellis and Paolo Coppo Dalton Trans., 2012,41, 8669-8674 DOI: 10.1039/C2DT30698K     

Recent progress in the synthesis of inorganic nanoparticles 
C. N. R. Rao ,  H. S. S. Ramakrishna Matte ,  Rakesh Voggu and A. Govindaraj 
Dalton Trans., 2012,41, 5089-5120 DOI: 10.1039/C2DT12266A     

Cycloruthenated Sensitizers: Improving the Dye-Sensitized Solar Cell with Classical Inorganic Chemistry Principles 
Kiyoshi C. D. Robson ,  Paolo G. Bomben and Curtis P. Berlinguette  
Dalton Trans., 2012,41, 7814-7829 DOI: 10.1039/C2DT30825H     

Epitaxial growth and electrochemical properties of Li4Ti5O12 thin-film lithium battery anodes  
Masaaki Hirayama ,  Kyungsu Kim ,  Takeshi Toujigamori ,  Woosuk Cho and Ryoji Kanno  
Dalton Trans., 2011,40, 2882-2887 DOI: 10.1039/C0DT01477J    

Aluminum complexes of the redox-active [ONO] pincer ligand 
Géza Szigethy and Alan F. Heyduk  
Dalton Trans., 2012,41, 8144-8152 DOI: 10.1039/C2DT30295K     

Transition Metal Complexes Meet the Rylenes 
Felix N. Castellano  
Dalton Trans., 2012,41, 8493-8501 DOI: 10.1039/C2DT30765K     

Nothing frustrating about “Frustrated Lewis pairs” 
Douglas W. Stephan  
Dalton Trans., 2012,41, 9015-9015 DOI: 10.1039/C2DT90093A     

Synthesis of Electroactive Multinuclear Dipyrrinato Complexes and Fe(III) Assisted Formation of ?-Alkoxy Substituted 5-Ferrocenyldipyrromethenes 
Rakesh Kumar Gupta ,  Rampal Pandey ,  Sanjeev Sharma and Daya Shankar Pandey  
Dalton Trans., 2012,41, 8556-8566 DOI: 10.1039/C2DT30212H     

Charge-Transfer Guest Interactions in Luminescent MOFs: Implications for Solid-state Temperature and Environmental Sensing 
Patrick L. Feng ,  Kirsty Leong and Mark D. Allendorf  
Dalton Trans., 2012,41, 8869-8877 DOI: 10.1039/C2DT30649B     

Why Nature chose Mn for the Water Oxidase in Photosystem II 
Ron J. Pace ,  Rob Stranger and Simon Petrie  
Dalton Trans., 2012,41, 7179-7189 DOI: 10.1039/C2DT30185G     

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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Frontier and Perspectives in Molecule-Based Quantum Magnets

Photo 1. The participants of the 62nd Fujihara Seminar

The 62nd Fujihara Seminar titled “Frontier and Perspectives in Molecule-Based Quantum Magnets” was held this spring in Sendai, Japan. The Seminar was organized and hosted by Professor Masahiro Yamashita from Tohoku University with the financial support from the Fujihara Foundation of Science. The Fujihara Foundation of Science was founded in 1959 by Mr. Ginjiro Fujihara, the former president of Oji Paper Co. Ltd. who revolutionized the paper industry in Japan and has been recognized as “King of Paper-making”. The main goal of the Fujihara Foundation of Science is to encourage cutting-edge research, leading to significant scientific and technological progress in Japan.
 
The Fujihara Seminars are usually held at Tomakomai in Hokkaido, where the headquarters of Oji Paper Company is located. This year, however, the Council of the Foundation agreed to make an exception and decided to hold the 62nd Fujihara Seminar in Sendai – the heart of Tohoku area, which was struck last year by the destructive earthquake, followed by a devastating tsunami and the Fukushima nuclear power plant disaster – to support its recovery. The Fujihara Foundation of Science covered all expenses of the Seminar including travel fees, accommodation and organization expenses.
 
Thirty leading scientists in the field of molecular quantum magnetism from all over the world accepted the invitation and participated in this fascinating scientific event (Photo 1). The Scientific program featured 29 lectures covering all recent aspects in the development of molecular quantum magnets, introduction of multifunctionality into these systems, and the yet unexplored blank spots on the map of quantum magnetism. The atmosphere of the seminar allowed for many fruitful discussions and for significant strengthening of the molecular magnetism community. The scientific level of the talks was very high, most of the presented results were very recent, sometimes not yet published and stimulated vigorous discussions about the future possible developments and directions in quantum magnetism. The talks given at the 62nd Fujihara Seminar are subject of the special issue of Dalton Transactions titled “Frontiers and Perspectives in Molecule-Based Quantum Magnets”, due to be published later this year.

Photo 2. Discussion between Professor Masahiro Yamashita and Professor Dante Gatteschi

Professor Masahiro Yamashita (Tohoku University, Japan) opened the seminar with a lecture on the history of Single-Molecule (SMM) and Single-Chain (SCM) Magnets. Despite the fact that most of the participants were already familiar with the development of the concept, such introduction based on the “milestones” of quantum magnetism offered a valuable insight into the past, present, and future directions of the field. One future direction was introduced in the second talk given by Professor George Christou (University of Florida, USA). Prof. Christou noted that, for future applications of molecular quantum magnets in spin-based quantum computation and spintronic devices, coupling of two or more SMMs to each other is essential. Such coupling must be very weak in order to maintain the intrinsic quantum properties of each individual SMM, but strong enough to allow them to “feel each other”. Professor Christou presented several examples of SMM aggregates coupled with specially designed organic ligands. Some of them display an exchange-bias of the quantum tunneling of magnetization steps in the hysteresis loops, which is a hallmark of weak interactions between SMM units. 

Photo 3. Informal discussions during the excursion to Hiraizumi – a World Heritage site

In the subsequent talk, Professor Michel Verdaguer (Université Pierre et Marie Curie, France) discussed early results in the field of SCMs and the usefulness of X-Ray Magnetic Circular Dichroism (XMCD) in the characterization of magnetic molecules (especially those deposited on various surfaces). He also presented research on the salicyamidoxime-based Mn6 SMMs and summarized the successes and failures of the cyanide chemistry of transition metals in the field of high-spin molecules and SMMs. 

Professor Dante Gatteschi, one of the founding fathers of molecular magnetism (Univeristà degli Studi di Firenze, Italy) gave the last talk of the first day. Professor Gatteschi summarized the last 30 years of research in the field of nanomagnetism by focusing on the comparison of molecular nanomagnets MNMs with magnetic nanoparticles MNPs. He pointed out that there are still blank spots on the map of MNMs and strongly encouraged the exploration of the no man’s land of magnetic molecules comprising 100–1000 paramagnetic ions. In addition, he reminded the participants that there is “plenty of room” in between the MNMs and MNPs regimes. Synthesis and investigation of 100–1000 ion clusters might be challenging, but the emergence of new fascinating physical phenomena is expected (Photo 2). 

The second day of the Seminar was also filled with extremely stimulating talks and discussions. The lecture of Professor Song Gao (Peking University, China) reflected the strong current trend in molecular quantum magnetism to re-discover the importance of rare-earth elements in the design of SMMs with enhanced characteristics. Professor Gao pointed out that, thanks to the large spin-orbit coupling effect, several mononuclear lanthanide or actinide complexes have been found to be  single ion magnets. Lanthanide-based SMMs seem to be the most promising from an application point of view. Especially the double decker complex TbPc2 (Pc = phthalocyanine) with high single-ion anisotropy and a very high blocking temperature is particularly appealing for the construction of supramolecular spintronic devices, according to Professors Mario Ruben (Université de Strasbourg, France and Karlsruhe Institute of Technology, Germany) and Masahiro Yamashita (Tohoku University, Japan), who gave the last two talks. Professor Ruben demonstrated the potential of TbPc2 in the construction of spin-valves, and Professor Yamashita showed, for the first time, that TbPc2 could act as single-molecule memory device.

The third and last day of the conference was designated as an informal discussion day. The participants could freely interact during an excursion to Hiraizumi (a World Heritage site) – temples, gardens and archeological sites representing the Buddhist Pure Land – and during a river cruise (Photo 3). 

The 62nd Fujihara Seminar ended with a banquet at Shozankan. This final event began with a traditional ceremony of kagami biraki – opening of wooden casks of iwai-zake (“celebration sake”) (Photo 4). During the Banquet the host, Professor Masahiro Yamashita, asked all the participants to visit Sendai again in three years during the next conference on Molecular Quantum Magnets to “report” their advances in this particular field. He suggested that the next meeting would be a great opportunity to verify how fruitful the discussions and new ideas spawned during the 62nd Fujihara Seminar have been. 

 

Photo 4. Ceremony of kagami biraki – opening of wooden casks of iwai-zake (“celebration sake”) – during the Seminar Banquet. 

In summary, the 62nd Fujihara Seminar “Frontier and Perspectives in Molecule-Based Quantum Magnets” was a great opportunity for the top molecular magnetism scientists to interact and discuss how to further advance the field. Look out for the upcoming themd issue later this year.
                                                                                                    

Written by Dr. Dawid Pinkowicz (Tohoku University)

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