Archive for November, 2012

The curious case of plutonium

Plutonium colloids

Plutonium colloids

Even 70 years after its discovery, the behaviour of plutonium still remains something of an enigma.  Now Swedish researchers have discovered that plutonium colloids shrink with age becoming very small (3–4 atoms) with a shortening of the average Pu–O bond and Pu⋯Pu distances, consistent with partial oxidation having occurred. 

Two types of colloidal materials were studied: high-fired crystalline PuO2, and freshly prepared Pu(IV) colloids. The structures of both types were determined by EXAFS at the beginning of the experiment and after controlled aging of up to five years.  The results show that even freshly prepared Pu(IV) colloids are polynuclear nano clusters with PuO2 structure, bringing new insight into the evolution of plutonium with time.

Read more about plutonium for FREE at:

The structure of plutonium(IV) oxide as hydrolysed clusters in aqueous suspensions
Christian Ekberg, Kristian Larsson, Gunnar Skarnemark, Arvid Ödegaard-Jensen and Ingmar Persson
Dalton Trans., 2013, Advance Article
DOI: 10.1039/C2DT32185H

Other Dalton papers by the same author are:

Crystal structure of [Eu(CyMe4-BTBP)2κ2O,O‘-(NO3)](NO3)2·n-C8H17OH and its structure in 1-octanol solution
Daniel Lundberg, Ingmar Persson and Christian Ekberg
Dalton Trans., 2013, Advance Article
DOI: 10.1039/C2DT32317F, Communication

Radiolysis of solvents containing C5-BTBP: identification of degradation products and their dependence on absorbed dose and dose rate
Anna Fermvik, Laurence Berthon, Christian Ekberg, Sofie Englund, Teodora Retegan and Nicole Zorz
Dalton Trans., 2009, 6421-6430
DOI: 10.1039/B907084B, Paper

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Hybrid nanotubes for high performance Li ion batteries

Commercial Lithium ion batteries (LIBs)  usually contain graphitic anode materials but their relatively low capacity means that they can’t be used for high capacity storage applications such as electric vehicles and aerospace transport. Alternative anode materials with higher specific capacities have been studied such as metal oxides and metal sulfides. One dimensional structured metal sulfides in particular have received significant research interest but during charge–discharge experiments, the metal sulfides suffer from volume expansion, limiting their cycling performance.

To overcome this issue, researchers have tried combining metal sulfides and conductive carbon based materials. With this in mind, Yaunzhe Piao and team have successfully made a 1D structured carbon nanotube – MoS2 (CNTs-MoS2) hybrid nanomaterial using an environmentally friendly synthetic procedure. The synthesis did not require any surfactants or harmful solvents but used a hydrothermal method with the amino acid, L-cysteine which helped the MoS2 nanosheets to bind to the CNTs.

The hybrid material has a higher specific capacity than just MoS2 or CNTs and even has a high specific capacity after 30 charge–discharge cycles. The synthetic approach towards MoS2-CNTs could be applied to other metal sulfides to explore their electrochemical properties.

To find out more about the electrochemical properties of the new CNT-MoS2, download the Dalton Transactions article now…

A simple L-cysteine-assisted method for the growth of MoS2 nanosheets on carbon nanotubes for high-performance lithium ion batteries

Seung-Keun Park, Seung-Ho Yu, Seung-Hee Woo, Bo Quan, Dong-Chan Lee, Min Kun Kim, Yung-Eun Sung and Yuanzhe Piao

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

4th Dalton Transactions International Symposium

This year’s Dalton Transactions International Symposium was held in November in Singapore and Shanghai, with the theme of organometallic chemistry and catalysis.

Day One of the Symposium was held in a hot and humid Singapore, at the A* Star Institute of Materials Research and Engineering (IMRE), where local host Professor TS Andy Hor welcomed both local and overseas speakers.  After an opening welcome by Andy and Editor Jamie Humphrey, Professor Pak-Hing Leung, from the Nanyang Technological University (NTU) in the west of Singapore began the scientific talks, with his presentation entitled ‘Palladacycle-catalysed asymmetric hydrophosphination: direct and efficient synthesis of functionalised chiral tertiary phosphines’. After the morning coffee break, served Singapore style, Professor Philip Mountford (University of Oxford, UK, and Dalton Transactions Editorial Board Chair) gave a talk about ‘New terminal titanium hydrazido complexes: exploring the chemistry of the Ti=N-NR2 functional group’ and Professor JJ Vittal, from the National University of Singapore (NUS), took us up to lunch by describing his research on the ‘Design and reactivity of coordination polymers’.

Following lunch, Professor Aaron Sadow (Iowa State University) began the afternoon session, sporting his new Singapore haircut which he had the day before, presenting his talk on ‘Main group compounds supported by oxazolinylborate ligands in catalysis’. Aaron was followed by Professor Kuo-Wei Huang (King Abdullah University of Science & Technology), speaking about ‘A new class of PN3-pincer ligands for metal-ligand cooperative catalysis’. The final session of the day included a presentation by Professor Jean-Francois Carpentier ( University of Rennes), on ‘Discrete complexes of alkaline- and rare-earth elements: useful catalysts for cyclic esters polymerisations and hydroelementation reactions’ and Professor Han Vinh Huynh (NUS), speaking about ‘Non-classical NHC ligands and a new electronic parameter for the  determination of ligand donor strengths’.

Philip Mountford and Jamie Humphrey
Philip Mountford and Jamie Humphrey visit the clean room at IMRE

After the formal end of the Symposium, the speakers were given a tour of the facilities at IMRE, including a tour of the clean room (with a very strict dress code…). Day One of the Symposium was a great success, with a series of excellent scientific talks and many opportunities for those attending the Symposium to meet and discuss science with the speakers.

The next day the travelling speakers flew to Shanghai, where even though the weather was rather chilly, they received the warmest of welcomes, from local host Professor Guo-Xin Jin and other friends, beginning with a welcome dinner at the Jin Mao Tower in the Pudong district of Shanghai.

Day Two of the Symposium saw the return to the exact same venue where we had organised the very first Dalton Transactions International Symposium in 2009, the Fuxian Hotel at Fudan University. Following the same pattern of Day One of the Symposium, local host Professor Guo-Xin Jin welcomed those in attendance and opened the scientific sessions.

Professor Kuiling Ding (Shanghai Institute of Organic Chemistry) began with a presentation on ‘Chiral catalyst evolution: rational design and serendipity’, and was joined by Professors Mountford, Sadow and Carpentier, and local speakers Professor Jie-Sheng Chen (Shanghai Jiao Tong University, ‘Electron transfer and its effects in porous solid’), Professor Aiwen Lei (Wuhan University, ‘Oxidative coupling: chemistry between two “nucleophiles” ‘) and Professor Tao Tu (Fudan University, ‘Synthesis, aggregation and applications of pincer type organometallics’). The day concluded with some closing remarks by Jamie Humphrey and dinner in the Fuxian Hotel.

The 4th Dalton Transactions International Symposium brought together world class organometallic chemists, allowing old friends to be reunited and new friendships to be made. It was great to see so many discussions during the breaks, and especially to see local students discussing chemistry with the speakers.

Very many thanks are due to the local hosts, Professors Andy Hor in Singapore and Guo-Xin Jin in Shanghai, for their tireless efforts to ensure a successful Symposium, to the co-sponsoring host organisations, IMRE and the Singapore National Institute of Chemistry (SNIC) and Fudan University, for their generous financial support, and to all 11 speakers!

Read a selection of recent Dalton Transactions articles by the Symposium speakers by following the links below:

Site selectivity and reversibility in the reactions of titanium hydrazides with Si–H, Si–X, C–X and H+ reagents: Ti Nα 1,2-silane addition, Nβ alkylation, Nα protonation and σ-bond metathesis
Pei Jen Tiong, Ainara Nova, Andrew D. Schwarz, Jonathan D. Selby, Eric Clot and Philip Mountford
Dalton Trans., 2012,41, 2277-2288
DOI: 10.1039/C2DT12359B

Unusual structural motif in a zwitterionic Fe(II) complex of a tetradentate phosphine
Barun Jana, Megan Hovey, Arkady Ellern, Oleg Pestovsky, Aaron D. Sadow and Andreja Bakac
Dalton Trans., 2012,41, 12781-12785
DOI: 10.1039/C2DT31437A

Allyl strontium compounds: synthesis, molecular structure and properties
Phillip Jochmann, Julien P. Davin, Stefanie Maslek, Thomas P. Spaniol, Yann Sarazin, Jean-Francois Carpentier and Jun Okuda
Dalton Trans., 2012,41, 9176-9181
DOI: 10.1039/C2DT30743J

One-step entry to olefin-tethered N,S-heterocyclic carbene complexes of ruthenium with mixed ligands
Nini Ding, Wenhua Zhang and T. S. Andy Hor
Dalton Trans., 2012,41, 5988-5994
DOI: 10.1039/C2DT12354A

Palladium(IV) chemistry supported by pincer type ligands
Heng Zhang and Aiwen Lei
Dalton Trans., 2011,40, 8745-8754
DOI: 10.1039/C1DT10373C

A precursor route to single-crystalline WO3 nanoplates with an uneven surface and enhanced sensing properties
Xiao-Xin Zou, Guo-Dong Li, Pei-Pei Wang, Juan Su, Jun Zhao, Li-Jing Zhou, Yu-Ning Wang and Jie-Sheng Chen
Dalton Trans., 2012,41, 9773-9780
DOI: 10.1039/C2DT30748K

Chiral cyclopalladated complex promoted asymmetric synthesis of diester-substituted P,N-ligands via stepwise hydrophosphination and hydroamination reactions
Ke Chen, Sumod A. Pullarkat, Mengtao Ma, Yongxin Li and Pak-Hing Leung
Dalton Trans., 2012,41, 5391-5400
DOI: 10.1039/C2DT12379G

Correlation of spectroscopically determined ligand donor strength and nucleophilicity of substituted pyrazoles
Jan Christopher Bernhammer and Han Vinh Huynh
Dalton Trans., 2012,41, 8600-8608
DOI: 10.1039/C2DT30526G

Bottom-up synthesis of coordination polymers based on carborane backbones and Cu2(CO2)4 paddle-wheel: ligand metathesis with metallotecons
Sheng-Li Huang, Lin-Hong Weng and Guo-Xin Jin
Dalton Trans., 2012,41, 11657-11662
DOI: 10.1039/C2DT30708A

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Photoluminescent DNA binder

Upon DNA binding, a 15-fold turn-on in emission intensity occurs.

Upon DNA binding, a 15-fold turn-on in emission intensity occurs.

Stephen Lippard and colleagues at Massachusetts Institute of Technology have synthesised and characterised a platinum(II) complex bearing the tetradentate, β-diketiminate ligand ([Pt(BDIQQ)]Cl).  Cytotoxic studies showed [Pt(BDIQQ)]Cl to have similar potency to cisplatin on cervical cancer (HeLa) cells, whereas on human lung carcinoma (A549) cells [Pt(BDIQQ)]Cl was four times more potent than cisplatin.  The complex elicits a strong photoluminescent turn-on response upon DNA binding and it is hoped this will be useful for further cellular imaging studies.

Read the article now to find out more…

Photoluminescent DNA binding and cytotoxic activity of a platinum(II) complex bearing a tetradentate β-diketiminate ligand
Jennifer M. Hope, Justin J. Wilson and Stephen J. Lippard
Dalton Trans., 2013
DOI: 10.1039/C2DT32462H, Communication

Other Dalton Transactions articles by this author include:

A C2-symmetric, basic Fe(III) carboxylate complex derived from a novel triptycene-based chelating carboxylate ligand
Yang Li, Justin J. Wilson, Loi H. Do, Ulf-Peter Apfel and Stephen J. Lippard
Dalton Trans., 2012,41, 9272-9275
DOI: 10.1039/C2DT31260C, Communication

Non-traditional platinum compounds for improved accumulation, oral bioavailability, and tumor targeting
Katherine S. Lovejoy and Stephen J. Lippard
Dalton Trans., 2009, 10651-10659
DOI: 10.1039/B913896J, Perspective
From themed issue Metal anticancer compounds

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

New antibiotic with reduced risk of future bacterial resistance

Biofilm growth of the bacteria, P. aeruginosa, is responsible for many chronic infections in patients and presents a major challenge for the medical industry since these bacteria are largely resistant to antibiotics, disinfectants and patients’ natural immune defences.

UK scientists have developed a new antibiotic based on gallium metal ions complexed with cellulose which effectively displays antibacterial activity against biofilms of P.aeroginosa. Risk of future resistance to these antibiotics is also reduced as they work by an entirely different mechanism to traditional antibiotics.

A disc diffusion assay shows the inhibitory action of the gallium-carboxymethyl cellulose on P.aeroginosa. The white arrow shows the spherical transparent inhibition zone.

This article is particularly topical considering recent UK news headlines on antibiotic resistance. Download the article now…

Effect of Novel Antibacterial Gallium-Carboxymethyl Cellulose on Pseudomonas aeruginosa
Sabeel P Valappil, Humphrey H.P. Yiu, Laurent Bouffier, Christopher Keith Hope, Gary Evans, John B Claridge,  Susan M Higham and Matthew J Rosseinsky

 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Ruthenium catalyst for cancer treatment

Scientists from Germany have designed a new complex which inhibits enzymes and reduces tumour cell growth.

The drug complex consists of N-heterocyclic carbene ligands coordinated to a ruthenium metal centre. Ruthenium N-heterocyclic carbene compounds are largely popular due to their catalytic properties but very little attention has been paid to the biological activity of these species.

Anti-cancer ruthenium N-heterocyclic carbenes

Why not download the article now to find out what the team did…?

Evaluation of arene ruthenium(II) N-heterocyclic carbene complexes as organometallics interacting with thiol and selenol containing biomolecules
Luciano Oehninger, Maria Stefanopoulou, Hamed Alborzinia, Julia Schur, Stephanie Ludewig, Kazuhiko Namikawa, Alvaro Muñoz-Castro, Reinhard W. Köster, Knut Baumann, Stefan Wölfl, William S. Sheldrick and Ingo Ott

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Homo- and heterogeneous photocatalytic water reduction

A highly stable polypyridyl-based cobalt catalyst for homo- and heterogeneous photocatalytic water reductionWith TONs up to 9000 H2/Co this Hot Communication by Peter Hamm and Roger Alberto et al. is worth a read.

The team have developed a stable, water reducing catalyst which operates under acidic conditions and indicates poly-pyridyl ligand frameworks are superior to some of the other commonly used chelators. They also show the cobalt complex retains catalytic activity when resin bound, meaning it is active as both a homogeneous and heterogeneous catalyst. For full details download the article below.

A highly stable polypyridyl-based cobalt catalyst for homo- and heterogeneous photocatalytic water reduction
Miguel Guttentag, Alexander Rodenberg, Cyril Bachmann, Anna Senn, Peter Hamm and Roger Alberto
Dalton Trans., 2012, Advance Article

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

International Symposium on Organometallic Chemistry (ISOMC) 2012

The seventh International Symposium on Organometallic Chemistry (ISOMC 2012) was held at Seoul National University in Korea between 1st and 3rd November, attended by Dalton Transactions Editorial Board Chairman, Professor Philip Mountford and New Journal of Chemistry associate editor Professor Peter Junk.  Eighteen stimulating lectures were given by a range of established and emerging scientists from academia and industry, representing  seven different countries. The poster prize was sponsored by Dalton Transactions and was awarded to Keishi Yamamoto from Professor Kazushi Mashima’s laboratory at Osaka University, Japan. The title of the poster was “Synthesis and structures of iminopyrrolyl and amidopyrrolyl complexes of Group 2 metals”. 

 

  

 Philip Mountford and Keishi Yamamoto

 Delegates at the International Symposium on Organometallic Chemistry (ISOMC 2012) 

 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)