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Color switching in lanthanoid based hybrid materials

12 Apr 2013

Research interest in hydrid inorganic–organic materials is being driven by their application light sources and optical displays. Lanthaniod elements are attractive as light emitters because of the purity of colours that can be produced and also by combining different lanthanoid elements, they can emit white light. However in lanthanoid elements, f–f transitions need to be activated by a bound ligand.

Mark I. Ogden, Massimiliano Massi and their research teams have found a way of solving the issue of phase segragation in lanthanoid based metallo polymers. When phase separation occurs, the metal complex separates from the organic portion which can affect the emission properties. To overcome this, they copolymerized methyl methacrycalate with a calixarene (basket shaped cyclic oligomer) and then introduced a lanthanoid ion to produce luminescent hybrid materials.

The materials can be changed by loading different combinations of lanthanoid ions which produces different colour emissions – as well as emitting white light.

To find out more, read the full Dalton Transactions article:

Recyclable calix[4]arene–lanthanoid luminescent hybrid materials with color-tuning and color-switching properties
Brendan W. Ennis, Sara Muzzioli, Brodie L. Reid, Daniel M. D’Alessio, Stefano Stagni, David H. Brown, Mark I. Ogden and Massimiliano Massi
Dalton Transactions, DOI: 10.1039/C3DT33059A

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New Grants Available For RSC Members!

04 Apr 2013

The RSC’s Divisions are keen to support their members with their careers and their scientific activities. To this end, we have launched two new grants which allow our members to apply for funding from their Divisions for various purposes.

If you are organising an activity, such as a small “no frills” meeting or a young researcher meeting, and you need funds, the Small Grants for Scientific Activities may be able to help, with grants of up to £2000. Our Divisions have already supported a number of people with their activities, such as Prof. Michael Glazer’s exhibition, entitled “The Two Braggs”, celebrating the centenary of the seminal work on X-ray diffraction by the eponymous father and son team.

In addition, the Small Grants are also available to support early career researchers (more than 5 years post PhD) with travel to conferences they are participating in. For full details, please visit the website at: http://rsc.li/small-grants.

We all know how important it is for young PhD students and post-doctoral researchers to participate in conferences and workshops. So, we’re very pleased to announce our new Travel Grants for PhD Students and Post-doctoral Researchers (within 5 years of completion of PhD). You can apply to your Division for up to £800 for travel to any conference or workshop anywhere in the world that will benefit you or your career. More information can be found at http://rsc.li/ecr-travel.

Both grants are available now. Application is easy; in each case, we ask that you read the terms & conditions and fill out a simple application form.

The spirit of these grants is to provide quick, flexible and transparent sources of funding for our members. You should typically receive a response from your Division within two or three months for the Small Grants and Travel Grants, respectively.

We look forward to receiving your applications.

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Green Suzuki–Miyaura coupling of heteroaryl chlorides

01 Mar 2013

N-heterocyclic carbenes are neutral σ donors and electron rich, making them attractive for use as ligands in transition metal catalysts. By changing the nature of the azole ring (nitrogen heterocycle containing at least one other atom of S, N or O) and the substituents, the electronic and steric properties can be modified.

X-Ray structure of a 6-membered N-heterocylic carbene complex of palladium

Studies of expanded NHCs containing a 6- or 7-membered ring have only recently started to appear in the literature. This includes that of Nechaev and colleagues who have synthesized a series of new 6- and 7-membered NHC palladium complexes. Kolychev and Nechaev screened the complexes as catalysts for Suzuki-Miyaura cross-coupling of heteroaryl chlorides and bromides. They tested the catalysts using ‘green‘ reaction conditions and showed that reaction products are clean with no homo coupling products formed.

These systems are very attractive – it will be exciting to see how expanded ring NHCs are utilized more in the future…

Download the full Dalton Transactions paper to find out more:

Expanded Ring Diaminocarbene Palladium Complexes: Synthesis, Structure, and Suzuki–Miyaura Cross-Coupling of Heteroaryl Chlorides in Water
Eugene Kolychev and Mikhail Nechaev
Dalton Trans., 2013, DOI: 10.1039/C3DT32860K

You may also be interested in this article:
Expanded ring N-heterocyclic carbenes: A comparative study of ring size in palladium (0) catalysed Mizoroki–Heck coupling

Jay J. Dunsford and Kingsley J. Cavell

Dalton Trans., 2011, 40, 9131-9135

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Crystal structure of a face-sharing fluoroaluminate anion

30 Jan 2013

Fluorides of aluminium are used in the aluminium industry and also as catalysts for ozone friendly alternatives to chlorofluorocarbons (CFC’s). Previously, crystal structures of some fluoroaluminate anions have been solved by the introduction of either organic or metal cations. But until now, the crystal structure of a particular fluoroaluminate anion, the bioctahedral Al₂F₉^3- anion had not been reported.

The crystal structure of this anion has recently been solved by Rika Hagiwara and colleagues at Kyoto University. They first synthesized the compound, [C₁₈MIm][AlF₄] (1-methyl-3-octadecylimidazolium tetrafluoroaluminate) and discovered that slow evaporation of the chloroform solution gave transluscent crystals of [C₁₈MIm]₃[Al₂F₉](CH₂Cl₂)_n. It is thought that this species was formed by the reaction below:

3[C₁₈MIm][AlF₄] + nCH₂Cl₂ → [C₁₈MIm]₃[Al₂F₉](CH₂Cl₂)_n + AlF₃

The Al₂F₉^3-anion has two octahedral AlF₆ units which are face-sharing and has D_3h symmetry.

To find out more, read the full Dalton Transactions article:

The first crystallographic example of a face-sharing fluoroaluminate anion Al₂F₉³⁻
Fei Xu, Kazuhiko Matsumoto and Rika Hagiwara

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IUPAC Provisional Recommendations on Metal-Organic Framework and Coordination Polymer Terminology

08 Jan 2013

The IUPAC task group: Coordination polymers and metal organic frameworks: terminology and nomenclature guidelines have published provisional recommendations. The article can be accessed directly here and any comments can be directed to the task group chair, Professor Lars Öhrström.

The task group was set-up in 2009 to document, analyse and evaluate the use of nomenclature and terminology in the areas of coordination polymers and metal-organic frameworks. As well as meeting on three occasions the group also published a Highlight article detailing the need for terminology guidelines and the provisional recommendations, which include the following definitions:

Term	Definition
Coordination Polymer	A coordination compound continuously extending in 1, 2 or 3 dimensions through coordination bonds
Coordination Network	A coordination compound extending, through coordination bonds, in 1 dimension, but with cross-links between two or more individual chains, loops or spiro-links, or a coordination compound extending through coordination bonds in 2 or 3 dimensions
Metal-Organic Framework	Metal-Organic Framework, abbreviated to MOF, is a Coordination Polymer (or alternatively Coordination Network) with an open framework containing potential voids

There are also recommendations on net and network topology, topology descriptors, nomenclature and the use of other terms (which explicitly discourages the term “hybrid organic-inorganic materials”)

Download the full article for the complete recommendations and take a look at the Highlight article published last year

Coordination polymers, metal–organic frameworks and the need for terminology guidelines
Stuart R. Batten, Neil R. Champness, Xiao-Ming Chen, Javier Garcia-Martinez, Susumu Kitagawa, Lars Öhrström, Michael O’Keeffe, Myunghyun Paik Suh and Jan Reedijk
CrystEngComm, 2012, 14, 3001-3004
DOI: 10.1039/C2CE06488J

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Phosphinimine-borane frustrated Lewis pairs

21 Dec 2012

The current issue of Dalton Transactions is a themed issue on boranes and borohydrides, of which one of the cover articles by Chunfang Jiang and Douglas W. Stephan explores phosphinimine-boranes in frustrated Lewis pair chemistry. Frustrated Lewis pairs are entities that consist of a Lewis acid and a Lewis base which, because of sterics, do not form an adduct. These systems are very reactive and are able to activate H₂, CO₂, and olefins amongst others without the need for a transition metal catalyst.

In this article, a series of phosphinimines (species contanining a phosphorous-nitrogen double bond) were combined with B(C₆F₅)₃ and in one case a Lewis acid-base adduct was formed. The reactivity of the adduct was compared to the other cases where frustrated Lewis pairs were generated. Remarkably, the researchers discovered that both the adduct and the frustrated Lewis pairs were able to activate H₂, CO₂ and phenylacetylene.

This work paves the way for discovering even more acid base combinations that could be used in frustrated Lewis pair systems for catalysis without the need for transition metals.

To find out more, read the full Dalton Transactions article:

Phosphinimine–borane combinations in frustrated Lewis pair chemistry
Chunfang Jiang and Douglas W. Stephan
Dalton Trans., 2013, 42, 630-637

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Divergent Activation Chemistry of Carbon Oxides at Uranium(III)

17 Dec 2012

Developing facile and economical technologies for utilizing CO and CO₂ as C1 building blocks remains a lucrative challenge, and this area has recently enjoyed a surge in interest and development. The current paradigm for activating these abundant carbon oxides invokes reduction of the strong C-O multiple bonds, typically facilitated by low-valent transition-metal and f-element complexes, to yield oligomerized ([CO_x]ⁿ^– )units or (CO)-incorporated organic materials.

Polly Arnold and co-workers have recently demonstrated that the discreet U(III) tris-amide complex [U(N(SiMe₃)₂)₃] is indeed a versatile reducing agent for such carbon oxide activation chemistry, cleanly reacting with CO to yield a stable ynediolate ([OCCO]^2-) adduct which features a newly formed C-C bond.

Reporting in Dalton Transactions, Arnold and co-workers now describe a modified U(III) platform which incorporates a hemi-labile, bidentate alkoxy-tethered NHC ligand, and divergent activation of carbon oxides at U(III). This report serves to underscore the potency of ligand design as an instrument for encouraging novel and unusual chemical transformations, in addition to describing a variety of new complexes incorporating activated carbon oxides.

Check out the full article to read more about these divergent carbon oxide activation pathways.

Carbon monoxide and carbon dioxide insertion chemistry of f-block N-heterocyclic carbene complexes
Polly L. Arnold, Zöe R. Turner, Anne I. Germeroth, Ian J. Casely, Gary S. Nichol, Ronan Bellabarba and Robert P. Tooze

Dalton Trans., 2013, Advance Article
DOI: 10.1039/C2DT31698F

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Hybrid nanotubes for high performance Li ion batteries

26 Nov 2012

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

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Dalton Transactions Blog

Archive for the ‘News’ Category

Top ten most accessed articles in February

Color switching in lanthanoid based hybrid materials

New Grants Available For RSC Members!

Top ten most accessed articles in January

Green Suzuki–Miyaura coupling of heteroaryl chlorides

Crystal structure of a face-sharing fluoroaluminate anion

IUPAC Provisional Recommendations on Metal-Organic Framework and Coordination Polymer Terminology

Phosphinimine-borane frustrated Lewis pairs

Divergent Activation Chemistry of Carbon Oxides at Uranium(III)

Hybrid nanotubes for high performance Li ion batteries

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