Archive for the ‘Hot Articles’ Category

A new class of molecular propellers

Scientist based in Italy have recently demonstrated a new class of molecular propellers based upon polyoxometalates (POMs).

POMs consist of a cluster of transition metal oxides that are water soluble and are used for a wide range of applications. In particular, Andrea Sartorel and Marcella Bonchio, from the Univerity of Padova, are interested in their use as photosynthetic oxygen-evolving catalysts. The team studied a series of POMs with different metal centres and their catalytic performance in the disproportionation of hydrogen peroxide (H2O2) to water and oxygen.

They found that of all the POMS studied, Ru4(SiW10)2 performed the best in terms of oxygen evolution. This production of oxygen could then be used to create movement of the POM;  in effect using H2O2as fuel to create oxygen that then propels the POM material in aqueous solution. A video of this can be seen here. This represents a step towards the use of light-driven molecular machines based on POMs.

If you are interested in finding out more, then why not download Sartorel and Bonchio’s ChemComm article for free today? Also, don’t forget to leave a comment below!

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Intramolecular cycloaddition leads to the pentacyclic core of cortistatins

Synthesising intriguing bioactive natural products in the most expedient and atom-efficient manner remains a highly active and competitive field of research. Cortistatins A and J, first isolated from the marine sponge Corticium simplex in 2006, have been identified as effective anti-angiogenics, which studies have found could suppress cancer recurrence when given in conjunction with traditional cancer drugs.

Lok Lok Liu and Pauline Chiu at the University of Hong Kong have reported a concise, high yielding, asymmetric synthesis of the pentacyclic framework of the cortistatins, in 12 steps from commercially available starting materials. Their synthesis employs a highly diastereoselective intramolecular [4+3] cycloaddition of epoxy enolsilanes as the key step and brings them close to their ultimate goal.

To find out more, download the ChemComm communication for free up until March 28th

To start a discussion, leave your comments below and for a related blog post see the Totally Synthetic blog pages.

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Confining supramolecular soft materials

Confining soft materials in a small space has a dramatic effect on the formation of fibre networks and their resulting properties. 

 
 

Optical micrographs of the gels studied

Xiang Yang Liu and collaborators showed that the formation of fibre networks under volume confinement is independent of temperature and solute concentration. They need to do more studies to understand the mechanism but say that their work should help scientists design new soft functional materials on a micro-/nanometre scale.

Fancy delving some more into the results reported? Then why not download the communication* today and leave some comments on the blog below. Perhaps you have a question for the authors, or you could tell us what you found interesting about these results.

 *This communication will be free to access until the 25th March 2011.

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Nanoflowers for protein immobilisation and separation

It is the quest of many a materials scientist to form core-shell nanostructures by self-assembly, in order to generate materials with unique structures and functions. In this area, hierarchical nanoarchitectures assembled from nanoscale units have recently stimulated tremendous interest because these superstructures might avoid aggregation and maintain high specific surface areas. In addition, magnetic materials have received considerable interest,  due to their ability to selectively capture target objects from complex mixtures.

Ken Cham-Fai Leung and colleagues – based in Hong Kong and Hefei, China – have reported a facile synthesis of monodispersed microparticles composed of superparamagnetic Fe3O4 cores, a SiO2 shell and a hierarchical g-AlOOH periphery with Au nanoparticles, obtaining nanoflower structures resembling daisies. As proof of principle for their use as selective protein capturing agents, these nanoflowers were applied as absorbents to successfully remove bovine serum albumin from bovine blood.

To find out more download the ChemComm communication, which is free to access until 15th March 2011.

Start a discussion about this research by leaving comments below.

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Congratulations to Jean-François Nierengarten

Jean-François NierengartenWhat’s special about Gene delivery with polycationic fullerene hexakis-adducts?

Well, that’s the topic of Jean-François Nierengarten’s recent ChemComm communication, rated as ‘hot’ by the referees and free to access* until 15th March. It is also his 25th independent research article in ChemComm.

To celebrate this achievement, Professor Nierengarten has taken some time out from his research to speak to ChemComm about his career.

What inspired you to become a scientist?
As far as I remember, I was always fascinated by natural sciences and wildlife. I started to study biology at the University of Strasbourg (Université Louis Pasteur at that time) with the idea of becoming a zoologist to discover unknown animals in the Amazon rainforest or in other wild places in the world. On the way, I discovered chemistry thanks to a couple of outstanding teachers and definitively switched from biology to chemistry after I met Jean-Pierre Sauvage at the end of my first year of Master. Fortunately, after my Master, I had the chance to prepare my PhD under the guidance of Jean-Pierre, and thus to become a chemist.

What was your motivation behind the work described in your ChemComm article?
The work described in this paper is a part of our research program on the use of click chemistry for the post-functionalisation of fullerene hexa-adducts (Chem. Commun. 2008, 2450; 2010, 46, 3860 and 4160; 2011, 47, 1321). The initial driving force for this work was to apply the synthetic methodology developed in the group to the preparation of new molecules with specific properties. As very often happens, applications with our compounds rely on collaborations with colleagues having the appropriate expertise. Indeed, Jean-Serge Remy, a well-established scientist in the field of transfection and synthetic vectors, is a very good friend and discussing about science one Friday evening in a pub brought us to the idea of testing fullerene hexa-adducts as synthetic vectors. We thus prepared a series of hexa-substituted fullerene derivatives decorated with dendritic branches bearing peripheral ammonium groups. Jean-Serge and his co-workers could then show that polyplexes prepared from DNA and these globular polycationic fullerene derivatives exhibit remarkable gene delivery capabilities. This result was quite unexpected as a generally admitted rule for the design of gene delivery vectors is that compact globular polycations with an isotropic distribution of positive charges are not suitable candidates for such studies. The results reported in our ChemComm article show that this is indeed not the case.

Why did you choose ChemComm to publish your work?
For fast publication of our important findings, ChemComm is an obvious choice. Over the years, it has been always a pleasure to work with the RSC Journals in general and with ChemComm in particular. All the steps from the submission to the publication are very efficient and all is organized in a very professional way. Publishing our work in ChemComm is also the guarantee for high visibility. Finally, I am a supporter of European journals in general and strongly believe that the best of European chemistry should be reported in European journals. Having top quality journals in Europe is essential to give credit to the European chemical community.

Where do you see your research heading next?
In addition to their remarkable gene delivery capabilities, the fullerene hexa-adduct derivatives have also revealed a very low toxicity if any. The fullerene hexa-adduct core is therefore a particularly appealing 3D-scaffold for the development of new multifunctional bioactive molecules. Based on the versatile fullerene hexa-adduct building blocks already developed in our group (Chem. Commun. 2010, 46, 4160), the successive grafting of up to three different groups on the fullerene core can be efficiently achieved. We are currently working on a new generation of vectors bearing targeting subunits for specific gene delivery to selected cells and/or fluorescent probes to monitor their intracellular pathway by confocal microscopy.

What do enjoy doing in your spare time?
Spending time with Iwona, my wife, and our two kids, cooking, listening to music, travelling. I like also reading and playing the guitar but have less and less time for it!

What would you be if you weren’t a scientist?
Hopefully as happy as I am to be a scientist! I guess that it could be the case if I would be an ébéniste [cabinet maker]. During my childhood, I had a lot of fun making stuff from wood in the workshop of my godfather, a very talented ébéniste particularly gifted for marquetry. I could spend hours watching him applying pieces of veneer to form decorative patterns or pictures onto the commodes or the tables he was restoring.

Also of interest:
Less is more – multiscale modelling of self-assembling multivalency and its impact on DNA binding and gene delivery
Paola Posocco, Sabrina Pricl, Simon Jones, Anna Barnard and David K. Smith
Chem. Sci., 2010, 1, 393-404

*Access our free content any time, any place – register for an RSC Publishing personal account today

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Sleeping Trojan horse to transport metal ions into cancer cells

UK researchers have used a cage-like molecule to smuggle metal ions into cells, which could improve medical imaging.

Medical imaging often requires getting unnatural materials such as metal ions into cells. Scientists have therefore had to come up with ways to disguise these compounds to get them past the cell membranes. Michael Coogan and colleagues at Cardiff University have come up with a way to avoid the current difficulties with some of these imaging treatments.

Graphical abstract: A ‘Sleeping Trojan Horse’ which transports metal ions into cells, localises in nucleoli, and has potential for bimodal fluorescence/PET imaging

Find out their solution by reading the news story in Chemistry World and downloading Coogan’s ChemComm communication.

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Paper spray ionisation of polar analytes using non-polar solvents

US analytical scientists have used non-polar solvents for the paper spray ionisation of polar compounds.

Polar compounds are normally ionised in mass spectrometry using a desorption ionisation method, such as MALDI, or from solution in a polar solvent using electrospray ionisation (ESI). However, ESI does not usually tolerate non-polar solvents and, as many reactions or purifications of compounds occur in non-polar solvents, this can present some difficulties.

Graham Cooks and co-workers from Purdue University have extended the scope of the recently developed paper spray ionisation technique to allow the use of non-polar solvents. When a low voltage is exposed to a triangle of paper wetted with a solvent such as hexane or toluene, droplets of that solvent are produced.  Polar compounds that are deposited on the paper are transported by the non-polar solvent compounds despite being sparingly soluble in them.

This technique can be applied to biological compounds, such as nucleotides, phospholipids and peptides, and avoids a typical problem associated with ESI where there capillary may clog when a non-ideal solvent is used. Furthermore, compounds may be analysed simply by ionising spots separated via TLC.

If you want to find out more then download the ChemComm article today. For wider look at analytical chemistry, why not check out these papers in our sister journal Chemical Science?

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Hot article round up for January

January can seem like an extra long month for many, with post-holiday blues and dark wintery evenings to contend with. However, the winter solstice has past, so the evenings are gradually getting lighter and here at the ChemComm Editorial Office we have published enough hot articles to keep the blues at bay. So why not take a look at the selection of hot articles below, which caught some of our referees attention…

  • Clostridium botulinum produces the most lethal toxins known to man and, as such, they are high-risk terrorist threats. Alarmingly, there is no approved therapeutic. Why not read Kim Janda‘s communication to find out about a small molecule he’s discovered that inhibits the neurotoxin.                                   
  • Matthias Beller and Anahit Pews-Davtyan synthesised a variety of substituted imidazoles from commercially available starting materials, via a hydroamination–cyclization sequence. Take a look at the communication to see the excellent yields obtained, helped by the presence of catalytic zinc triflate.
  • Enhanced white-light emission was achieved by cleverly loading green- and red-light-emitting donor–acceptor pairs in the separate micellar cores, and inserting blue-light-emitting polymers around their periphery. To find out more on how this system works, take a look at Juan Peng‘s communication.
  • Juyoung Yoon and her colleagues from Ewha Womans University, have developed a unique pyrene-based colourimetric sensor that changes colour, from light yellow to pink, in the presence of lysine. More details can be found in the communication.
  • An observation reported by Gerhard Erker in ChemComm has opened up a new way of utilising frustrated Lewis pair chemistry. To see what has been uncovered in more detail, download their communication today!
  • Andreas Herrmann and co-workers have made ultra-high molecular weight DNA/polymer hybrid materials using molecular biology techniques. Take a look at the communication and read more about this fascinating advance.
  • Molly Stevens and her colleagues have shown that peptide-modified gold nanoparticles can be enzymatically phosphorylated and rapidly aggregated onto a surface or in solution by action of phosphospecific antibodies. The simple and rapid colorimetric response of the assays makes them an attractive approach for drug-screening applications – so why not download the communication to find out more about this exciting research?
  • QM/MM mechanistic modelling has been used to help understand the role of carbamate reactivity in fatty acid amide hydrolase inhibition, as reported in Adrian Mulholland‘s latest communication in ChemComm.
  • Paul O’Brien reports slow temperature growth of crystalline PbS films on plastic substrates by Chemical Vapour Deposition using xanthate. Why not read the communication for further details on the method, as well as looking at the mechanism proposed by the team, with the help of density functional theory calculations.
  • Jeremy Sanders and Ulrich Lüning present the efficient synthesis of a new type of a multi-hydrazone based macrocyclic receptor and investigates its complexation properties with alkali and alkaline earth metal ions using a dynamic combinatorial approach. Read more by downloading the communication today!

All communications have been made freely available until the 7th March 2011, so why not download the ones that interest you today and let us know what you think in our blog below.

If you have some of your own exciting, high impact research to publish then consider submitting your communication to ChemComm, via our online submission system.

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Negishi cross-coupling using a bulky Pd-NHC catalyst

The hugely important field of transition metal catalysed C–C cross-coupling has come a long way over the years, but efficient coupling between Csp2 and secondary Csp3 centres remains a challenge. To achieve just that, Michael Organ and his colleague Selcuk Calimsiz (York University, Toronto) have developed and used a bulky Pd-NHC (N-heterocyclic carbene) catalyst called Pd-PEPPSI-IPent.

In the reactions of secondary alkylzincs with a variety aryl or heteroaryl halides, this catalyst provided excellent regioselectivity for the branched product over the isomerised unbranched product, far outperforming the less bulky Pd-PEPPSI-IPr analogue.

To see the impressive scope of the reaction download the ChemComm communication for free up until 7th March 2011 and leave your comments below.

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Novel chemical tag illuminates protein cholesterylation in cells

UK chemists have for the first time used a chemical probe to study the post- translational cholesterylation of proteins in living cells.

Post-translational modification (PTM) in cells plays an important role in the function of proteins in vivo. One example is the mammalian Hedgehog (Hh) protein family: the post-translational cholesterylation of Sonic hedgehog (shh) protein regulates its secretion. However, mis-regulation of this protein can promote different types of cancers. Therefore a simple way of studying this type of modification is important.

Graphical abstract: Bioorthogonal chemical tagging of protein cholesterylation in living cells

Edward Tate and colleagues at Imperial College, London have done just this. They first modified cholesterol molecules to bear an azide group and then gave this to their target cells, where it was used in PTM. They next managed to attach, via ‘click’ chemistry, a dye molecule called TAMRA to the modified proteins that carried the synthetic cholesterol. The team used this dye for ‘fluorescence visualisation’ of the target protein.

When compared to traditional techniques for studying cholesterylated proteins, this new method stacks up well. It makes significant savings in both time and expense, as well as avoiding the use of potentially harmful radiation. Furthermore, Tate suspects that in the future an optimised version of this process might be used to search for new cholesterylated proteins.

Want to find out more? Then download the ChemComm article for free today. You can also check out coverage of this article in C&EN.

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