Author Archive

Trapping cisplatin in a metallocage

The anticancer drug cisplatin has revolutionised cancer chemotherapy. Its ability to effectively treat a wide range of cancers has made this drug a popular therapeutic choice but the side effects can be severe, including possible damage to the kidneys and nervous system. Researchers have been trying to avoid these side effects by designing systems to deliver the cisplatin to the target area, where it can be released to selectively destroy the cancer tissue.

Promising delivery vehicles for platinum-based drugs include liposomes, polymers and dendrimers, organic macrocycles, nanoparticles, viruses and carbon nanotubes. Now, James Crowley’s group at the University of Otago, New Zealand, have reported the first example of cisplatin inclusion in a metallosupramolecular cage.

Two cisplatin molecules are bound within the cage and can be released on demand by introducing Cl or 4-dimethylaminopyridine (DMAP). These ligands compete for binding with the cage PdII centres and induce dissociation of the cage structure. If the cage is deconstructed using Cl, it can be reassembled by adding Ag+ ions, which precipitate the Cl out of the system and allow the cage to re-form. This is particularly impressive since there are few reported examples of stimulus-induced cage assembly and disassembly. This controllable uptake and release of a drug molecule shows that similar systems may have real application for drug delivery in the future.

Researcher’s perspective: 
We had been working on this system for a while and had some solution phase evidence that our cage was encapsulating cisplatin, but it was so exciting and satisfying the day we finally got the X-ray crystal structure to prove it irrevocably. To literally see it right there in front of us, vindicating our results, was a great feeling. In research we quite often have to deal with failures and so it’s always rewarding to get a result like that to keep us motivated.

Jamie Lewis, a researcher in the Crowley group

To find out more about Crowley’s metallosupramolecular cage, read the full article.

Posted on behalf of Cally Haynes, Chemical Science web writer.

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RSC Macrocyclic and Supramolecular Chemistry Meeting

The RSC Macrocylic and Supramolecular Chemistry meeting (MASC-11) is taking place on the 19th and 20th December 2011 at the University of Bath, UK.

A number of high profile authors will be speaking at the meeting including Chem Soc Rev Associate Editor, Professor Phil Gale, and Professor Kay Severin who is giving the Chemical Science sponsored lecture. To find out more about Professor Severin’s research, download his latest Chemical Science articles:

Dr Jonathan Nitschke will be delivering the Dalton Transactions lecture as a result of being awarded the 2011 Dalton Transactions European/African Lectureship earlier on this year. Jonathan has also recently been awarded the ChemComm 2012 Cram Lehn Pedersen award.

Read more about Jonathan’s research by downloading his Chemical Science articles: 

ChemComm, Chemical Science and Chem Soc Rev Deputy Editor, Joanne Thomson, will be attending the event. If you would like to arrange a meeting with Joanne, please email her at the Editorial Office.

To attend MASC-11, register before the 12th December 2011. The deadline for poster abstract submissions is 1st December.

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The lightest rotaxane

Rotaxanes are dumbbell-shaped molecules that are threaded through a separate macrocylic molecule. The two molecules are not chemically bonded to one another but instead are mechanically interlocked – a feature that can be exploited for molecular switches in molecular electronics, actuators and controlled drug release.

In a quest to understand the spatial requirements of these molecules, Suvankar Dasgupta and Jishan Wu from the National University of Singapore have discovered the lightest rotaxane to date. The rotaxanes in question were composed of a dibenzylammonium ion which was threaded through crown ether molecules of various sizes. As a result of their investigations, Dasgupta and Wu found that a [20]crown ether was capable of encompassing the dibenzylammonium dumbbell.

To find out more about this research, download the Chemical Science article today.

Also of interest…

Visit the ChemComm Supramolecular web theme issue for lots more on Rotaxane structures.

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AzkoNobel UK Science Award

Nominations are now open for the AzkoNobel UK Science Award. This biennial award will be presented to an individual in recognition of outstanding scientific contributions in the fields of chemistry and materials sciences. The winner of the award will be gifted £50,000.

The AkzoNobel awards have run since 1970, beginning in the Netherlands, and are being expanded to include China, the UK and the US.  Recent winners include Professor Jonas Frisén (Sweden 2011), Professor Bert Meijer (Netherlands 2010) and Professors Xi Zhang, Yanlin Song and Chunhua Yan (China 2010).

Nominators are asked to submit:

  •  a supporting statement addressing the selection criteria of no longer than one A4 side of 11pt text and
  • a one page CV for the candidate which should include their date of birth, website URL, summary of education and career, a list of 5 relevant recent publications and total numbers of publications and patents

Please note that candidates may not nominate themselves.

Visit the RSC award website to make a nomination and for details on the scientific scope. Closing date for nominations is 31st October 2011.

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Chemical Science wins prestigious ‘best new journal’ award

The Royal Society of Chemistry’s new flagship journal Chemical Science won ‘Best New Journal’  last night at a prestigious publishing awards ceremony.

The Association of Learned and Professional Society Publishers (ALPSP) praised Chemical Science for its relevance and quality.

“Launched to present high quality cutting edge research across the chemical sciences, it has achieved swift success. There are very close links with the community and the journal is clearly defined by the science and the user,” said ALPSP in the award citation on their website.

Dr Robert Eagling, Managing Editor of Chemical Science, said: “We are thrilled to receive this prestigious award against such tough competition. This is the culmination of over three years’ hard work by the team, and I thank them all for their efforts.
 
“I would also like to extend a special thanks to the Associate Editors and, in particular, the Editor-in-Chief, Professor David MacMillan, who have been instrumental in getting Chemical Science where it is today.”

Chemical Science publishes original research articles of exceptional significance from across the chemical sciences. The journal helps to define the important areas by publishing the most significant cutting-edge research. Submissions must appeal to the general chemical science community, or be of exceptional interest to specialist researchers.

Launched last year with a groundbreaking series of three conferences held in three continents over three sequential weeks – the ‘International Symposia on Advancing the Chemical Sciences’ (ISACS) – Chemical Science has already established itself as the home of truly excellent chemical science research. A further three international conferences were held earlier this year, in Boston, Manchester and Beijing, with planning for the 2012 events well underway.

James Milne receives the award from Hazel Woodward, chair of the judging panel and University Librarian and Director of Cranfield Press

Dr James Milne, RSC’s Acting Managing Director of publishing, said: “This award is worthy recognition of the incredible efforts of everyone involved in making Chemical Science the success it has so quickly become – our authors, reviewers and the journal’s dynamic editorial board.
 
“It is also great recognition for the exceptional service provided by the RSC’s dedicated editorial, production and marketing staff; providing authors and customers with the best experience possible whenever they interact with this new leading journal for the chemical sciences.”

The ALPSP Award for Best New Journal is open to any peer-reviewed journal launched in the last 1-3 years. The judges consider the main aspects of the journal including its launch: market research, editorial strategy, marketing and commercial success.

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1st Chemical Science Symposium

This month, Nanjing University, China hosted the 1st Chemical Science Symposium. Nine of the world’s leading scientists in organic materials and supramolecular chemistry presented their research over the course of the day. The morning was kick-started by Professor Colin Nuckolls, Associate Editor for Chemical Science, who spoke about his latest work on nanostructured carbon. Next to take the floor was Dr Scott Dalgarno who delivered his ChemComm Emerging Investigator award lecture on metal–organic calixarene assemblies. The day was rich with outstanding quality research and ranged from non-covalent supramolecular systems (Professor Bert Meijer) to artificial cellular organelles (Professor van Hest).

 

Chemical Science would like to say a big “thank you” to all of the speakers and local organisers, in particular Professors Wenbing Hu and Zijian Guo for all of their efforts.

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Tying knots in molecules

UK researchers have embarked upon a new method to create structurally diverse molecules for drug discovery.

Finding new lead compounds for drug discovery is a formidable challenge which has traditionally relied on natural product isolation and combinatorial chemistry. Despite significant investment in combinatorial chemistry, this approach has found very limited success due to a lack of chirality and structural rigidity in the compounds produced. To tackle this problem, chemists are using diversity orientated synthesis (DOS) which aims to produce compounds that are structurally diverse in shape and stereochemistry and also in functionality.

Robert Stockman from the University of Nottingham and his team have pioneered an approach that combines two-directional synthesis with tandem reactions as a tool for DOS. The starting material is a simple trifunctional, linear molecule that can be folded back on itself in a number of ways to produce a wide range of structures – like tying knots in a piece of rope.

12 products are synthesised from one molecule by combining two-directional synthesis and tandem reactions

The researchers were able to create twelve natural product-like structures from only one compound, in just fifteen reactions. Stockman and his team found that a number of compounds derived from one of the products were effective against cancer cell lines, proving that compounds synthesised by this approach are promising candidates for use in new medicines.

To find out more, watch Dr Stockman’s video and download the Chemical Science Edge article.

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Poking aspirin with a sharp stick

Scientists from India and Denmark have found a way to go one better than x-ray crystallography to examine pharmaceutical crystals at an even deeper level. Their method could be used to distinguish between polymorphs – different crystal forms – of a compound to aid in drug design. 

The team, led by Upadrasta Ramamurty and Gautam Desiraju from the Indian Institute of Science, Bangalore, and Andrew Bond from the University of Southern Denmark, have used nanoindentation to analyse two different polymorphs of aspirin. Polymorphs are crystals of the same compound but with a different molecular arrangement. Although two crystals may appear similar in structure, they can have dramatically different properties, and many drugs only receive regulatory approval for one form. ‘One of the current areas of research is trying to link crystal properties to crystal structure and to try to understand how polymorphism occurs,’ says Bond.

The nanoidentation technique involves depressing a nano-sized tip into the crystal. The researchers then measured the imprint left in the sample to determine the material’s mechanical properties, such as plasticity and elasticity (how easily a substance is deformed permanently and non-permanently, respectively).

The team discovered that two polymorph crystals of aspirin, which appeared to be pure by x-ray crystallography, in fact contained a mixture of the polymorph types. Nanoindentation could have an impact on the pharmaceutical industry, which currently relies on x-ray crystallography to establish whether or not a new drug has been made, for intellectual property rights.

Read the full story in Chemistry World and find out more by downloading the Chemical Science Edge article.

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Rapid route to huperzine A

US chemists have devised an efficient synthesis of a natural product with great potential as a protectant against chemical warfare agents and in the treatment of Alzheimer’s disease.

Huperzia serrata, one of an ancient lineage of plants known as the firmosses, has been much in demand lately because it contains a chemical known as (-)-huperzine A. This alkaloid is a potent and selective inhibitor of acetylcholine esterase, and as a result is able to counteract the action of certain chemical warfare agents, such as sarin and VX. There are also strong suggestions that it may slow the progression of neurological diseases such as Alzheimer’s disease. A team of organic chemists led by Seth Herzon at Yale University, New Haven, has now developed a high-yielding route to this elusive natural product, opening up opportunities for its wider clinical evaluation.

‘The primary obstacle to the clinical development of (-)-huperzine A has been one of supply,’ says Herzon. He points out that the average yield from the dried herb is just 0.011 per cent, a problem compounded by the nearly 20 years it takes to reach maturity, coupled with its increasing scarcity due to overharvesting in its native China.  To address these problems, several groups have in the past devised syntheses of (-)-huperzine A, with the best to date employing 16 steps and giving an overall yield of about 2.8 per cent. Herzon and his team have now beaten this by a factor of 16, with an eight-step synthesis that gives 25-45 per cent overall yield.

Read the full story in Chemistry World and download Herzon’s Chemical Science Edge article.

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Waterproof solar cells

A team of researchers led by Takashi Nakanishi from the National Institute for Materials Science in Japan have made a nanocarbon hybrid of a C60 derivative and single-walled carbon nanotube (SWCNT) to be used in photovoltaic devices.  The high performance of the nanomaterial is the result of a combination of the optical and electronic properties of the SWCNTs with the electron-accepting property of C60.

Photoconductivity experiment using a field-effect transistor equipped with the carbon nanohybrid

The C60 is decorated with long alkyl chains which have an affinity for the SWCNT surface, avoiding the problems associated with covalent functionalisation when combining such materials. By incorporating C60 into the hybrid, the SWCNTs were soluble in organic solvents meaning classic wet processes can be used to fabricate the photovoltaic device.

The nanocarbon material also has the added benefit of being superhydrophobic, providing the device with waterproof properties.

 To find out more about this research, read the Chemical Science Edge article.

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