November 2010 – Chemical Communications Blog

Archive for November, 2010

A testament to undergraduates & women in science

25 Nov 2010

Great research can start anywhere including your own undergraduate laboratory, as recently demonstrated by scientists in the US.

Whilst running a teaching laboratory at the Texas Woman’s University, Manal Rawashdeh-Omary had senior undergraduate students attempting to reproduce literature findings published 10 years previously by Rasika Dias (from the University of Texas at Arlington) her collaborator. The students were asked to recreate a trinuclear silver pyrazolate complex, where one group of students obtained the expected non-luminescent dry product, whilst the other attained an unexpected green-luminescent product. Rather than simply dismissing the green product as experimental error, Rawashdeh-Omary directed her research group to investigate the reason for this ‘mistake’.

(From left to right): Samuel Kiplagat, Tiffany Vaughan, Manal Rawashdeh-Omary, Shylaja Dharanipathi & Jacqueline Washington

The group realised that the green-luminescent complex was actually reacting with benzene – a highly toxic chemical, known for its carcinogenic properties. By incorporating the complex into thin films, the sensor could detect minute amounts of benzene vapour (and other small organic vapours) with remarkable reversibility, selectivity, speed and sensitivity. This is an important development for environmental and health issues, as well as making advancements in fundamental chemical phenomena for donor-acceptor and acid-base chemistry.

It is refreshing to see high quality research coming from universities and departments actively supporting women in science. Texas Woman’s University is the largest university primarily for women in the USA, with over 90% of the undergraduate population being female. Omary explains that many of the staff and students are mothers, balancing their research and studies with family responsibilities. So it is inspiring to learn that top quality research can be produced from all levels of academia and this is a true testament to undergraduates, showing what hard work and dedication can achieve.

Fancy reading more about this on/off benzene sensor? Then why not download the article today, which has been published in ChemComm and will be free to access until the 24th December.

Written by Edward Morgan

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Versatile variation on the Fischer indole synthesis

24 Nov 2010

UK chemists have developed a new variation on a famous route to indoles that uses more readily available starting materials.

The Fischer reaction involves the functionalisation of an unactivated C-H position by way of a [3,3]-sigmatropic shift. It is simple and convenient – it couples a mono-functionalised arene with a readily available ketone or aldehyde – but is hindered by the lack of availability of aryl hydrazine starting materials.

Instead Christopher Moody and Martyn Inman at the University of Nottingham started from readily available haloarenes. They converted them into a wide range of indoles in just two steps by halogen-magnesium exchange, quenching with di-tert-butyl azodicarboxylate, then reacting with ketones under acidic conditions.

Graphical abstract: A two step route to indoles from haloarenes—a versatile variation on the Fischer indole synthesis

This new variation is simple and versatile, says Moody, making it a highly practical alternative modern protocol for making the fundamentally important indole ring system.

Download the article for free until 24th December and let us know what you think of this new route below.

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5th ChemComm International Symposium

23 Nov 2010

The 5th ChemComm International Symposium will take place in Japan and China in May 2011. The purpose of RSC journal symposia is to bring together scientists in a stimulating and friendly environment that will foster collaborations between the researchers and the universities involved in the meetings.

The symposium will feature three one-day meetings. Each one day meeting will feature a selection of lectures covering organic chemistry and catalysis given by some of the world’s leading international scientists. The first one-day meeting, will be held at Kyoto University, Japan, before the symposium moves to China for two further events. The second one-day meeting will be held in Lanzhou University with the final instalment taking place at Nankai University, Tianjin. The symposium is organised by Chemical Communications, the Royal Society of Chemistry and the local host organisations.

The symposium will appeal to academic and industrial scientists with an interest in organic chemistry and catalysis. Attendance at the symposium is free of charge and student participation is strongly encouraged.

For more information on the dates, venues and speakers please visit the symposium website.

ChemComm Editor Robert Eagling with his two Korean hosts from the 4th ChemComm symposia

ChemComm Editor Robert Eagling with his two Korean hosts from the 4th ChemComm symposium

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Controlled manipulation of cells using catalytic microbots

22 Nov 2010

Microjet engines called microbots that can transport cells within a fluid to any desired location have been developed by scientists in Germany.

Manipulating nanomachines to transport biological matter in the body has been a challenge until now. Samuel Sanchez, from the Institute for Integrative Nanosciences in Dresden, and colleagues have shown that by using a magnet it is possible to navigate a microbot towards a specific cell within the body, pick it up from point A and transport it to point B.

The group made machines made up of hollow tubular structures containing a thin layer of platinum on the inside. They found that the machines moved independently in a peroxide solution when controlled externally by a small magnet manipulated with a joystick. The microbots can be directed towards suspended cells in solution, where they pick them up and transport them to the desired location. They released the cells from the tube by rapidly turning the magnet.

Graphical abstract: Controlled manipulation of multiple=

Sanchez and his team hope that in the future their microbots could perform visionary tasks within the body. “I would like to see our microbots swimming inside the bodies of animals, delivering drugs to required locations, for example, in the vicinity of cancer cells or replacing diseased cells with healthy ones,” he says.

For more information download Sanchez’s communication, where you can find videos of the swimming microbots in the ESI.

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Large scale production of graphene

19 Nov 2010

Chinese chemists have prepared graphene via carbonisation of microwave-synthesised metal phthalocyanine, followed by a rapid cooling process. They controlled the thickness of the graphene by using different coolants.

Graphical abstract: Large-scale production of graphene by microwave synthesis and rapid cooling

Download their ChemComm communication, free to access until 24th December, to find out more.

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Major groove for anti-cancer drug

18 Nov 2010

A platinum(II)-based major groove binder was identified as a potent human topoisomerase IIα poison, showing anti-proliferation activities in human cancer cells.

Chi-Ming Che and colleagues from the University of Hong Kong were able to stabilise the covalent TopoIIα–DNA cleavage complex and induce cancer cell death with its high potency – apparently it’s significantly higher than a clinically used TopoIIα poison.

Fancy reading more? Then why not download the article today and blog some comments below. The communication, published in ChemComm will be free to access until the 24th December.

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Chemical synthesis on SU-8 particles

18 Nov 2010

Chemists in Denmark have developed a procedure for modifying the surface of SU-8 microparticles and then using it for quantitative multi-step organic synthesis.

SU-8 is a novolac-epoxy resin used in the field of microfabrication and micropatterning. Thomas Nielsen, at Technical University of Denmark, and colleagues demonstrated how common linkers can be attached to the support surface and effectively used for solid-supported synthesis.

Graphical abstract: Chemical synthesis on SU-8

They report transformations including reduction, oxidation, multi-step peptide synthesis and metal-catalysed cycloaddition and cross-coupling reactions in their ChemComm communication, free to download until 24th December.

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Temperature breakthrough for hydrogen storage

17 Nov 2010

A compound first made in 1923 releases hydrogen at a lower temperature than ammonia borane, one of the most studied materials for hydrogen storage.

Efficient hydrogen storage is an important step in developing a hydrogen economy. One way of storing hydrogen is in chemical compounds that reversibly release hydrogen when they are heated. Diammoniate of diborane (DADB, [(NH₃)₂BH₂]⁺[BH₄]^–) as a hydrogen-containing species has the potential to be a storage material, but the crystal structure of the compound that would give valuable information about its properties has not been resolved until now.

Using a combination of X-ray and neutron powder diffraction patterns, Mark Bowden and Tom Autrey at the Pacific Northwest National Laboratory, Richland, and the Los Alamos National Laboratory, and coworkers resolved the crystal structure. ‘DADB is an interesting compound because it contains a high weight fraction of hydrogen, one of the highest for a stable material at room temperature,’ says Bowden.

Diammoniate of diborane contains a high weight fraction of hydrogen, one of the highest for a stable material at room temperature

When Bowden and the team heated DADB, they found that it behaved in a similar way to ammonia borane, but DADB releases hydrogen at 85°C, whereas ammonia borane releases hydrogen at 110°C.

Hydrogen release at this temperature is very interesting since it is in this temperature range that a practical hydrogen storage system must operate, says Stewart Parker of the Rutherford Appleton Laboratory, Didcot, UK, but it is important to have better knowledge of the system’s reversibility.

Jon Counsell

Enjoy this story? Download the full article from ChemComm and add your comments below.

Also of interest: the ChemComm web themed issue on Hydrogen.

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Safer sunscreens

17 Nov 2010

Coating titania nanoparticles with carbon could result in a safer UV filter to be used in sunscreen, say Italian scientists.

Long-term exposure to UVA and UVB radiation from sunlight can cause wrinkles, damaged skin and, in some cases, skin cancer. Titania (TiO₂), one of the main components in sunscreens, can absorb and scatter UVA and UVB radiation. However, titania can also become reactive under UV rays and in contact with water, generating free radicals that cause skin damage.

Now, Ivana Fenoglio from the University of Torino and Stefano Livraghi from the Institute for Health and Consumer Protection, Ispra, and their teams have modified the surface of titania nanoparticles to decrease their reactivity under UV. The groups coated the nanoparticles with ethylene glycol and heated the resulting compound to 300ºC to carbonise it. They found that this reduced the nanoparticles’ oxidative power and consequently decreased free radical formation. ‘It was very surprising to find out that by using ethylene glycol as a precursor, the formation of free radicals is reduced. This differs from the results of other studies done with titania nanoparticles modified with carbon,’ says Fenoglio.

Long-term exposure to UV radiation from sunlight can cause wrinkles, damaged skin and, in some cases, skin cancer

‘To use titania particles for skin care, a delicate balance is needed to prevent formation of reactive oxygen species, which have been suspected to cause skin damage, without affecting the desirable optical properties,’ says Sefik Suzer, an expert in inorganic nanoparticles at Bilkent University in Ankara, Turkey. ‘This research will undoubtedly help in developing a new generation of cosmetic products as well as leading to formulation of new routes for special applications of titania.’

‘This research may be a starting point for setting up protocols to produce UV filters that may find applications in different fields including the cosmetics industry,’ says Fenoglio.

Lorena Tomas Laudo

Download the full ChemComm communication to find out more about this work.

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Decorating peptide-polymer nanotapes

16 Nov 2010

Peptide–polymer nanotapes can be decorated with diverse functionalities thanks to a versatile strategy developed by scientists in Germany.

Hans Börner, at the Max Planck Institute of Colloids and Interfaces in Potsdam, and colleagues modified self-assembled nanotapes of poly(ethylene oxide)–peptide conjugates by a simple amine–azide transfer to create azide-containing nanofibres. Using click chemistry, they then introduced different carboxyl-bearing entities to modulate the calcium binding properties of the nanotapes.

Graphical abstract: A modular approach towards functional decoration of peptide–polymer nanotapes

To find out more, download Börner’s communication, which is free to access until 9th December.

Also of interest: Anti-wrinkle creams aided by nanotapes

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