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Challenging the consensus on nanotube electrochemistry

08 Jun 2012

Field emission-scanning electron microscopy image of a single walled carbon nanotube forest

UK scientists have shown that the sidewalls and closed ends of carbon nanotubes can support fast electron transfer, challenging the belief that they are electrochemically inert.

Carbon nanotubes (CNTs) have wide ranging electrochemical applications for sensing and energy. Forests of vertically aligned CNTs have been proposed for use as electrodes, but it was thought that the inert sidewalls would have to be insulated and the ends opened to allow electron transfer.

Scientists from the University of Warwick have now challenged this position by showing that the sidewalls and closed ends of CNTs can support fast electron transfer.

See the full article in Chemistry World

Link to journal article
Electrochemistry at carbon nanotube forests: sidewalls and closed ends allow fast electron transfer
Thomas S. Miller, Neil Ebejer, Aleix G. Güell, Julie V. Macpherson and Patrick R. Unwin
Chem. Commun., 2012, Advance Article, DOI: 10.1039/C2CC32890A, Communication

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Personal glucose sensors can be adapted to detect cancer too

06 Jun 2012

Personal glucose sensors (PGS) can be used to detect cancer, say Chinese scientists.

The team loaded magnetic beads with invertase (an enzyme that catalyses the hydrolysis of sucrose to glucose) and an antibody. The beads acted as a label for a lung cancer biomarker that had been captured on an antibody-coated ELISA plate. By monitoring the production of glucose from sucrose with a PGS, they could indirectly measure the amount of the biomarker down to the sub-nanogram per millilitre level.

Link to journal article
Personal glucose sensor for point-of-care early cancer diagnosis
Jiao Su, Jin Xu, Ying Chen, Yun Xiang, Ruo Yuan and Yaqin Cha
Chem. Commun., 2012, Accepted Manuscript, DOI: 10.1039/C2CC32729E

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Electronic skin for health and security checks

01 Jun 2012

The tattoo incorporates a sensor that could be used to detect environmental hazards

Scientists in the US have developed an electrochemical sensor incorporated into a temporary transfer tattoo (T3) to be used as a device to warn the wearer of any health or security threats. Not only is the sensor non-invasive, it can also be concealed in an inconspicuous tattoo design, without compromising its resolution or performance.

Joseph Wang and his colleagues from the University of California, San Diego, have combined their expertise in printing flexible chemical sensors with commercially-available temporary tattoo paper. Integrating the electrochemical sensor within T3 maximises its contact with skin, including all epidermal irregularities, thanks to the elasticity of the T3 material. In addition to this, the team dispersed carbon fibre (CF) segments into the tattoo ink, providing an interlinked conductive backbone that enhances the sensor’s electrochemical behaviour. The CF constituents also help to counteract cracking and provide the mechanical reinforcement needed to protect the sensor against routine wear-and-tear while on the skin. The team also showed that the T3 sensor (on pig skin) could be used for detecting explosives like 2,4,6-trinitrotoluene (TNT), in connection with square wave voltammetry.

Read the full article in Chemistry World

Link to journal article
Electrochemical Sensing Based on Printable Temporary Transfer Tattoos
Joseph Wang
Chem. Commun., 2012, Accepted Manuscript, DOI: 10.1039/C2CC32839A, Communication

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Exhaust emissions caught in a trap

01 Jun 2012

The trap captures and retains light hydrocarbons for longer than current traps

A trap that adsorbs exhaust emission gases given off during the first two minutes after firing up an internal combustion engine has been developed by scientists in Spain. It’s during this cold start period that 50–80% of the total hydrocarbon emissions are produced, they say, so the trap could minimise levels of harmful exhaust gases pumped into the atmosphere.

Current traps are made from porous zeolites. They work well for the heavy hydrocarbons in fuel, which are retained until the engine’s temperature reaches 200–300oC (the light-off temperature), at which point, they are released and oxidised to carbon dioxide and water in a catalytic converter before being expelled into the atmosphere. But lighter hydrocarbons, such as ethane and propene, desorb from the trap before this temperature is reached and escape, unoxidised.

Read the full article in Chemistry World

Link to journal article
Molecular simulation design of a multisite solid for the abatement of cold start emissions
B. Puértolas, M. Navlani-García, J. M. López, T. García, R. Murillo, A. M. Mastral, M. V. Navarro, D. Lozano-Castelló, A. Bueno-López and D. Cazorla-Amorós
Chem. Commun., 2012, Advance Article, DOI: 10.1039/C2CC30688C, Communication

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Easy synthesis of nanocups and nanopatches

29 May 2012

Graphical abstract: Facile synthesis of functional Au nanopatches and nanocups A gold nanocup – it sounds like something a posh fairy might drink out of. But actually, metal nanocups are promising particles for sensing and nanoelectronics thanks to their plasmon coupling and light scattering properties. Until now, they have been difficult to make but Jinlong Gong at Tianjin University, China, Zhihong Nie, at the University of Maryland, USA, and colleagues have developed a new easy route suitable for large scale synthesis.

The team used a template-free, liquid-liquid interfacial reaction to build up the gold cups round polymer particles. These so called ‘patchy particles’ are themselves attractive as building blocks for nanostructures due to the directional interactions between the metal patches. Removing the polymers using organic solvent revealed the nanocups with diameters as small as 76 nm. The team demonstrated that the cups can enhance surface enhanced Raman scattering intensity up to the order of 10⁸.

Find out more – download Gong’s ChemComm communication

Want to learn more about surface enhanced Raman spectroscopy? Check out the ChemComm web theme >

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A Celebration of Organic Chemistry

28 May 2012

On Friday 15 June, Professor Keith Smith will host a symposium showcasing the very best in Organic Chemistry.

The symposium features lectures by two Nobel Laureates and an RSC Prize Winner, as well as marking Keith’s retirement from Cardiff University, and celebrating his work within the Organic Chemistry Community.

This event is free to attend but places are limited, and attendance is only guaranteed by pre-registration – so act now!

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Chiral Control for the Future?

24 May 2012

Tragedies such as the thalidomide scandal led to a re-think as to how pharmaceutical drugs are tested and examined before their sale to the public. Prior to this, racemic mixtures were often administered yet sometimes only one enantiomer of the compound gave the therapeutic properties while the other caused serious side effects. For this reason, huge interest developed in controlling reactions so that only enantiomer would be formed – not a trivial task for the many millions of molecules tumbling around in a round bottom flask! Such is the significance of this problem that the 2001 Nobel Prize for Chemistry was awarded to Sharpless, Noyori and Knowles for work in this field.

: Figure 1: Preparation of chiral-at-copper complexes

Many of the methods to obtain this selectivity focus on controlling the orientation of the molecule by building a bulky pocket around the reaction site. Doing so means a reaction can only occur on one side and, as a result, only one enantiomer is created. While this technique has been shown to work well, an alternative approach is to create a reaction site which itself can control the orientation of the molecule. It is exactly this that Paul Newman, Kingsley Cavell and Benson Kariuki at Cardiff University have achieved.

The idea behind the concept is that the reaction site itself is a more efficient way of transferring the control of the chirality. To do this they have created a ‘chiral-at-metal’ Cu(I) complex (Figure 1) which is itself very rare due to the instability of these types of compounds. The characterisation of such an exciting complex is certainly worthy of rapid communication but I hope to see further papers on this work in the near future, giving us an insight into how well this complex performs as a catalyst and how effective it is at transferring chirality. Over time, the catalyst will surely undergo many subtle alterations to improve its performance but only time will tell if this is truly going to be the most effective method of controlling chirality.

Keen to read more? Download this ChemComm article here.

Posted on behalf of Ruaraidh McIntosh, Chemical Communications web writer.

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REMINDER: ChemComm-RSC Prizes and Awards Symposium in Oxford on Wednesday

21 May 2012

Don’t miss out on Wednesday’s ChemComm–RSC Prizes & Awards Symposium jointly organised with the RSC Dalton Division!

Date: Wednesday 23rd May 2012
Location: Inorganic Chemistry Laboratory lecture theatre, South Parks Road, University of Oxford, UK
Time: 11am – 6.45 pm

The purpose of this event is to bring together scientists in a stimulating and friendly environment to recognise the achievements of individuals in advancing the chemical sciences and also to foster collaborations. The symposium will appeal to academic and industrial scientists with an interest in inorganic and supramolecular chemistry. Attendance at the symposium is FREE OF CHARGE and student participation is strongly encouraged.

The following distinguished scientists have agreed to speak:

Professor Manfred Scheer, University of Regensburg, Germany (ChemComm sponsored speaker) – Polyphosphorus Ligands in Supramolecular Chemistry
Professor Kay Severin, EPFL, Switzerland (ChemComm sponsored speaker) – Multicomponent Assembly of Molecular and Polymeric Nanostructures
Professor Andrew Cooper, University of Liverpool, UK (ChemComm sponsored speaker) – Porous Organic Cages: MOFs Minus the Metals?
Professor Lawrence Que, University of Minnesota, USA (Inorganic Mechanisms Award 2011 Winner) – C-H Bond Cleavage by High-Valent Non-haem Iron-Oxo Complexes
Professor Russell Morris, University of St Andrews, UK (Applied Inorganic Chemistry Award 2011 Winner) – Adsorption, storage and delivery of medically important gases in porous solids
Dr Jonathan Nitschke, University of Cambridge, UK (Corday-Morgan Prize 2011 Winner ) – Designing complexity and function within self-assembled chemical systems

To register for the symposium, please complete the online registration form.

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Nanoscopic electrochemical cells probe forests

16 May 2012

3D carbon nanotube forests are of particular interest in the electrochemical arenas of sensing and energy applications. Some researchers have suggested that it is necessary to use open-ended carbon nanotubes and carry out a pre-treatment or activation step to support fast electrochemistry, but is this always the case?

Patrick Unwin and co-workers set out to investigate. They prepared carbon nanotube forests using a chemical vapour deposition growth method. To probe the local electrochemical response of the forests, they used a nanoscopic double barrelled pipette tip, filled with supporting electrolyte and redox species. This allowed the team to interrogate the sidewalls and closed ends of the nanotubes that made up the forest with high spatial resolution.

Both sidewalls and the closed tube ends were capable of fast electron transfer proving that single walled carbon nanotubes do not require open ends for fast electrochemistry with outer sphere redox couples. This overturns the current consensus, based on averaged macro-sized measurements, that open ends dominate nanotube forest electrochemistry.

Without the requirement for pre-treatment or activation, electrochemical nanotube forest applications will be easier to achieve.

To find out more, download the ChemComm article today.

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Chiral confusion

15 May 2012

Scientists in Israel have shown that non-biological chiral crystals are much more abundant than previously thought and their findings could clear up a possible confusion over the term ‘chiral’.

‘Chiral’ describes an object whose mirror image cannot be superimposed, for example human hands are chiral. Chirality is important to understand and recognise, as the production of a chiral molecule can lead to both mirror images – or enantiomers – being produced, and these often have very different chemical properties. Chiral crystals selective for one enantiomer that could be used for separation or as catalysts are therefore highly sought.

Read the full article in Chemistry World

Link to journal article
On the abundance of chiral crystals
Chaim Dryzun and David Avnir
Chem. Commun., 2012, Advance Article, DOI: 10.1039/C2CC17727G

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