News

The @BonLab at the University of Warwick has devised a new powerful and very versatile way of controlling the speed and direction of motion of microscopic structures in water using what they have dubbed chemically ‘motorised microscopic matchsticks’.

Before now most research seeking to influence the direction of motion of microscopic components have had to use outside influences such as a magnetic field or the application of light. The University of Warwick team have now found a way to do it by simply adding a chemical in a specific spot and then watching the microscopic matchstick particles move towards it, a phenomenon known as chemotaxis.

The research published in the journal Materials Horizons (RSC) in a paper entitled Chemotaxis of catalytic silica–manganese oxide “matchstick” particles found that by adding a small amount of a catalyst to the head of a set microscopic rods, they could then cause the rods to be propelled towards the location of an appropriate ‘chemical fuel’ that was then added to a mixture.

For the purposes of this experiment the researchers placed silica–manganese oxide ‘heads’ on the matchstick material and introduced hydrogen peroxide as the chemical fuel in one particular place.

They placed the ‘matchsticks’ in a mixture alongside ordinary polymer microspheres.

When the hydrogen peroxide was added the microspheres continued to move in the direction of convection currents or under Brownian motion but the matchsticks were clearly rapidly propelled towards the chemical gradient where the hydrogen peroxide could be found.

The reaction was so strong that more than half of the matchstick particles did not reverse their orientation once over their 90 seconds of travel towards the hydrogen peroxide – even though they were contending with significant convection and Brownian rotation.

University of Warwick research chemical engineer Dr Stefan Bon who led the research said:

“We choose high aspect ratio rod-like particles as they are a favourable geometry for chemotactic swimmers, as seen for example in nature in the shapes of certain motile organisms”

“We placed the ‘engine’ that drives the self-propulsion as a matchstick head on the rods because having the engine in the ‘head’ of the rod helps us align the rod along the direction of travel, would also show the asymmetry perpendicular to the direction of self-propulsion, and at the same time it maintains rotational symmetry parallel to the plane of motion.

“Our approach is very versatile and should allow for future fabrication of micro-components of added complexity.

“The ability to direct motion of these colloidal structures can form a platform for advances in supracolloidal science, the self-assembly of small objects.

“It may even provide some insight into how rod shapes were selected for self-propelled microscopic shapes in the natural world.”

Notes for editors:

 Dr Stefan Bon can be contacted on S.Bon@warwick.ac.ukor +44 (0)2476 574009 or + 44 (0)7736932205

Or you can contact Anna Blackaby, University of Warwick press officer, on +44 (0)2476 575910 or +44 (0) 7785 433155 ora.blackaby@warwick.ac.uk

 The research has just been published in the journal “Materials Horizons” in a paper entitled Chemotaxis of catalytic silica–manganese oxide “matchstick” particles DOI: 10.1039/c3mh00003f

The authors wish to thank Peter W. Dunne, David Burnett, and Luke A. Rochford for help with XRD analysis. We thank EPSRC, Chemistry Innovation, and AkzoNobel for funding (ARM). Some of the equipment used was funded by West Midlands AM2 Science City initiative.

Optically pure heterobimetallic helicates from self-assembly and click strategies (or how to control chirality at linked metal centres)

The Royal Society has announced the appointment of 22 new Royal Society Wolfson Research Merit Award holders including Professor Greg Challis of the Department of Chemistry.

Congratulations to the winner of the "Chemistry In Action" Art & Photography Competition, David Withall (PhD student in Challis group), for his entry "Chemically Synthesised Undecylprodigiosin".

David will receive a £50 Amazon Voucher from the Head of Department and Chair of the Welfare & Communications Committee, plus the artwork will soon be displayed prominently in the Department.

Thank you to all those who entered the competition, the final decision was very diffcult for the judging panel as there were so many interesting entries and the standard was very high. Well done David!

Visit http://www2.warwick.ac.uk/fac/sci/chemistry/chemintra/communications/art_competition/ for further details.

In collaboration with the groups of Neil Wilson and Gavin Bell in Physics at Warwick and groups at the synchrotrons of ELETTRA in Trieste and SOLEIL in Paris, the Costantini group has published a Rapid Research Letter in the journal Physica Status Solidi on the natural doping of graphene grown on copper foil by chemical vapour deposition (CVD).

Using nano-spot angle-resolved photoemission spectroscopy (ARPES) it has been shown that graphene grown on copper foil is undoped with an ideal gapless band structure, even after air exposure. Up to 200 °C annealing, the band structure is that of pristine undoped graphene but, upon annealing to 500 °C, the formation of a band gap is observed together with evidence of doping.

The work contributes to recent discussion on the electronic properties of technologically relevant graphene grown on low-cost copper foil. In the long-term, commercialisation of graphene will require economical techniques for its fabrication on a large scale. Therefore, its growth under low-pressure conditions on low-cost polycrystalline Cu foils represents a strong step towards a number of graphene applications.

Further details can be read at http://onlinelibrary.wiley.com/doi/10.1002/pssr.201307224/abstract

Congratulations to all our graduands, who are receiving their degrees today.

All staff, colleagues and friends from the Department look forward to this occasion and the opportunity to celebrate your achievements with you and your guests on such a memorable day.

We wish you well and many congratulations on your success!

For theory to make proper contact with experiment, we must average over a large number of geometrical configurations. For big metalloproteins like Type I copper plastocyanin and cucumber basic protein, generating the structures is too expensive for quantum chemistry. In contrast, the empirical ligand field molecular mechanics model invented by the Deeth group at Warwick can quickly generate the geometries required. Based on our structures, Nick Besley's group in Nottingham excise the active sites and use them to compute using high level QM methods the absorption and CD spectra. Agreement with experiment is impressive. See the ACS Journal of Physical Chemistry B: 10.1021/jp404107j

The 11^th International Conference on Materials Chemistry (MC11) is being hosted by the Department of Chemistry this week (8-11^th July). Monday 8^th July saw the visit of two Nobel Laureates in Chemistry. Professor Dan Shechtman, Technion, Israel Institute of Technology (Nobel Prize 2011) and Professor Sir Harry Kroto FRS, Florida State University, (Nobel Prize 1996) each gave a lecture to an audience of over 500 delegates from around the world.

An inter-university collaboration between the Costantini, Jones, Bonifazi (Namur) and de Vita (King’s College) groups showed the role of deprotonation on the two dimensional assembly of novel borazine compounds on a copper substrate. The results are published in Angewandte Chemie International Edition.

Chemistry hires three new Professors in the areas of Sustainable Chemistry and Polymers as part of the Monash-Warwick Strategic Research Alliance.

Adam Lee, Sebastien Perrier and Tom Davis are all joining the Department over the coming months.

The full details can be found at:-

http://www2.warwick.ac.uk/newsandevents/pressreleases/first_joint_professors/

Ken Lewtas, Chief Scientist at Infineum and visiting professor in the Department of Chemistry has been awarded the RSC Creativity in Industry Prize 2013 for "his skill in applying fundamental polymer science to industrially relevant systems, and transforming the results into profitable products."