News

Costantini and collaborators have reported in a special themed issue of Chemical Communications about a novel chemical pathway observed only in the presence of a metal substrate. In solution chemistry, assuming no kinetic limitations, the thermodynamic product is formed independently of the absolute reactant concentration. However, inclusion of a metallic substrate introduces a further variable which ultimately defines the chemistry observed. In their recent work, terephthalic acid was deposited onto a Cu(110) substrate, where, at low surface coverages, 2-dimensional metal-organic structures form. However, with increasing coverage, the interaction between molecule and metal induces the formation of a denser, less energetically-favoured hydrogen-bonded network.

The article can be read here.

New magnetic materials have been created from simple components by Lihong Li, a Warwick Postgraduate Research Fellow and co-workers in the Scott group at Warwick University. The resarchers have engineered magnetic diamond-like 3D networks and layered 2D net structures. A rare example of a molecular hard magnet (which like a regular magnet keeps its magnetic properties over time) is produced. The chemistry is simple, reliable and scalable so the group hope to make many new materials in the future for applications in data storage, and quantum computing. The work is published in Chemical Communications.

Gibson and O'Reilly groups have published a manuscript in Chemical Communications which demonstrate the critical importance of nanoparticle diameter on its thermo-responsive behaviour, as demonstrated using a panel of gold and self-assembled polymer nanoparticles. These findings have implications for the rationale design of 'smart' nanomaterials for biotechnological applications.

Read the article here.

The BonLab reports on the fabrication of “soft” nanocomposite clay armored polymer latexes with their latest work published in the ACS journal Macromolecules.

Laponite clay XLS is used as stabilizer in the Pickering emulsion polymerization of a variety of monomer mixtures, that is, methyl methacrylate and n-butyl acrylate, styrene and n-butyl acrylate, and styrene and 2-ethylhexyl acrylate. Overall solids contents of the hybrid latexes in complete absence of coagulation of up to 24 wt % are reported under batch conditions. Key mechanistic aspects of the Pickering emulsion polymerization process are discussed. The use of monomers that have high water solubility and are prone to hydrolyze under basic conditions, for example methyl methacrylate, should be restricted. The use of small amounts of methacrylic acid as auxiliary monomer promotes clay adhesion to the surface of the particles in the Pickering emulsion (co)polymerization of hydrophobic monomers. Detailed kinetic studies at both 60 and 80 °C of the Pickering emulsion copolymerization of styrene and n-butyl acrylate (Sty:BA = 0.67 w/w) are reported, with varying amounts of Pickering stabilizer. The Laponite clay discs play a crucial role in the particle formation (nucleation) stage of the Pickering emulsion polymerization process. Use of increasing amounts leads to smaller average particle sizes but inflicts longer nucleation periods, thereby broadening the particle size distributions. We report the occurrence of a catastrophic coagulation phenomenon for Pickering emulsion polymerizations carried out at a low initiator (ammonium persulfate) flux at 60 °C, for a small window of concentrations of Laponite clay discs.

Read the paper: http://dx.doi.org/10.1021/ma201691u

More info on the BonLab: http://www.bonlab.info

Costantini and collaborators report on the importance of metallic atoms in Si surface alloys for their use as effective substrates for 2D supramolecular self-assembly.
Scanning tunnelling microscopy is used to compare the assembly properties of terephthalic acid on two Bi-Si surface alloys with different metallic surface density. Results published in Surface Science show that, besides the absence of semiconductor dangling bonds, also a high density of Bi surface atoms is essential to smoothen the energy landscape experienced by adsorbed molecules and therefore promote their diffusion and assembly. More at http://www.sciencedirect.com/science/article/pii/S0039602811003177

Walton’s group, in collaboration with colleagues in the Department of Physics and at Johnson Matthey plc have a paper published this week in the RSC journal Chemical Science: this describes mild synthetic chemical routes to complex extended structures that contain the metal iridium in various oxidation states. This illustrates the scope for the discovery of new functional materials by exploration of novel reaction conditions and using the chemistry of lesser studied elements.

http://pubs.rsc.org/en/content/articlelanding/2011/sc/c1sc00192b/

Cisplatin is the most widely used anti-cancer drug, and the side-effects of cisplatin chemotherapy are largely due to side reactions of cisplatin with other molecules in the body, chiefly proteins. In a joint publication between the O'Connor group and the Sadler group, it's reported that the anticancer drug, cisplatin, can act as a protein crosslinker which is of use in the field of proteomics. Cisplatin has novel features as a protein crosslinker: 1) it's charged, so it improves the sensitivity of any modified peptides over non-reacted peptides, 2) it targets methionine and histidine primarily, which are residues that are not targetted by traditional crosslinkers, 3) it has an unusual isotopic pattern compared to typical peptides or peptide crosslinkers, which can be used as a signature to flag those peptides which are modified with platinum, 4) it has a fixed arm-length of about 4.5 Angstroms, but has the potential for addition of other chemical moities to extend the arm-length. This observation allows new kinds of proteomics that focuses on those proteins which are modified by cisplatin directly - thus potentially profiling all molecules which are directly responsible for the deleterious side-effects in chemotherapy. This paper has just been published in Analytical Chemistry: http://pubs.acs.org/doi/abs/10.1021/ac200861k

The group of prof. Challis together with their collaborators feature on the cover of Chemistry & Biology.

Through screening of Burkholderia cepaciacomplex bacteria, Mahenthiralingam et al. (pp. 665–677) identified one species (Burkholderia ambifaria) that produces potent polyketide antibiotics called enacyloxins, using an unusual hybrid, cis-AT/trans-AT polyketide synthase. The findings suggest that Burkholderiabacteria are a promising resource for the discovery of new antibiotics, with unusual production pathways and potent activity against drug-resistant bacteria. The cover shows a TLC plate on which Burkholderiaculture extracts were fractionated, illustrating the diversity of antimicrobial secondary metabolites. After overlaying this plate with agar seeded with the yeast Candida albicans, secondary metabolites with antimicrobial activity are revealed by the zones of clearing. Classical plate inhibition assays with Burkholderiastrains demonstrating antagonistic activity against a range of bacteria and fungi as well as the structure of enacyloxin IIa are also shown

To read the paper: http://dx.doi.org/10.1016/j.chembiol.2011.01.020

Researchers funded by the Biotechnology and Biological Sciences Research Council (BBSRC)-led Integrated Biorefining Research and Technology (IBTI) Club have identified an enzyme in bacteria which could be used to make biofuel production more efficient. The research is published in the 14 June issue of the American Chemical Society journal Biochemistry.

This research, carried out by teams at the Universities of Warwick and British Columbia, could make sustainable sources of biofuels, such as woody plants and the inedible parts of crops, more economically viable.

The researchers, who were also supported by the Engineering and Physical Sciences Research Council, have discovered an enzyme which is important in breaking down lignin, one of the components of the woody parts of plants. Lignin is important in making plants sturdy and rigid but, because it is difficult to break down, it makes extracting the energy-rich sugars used to produce bioethanol more difficult. Fast-growing woody plants and the inedible by-products of crops could both be valuable sources of biofuels but it is difficult to extract enough sugar from them for the process to be economically viable. Using an enzyme to break down lignin would allow more fuel to be produced from the same amount of plant mass.

The researchers identified the gene for breaking down lignin in a soil-living bacterium called Rhodococcus jostii. Although such enzymes have been found before in fungi, this is the first time that they have been identified in bacteria. The bacterium's genome has already been sequenced which means that it could be modified more easily to produce large amounts of the required enzyme. In addition, bacteria are quick and easy to grow, so this research raises the prospect of producing enzymes which can break down lignin on an industrial scale.

Professor Timothy Bugg, from the University of Warwick, who led the team, said "For biofuels to be a sustainable alternative to fossil fuels we need to extract the maximum possible energy available from plants. By raising the exciting possibility of being able to produce lignin-degrading enzymes from bacteria on an industrial scale this research could help unlock currently unattainable sources of biofuels.

"By making woody plants and the inedible by-products of crops economically viable the eventual hope is to be able to produce biofuels that don't compete with food production."

The team at Warwick have been collaborating with colleagues in Canada at the University of British Columbia who have been working to unravel the structure of the enzyme. They hope next to find similar enzymes in bacteria which live in very hot environments such as near volcanic vents. Enzymes in these bacteria have evolved to work best at high temperatures meaning they are ideally suited to be used in industrial processes.

Duncan Eggar, BBSRC Sustainable Bioenergy Champion, said: "Burning wood has long been a significant source of energy. Using modern bioscience we can use woody plants in more sophisticated ways to fuel our vehicles and to produce materials and industrial chemicals. This must all be done both ethically and sustainably. Work like this which develops conversion processes and improves efficiencies is vital."

ENDS

Notes to editors
This paper is available online here: http://pubs.acs.org/doi/abs/10.1021/bi101892z

Magnetic interactions between metal atoms in a family of chiral materials respond to subtle changes in their organic chemistry. The work forms part of the PhD research by Lihong Li in the Scott group in Warwick Chemistry department. Read the article at Inorg. Chem. 2011

Organic solar cells have potential as a low cost, easily producible renewable energy source. One of the key parameters determining the overall efficiency of the cells, the open-circuit voltage (VOC) generated, is critically dependent on the choice of active materials. Specifically, in a typical device where the current generation occurs at a hetero-interface between an electron donating material and an electron accepting material, the energy offset between the donor material's highest occupied molecular orbital (HOMO) and the acceptor material's lowest occupied molecular orbital (LUMO) dictates the magnitude of the generated VOC. Whilst an abundance of donor materials are known and reported, acceptor materials are typically limited to fullerene derivatives (especially C60) whose relatively low-lying LUMO energies limit the obtainable VOC. In the recent edition of "Advanced Energy Materials" (Vol. 1, Issue 3), the cover article by the Jones, Shipman and Hatton groups, along with collaborators at the University of Birmingham, reports a new synthetic design route to produce light harvesting electron acceptor materials which allow for high open-circuit voltages and power conversion efficiencies. By selective halogenation of the periphery of the organic framework of the traditional donor material boron subphthalocyanine chloride (SubPc), the HOMO and LUMO levels can be tuned such that the material can be used as an acceptor material in conjunction with an unsubstituted SubPc as the donor material. Optimisation of the number and type of halogen substituents such that efficient current generation takes place at the interface whilst maximising the interfacial energy offset results in a SubPc / Cl6-SubPc device which gives an exceptionally high VOC of over 1.3V and power conversion efficiencies approaching 3%. Further, as the unstable fullerene acceptor has been replaced by a subphthalocyanine derivative, a significant improvement in device stability is seen which is important for future commercialisation.

Front Cover (Design by Paul Sullivan): http://dx.doi.org/10.1002/aenm.201190011

Article: http://dx.doi.org/10.1002/aenm.201100036

Professor Patrick Unwin, Department of Chemistry has been made a Fellow of the International Society of Electrochemistry (ISE). This award comes in recognition of the outstanding contributions Professor Unwin has made to the field of electrochemistry throughout his career.

Professor Unwin leads the Warwick Electrochemistry and Interfaces Group, who are known for developing innovative methods for functional imaging of surfaces and interfaces. They are currently in the process of developing a whole suite of new nanoscale electrochemical imaging methods with support from the European Research Council.

Professor Unwin said:

"I have been fortunate to have many good colleagues and fantastic students and postdocs in my 20 years at Warwick. They are great fun to work with and have contributed significantly to me winning this award."

About ISE
ISE is a large non-profit-making organisation set up to promote work done in the field of electrochemistry and provide an international community for those involved. It has around 2,300 members based in more than 60 countries worldwide.