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Borromean chainmail in Nature Chemistry

6 May 2015

A team of researchers in Leeds have discovered a new coordination material which shows a unique chemical topology.

Dr Flora Thorp-Greenwood, a postdoctoral researcher in Prof Michaele Hardie’s research group, synthesised a new crystalline material from CuBr2 and a pyramidal shaped organic bridging ligand where the crystal structure revealed formation of Cu6L6 metallacycles in a chair-like conformation. The metallacycles form an unprecedented 2D network where each metallacycles forms multiple Borromean ring associations. A Borromean ring is a construct of three cyclic rings where there are no chain-like links between the rings yet the three rings are entangled and cannot be separated without breaking one of them. Chemists have synthesised Borromean rings before but what is different about this material is that each ring is involved in six Borromean ring associations and a 2D network of rings is formed giving an overall chainmail array.

Examples of individual chemical rings that associate into chainmail arrays are highly unusual and this Borromean-like example is the first of its kind, and illustrates that there still much to be discovered about the topology of chemical assemblies. The crystals themselves grow in hollow tubular shapes which Flora investigated with Dr Alex Kulak using SEM.

This work is reported as an advance article this week in Nature Chemistry in the article F. L. Thorp-Greenwood, A. N. Kulak and M. J. Hardie, “An infinite chainmail of M6L6 metallacycles featuring multiple Borromean links”: doi:10.1038/nchem.2259




Leeds cancer researchers in marathon effort

28 April 2015

Seasoned runner Colin Fishwick completed the 2015 Virgin Money London Marathon on Sunday, 26 April, in support of Cancer Research UK, together with two colleagues from Leeds involved in cancer research

Colin is Professor of Medicinal Chemistry and heads up a research group in the School of Chemistry who are trying to discover new medicines to treat a range of diseases, including cancer.  

Colin explained: “We design and make new molecules that we predict may have the correct properties to be a future medicine.  We then work with our clinical and biological colleagues to put our molecules through their paces to see if they work and hopefully they will go on to become new, highly effective and non-toxic, treatments for cancer patients”

He has already completed three other marathons, but Colin has a personal reason to run his first Virgin Money London Marathon for Cancer Research UK.  “I lost my mum Joyce to breast cancer in 2013 and just a few months later my father-in-law Jack to stomach cancer. 

“Through my research work I understand the important aspects of what cancer is, but the recent deaths of people close to me has underlined the terrible loss that we, as well as many others, face on a daily basis because of cancer – and the continuing need to win the fight against this terrible disease.

“By raising money through taking part in the Virgin Money London Marathon, all three of us want to help the charity ensure more people are treated successfully.”  

You can still sponsor Colin at www.justgiving.com/Colin-Fishwick1

A field of over 40,000 competitors, including serious and fun runners, took part in the 2015 Virgin Money London Marathon.

As part of its special year of running, Cancer Research UK has invited people of all ages and abilities to ‘go the distance’ by taking on a running challenge and raising vital funds to accelerate life-saving research.




Catalyst mystery: disappearing chlorides.

24 March 2015

A collaborative team of iPRD chemists and beamline scientists at the European Synchrotron Radiation Facility, led by Dr Bao Nguyen, have reported in J. Am. Chem. Soc. a study using synchrotron-base spectroscopic techniques to study the deactivation of a robust immobilised Cp*Ir catalyst for transfer hydrogenation (developed by Yorkshire Process Technology).

The technique takes advantage of the brilliant light source provided by the synchrotron to study electronic and bonding environment around the element of interest. In contrast to the common practice of focusing on the metal centre, the team employed a holistic approach to investigate the bonding environment around Ir, Cl and K during catalytic turnover.

The slow loss of catalytic activity over time was associated with the loss of chloride ligands from the iridium catalyst. In situ monitoring of the catalyst over time led to the discovery of a concurrent increase in potassium content, which happened as the chloride ligands were replaced with alkoxides to generate a less active Cp*Ir-trialkoxide complex.

Appropriate reactivation strategies have consequently been developed based on these findings to regenerate the catalyst to its original reactivity.




Environmentally Friendly Materials Synthesis

23 March 2015

Andy Wilson's group have developed a new method for the synthesis of supramolecular polyurethanes.

A major objective in modern materials science is to develop methods of synthesis that minimize environmental impact. Polyurethanes are popular construction materials and find use in everyday life e.g. as adhesives, coatings and in footwear products. One means to achieve improved synthesis is to avoid the use of organic solvents or preferably the use of any solvent at all during synthesis, however this is challenging to achieve for covalent polymers.

PhD researchers Kelly Houton and George Burslem focused on supramolecular polyurethanes; supramolecular polymers have received enormous attention over the last 15 years as they can be assembled from small easy to synthesise molecules and exhibit stimuli-responsive properties and such small-molecules are more amenable to solvent free synthesis. The team first exploiting ball-milling to develop a solvent free method for synthesis of ureas and urethanes and then applied this to a supramolecular polyurethane, which gave comparable materials properties to those obtained using a solution based synthetic method. The work was reported in Chemical Science and can be read at: http://pubs.rsc.org/en/content/articlelanding/2015/sc/c4sc03804e#divAbstract




Informational Oligomers

19 March 2015

A collaborative team from the Astbury Centre for Structural Molecular Biology led by Prof Andy Wilson have identified a series of “foldamers” that exhibit all the hallmarks required of an informational oligomer.

A major challenge in contemporary science is to design and synthesize molecules with architectural complexity and function comparable to that of protein secondary and tertiary structures; such studies ultimately aim to probe whether or not the proteinogenic code for 3D structure and recognition is limited to polymers of -amino acids. Synthetic foldamers can be defined as oligomeric or polymeric molecules that adopt specific compact conformations. The team which included academics Julie Fisher,  Thomas Edwards, Stuart Warriner and Andy Wilson pursued a different approach to this challenge: rather than trying to design secondary and tertiary structures from the “bottom-up” they focused on developing short oligomers capable of recognizing protein-surfaces in a specific and selective manner.
The work published in Chemical Science (http://pubs.rsc.org/en/Content/ArticleLanding/2015/SC/C4SC03559C#divAbstract) identified oligomers that could mimic the secondary structure of an alpha-helix and selectively recognise the protein hDM2. More significantly, the work demonstrated that the composition, spatial projection and stereochemistry of functional groups appended to the oligomers impacted upon molecular recognition allowing the selective recognition of  hDM2 versus Mcl-1 (an alternative helix binding protein) to be controlled.  




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