Chemical Science Blog

Helical poly(arginine) mimics with superior cell-penetrating and molecular transporting properties
Haoyu Tang, Lichen Yin, Kyung Hoon Kim and Jianjun Cheng
Chem. Sci., 2013, Advance Article
DOI: 10.1039/C3SC51328A, Edge Article

Free to access until 29th September 2013

Self-assembled light-driven photosynthetic-respiratory electron transport chain hybrid proton pump
David Hvasanov, Joshua R. Peterson and Pall Thordarson
Chem. Sci., 2013, Advance Article
DOI: 10.1039/C3SC51780B, Edge Article

Free to access until 29th September 2013

3D optical imaging of multiple SERS nanotags in cells
Sarah McAughtrie, Katherine Lau, Karen Faulds and Duncan Graham
Chem. Sci., 2013,4, 3566-3572
DOI: 10.1039/C3SC51437D, Edge Article

Free to access until 29th September 2013

Rotationally inelastic scattering of CD₃ and CH₃ with He: comparison of velocity map-imaging data with quantum scattering calculations
Ondřej Tkáč, Alan G. Sage, Stuart J. Greaves, Andrew J. Orr-Ewing, Paul J. Dagdigian, Qianli Ma and Millard H. Alexander
Chem. Sci., 2013, Advance Article
DOI: 10.1039/C3SC52002A, Edge Article

Free to access until 29th September 2013

One pathway, many compounds: heterologous expression of a fungal biosynthetic pathway reveals its intrinsic potential for diversity
Zahida Wasil, Khomaizon A. K. Pahirulzaman, Craig Butts, Thomas J. Simpson, Colin M. Lazarus and Russell J. Cox
Chem. Sci., 2013, Advance Article
DOI: 10.1039/C3SC51785C, Edge Article

Free to access until 29th September 2013

Interrogating the photogenerated Ir(IV) state of a water oxidation catalyst using ultrafast optical and X-ray absorption spectroscopy
Michael T. Vagnini, Michael W. Mara, Michael R. Harpham, Jier Huang, Megan L. Shelby, Lin X. Chen and Michael R. Wasielewski
Chem. Sci., 2013, Advance Article
DOI: 10.1039/C3SC51511G, Edge Article

Free to access until 29th September 2013

After seven years of work, a team of chemists based in four labs across the globe has successfully prepared a cocrystal previously believed to be unobtainable.

Cocrystals are crystalline materials composed of two or more molecules held together within the same crystal lattice. Cocrystallisation is significant in the pharmaceutical industry, where drug molecules are screened for cocrystal formation in order to improve their solubility, stability and bioavailability. This has the added advantage of increasing the number of crystal forms that can be considered for drug formulation while simultaneously maximising patent protection.

Despite a computational study suggesting a stable cocrystal should form between caffeine and benzoic acid, all previous attempts over the last 60 years have failed. ‘When a cocrystal doesn’t form, we like to understand why that is – patients could miss out on better medical treatment if we miss out on crystal forms,’ says Dejan-Krešimir Bučar at the University of Cambridge in the UK, who led the study. ‘We hypothesised that a kinetic barrier hindered cocrystal formation, so our idea was to add a molecular species similar to that found in the nucleus of the caffeine·benzoic acid cocrystal as a seed to facilitate crystallisation.

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Read the original journal article in Chemical Science:
The curious case of (caffeine)⋅(benzoic acid): How heteronuclear seeding allowed the formation of an elusive cocrystal
Dejan-Kresimir Bucar, Graeme Matthew Day, Ivan Halasz, Geoff G. Z. Zhang, John R. G. Sander, David G Reid, Leonard R. G. MacGillivray, M J Duer and William Jones  
Chem. Sci., 2013, Accepted Manuscript, DOI: 10.1039/C3SC51419F

Scientists from the US and South Korea have developed a probe that can detect the highly toxic chemical hydrazine in a variety of different environments, including living cells.

Hydrazine plays an important role in a number of industrial processes. It’s used in pesticides, in nuclear and conventional electric power plants to reduce corrosion, and as a gas-forming agent in air bags. It’s even found in rocket fuel.

Although contact with small amounts of hydrazine is unlikely to cause harm, long term exposure can damage the liver, kidneys and central nervous system. Hydrazine has also been classified by the US Environmental Protection Agency (EPA) as a probable carcinogen.

Accidental leakage of hydrazine into the environment is rare and as hydrazine breaks down rapidly in oxygen, finding high levels of hydrazine in the environment is unlikely. However, hydrazine exposure in the workplace can be a real danger for individuals who come into contact with it. This makes the development of hydrazine sensors an important area of research.

The probe reacts with hydrazine to make a five-membered ring, resulting in a fluorescent response and a visible colour change

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Read the original journal article in ChemComm:
Naphthalimide trifluoroacetyl acetonate: a hydrazine-selective chemodosimetric sensor
Min Hee Lee, Byungkwon Yoon, Jong Seung Kim and Jonathan L. Sessler  
Chem. Sci., 2013, Advance Article, DOI: 10.1039/C3SC51813B

The first example of stable and environmentally friendly foam that can be broken down by any one of three external stimuli has been developed by an international team of scientists.

From left to right: foam before and after an increase in temperature, UV irradiation and exposure to a magnetic field

Foams are commonly applied in the clean-up of chemical spills, where they are sprayed over large areas to prevent evaporation of volatile and harmful organic materials. While this demands stability, the foam then needs to be destabilised for transport due to its voluminous nature, often accomplished by the addition of an anti-foaming agent. The resulting liquid mixture can then be removed and the components recovered. Recent studies have tried to create stable foams which can be destabilised by external stimuli to remove the need for the addition of extra chemicals.

Orlin Velev and Stephanie Lam of North Carolina State University have collaborated with Anne-Laure Fameau from the French National Institute for Agricultural Research, to pool their multidisciplinary backgrounds in foams and emulsions, and colloids.

Read the full article in Chemistry World»

Read the original journal article in Chemical Science:
Multi-stimuli responsive foams combining particles and self-assembling fatty acids
Anne-Laure Fameau, Stephanie Lam and Orlin D. Velev  
Chem. Sci., 2013, Advance Article, DOI: 10.1039/C3SC51774H

Scientists from the US and China have identified a polymer that makes lithium sulfide batteries last longer.

 Amongst batteries in-use today, lithium ion ones produce more energy per unit mass than most others. However, electric vehicles demand even higher energy batteries with longer charge intervals.

Lithium sulfide batteries can hold much more energy than present-day lithium ion batteries but are limited by their short battery life. This is due to an irregular dispersion of lithium in their electrode slurry, as well as soluble polysulfides being lost when they dissolve in the electrolyte.

Initial numerical modelling followed by lab tests lead Yi Cui at Stanford University and his co-workers to discover that polyvinylpyrrolidone (PVP) can be used to hold a battery’s lithium sulfide and polysulfides during cycling. The PVP allows lithium ions…

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Read the original journal article in Chemical Science:
Stable cycling of lithium sulfide cathodes through strong affinity with a bifunctional binder
Zhi Wei Seh, Qianfan Zhang, Weiyang Li, Guangyuan Zheng, Hongbin Yao and Yi Cui  
Chem. Sci., 2013, 4, 3673-3677
DOI: 10.1039/C3SC51476E, Edge Article

New research shows that a water-soluble catalyst developed by scientists in the US can electrocatalytically transform carbon dioxide into a useful chemical feedstock.

The global demand for fuel is rising, as are carbon dioxide levels in the atmosphere. Recent studies have attempted to address the global carbon imbalance by exploring ways to recycle carbon dioxide into liquid fuels. Formate, the anion of formic acid, is an intermediate of carbon dioxide reduction and can be used as a fuel in formic acid fuel cells. However, the selective production of formate, without using organic solvents, is challenging. Water, being inexpensive and environmentally-friendly, is obviously preferred over organic solvents as a reaction medium. On the other hand, the reduction of carbon dioxide in water is complicated by the reduction of water to hydrogen being a more kinetically favourable process.

Thomas Meyer, Maurice Brookhart and Peng Kang at the University of North Carolina, have designed an iridium pincer catalyst that can selectively reduce carbon dioxide into formate in almost pure water…

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Read the original journal article in Chemical Science:
Selective electrocatalytic reduction of carbon dioxide to formate by a water-soluble iridium pincer catalyst
Peng Kang, Thomas J. Meyer and Maurice Brookhart  
Chem. Sci., 2013, Advance Article
DOI: 10.1039/C3SC51339D

Scientists from the UK and Germany have developed new compounds that target and bind to brain proteins linked to serious neurological disorders. By acting as markers, these compounds enhance the contrast of magnetic resonance imaging (MRI) scans to show the location of receptors.

David Parker and Anurag Mishra at Durham University, and colleagues, have synthesised a series of novel MRI contrast agents that can pinpoint NMDA receptors in vitro, effectively mapping the location…

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Read the original journal article in Chemical Science:
Responsive MR-imaging probes for N-methyl-D-aspartate receptors and direct visualisation of the cell-surface receptors by optical microscopy
Neil Sim, Sven Gottschalk, Robert Pal, Jörn Engelmann, David Parker and Anurag Mishra  
Chem. Sci., 2013, 4, 3148-3153
DOI: 10.1039/C3SC50903F

Scientists in the UK have used reactors made on a 3D printer to complete a three stage organic synthesis. The reagents, catalyst and purification step for the synthesis are completely integrated into the chambers of the sealed reactor. When the reactor is rotated, gravity pulls reactants through the different chambers to complete the synthesis.

Initially, Leroy Cronin, who lead the work at the University of Glasgow, had envisaged a ‘Rubik’s cube for synthesis’, where different manipulations of the reactor would produce different products. ‘The code, like opening a safe, would be in the rotation,’ he explains. ‘I thought it was genius. My group told me I was stupid.’ The team convinced Cronin to start with an easier L-shaped three step reactor, but he still plans to create the Rubik’s cube in the future.

A three-step organic reaction sequence was performed in the L-shaped reactor. The sequence began with…

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Read the original journal article in Chemical Science:
Combining 3D printing and liquid handling to produce user-friendly reactionware for chemical synthesis and purification
Philip J. Kitson, Mark D. Symes, Vincenza Dragone and Leroy Cronin  
Chem. Sci., 2013, Advance Article
DOI: 10.1039/C3SC51253C

Scientists in France have combined homogeneous catalysis and atomic force microscopy to create intricate surface patterns.

Atomic Force Microscopy (AFM) works by dragging a sharp tip across a material’s surface to map nanoscale surface topologies or measure surface interactions. Innovations in the design of AFM tips have allowed AFM to become a tool, not only for reading, but also for writing onto surfaces, analogous to creating tattoos on a molecular scale.

To date, AFM tips have only been able to use a narrow range of chemical transformations, including heterogeneous catalysis, to create patterns on a surface.

Now, Jean-Luc Parrain, Sylvain Clair, Olivier Chuzel and colleagues from Aix Marseille University and the National Centre for Scientific Research (CNRS), have attached a homogeneous catalyst to a commercially available AFM probe and used it to carry out…

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Read the original journal article in Chemical Science:
Grafting a homogeneous transition metal catalyst onto a silicon AFM probe: a promising strategy for chemically constructive nanolithography
Dmitry A. Valyaev, Sylvain Clair, Lionel Patrone, Mathieu Abel, Louis Porte, Olivier Chuzel and Jean-Luc Parrain  
Chem. Sci., 2013, 4, 2815-2821
DOI: 10.1039/C3SC50979F