Chemical Communications Blog

Researchers in China have designed a smart supercapacitor that reversibly shuts down when it gets too hot.

The polymer shrinks when it gets too hot, inhibiting charge transfer

Supercapacitors are similar to batteries, but instead of redox reactions, electrical energy generation typically depends on electrical double layers and pseudocapacitors. They have significantly higher power densities, meaning faster charge/discharge cycles and long cycling lifespans. This makes them ideal for use in electric vehicles and other high power output applications.

However, these properties also mean that supercapacitors are prone to a self-propagating uncontrolled temperature increase, an effect known as thermal runaway. This dangerous effect is already widely known in lithium ion batteries, where explosions have caused high profile recalls of laptops from high-end manufacturers.

Min Wei and other researchers at the Beijing University of Chemical Technology may have solved the problem in supercapacitors by using a temperature-responsive electrode.

Read the full article in Chemistry World»

Read the original journal article in ChemComm:
Reversible thermally-responsive electrochemical energy storage based on smart LDH@P(NIPAM-co-SPMA) films
Yibo Dou, Ting Pan, Awu Zhou, Simin Xu, Xiaoxi Liu, Jingbin Han, Min Wei, David G. Evans and Xue Duan  
Chem. Commun., 2013, Advance Article, DOI: 10.1039/C3CC43039A

Researchers in Israel have identified an antioxidant that can lower cholesterol levels as well as eliminating free radicals. This compound could be a promising alternative to statins, the most prescribed cholesterol-lowering drugs in the world.

1-Fe

High cholesterol and excess free radicals in the body are major risk factors for developing cardiovascular diseases (CVD). Healthy lifestyle and low cholesterol intake certainly help prevent CVD, but people still often fail to maintain the levels of cholesterol required.

Most cholesterol in the body does not come from food, but is produced internally. Statins reduce cholesterol levels by acting as competitive inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, an enzyme that catalyses cholesterol biosynthesis. Yet, some people do not respond to statins.

Now, Adi Haber, Zeev Gross and colleagues at Technion – Israel Institute of Technology in Haifa, have proposed a new alternative to statins.

Read the full article in Chemistry World»

Read the original journal article in ChemComm:
Allosteric inhibitors of HMG-CoA reductase, the key enzyme involved in cholesterol biosynthesis
Adi Haber, Amona Abu-Younis Ali, Michael Aviram and Zeev Gross  
Chem. Commun., 2013, Advance Article, DOI: 10.1039/C3CC44740E

A gel that can move backwards and forwards in a tube in response to changes in light intensity has been developed by an international team of chemists. As it can change its direction of travel, the gel could one day be used as a material to allow tiny intelligent robots to approach more favourable environments or flee advere stimuli.                                      

The gel’s ability to move is thanks to the Belousov–Zhabotinsky (BZ) reaction. BZ reactions are known for their unusual oscillatory properties caused by the non-equilibrium thermodynamics of the reaction. By including the BZ reaction in specific gels, it is possible to obtain soft materials which can show repeated swelling and shrinking on a scale that can even push objects through a tube.

When one end of a BZ gel is made to oscillate faster than the other…

Gel moving away from the light (left) and gel moving towards the light (right)

Read the full article in Chemistry World

Read the original journal article in ChemComm:
Photophobic and phototropic movement of a self-oscillating gel
Xingjie Lu, Lin Ren, Qingyu Gao, Yuemin Zhao, Shaorong Wang, Jiaping Yang and Irving R. Epstein  
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC44480E, Communication

The cuboctahedron consists of copper paddle-wheel nodes and carborane–isophthalic acids

Scientists in the US have made a molecular species containing the highest number of boron atoms ever recorded in a crystallographically characterised molecular species. The unique supramolecular cuboctahedron contains 240 boron atoms and was synthesised by Chad Mirkin and colleagues at Northwestern University in Evanston, Illinois, via coordination-driven assembly.

The previous record for the most boron atoms in a single molecular species was a heptanuclear silver aggregate reported by Lars Wesemann in 2010, but this species only contained 88 boron atoms.

Boron-rich nanostructures form the basis of high-energy materials, nanoelectronic materials and boron neutron capture therapy agents. It is therefore surprising that, in comparison to the myriad of methods for making carbon-rich nanostrucutres, there are relatively few strategies for making boron-rich ones. Mirkin’s team are now pursuing the synthesis of other boron-rich supramolecular assemblies.

This article was originally published in Chemistry World

You can also read the original journal article in ChemComm:
An exceptionally high boron content supramolecular cuboctahedron
Daniel J. Clingerman, Robert D. Kennedy, Joseph E. Mondloch, Amy A. Sarjeant, Joseph T. Hupp, Omar K. Farha and Chad A. Mirkin  
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC44173C, Communication

A chemosensor has been developed by scientists in the US to speed up the quantitative stereochemical analysis of chiral amino alcohols and diamines. Faster stereochemical analysis will help progress the identification of new asymmetric catalysts.  

Different enantiomers of chiral compounds can have similar physicochemical properties but their biological properties may bear no resemblance to each other. Drugs are often chiral molecules but there can be significant differences between the toxicities of enantiomers.

The administration of just the active enantiomer eliminates the toxic effects of other enantiomers and could make administering lower drug doses possible. Asymmetric catalysts that favour the production of one enantiomer over the other provide a way to produce an excess of desired enantiomers and can lower costs by avoiding the labour-intensive and time-consuming separation of enantiomers.

Driven by industrial demand for efficiency, researchers are producing many potential asymmetric catalysts for drugs and other compounds…

Read the full article in Chemistry World»

Read the original journal article in ChemComm:
Sensing of the concentration and enantiomeric excess of chiral compounds with tropos ligand derived metal complexes
Peng Zhang and Christian Wolf  
Chem. Commun., 2013, 49, 7010-7012
DOI: 10.1039/C3CC43653E, Communication