Chemical Communications Blog

Catalyst to wash tarnished metals in industry

24 Nov 2011

A simple and cheap way to clean tarnished metals using a UV activated photocatalyst ink has been developed by UK scientists. Removing steel corrosion is a major concern in many industries. Most metals are thermodynamically unstable in air and aqueous solution but owe their durability to metal oxides that form on the surface. However, when the metal oxides thicken, it leads to contamination with undesirable corrosion products that need to be removed. Aggressive chemicals such as strong acids and chelating agents are usually required to remove them.

The photocatalyst ink was applied to the tarnished metal and then UV light was shone onto it. This produced conduction band electrons and valence band holes. An electron donor species in the ink reacted with the holes, leaving the photogenerated electrons to react with absorbed metal ions. The metal oxide layer could then be removed with water.

: Photographs of an annealed stainless steel coupon without (A) and with (B) a rectangle of the inks cast on its surface. UVA irradiation of sample B through a brass ‘TiO2’ template (C) revealed an image of the ‘TiO2’ template on the coupon, (D)

Reference:
Photocatalyst film and ink for cleaning tarnished metals
A Mills and D Hazafy, Chem. Commun., 2011
DOI: 10.1039/c1cc15774d

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One nanoparticle, two nanoparticles, three nanoparticles, four!

22 Nov 2011

By Fiona McKenzie, Executive Editor.

Nanoparticles might be small but they frequent the pages of many a journal due to the ongoing boom in nanotechnology research. Whilst they are useful in a myriad of fields, it is still difficult to directly characterise these extraordinarily small entities. King among the visualisation techniques is electron microscopy but this often requires the isolation of the sample on a support – hardly sufficient for analysing a dynamic sample in solution! Dynamic light scattering is another potential technique but finds limitations when it comes to much smaller nanoparticle sizes.

Ideally, you want to be able to count and size individual nanoparticles at a rate which produces reliable statistics. To address this challenge, Richard Compton and his team, including Neil Rees and Yi-ge Zhou who conducted the experiments alongside Jeseelan Pillay, Robert Tshikhudo and Sibulelo Vilakazi from Mintek, Randburg, have used anodic particle coulometry (APC) to measure gold nanoparticle collisions with a glassy carbon microelectrode and thus count and size individual nanoparticles.

With the electrode potential set above +1.0 V, they were able to record oxidative Faradaic transients from nanoparticle collisions and calculate an average nanoparticle radius which compared extremely well to the radius obtained from scanning electron microscopy measurements. They were also able to observe nanoparticle aggregation, which holds great promise for monitoring dynamic aggregation reactions.

It shouldn’t be long before this technique is routinely used to gain more information on all sizes of metallic nanoparticles which are currently being used in a variety of applications.

Read the ChemComm article by Compton and team for more.

Posted on behalf of Iain Larmour, web science writer for ChemComm.

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Super-fast crystals

22 Nov 2011

By Fiona McKenzie, Executive Editor.

Using surface-enhanced crystallisation, scientists from Germany have established an unusually fast glass transition and polymorph transformation of a drug compound.

Identification of all solid forms of a pharmaceutical is important for drug delivery, due to the potential variability in the physical and chemical properties between amorphous and crystalline forms. The amorphous form of a compound is typically more soluble, but less stable than its crystalline counterpart. Not only that but different polymorphs of the crystalline compound can also have significantly different properties. To accurately characterise drug action, these polymorphs need to be identified.

Using small-scale crystallisation and in-situ Raman spectroscopic analysis of the antihypertensive drug, nifedipine, Franziska Emmerling and colleagues discovered an extraordinarily fast transition from the glassy amorphous state to the metastable β polymorph in less than a minute. The β polymorph is stable for less than ten minutes before transforming again, to the thermodynamically stable α polymorph.

The speed at which the transformations take place implies that classical diffusion is not responsible for the different polymorphs but could instead be the result of small intramolecular changes arising from a pre-ordered physical arrangement of the molecules.

In an industrial world where screening for solid drug forms is always leaning towards scale-reduction and time-reduction, three physical forms on a glass slide in less than twenty minutes is pretty impressive!

To find out more, download the ChemComm article.

Also of interest… Read Andrew Bond, U. Ramamurty, and Gautam Desiraju’s Chemical Science article on “Interaction anisotropy and shear instability of aspirin polymorphs established by nanoidentation“.

Posted on behalf of Scott McKellar, web science writer for ChemComm.

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40 days until 100 issues…

22 Nov 2011

By Joanne Thomson.

….and did you know….?

In 2005, ChemComm published a series of Focus Articles to celebrate its 40th anniversary. In the first Focus Article, Bert Meijer reviewed the career of Hans Wynberg, the author of the first ever ChemComm paper back in 1965. Coincidentally, Bert Meijer was the author of the first ever Chemical Science article in 2010.

Focus Articles aren’t the only ‘special’ article type to be published ChemComm. This year we’ve published a series of Highlights in Chemistry to celebrate the International Year of Chemistry. And next year, to celebrate our move to 100 issues, we’ll be introducing some exciting new content – stay tuned for our issue 1, 2012 Editorial to find out more!

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43 days until 100 issues…

18 Nov 2011

By Joanne Thomson.

….and did you know….?

43 is the number of cookies Editor Robert Eagling brought in to celebrate his last birthday. He assured us that this number was in no way linked to his age.

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44 days until 100 issues…

18 Nov 2011

By Joanne Thomson.

….and did you know….?

ChemComm currently has 44 Advisory Editorial Board members, who, aside from being world-leading scientists, represent and promote ChemComm and advise the Editorial Board and authors on scientific matters. To find out who they are, visit the journal website.

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Hybrid biofuel cell

16 Nov 2011

By Fiona McKenzie, Executive Editor.

Scientists from Israel have designed a biofuel cell that combines the advantages of both enzymatic and microbial fuel cells.

Biofuel cells use redox enzymes to convert chemical energy into electricity. These cells can be divided into two categories: enzymatic fuel cells which require the enzymes to be purified and microbial fuel cells which make use of an entire microorganism. There are pros and cons to both strategies – enzymatic fuel cells tend to have increased power output whilst microbial fuel cells enable full oxidation of a wider range of fuels.

Yet now, Lital Alfonta and co-workers demonstrate that by designing a hybrid cell, one can have the best of both worlds. The team have modified yeast to display redox enzymes on their surface and then introduced this into both the anode and cathode compartments. This approach removes the need to purify the enzymes and enables regeneration of both fuel compartments.

To find out more about Alfonta’s biofuel cell device, read the ChemComm article today.

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Nitron, the new N-heterocyclic carbene

15 Nov 2011

By Fiona McKenzie, Executive Editor.

German scientists have discovered the cheapest N-heterocyclic carbene to date – and it has been under our noses for more than a century!

N-heterocyclic carbenes (NHCs) are extremely useful reagents in synthesis and catalysis, but unfortunately they are expensive with 1 gram costing several hundred US dollars.

However, as Ulrich Siemeling and his colleagues report in their latest ChemComm, it seems that a much cheaper alternative is on the horizon…

The team of scientists based at the University of Kassel have discovered that Nitron, a low cost analytical reagent, exhibits surprising NHC reactivity, more akin to that of its tautomeric form than its conventional Lewis structure. By reacting Nitron with typical carbene trapping reagents such as elemental sulphur, CS₂, and rhodium complexes, they have proven that it is indeed Nitron’s tautomer that it responsible for its NHC-like reactivity in solution, despite being present at concentrations undetectable by NMR spectroscopy.

At a fraction of the price and already commercially available, Nitron may soon become a very popular choice in NHC reactions.

To read more about how Siemeling and co-workers established the cause for Nitron’s unusual reactivity, download the ChemComm article.

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Simple aptasensor for detecting protein

15 Nov 2011

By Joanne Thomson.

Graphical abstract: Nicking enzyme based homogeneous aptasensors for amplification detection of protein Chinese scientists have made a simple and sensitive sensor for detecting proteins, which could lead to improved disease detection.

Huang-Hao Yang and colleagues at Fuzhou University used single-stranded nucleic acids known as aptamers to detect thrombin, an important protein involved in blood clotting.

Although other aptasensors are known, they are more complex than this new sensor, says Yang. And the sensitivity here is three orders of magnitude higher than traditional homogeneous aptasensors.

The improvement is thanks to a nicking enzyme, which Yang used instead of the more usual polymerase. A nicking enzyme recognises a specific sequence in double-stranded DNA. It then cleaves only one strand, leaving a nick in the DNA.

The aptasensor is capable of detecting thrombin in real samples and could be expanded to other proteins simply by changing the aptamer sequence.

To find out more about how it works, download Yang’s ChemComm communication.

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47 days until 100 issues…

14 Nov 2011

By Joanne Thomson.

….and did you know….?

47 is ChemComm‘s 2011 volume number, its second ever volume number.

The journal was not assigned a volume number when first published but we found that this caused problems for customers, in particular with online links to journal articles. Previous volumes published before 2010 have not been numbered retrospectively.

Articles published from issue 1, 2010, onwards should be cited as Chem. Commun., [year], [volume number], [page number].

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Chemical Communications Blog

Catalyst to wash tarnished metals in industry

One nanoparticle, two nanoparticles, three nanoparticles, four!

Super-fast crystals

40 days until 100 issues…

43 days until 100 issues…

44 days until 100 issues…

Hybrid biofuel cell

Nitron, the new N-heterocyclic carbene

Simple aptasensor for detecting protein

47 days until 100 issues…

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