Chemical Communications Blog

Evidence that water came to Earth during its formation from cosmic dust, rather than following later in asteroids, has been shown by a group of international scientists.

The origin of the abundant levels of water on Earth has long been debated with the main differences in the theories being the nature of the material that carries the water, and whether the water came during or after planet formation.

Now, Nora de Leeuw at University College London, UK, and colleagues have used molecular-level calculations to prove that dissociative chemisorption of water onto the surface of olivine rich minerals, such as forsterite, is highly exothermic. And so when these mineral dust particles came together during Earth formation, gas-solid interactions could have resulted in water being adsorbed onto the surface of the dust particles. This means that water could have been part of the Earth from the very beginning.

Water could have been adsorbed onto minerals that created the Earth

‘Our calculations indicate that it is viable for water to become adsorbed at the surfaces of dust particles in the interstellar medium, where planets are formed. The water is thus trapped and becomes incorporated into the Earth,’ says de Leeuw.

De Leeuw’s work challenges the common assumption made by astronomers that the Earth’s water originated from bodies in the asteroid belt. ‘The work will be of tremendous interest to those modelling the geology and habitability of extrasolar terrestrial planets,’ comments Philip Armitage, an expert in astrophysical and planetary sciences at the University of Colorado, Boulder, US.

Rebecca Brodie

Find out more in de Leeuw’s communication. Are you sitting on results that are out of this world? Submit today to ChemComm and make an impact.

Scientists in the US have used restriction endonucleases to detect nucleic acids that do not contain restriction endonuclease recognition sites. Herman Sintim and colleagues at the University of Maryland, College Park, show that the topology of DNA probes used in this detection strategy remarkably affects the efficiency of RNA/DNA detection.

Want to find out more? Why not download the article and let us know your thoughts by blogging some comments below. Published in ChemComm this article will be free to access until the 5th November. 

This article is also part of the ‘Emerging Investigators’ issue, due to be published later on this year.
This issue will highlight the very best work from scientists in the early stages of their independent career
from across the chemical sciences.

Hydride transfer from dihydronicotinamide adenine dinucleotide (NADH) analogues to manganese(V)–oxo
corroles has been shown for the first time by scientists in Korea and Japan. Wonwoo Nam and colleagues at Ewha Womans University collaborated with Shunichi Fukuzumi from Osaka University to show that the reaction proceeds via proton-coupled electron transfer, followed by rapid electron transfer.

Fancy reading more? Why not download the article today and blog some comments below. Published in ChemComm,
this article will be free to access until the 12th November.

By replacing a single active-site amino acid residue in an aminomutase enzyme, scientists in the Netherlands have engineered a variant that can catalyse the formation of β-tyrosine, an important building block in bioactive compounds.

Phenylalanine aminomutase (PAM) is an enzyme that catalyses a chemically challenging α,β-amine shift, forming β-phenylalanine from β-phenylalanine. It can tolerate a wide variety of substituents on the aromatic ring of the substrate but not a para hydroxyl group and so it cannot be used to synthesis β-tyrosine. Although tyrosine aminomutase (TAM) catalyses the amine shift in α-tyrosine to generate β-tyrosine, it has a more limited substrate scope than PAM and has low enantioselectivity towards β-tyrosine.

So Dick Janssen and colleagues replaced a cysteine residue with serine in phenylalanine aminomutase to make an enzyme with both TAM and PAM activity and high enantioselectivity. This engineering enzyme can catalyse the formation of β-tyrosine from p-coumaric acid and may prove useful for synthesising enantiopure β-tyrosine and its derivatives, Janssen says.

For more details, read Janssen’s ChemComm communication, free to access until 12th November. This communication is part of the Enzymes and Proteins web theme issue.

¹³C NMR shifts can be used, alone or in combination with ¹H NMR, to assign the absolute configuration of organic compounds, claim Spanish scientists.

Ricardo Riguera and colleagues at the University of Santiago de Compostela examined the ¹³C NMR data for a collection of chiral samples, including carboxylic acids and cyanohydrins, derivatised with common auxiliaries. In all cases they found a perfect correlation between the sign of Δδ^RS (the difference in chemical shift for the protons around the asymmetric carbon in the R and S substrates) and the absolute configuration of the substrate.

The foundations of the method reside in the aromatic shielding effect produced by the auxiliary on the protons and carbons of the substrate, Riguera explains.

Read the full report in Riguera’s ChemComm communication, free to access until 12th November 2010. And if you enjoy the communication, you might also enjoy NMR methods for unravelling the spectra of complex mixtures, a review in Natural Product Reports by Riguera et al.

A bimetallic iron(III) catalyst can couple together an epoxide (cyclohexene oxide) and carbon dioxide (CO₂) to yield poly-(cyclohexene carbonate), under mild conditions.

Charlotte K. Williams and co-workers at the Imperial College London, in the UK, believe that this method provides a sustainable alternative for the synthesis of carbonates, as metal catalysed coupling of CO₂ and epoxides is one of the few processes that actually consumes (rather than releases!) this harmful greenhouse gas.

Fancy reading more? Why not download the article today and blog some comments below? Published in ChemComm, this article is free to access until the 12th November.

This article is also part of the ‘Emerging Investigators’ issue, due to be published later on this year. This issue will highlight the very best work from scientists in the early stages of their independent career from across the chemical sciences.

Highly pure poly(3-hexylthiophene)-containing block copolymers have been made, which is a great result for future optoelectronic applications, say US scientists.

Christopher Bielawski and colleagues as the University of Texas at Austin used click chemistry and a clever purification procedure to produce the block copolymers without the typical homopolymer impurity.

To find out more, why not download the article today? Published in ChemComm, this article is free to access until the 12th November. If you enjoyed reading this article, why not let us know your thoughts by blogging some comments below.

This article is also part of the ‘Emerging Investigators’ issue, due to be published later on this year. This issue will highlight the very best work from scientists in the early stages of their independent career from across the chemical sciences.

A new type hypervalent iodine reagent could enable more efficient and green catalytic oxidations, report Japanese chemists.

Hypervalent iodine reagents have emerged as promising organo-oxidants, replacing classical heavy metal oxidants such as lead and mercury. m-Chloroperbenzoic acid is commonly used as a stoichiometric reoxidant to regenerate the reactive iodine species, but scientists would like to use other, more environmentally friendly oxidants, such as peracetic acid, instead. Until now, however, no efficient iodine catalyst that works well with peracetic acid has been found.

Yasuyuki Kita, at Ritsumeikan University, Kusatsu, and colleagues discovered that their µ-oxo-bridged hypervalent iodine(III) compounds, in the presence of peracetic acid, could catalyse spirolactam formation. They also believe the compounds can catalyse other types of oxidation, such as phenolic oxidation, and, because they have a chiral structure, could have potential in asymmetric oxidative transformations.

Download the communication for free until 5th November 2011. And if you have some exciting research of your own to report, submit your manuscript to ChemComm today.

Depletion attraction forces can be used to assemble nanorod superlattices and branched nanocrystal networks, say Italian chemists. The nanostructures could be used in a variety of applications, including photovoltaics, they claim.

Liberato Manna and colleagues at the Italian Institute of Technology, Genova, discovered that in the presence of molecules such as oleic acid, nanorods assemble into superlattices. They also found that tetrapod-shaped nanocrystals form networks under similar conditions.

Want to find out how this works? Read the ChemComm article, which is free to access until 5th November, and add your comments on the work below.