The Alchemist Newsletter: February 25, 2011

Van Gogh was apparently no chemical genius The Alchemist learns this week, but modern-day chemical geniuses have turned their attention once more to that most infamous of natural products, strychnine. In materials and physical chemistry control of electron fluids seems possible and could open up a whole new area of interfaces, while in pharmaceutical news a Tropical seaweed might yield the next antimalarial. Organic chemists have a new tool in the form of a Wolfram-Alpha widget that could speed up form filling and the Wolf Foundation is set to dole out prizes to three chemists for their highly creative work.

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Van Gogh's chemical error

Although a great painter, Van Gogh was certainly not a chemist otherwise he would have avoided adding degrading white pigments to the yellow of his "Sunflowers." New studies reveal how in using the bright pigment, chrome yellow, which contains lead chromates together with white pigments containing barium sulfate or aluminum silicate, Van Gogh was dooming his paintings to dullness. A large European team used X-ray techniques as well as Raman and infrared spectroscopy to demonstrate how the white additives cause degradation of lead chromate to viridian green (hydrated chromium(III) oxide).

X-rays show why van Gogh's yellows have darkened

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Strictly strychnine

A concise six-step synthesis by Christopher Vanderwal and colleagues at the University of California, Irvine uses readily available materials to generate the infamous poison strychnine. Their approach puts a new twist on some well-known chemistry. Vanderwal and colleagues explain how two previous approaches to strychnine have successfully exploited the Diels-Alder cycloaddition reaction. However, the researchers knew that tryptamine-derived Zincke aldehyde could be used to shorten the reaction scheme. Their Zincke aldehyde approach places appropriate groups in the right place and in the appropriate oxidation state for the final step to product. While yield is not exceptional, they emphasise how a mere four chemical steps are needed to create four new carbon-carbon bonds and one carbon-oxygen bond, generating a five-carbon donor-acceptor diene for the Diels-Alder step.

Strychnine in just six steps

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Electronic manipulation

Researchers in the US have discovered how to manipulate electrons at oxide interfaces by inserting a single layer of atoms. Chang-Beom Eom and colleagues inserted a monolayer of a rare earth element between two pieces of precisely grown strontium titanate and found that they could produce an electron "fluid" in this layer, with many interesting and potentially useful characteristics. This research is the first demonstration of strong correlation among electrons at an oxide interface. The electron layer displayed distinct characteristics depending on the particular rare-earth element the team used. Materials with larger ionic radii, such as lanthanum, neodymium and praseodymium, are conducting, whereas materials with smaller radii, including samarium and yttrium, are insulating. "This advancement could make a broad impact in fields even beyond physics, materials or chemistry," Eom says. "People can use the idea that an interface made from a single atomic layer of different ions can be used to create all kinds of properties."

Engineering atomic interfaces for new electronics

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Seaweed fights malaria

Tropical seaweed that contains natural fungicides is the surprising source for antimalarial drug leads. The bromophycolides are found at injury sites on the surface of the seaweed. The work is part of a long-term study of chemical signaling among organisms that are part of coral reef communities. Julia Kubanek, an associate professor in Georgia Tech’s School of Biology and School of Chemistry and Biochemistry, suggests that, “We can co-opt these chemical processes for human benefit in the form of new treatments for diseases." The bromophycolides tested positive in the laboratory against the malaria parasite and the next step will be to test the lead compounds in a mouse model.

Seaweed compound may be promising antimalarial drug

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Widgetized chemistry

A literally neat tool that uses the Wolfram-Alpha computational knowledge engine to collate chemical information has been developed by organic chemist Adam Azman of Butler University. The tool lets you look up valid (and CAS enabled) chemistry data. Simply type in the chemical name and the tool returns the molecular formula and structure (just to verify you entered the right compound), and tells you the molecular mass, density, boiling point and a few other physical properties, everything you usually need to complete a reagent table. It also recognizes chemical formulas, like TiCl4, and shorthand notation, like EtOH, explains Azman.

The Wolfram-Alpha "Reagent Table Widget"

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Wolf prize

Israel's Wolf Foundation is to award its prestigious chemistry prize to Krzysztof Matyjaszewski of Carnegie Mellon University, Stuart Alan Rice of the University of Chicago and Ching Tang of the University of Rochester, for their "deep creative contributions to the chemical sciences". 262 scientists from around the world have so far received the prize which has been awarded for the past 33 years. Of the chemists, physicists and medical scientists to have received the prize one in three has subsequently earned a Nobel Prize. They will receive the Wolf prize from the President of the State of Israel and the Israeli Minister of Education at a special ceremony at the Israeli Parliament on May 29.

Carnegie Mellon's Matyjaszewski to receive Wolf Prize in Chemistry

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