The Alchemist Newsletter: August 30, 2007

This week, iron and chemical education skills are rewarded, while analytical and synthetic efforts finally pay off after almost four decades or work on a natural insecticide with the first total synthesis of the neem tree extract azadirachtin. The Alchemist also discovers that diamonds really are almost forever and nanoscopic polymer capsules can facilitate one-pot cascading biotransformations. Finally, a new range of fluorinated contrast agents for medical imaging could make cancer diagnostics stick and computational developments on actinide compounds could revolutionize our understanding of the chemistry of radioactive materials.

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Iron will wins award

Chemist Elizabeth Theil of the Children's Hospital & Research Center at Oakland will receive the prestigious Garvan-Olin Medal for her research on the chemistry of iron in biology and for her advocacy of biochemistry studies in the education of all chemists. The 2008 award was announced at the American Chemical Society meeting in Boston during August.

Elizabeth Theil, Ph.D. selected for prestigious award

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Insecticidal synthesis

Professor Steven Ley of Cambridge University and past and present colleagues, including 40 PhD students have spent more than two decades on a chemical odyssey and have finally achieved a total synthesis of the natural insecticide azadirachtin. This hugely complex natural product was first extracted from the Indian neem tree in 1968, but a definitive structure was only wrought some seventeen years later. Since then several major organic groups across the globe have attempted to synthesise the compound. Ley's team published their 64-step total synthesis in the journal Angewandte Chemie and describe the molecule as an "exceptionally challenging synthetic target by virtue of its sixteen contiguous stereogenic centers and complex pattern of oxygen-containing functionalities."

Natural Insecticide Re-Created in the Lab

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Diamonds are forever

Astronomers recently hinted that the ends of the universe might be populated by dead stars that exist as enormous diamonds spread thinly across the universe. At the other end of the cosmological spectrum geochemists have now discovered the earth's oldest diamonds trapped as occlusions in zircon crystals almost as old as the earth itself. Martina Menneken of the WestfŠlische Wilhelms University of MŸnster, Germany, and her colleagues probed, using Raman spectroscopy, 1000 ancient zircon, formed when the earth was just 250 million years old. Previously, geo scientists had assumed that not even rock from this period would survive because of the earth's fiery and boiling state until at least 500 million years ago. The results suggest that the earth was quieter, cooler and perhaps even habitable much sooner after its formation than previously thought.

Nothing Says "Early Earth Was Cool" Like World's Oldest Diamonds

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Cascading capsules

A one-pot chemical reaction system based on compartmentalizing three different enzymes in a porous polymer membrane has been designed and tested by Jan van Hest and Alan Rowan of the Nijmegen University in The Netherlands. The system allows the team to cascade the reaction of an acetylated glucose molecule via reaction by lipase B to free glucose which is then oxidized on contact with glucose oxidase and the product of this reaction is then used to release hydrogen peroxide using horseradish peroxidase. This proof of principle demonstrate the potential of undertaking biotransformation in a one-pot cascade reaction without time-consuming and wasteful separation and purification stages.

Sweet nanoreactor

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Chemical sensitivity

Intrusive biopsies for people with cancer could be sidestepped thanks to the development of a new class of fluorine-containing contrast agents by David Parker and colleagues at Durham University. The lack of fluorine chemistry in the human body means these compounds will show up with high contrast in magnetic resonance imaging to reveal a detailed view of acidic regions, such as those containing cancer cells. These agents should allow faster acquisition of ¹⁹F magnetic resonance data, say the researchers, as well as amplifying chemical shift non-equivalence. This will allow detailed magnetic resonance information to be obtained quickly and at a dosage well below the safety threshold.

New 'chemically-sensitive MRI scan' may bypass some invasive diagnostic tests in next decade

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Actinide action

Jun Li Pacific Northwest National Laboratory hopes to solve actinide chemistry computationally, a problem that will allow scientists to interpret and predict the chemical and physical properties of actinide compounds and materials using first principle theory. Progress in relativistic quantum chemistry, computer hardware and computational chemistry software has enabled computational actinide chemistry to emerge as a powerful and predictive tool for research in actinide chemistry, Li told the ACS meeting in Boston in August. "These discoveries will have deep impact for heavy-element science and will greatly improve the fundamental understanding of actinides essential to develop advanced nuclear energy systems, atomic weapons and environmental remediation technologies," he said.

Computational Actinide Chemistry: Are We There Yet?

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-- David Bradley, Science Journalist