ChemWeb Newsletter

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overview

The stars look very different today...The Alchemist thinks, thanks to recent revelations about the formation of complex organic molecules in space. Also, different is an approach to generating fluorine-18 molecules for medical imaging and a technique to assess the risks associated with carbon nanotubes in the environment. A new sensor for the diagnostically important potassium ion comes up with glowing colors, and chemists achieve closure with a new metathesis catalyst for making natural products. Finally, official recognition of the formal names for elements 110, 111 and 112. Time to update your periodic tables.




Last month scientists discovered some of the most complex organic molecules in space. Now, astrobiologists at Rensselaer Polytechnic Institute, in Troy, New York, have compiled years of research to home in on the "sweet spots" where organic molecules might form in space from the carbon-rich debris of supernovae. Specifically, they focused on methanol, which is perceived as a key ingredient among the organic seeds that led to life. Team leader Douglas Whittet said: follow the methanol and you may be able to follow the chemistry that leads to life.





A palladium fluorinating agent can rapidly produce suitable small molecules rich in fluorine-18 for positron emission tomography. Despite the widespread use of radio-fluorodeoxyglucose, there is no simple and fast way to produce other molecules containing this isotope for a range of PET applications. Now, US researchers have extended their earlier work on the fluorination of palladium aryl complexes to produce an electrophilic fluorination reagent that can generalize the rapid synthesis. Time is of the essence in handling 18-fluorine compounds as its half life is just 110 minutes.





An interdisciplinary team of scientists from Empa and the Agroscope Reckenholz-Taenikon (ART) Research Station are investigating how carbon nanotubes might affect the environment, specifically when they reach waterways and lakes. The team has developed a chemical method for measuring growth and photosynthetic activity in green algae exposed to CNTs. They found that even in the presence of high concentrations of CNTs, the algae continue to photosynthesize although growth rates slow a little. Moreover, CNTs seem to cause clumping of the algae but are not absorbed by these aquatic species, the clumping reduces available light, hence the slightly lowered rate of growth. "Our study shows how difficult it is to understand in detail the effect of nanomaterials on organisms," explains team member Fabienne Schwab.





The Alchemist has always had a soft spot for molecular recognition. Now, researchers at Arizona State University have developed a new sensor molecule by combining an electron-withdrawing group, 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran, with an electron-donating group based on a triazacryptand ligand to create a potassium-selective, red-fluorescent sensor. Used with confocal fluorescence microscopy, the sensor can image the distribution of potassium ions without interference from other metals. Given that potassium is such a critical part of many biological functions, being able to image changes in concentration is a useful an indicator of a variety of diseases states.





Ring-closing metathesis is almost perfect for assembling macrocyclic olefins, but there is a problem: poor stereoselectivity. Now, a team from Boston College and MIT have put together a new tungsten alkylidene catalyst that can make Z olefins with up to 97% selectivity via this reaction. They have demonstrated just how useful the catalysts can be by significantly boosting the yields of two well-known natural products epothilone C and nakadomarin A. Scripps synthetic chemist "KC" Nicolaou told C&EN that, "This milestone achievement will be welcomed by the synthetic community as a major advance in organic synthesis."





Elements 110, 111 and 112 were given their official names of darmstadtium (Ds), roentgenium (Rg) and copernicium (Cn) respectively following suggestions from the Joint Working Party on the Discovery of Elements, which is a joint body of the International Union of Pure and Applied Chemistry (IUPAC) and its physics counterpart IUPAP. The naming ceremony took place at the Institute of Physics in London on November 4. Robert Kirby-Harris, Chief Executive at IOP and Secretary-General of IUPAP, said, "The naming of these elements has been agreed in consultation with physicists around the world and we're delighted to see them now being introduced to the Periodic Table."