ChemWeb Newsletter

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Chemistry matters that caught the attention of The Alchemist this week include: recycling powerful magnets with a ligand-based filtration technique, an on-chip carbon-based light source, a protective gel for biocatalysts, concerns over the safety of "alternative" plasticizers, 3D printing with wood-derived "ink" and finally a grant for an iron boost to pharma synthesis.

A protective shield for catalysts sensitive to oxidative damage has been developed by an international team. The hydrogel coating was used in a proof of principle experiment to protect the hydrogenase enzyme from the green alga Chlamydomonas rheinhardtii. Such biological catalysts could be used in future as highly specific and efficient catalysts to replace costly and general precious metal catalysts, such as platinum and palladium for a wide range of reactions. Until now, their tendency to degrade has made them industrially untenable in many cases. The same protective coating might also assist in the development of new fuel cell technology where, again, a biocatalyst might be used instead of a metal. “In future, we will thus no longer have to pay attention to the robustness or suitable reactivation processes when developing catalysts for technical applications,” explains chemist Olaf Rüdiger of the Max Planck Institute for Chemical Energy Conversion. “We can focus solely on maximising the catalyst’s activity."

Phthalate plasticizers are controversial because of concerns about their impact on the environment and human health. Alternatives such as 1,2-cyclohexane dicarboxylic acid diisononyl ester, which has the trade name "DINCH", an aliphatic ester, are now commonly used in the manufacture of flexible plastic articles in sensitive application areas such as toys, medical devices and food packaging. However, according to scientists at McGill University in Canada, there have been no publicly available peer-reviewed data on this compound's toxicology. A study carried out by the Research Institute of the McGill University Health Centre (RI-MUHC) in Montreal, suggests that DINCH has biological effects on metabolic processes in mammals. The findings, published in the journal Environmental Research, could have implications for health and safety.

How's this for repurposing? Researchers at Chalmers University of Technology in Sweden have taken the biopolymer cellulose extracted from wood and used it as the ink in their 3D printer to create three-dimensional objects of precise shape and structure but with a natural twist. By using carbon nanotubes, or other functional materials, as an additive they can also endow these woody objects with electrical conductivity and perhaps other properties. "Combing the use of cellulose to the fast technological development of 3D printing offers great environmental advantages," explains Chalmers' Paul Gatenholm. "Cellulose is an unlimited renewable commodity that is completely biodegradable."

Neal Mankad of the University of Illinois at Chicago is to receive a $100,000 from the ACS GCI Pharmaceutical Roundtable to help pursue research into iron catalysts. He and his team will use the money of the next year or two to work on a bimetallic approach to iron-catalyzed coupling reactions for pharmaceutical syntheses. "As an academic scientist who does research of a fundamental nature almost exclusively, it is invaluable to me to direct those efforts towards areas of importance to industry," Mankad says.

A simple way to separate the rare earth magnetic metals neodymium and dysprosium has been developed by researchers in the USA. These metals are, as their name might imply rare, and so are costly yet required in a wide range of electronic devices and scientific instruments. Separating them at device end-of-life has always been an expensive and time-consuming process. Now, Eric Schelter and colleagues have used a selective ligand that binds to one metal and not the other to provide a way to filter the soluble form from the other in a non-soluble form. “It’s, in principle, easier to get the neodymium and dysprosium out of technology than it is to go back and mine more of the minerals they are originally found in,” Schelter said. “Those minerals have five elements to separate, whereas the neodymium magnet in a wind turbine generator only has two.”

US and Korean researchers have turned to graphene in the quest for a filament material that could be used in a kind of incandescent, on-chip light source, without melting the surrounding electronics. The research published in the journal Nature Nanotechnology brings carbon full circle as pioneering lightbulb inventor Joseph Swan experimented with carbonized paper filaments long before Thomas Edison lit up the world with his version of the light bulb. Bright, on-chip light sources could pave the way to future photonic circuitry and perhaps the optical computer.