ChemWeb Newsletter

Not a subscriber? Join now.January 10, 2006


This week, The Alchemist sniffs out a pong detector, looks at floppy space-age molecules, measures an enantiomeric success, and finds out how ongoing studies have revealed the longer-term benefits of the Alzheimer's drug Namenda. Finally, we go atmospheric to unearth the complex interactions of water and carbon dioxide.

Krishna Persaud and colleagues at the University of Manchester, UK, have developed a remote sensor for monitoring foul odors emerging from landfill and waste-water treatment sites. The new device makes manual sampling and human sniffers redundant by allowing real-time measurements of low concentration odorous gases to be detected. "Ultimately, this device has the potential to create a much healthier environment which will benefit both local communities and waste management companies by alerting them to the build up of bad odours and enabling them to ensure monitor methane emissions remain at a safe level," says Persaud.

US researchers hope to boldly go where no chemist has gone before, by taking the first step toward overcoming a decades-old challenge in chemistry - explaining reactions that occur within very cold clouds among the stars. Their findings could lead to new approaches to more down to earth chemistry. David Nesbitt and colleagues at JILA, a joint institute of the Commerce Department's National Institute of Standards and Technology (NIST) and University of Colorado at Boulder, and Joel Bowman at Emory University, Atlanta and Anne McCoy at The Ohio State University in Columbus, are investigating the super-acid protonated methane, a carbon with five hydrogens and a positive charge. Cryogenic infrared spectroscopy is revealing how this species behaves as it "morphs" between isoenergetic structures and could provide new clues as to how cosmic reactions occur.

A novel approach to determining enantiomeric excesses in pharmaceutical reaction schemes based on NMR has been developed by French chemists. The researchers exploit the intramolecular dynamic processes of bi-aryl derivatives of compounds of interest using deuterium NMR. The weak ordering revealed by a polypeptide chiral liquid crystal solvent can be used to calculate activation energies for the conformational exchanges. Philippe Lesot and colleagues at the Université de Paris-Sud envisage using a series of chiral atropisomers to determine the effect of the position and size of substituent on the internal rotation barrier of small molecules.

Namenda - memantine hydrochloride - can slow the development of symptoms in patients with moderate to severe Alzheimer's disease for at least a year, according to a multicenter study carried out by US researchers. Barry Reisberg of New York University and colleagues have verified that this medication "continues to be beneficial and is safe with remarkably few side effects". Namenda, 1-amino-3,5-dimethyl adamantane hydrochloride, was approved initially in October 2003 by the Food and Drug Administration based partly on a 28-week placebo-controlled clinical trial of 252 people. The new results - an open label extension - followed up 175 patients, 80 of whom had received placebo in the initial trial. The follow-up trial was funded by the drug's German distributor Merz Pharmaceutical.

The formation of the 1:1 complex between water and carbon dioxide could provide climatologists with important insights into the behavior of these atmospheric molecules, according to Patrick Chaquin of the Pierre and Marie Curie University and colleagues. He and his team have isolated the 1:1 complex of water and carbon dioxide in a nitrogen matrix and carried out an IR analysis using isotopic substitution of water. Their results suggest that there are two very weak complexes that can form each with an almost T-shaped structure in which the carbon atom is bonded to the water oxygen. Such chemical interactions could be important clues to understanding the role of these molecules in the so-called greenhouse effect.