ChemWeb Newsletter

Not a subscriber? Join now.November 30, 2004


This week, we report on how peptides could be the next zeolites, a super strong acid with the gentle touch, and the growth of crystals that could have marine biologists hiding in their shells. Also in this issue, magnetic smart dust that could revolutionize microfluidics for analytical scientists and the discovery of a frustrated material with contrary expansion plans.

Tiny grains of silicon can surround and control the motion of molecules, cells, and bacteria within a droplet of liquid, according to chemists at the University of California, San Diego. Now, the team has made their "lab-in-a-drop" (as opposed to "lab-on-a-chip") technology magnetic to facilitate the development of microfluidic devices for nanoscale analytical chemistry and spectroscopy. Michael Sailor and his colleagues use their silicon chaperones to manipulate tiny samples. However, with the addition of a magnetic component they can now do this with a simple magnet, which will allow them use their smart dust for many more applications.

Most materials contract when cooled and expand when heated. Water is a well-known exception but it only breaks the rules in a narrow temperature band. However, Us researchers have discovered a new contrary material that does the opposite of what one would expect over a very wide temperature range. Zack Schlesinger of the University of California, Santa Cruz and colleague at other institutions found that zirconium tungstate is a frustrated material that does not fit the normal pattern of inorganic solids. The researchers suggest that mixing the right "normal" materials with this or a related compound could lead to composite materials that neither expand nor contract on heating or cooling. Such materials could have applications in almost every area of engineering from aerospace to satellite technology.

A Russian-Canadian collaboration could lead to a new generation of porous materials to complement the zeolites. Rather than being based on conventional inorganic salts, however, the materials will be based on peptides. Dmitriy Soldatov and Igor Moudrakovski of the Russian Academy of Sciences in Novosibirsk working with Steacie Institute researcher John Ripmeester have turned to oligomeric peptides as alternative building blocks for porous organic materials. They point out that many peptides have a natural hosting capacity for smaller guest molecules making them perhaps the ideal candidate for creating functional porous materials.

US scientists have invented the world's strongest acid. The carborane acid is effectively a million times as good at donating its proton as sulfuric acid, but because the residual boron-carbon anion itself is so stable it does not then react readily with other materials so is non-corrosive. The previous record holder fluorosulfuric acid was strong but also highly corrosive and eats through glass reaction vessels. The carborane super acid delivers "clean acidity without ferocity", says team leader Christopher Reed of the University of California, Riverside.

Controlling the formation of crystals is an enormous growth area in chemical science. Now, Jim De Yoreo and colleagues at the Lawrence Livermore National Laboratory recently exploited protein extracts from the abalone, a sea creature with a pearlescent lining to its shell, to carry out their crystal engineering. The proteins allowed the team to control the growth of the mineral calcite in such a novel way that the results suggest the current theory about how the abalone and other creatures produce their shells might be wrong.