Magnets are commonly found holding up photographs on home refrigerators and are perhaps best known as northward pointing needles in compasses. But they are far more common; indeed, their use is ubiquitous in industry and consumer products. Today a car uses no less than 300 parts that use the phenomenon of magnetism. Scientists are engaged in a search for new materials featuring magnetic properties and in understanding the basic fundamentals of magnetism.
Now, researchers Guy Bertrand and David Scheschkewitz of the University of California, Riverside, and colleagues are opening new doors to understanding magnetic properties. On the other side of these doors lies the potential for developing new medical imaging devices and implants, efficient electrical conductors and non-metallic magnets.
Put simply, all substances are formed by bonding atoms together using the atoms' valence electrons (valence electrons are electrons that are actively involved in chemical change). When one of these electrons is not used to form a bond, it results in a non-bonding electron, also called a radical. Magnetism results from the presence of many of these radicals coming close to one another.
Several research groups worldwide have shown that materials based on "diradicals" will be even more magnetically active. In a diradical, two atoms which are close to each other have electrons ready to form a bond. And indeed, the difficulty is that usually the bond is formed, resulting in no magnetism.
The UC Riverside chemists and their colleagues report in the 8 March 2002 issue of Science that they have prepared a "singlet diradical" where the two non-bonding electrons do not combine to form a bond. "The substance still remains a diradical," says Bertrand. "We have been able to obtain this diradical using the specific properties of two non-metallic elements boron and phosphorus."
Until now, the most stable singlet diradical, which can be used as a basic building block for making materials, had a lifetime in the order of micro seconds at room temperature. The new singlet diradical, on the other hand, is stable at room temperature, both in solution and in the solid state.
"This should pave the way for the availability of many stable singlet and triplet diradicals in the near future," says Bertrand. "Our new diradical can be handled under standard laboratory conditions, which is very beneficial. The next challenge will be to prepare the materials by replication of the diradicals. We can hope to get materials that would have the mechanical properties, the transparence, and the low density required for a new generation of magnets, magneto-optical and electrical devices."
Journal
Science