A diamond ring sparks a paradigm shift
Monday, June 6, 2011 - 10:00
in Physics & Chemistry
The sweet smell of benzene gave birth to the term aromatic molecules, but it is the chemical bonds within these compounds that have fascinated researchers for almost 200 years. Encasing alternating double- and single-bonded carbon atoms inside a flat ring allows so-called pi-electrons to delocalize and move around the cyclic framework. And thanks to the curious rules of quantum mechanics, this pi-electron sharing has radical consequences for differently sized rings. While aromaticity makes hexagonal systems like benzene exceptionally stable, anti-aromaticity makes four-membered rings like cyclobutadiene show opposite tendenciesthe delocalized electrons try to rip the molecule apart.