Reversible Bergman cyclization, AFM images

Reversible Bergman cyclization, atomic force microscopy (AFM) images (right) and structural diagrams (left). Researchers used non-contact AFM to observe this molecular rearrangement, a key step in several organic synthesis and pharmacology reactions. It was first described in 1972 by American chemist Robert George Bergman. The molecule studied here was an aromatic diradical (third from top), which was prepared from a brominated aromatic starting point (top). The diradical was rearranged into a highly strained ten-membered diyne (bottom) using atomic manipulation. It was found that the diradical and the diyne exhibit different properties associated with the bond changes. The results were published in 2016 in the journal 'Nature Chemistry', in a collaboration between IBM researchers in Zurich, Switzerland, and CiQUS researchers at the University of Santiago de Compostela, Spain. See also images C032/5432-5434.