Hydrogen bonds help porphyrin bend aromaticity rules
Molecule undergoes unprecedented topology switch from Möbius aromatic to Hückel anti-aromatic when immersed in polar solvent
Scientists in Japan have developed a system that can switch its topology from being Möbius to Hückel and back again. Not only was this type of reversible switch unexpected, it could also be triggered by external stimuli such as a polar solvent.