phys.org
18-member nanoring pushes the boundaries of global aromaticity
Pushing the limits of size constraints in chemistry, an 8-nanometer 18-porphyrin nanoring (c-P18) becomes the largest known cyclic molecule to exhibit detectable global aromaticity. This phenomenon, where π-electrons are delocalized not just over individual aromatic units but around the entire macrocyclic ring, is mostly seen in smaller aromatic molecules but rarely found in macrocyclic entities.