Alternating behavior in furan-acetylene macrocycles reveals the size-dependency of Huckel's rule in neutral molecules.

ABSTRACT: Aromaticity can be assigned by Hückel's rule, which predicts that planar rings with delocalized (4n + 2) π-electrons are aromatic, whereas those with 4n π-electrons are antiaromatic. However, for neutral rings, the maximal value of "n" to which Hückel's rule applies remains unknown. Large macrocycles exhibiting global ring current can serve as models for addressing this question, but the global ring current are often overshadowed in these molecules by the local ring current of the constituent units. Here, we present a series of furan-acetylene macrocycles, ranging from the pentamer to octamer, whose neutral states display alternating contributions from global aromatic and antiaromatic ring currents. We find that the odd-membered macrocycles display global aromatic characteristics, whereas

SUBMITTER: Rahav Y 

PROVIDER: S-EPMC10224948 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature