TY - JOUR
T1 - Alternating behavior in furan-acetylene macrocycles reveals the size-dependency of Hückel’s rule in neutral molecules
AU - Rahav, Yuval
AU - Rajagopal, Shinaj K.
AU - Dishi, Or
AU - Bogoslavsky, Benny
AU - Gidron, Ori
N1 - Publisher Copyright: © 2023, The Author(s).
PY - 2023/5/27
Y1 - 2023/5/27
N2 - 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 the even-membered macrocycles display contributions from globally antiaromatic ring current. These factors are expressed electronically (oxidation potentials), optically (emission spectra), and magnetically (chemical shifts), and DFT calculations predict global ring current alternations up to 54 π-electrons.
AB - 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 the even-membered macrocycles display contributions from globally antiaromatic ring current. These factors are expressed electronically (oxidation potentials), optically (emission spectra), and magnetically (chemical shifts), and DFT calculations predict global ring current alternations up to 54 π-electrons.
UR - http://www.scopus.com/inward/record.url?scp=85160215514&partnerID=8YFLogxK
U2 - https://doi.org/10.1038/s42004-023-00902-9
DO - https://doi.org/10.1038/s42004-023-00902-9
M3 - مقالة
C2 - 37244950
SN - 2399-3669
VL - 6
JO - Communications Chemistry
JF - Communications Chemistry
IS - 1
M1 - 100
ER -