Macrocyclic Oligofurans: A Computational Study

Macrocyclic
oligothiophenes (nCT)
have been extensively explored for their unique optical and electronic
properties, while their oxygen-containing analogues, macrocyclic oligofurans
(nCF), are not known. In this work,
macrocyclic oligofurans bearing 5–16 units (5CF–16CF) are studied theoretically at the B3LYP/6-311G­(d)
level. We find that small macrocycles (6CF–8CF) exhibit planar or nearly planar geometries, low strain
energies, low HOMO–LUMO gaps, and strong π-conjugation
as also reflected in their Raman spectra. These findings are in sharp
contrast to macrocyclic oligothiophenes of the same size, which are
distorted from planarity. Additionally, small macrocyclic furans display
significantly lower reorganization energies and ionization potentials
compared with their thiophene analogues. Overall, the observed properties
highlight the potential of macrocyclic oligofurans to function as
p-type organic electronic materials.