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.