Charge Transport Parameters and Structural and Electronic Properties of Octathio[8]circulene and Its Plate-like Derivatives

The first fully heterocyclic circulene very recently isolated, C16S8, was studied by means of high accurate methods, allowing reliable predictions and interpretations of the structural and electronic properties of organic molecules bearing sulfur and selenium atoms. The changes induced by the oxidation process and the S/Se substitution on some of its properties and the infrared (IR) spectra were analyzed, allowing a comprehensive assignment of the bands observed in the case of C16S8. The results confirmed the planarity and a large surface area of C16S8, which remain in C16S4Se4 and C16Se4 derivatives, favoring their use for H-2 adsorption. The molecules were shown to have a strong aromatic character, while the IR spectrum of C16S8 was elucidated, toward its possible application for a better understanding of the new class of materials; the IR signal associated to the asymmetric stretching of the C=C bonds can be used as a structural signature,to identify the neutral from the radical forms whose structural planarity was found to resist against the oxidation process. Some of the electronic and physical properties characterizing good electron-donating (ED) and charge-tran sporting (CT) capacity such as the frontier molecular orbital energies (E-HOMO, E-LUMO), the ionization potential (IP), and the reorganization energy (lambda(h)/lambda(e) for hole/electron) were calculated and the influence of the cyclic structure Of C16S8 on them discussed. C16S8, C16S4Se4, and C16Se4 were found to display a comparable/much lower lambda(h) and higher IP and E-LUMO than those for some of the already well-known field-effect transistors (FET) materials such as pentacene, anthracene, and DT-TTF; further investigation for this issue is strongly recommended.