Nature (Hole or Electron) of Charge-Transfer Ability of Substituted Cyclopyrenylene Hoop-Shaped Compounds

Abstract

We theoretically investigate here by means of DFT methods how the selective substitution in cyclic organic nanorings composed of pyrene units may promote semiconducting properties, analyzing the energy needed for a hole-or electron-transfer accommodation as a function of the substitution pattern and the system size (i.e. number of pyrene units). We choose to study both [3]Cyclo-2,7-pyrenylene ([3]CPY) and[4]Cyclo-2,7-pyrenylene ([4]CPY) compounds, the latter already synthesized, with substituents other than hydrogen acting in ipso and ortho positions, as well as the effect of the per -substitution. As substituents, we selected a set of electroactive halogen atoms (F, Cl, Br) and groups (CN) to disclose structure-property relationships allowing thus to anticipate the use of these systems as organic molecular semiconductors.2

Theoretical Insights for Materials Properties of Cyclic Organic Nanorings

“…The pyrene units, on the other hand, offer a more versatile template for substitutions in ipso and ortho positions, with the effect of electroactive atoms (i.e., F, Cl, Br) and groups (CN) recently studied allowing thus to anticipate the use of these systems as organic (ambipolar) molecular semiconductors. [ 227 ]…”