4 research outputs found
Excited-state switching by per-flurination of para-oligophenylenes
Fluorination has become a versatile route to tune the electronic and optical properties of organic conjugated
materials. Herein we report a new phenomenon, excited-state switching by per-fluorination
of para-oligophenylenes, placing a low intensity 11B2 state below the 11B1 state, giving rise to
large Stokes shifts. The switching is attributed to the specific impact of fluorine on the delocalized
and localized frontier orbitals as elucidated by quantum-chemical calculations. The sterical
demands of the fluorine atom additionally diminish efficient conjugation along the chain, leading
to hypsochromic shifts with respect to the unsubstituted counterparts and to a weak chain length
dependence of the absorption and unstructured emission spectra and enhanced internal conversion