Perfluorinated and Half-Fluorinated Rubrenes: Synthesis and Crystal Packing Arrangements

Perfluororubrene
(PF-RUB) has been synthesized by cycloaddition
of perfluorinated 1,3-diphenylisobenzofuran and 1,4-diphenyl-2,3-didehydronaphthalene
followed by reductive deoxygenation. This method was easily applied
for the synthesis of half-fluorinated rubrene (F14-RUB).
The electrochemical measurements and DFT calculations indicate that
perfluorination strongly lowers the HOMO and LUMO energies. Recrystallization
and sublimation of PF-RUB gave two different crystals with planar
and twisted conformations, respectively. In both cases, perfluorination
leads to the formation of short C–F and F–F contacts
and completely disrupts face-to-face π interactions. Single
crystals of F14-RUB were grown by sublimation, and twisted
molecules display the two-dimensional π-stacking with a face-to-face
distance of 3.54 Å.