Expanding the carbo‐Benzene Chemical Space for Electron‐Accepting Ability: Trifluorotolyl/Tertiobutyl Substitution Balance

Abstract

AbstractWith the view to altering the lipophilicity and electron accepting ability of the tetraphenyl‐carbo‐benzene scaffold, peripheral fluorination of the C18 ring through aromatic linkers was envisaged from the C18Ph6 and o‐tBu2C18Ph4 references, by replacement of two Ph substituents with two p‐CF3‐C6H4 counterparts (FTol). The synthesis relied on a [8+10] macrocyclization involving a common bis(trifluorotolyl)‐tetraynedione, followed by reductive aromatization of the resulting [6]pericyclynediols. While p‐FTol2C18Ph4 proved to be hardly tractable due to an extremely low solubility, p‐FTol2‐o‐tBu2C18Ph2 could be extensively studied by X‐ray crystallography, NMR and UV/Vis spectroscopy, voltammetry, STM imaging of monolayers, and AFM imaging of binary films with P3HT or PC71BM fabricated by spin‐coating for organic photovoltaic cells and J−V curve measurement thereof. The electronic and polarity properties are correlated with moderate but consistent electron‐withdrawing effects of the CF3 groups, in agreement with the DFT‐calculated frontier orbitals and multipole moments. The results provide guidelines for optimization of fluorinated carbo‐benzene targets.