Tuning the Electron Affinity and Stacking Properties of Corannulene by Introduction of Fluorinated Thioethers

Trifluoromethylthio-substituted corannulene can be easily synthesized in good yield by the reaction of iodocorannulene with CuSCF3. Oxidation with meta-chloroperbenzoic acid (mCPBA) yields the corresponding sulfonyl compound which exhibits the largest anodic shift of the redox potential caused by a single substituent. Similarly, four SCF3, SC6F5 and SeC6F5 substituents are introduced in the 1,2,5,6-positions of corannulene starting with 1,2,5,6-tetraiodo- or 1,2,5,6-tetrabromocorannulene, respectively. The reactions are performed in polar aprotic solvents and are believed to follow SNAr-type substitution mechanisms. Crystal and molecular structures of selected compounds were elucidated by X-ray crystallography. Trifluoromethanesulfonyl corannulene and the fourfold-substituted trifluoromethylthioether exhibit a perfect columnar stacking of the bowls. The substituted corannulenes were investigated electrochemically by cyclic voltammetry giving raise to large anodic shifts owing to substitution with electron-withdrawing groups.