Non- planar dodecaalkoxy-hexa-peri-hexabenzocoronene with six reversible oxidation States

Abstract

A non planar, electron rich HBCs, dodecamethoxy-hexa-peri-hexabenzocoronene 4a and dodecahexyloxy-hexa-peri-hexabenzocoronene 4b were successfully synthesized by an smooth oxidative cyclodehydrogenation of hexakis(3,5-dimethoxyphenyl)benzene 3a and hexakis(3,5-dihexyloxyphenyl)benzene 3b respectively using either FeCl3 or DDQ/CH3SO3H in dichloromethane in nearly quantitative yield. The structure of 4a was characterized by 1H NMR spectroscopy and the structures of 4b was characterized by 1H NMR and 13C NMR spectroscopy. The structure of highly crystalline 4a was further confirmed by X-ray crystallography and a flipping sofa like structure was observed. Non crystalline 4b also predicted the flipping behavior from its variable temperature NMR studies. Although 4a produced ill-defined cyclicvoltammogram due to poor solubility the highly soluble 4b produced well-defined cyclicvoltammogram under identical conditions. Further the electrochemistry showed that 4b undergoes sequential ejection of six electrons reversibly at the potentials of 0.45, 0.61, 0.84, 1.02, 1.18, 1.34 V vs SCE. With 160–200 mV gap between each successive ejection of electrons.