Carpet Beater Molecules: Synthesis and Characterization of Functional Hexa‐peri‐benzocoronene–Alkyne Coupling Products

Abstract

AbstractWithin the scope of this paper, nine π‐expanded mono‐substituted 5,8,11,14,17‐pentakis‐(tert‐butyl)‐hexa‐peri‐hexabenzocoronenes (HBC) are introduced. 2‐Iodo‐5,8,11,14,17‐pentakis‐(tert‐butyl)‐hexa‐peri‐hexabenzocoronene served as precursor and was reacted with ethynyltrimethylsilane in a Sonogashira coupling reaction. The acetylene unit is used as a linker and can undergo another Sonogashira coupling reaction combining different phenyl coupling partners with the HBC core. The electron‐withdrawing groups such as nitrile, pyridine and carbonyl species (aldehyde, methylester, carboxylic acid) as well as the three quinoxaline based species (diphenylquinoxaline, dibenzo[a,c]phenazine, phenanthro[4’,5’‐a,b,c]phenazine) serve as substitution moieties. Their influence on the optoelectronic properties were investigated by UV/Vis absorption spectroscopy demonstrating a maximum redshift of 7 nm compared to starting compound 2‐Iodo‐5,8,11,14,17‐pentakis‐(tert‐butyl) HBC. As for the phenanthro[4’,5’‐a,b,c]phenazine substituted HBC a dramatic decrease in the intensity of the absorption of the UV/Vis spectrum was observed. The fluorescence spectroscopy pointed out that the dibenzo[a,c]phenazine and phenanthro[4’,5’‐a,b,c]phenazine substitution changed the spectra to one broad peak departing from the characteristic HBC‐like emission pattern.