Polysubstituted Hexa-cata-hexabenzocoronenes: Syntheses, Characterization, and Their Potential as Semiconducting Materials in Transistor Applications

A series
of tetra- and octa-substituted hexa-cata-hexabenzocoronenes
(cata-HBCs) were synthesized from tetraryl olefins via iodine- and
iron chloride-catalyzed oxidative cyclodehydrogenation reactions.
The substitutions on the periphery of the parent HBC serve to modify
the photophysical properties, highest occupied molecular orbital–lowest
unoccupied molecular orbital gaps, and thermal stabilities of the
respective derivatives. The crystal structures were determined to
display multiple twists in the framework, resulting in different packing
motifs depending on the position, type, and number of functional groups
on the hexabenzocoronene framework. Nearly perfect co-facial packing
to marginally or extensively shifted co-facial stacks were obtained
due to substitution. The single crystals of parent HBC were used to
fabricate single-crystal field-effect transistors, from which the
highest p-channel mobility of 0.51 cm2 V–1 s–1 was measured. Thin-film transistors of selected
HBCs were also prepared, and 0.61 cm2 V–1 s–1 was obtained for MeHBC-2. These results attest
the potential of these materials as semiconducting materials.