Structural and electronic effects in perfluorobenzylated perylenes

Abstract

Synthesis of a new family of fluorous perylenes is reported here that involves direct substitution of perfluorobenzyl groups in a solution-phase copper-promoted high-temperature reaction. Formation of the molecules with up to five substituents was observed, and five major products with one, two, and three perfluorobenzyl groups were isolated with high purity. The isolated compounds were characterized spectroscopically, and in two cases, for mono- and bis-substituted perylenes, with single-crystal X-ray crystallography. The observed evolution of solid-state packing from herringbone packing to tight columnar π–π stacking upon gradual addition of perfluorobenzyl groups provides initial insight into the role of perfluorobenzyl groups, which have not previously been used for crystal engineering of organic semiconductor materials. Electronic effects studied by cyclic voltammetry reveal that the perfluorobenzyl group has an equally strong, if not stronger, electron withdrawing effect compared to a CF3 group, making it a viable alternative in molecular designs of organic electron acceptors.