Modulating Strain in Twisted Pyrene-Fused Azaacenes.

The design and synthesis of strained aromatics provide an additional insight into the relationship between structure and properties. In the last years, several approaches to twist pyrene-fused azaacenes have been developed that allow to introduce twists of different sizes. Herein, we describe the synthesis of a new set of twisted dibenzotetraazahexacenes constituted by fused pyrene and quinoxaline residues that have been distorted by introducing increasingly larger substituents on the quinoxaline residues. Their twisted structure has been demonstrated by single-crystal X-ray diffraction. Furthermore, absorption, fluorescence, electrochemical and theoretical studies shine light on the effects of the substituents and twists on the optoelectronic and redox properties.

Increasing and dispersing strain in pyrene-fused azaacenes.

A new strategy to obtain distorted pyrene-fused azaacenes is reported. The careful alignment and selection of substituents give rise to highly twisted pyrene-fused azaacenes. A combined global and local theoretical analysis shows how the strain is generated and dispersed across the aromatic backbone. Furthermore, simulation of the observed optoelectronic properties shines light on the structural factors that govern the properties of twisted pyrene-fused azaacenes.