Redox-Active Heteroacene Chromophores Derived from a Non-Linear Aromatic Diimide

This work describes a three-step chromatography-free protocol for the synthesis of a novel organic materials
building block, dichlorinated mellophanic diimide (MDI), that is shown to undergo nucleophilic substitution
with a variety of ortho disubstituted benzenes to yield a series of chromophores. Furthermore, 1,2,4,5-
tetrasubstituted benzenes can be used to synthesize tetraimide heteropentacene derivatives endcapped by
MDI motifs. The fine-tuning effects of heteroatom identity were investigated by UV-Vis and fluorescence
spectroscopy, cyclic and differential pulse voltammetries, and density functional theory calculations. Oxidation
of diamino MDI derivatives yields di- and tetraimide functionalized azaacenes with significantly lowered LUMO
levels (down to –4.49 eV), narrowed bandgaps (down to 1.81 eV), and high molar absorptivities (up to 84,000
M–1 cm–1).