Three series of dimers containing pyrrolo [3, 4-e][2, 1, 3] benzothiadiazole units have been prepared by application of the Pd-catalyzed Suzuki coupling. The dependence of the HOMO– LUMO separation on coplanarity has been evaluated by means of electronic absorption spectra and cyclic voltammetry. The pyrrole dimer 5c shows a narrow HOMO–LUMO separation owing to its intrinsically planar structure, as confirmed by 1 H NMR.
