Different approaches to brominate dialkyl isothianaphthene-5,6- dicarboxylate were tried and single crystals of target molecule and side product were obtained. A planar copolymer with the trans-ethene has been prepared, which shows good solubility in common organic solvents and broad absorption with edge to 967 nm in film. Isothianaphthene derivatives have been brominated successfully, which could be used directly as bulilding block in Stille couplings towards the application in organic electronics. A planar copolymer with the trans-ethene was synthesized which shows broad absorption with edge to 967 nm in film. Copyright © 2013 SIOC, CAS, Shanghai & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.