Identification of oligophenylene vinylene-naphthalene diimide heterocomplexes by scanning tunneling microscopy and spectroscopy at the liquid/solid interface

2,3,6,7-Tetrabromo-1,4,5,8-naphthalenetetracarboxylic acid diimide (2) A mixture of tetrabromonaphthalene dianhydride 1 (500 mg, 0.857 mmol) and ammonium acetate (1.32 g, 17.1 mmol) in 20 mL of glacial acetic acid was heated to reflux for 2 h. At the beginning a yellow solution was formed and in the further reaction course a yellow solid was precipitated, which was separated from hot solution by filtration, washed with glacial acetic acid (3 mL), water (5 mL), saturated aqueous sodium bicarbonate (3 mL), and dried over phosphorous pentaoxide to afford 150 mg (30%) of 2. MP: > 350 oC. MS (EI): m/z 581.7 [M] (calcd for C14H2Br4N2O4 581.7). This compound is not sufficiently soluble in common organic solvents, thus no NMR spectra could be recorded.