Novel Benzimidazole‐Containing Heterocyclic Compounds: Synthesis, Physical Properties and OLED Application

Abstract Three novel heterocyclic compounds containing one ( M1 ) or two (isomers M2 and M3 ) benzimidazole units have been synthesized and fully characterized. The isomers M2 and M3 could be easily separated by column chromatography. Studies showed that the decrease of intermolecular π‐π stackings could enhance the fluorescence intensity of target compounds obviously. The single‐site compound M1 shows the lowest fluorescent quantum yield ( Φ M1 =0.013) in CH 2 Cl 2 than that of the double‐site isomers M2 ( anti ‐type, Φ M2 =0.148) and M3 ( syn ‐type, Φ M3 =0.053). Electroluminescent performances of M2 and M3 in organic light‐emitting diodes were studied. As expected, M2 exhibits more than 2 times higher current efficiency than M3 with M2 showing a maximum current efficiency of 7.8 cd/A as compare to 3.6 cd/A for M3 .