A new series of 2,8-disubstituted dibenzothiophenes have been successfully synthesized via palladium-catalyzed C-N or C-C bond formation using 2,8-dibromodibenzothiophene and diarylamines as starting materials. These new dibenzothiophene derivatives are amorphous with a glass transition temperature ranging from 86 to 190 uC. Furthermore, they are fluorescent in the blue to bluish green region. Two types of light-emitting diodes (LED) were constructed from these compounds, (I)

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... and (II) ITO/Cpd/Alq 3 /LiF/Al, where TPBI and Alq 3 are 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene and tris(8-hydroxyquinolinato)aluminium, respectively. In type I devices, the compounds function as the hole-transporting and emitting material. In type II devices, emission from Alq 3 is observed. Several type I devices emit pure blue light, and most of the devices II have very promising performance. The relation between the energy levels of the materials and the performance of the light-emitting diodes is discussed.