Compounds of formula (I) and their use in electronic devices, especially electroluminescent devices: (I) wherein at least two of the substituents R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, or R7 and R8 form together one of the following ring systems (IIa), (IIb) (IIc). When used as charge transport material, charge blocker material and/or host material in electroluminescent devices, the compounds of formula (I) may provide improved efficiency, stability, manufacturability, or spectral characteristics of electroluminescent devices and reduced driving voltage of electroluminescent devices.