1,6-Dinitroperylene Bisimide Dyes: Synthesis, Characterization and Photophysical Properties

1,6- and 1,7-regioisomers of dinitro-substituted perylene bisimides (1a1b and 2a2b) were synthesized under mild condition in high yields. The 1,6- and 1,7-regioisomers were successfully isolated from the regioisomeric mixture using conventional methods of separation and subsequently characterized by 500 MHz H-1 NMR spectroscopy. This is the first time when 1,6-dinitroperylene bisimides (1a1b) are obtained in pure form. Furthermore, the photophysical and electrochemical properties of 1 and 2 were found to be almost the same. The nitro functionalities provide stability of n-type charge carriers by lowering the LUMO to resist ambient oxidation, which may offer potential applications in air-stable n-type organic semiconductors.