Bis(n-octylamino)perylene-3,4:9,10-bis(dicarboximide)s and their radical cations: synthesis, electrochemistry, and ENDOR spectroscopy

1,6- and 1,7-bis(n-octylamino)perylene-3,4:9,10-bis(dicarboximide) were synthesized by reaction of n-octylamine with the corresponding dibromo compounds. These compounds display intense charge-transfer optical transitions in the visible spectrum (approximately 550-750 nm) and fluoresce weakly (Phi(F) < 0.06). Cyclic voltammetry reveals that each chromophore undergoes facile and reversible oxidation and reduction. Spectroelectrochemical studies show that the radical cations of these chromophores are stable and show no signs of deprotonation of the secondary amines. Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) studies of the chemically generated radical cations of these chromophores corroborate the spectroelectrochemical data by showing that the radical cations persist for days at room temperature in methylene chloride solution. These experiments and complementary density functional theory (DFT) calculations provide a comprehensive picture of the molecular orbitals, spin density distributions, and geometries of the radical cations. The redox properties and stability of these alkylamino-functionalized perylene compounds make them a valuable addition to the family of robust perylene-based chromophores that can be used to develop new photoactive charge transport materials.