Peryleneimide compounds are industrially important pigments that exhibit a variety of shades from vivid red to black. We have focused on the title compound benzimidazo perylene (BIP) as a potential substitute for carbon black used widely as the black pigment in paint and imaging industries. In the present investigation, electronic characterization of the cis and trans form of BIP has been carried out on the basis of the crystal structure and intermolecular interactions. The black color of BIP is characterized by two absorption bands in the visible region in both isomers: the shorter-wavelength band is due to individual molecules and the longer-wavelength band appears as a result of excitonic interactions between transition dipoles. Especially, the interaction along the molecular stack is attributed to the appearance of the longer-wavelength band to cover the whole visible region together with the molecular band. BIP is also found to be quite insoluble in any organic solvents and extremely resistant to light and heat.
J. Mizuguchi, N. Shimo, "Electronic Structure of the cis and trans Isomers of Benzimidazo Perylene Derivatives and their Use as Black Pigments" in Journal of Imaging Science and Technology, 2006, pp 115 - 121, https://doi.org/10.2352/J.ImagingSci.Technol.(2006)50:1(115)