Organic dyes are important components of liquid crystal displays, solar panels and organic light-emitting diodes. Perylene bisimides are examples of such dichroic dyes, meaning their absorption at a specific wavelength can change from low to high depending on their molecular orientation and assembly.

Albertus P. H. J. Schenning, Eindhoven University of Technology, Netherlands, and colleagues modified the organic dye peryline bismide PB-1 (pictured) in one step, thereby changing its alignment and self-assembly properties. The researchers also showed the first instance of formation of ultra-long dye fibers for these perylene bisimides. Four phenylethyl groups were added to PB-1 by Ru(H₂)(CO)(PPh₃)₃ in a single step.
This simple modification increased the dye’s solubility, reversed its dichroic properties and affected its self-assembly. These changes may be interesting for the tuning properties of optoelectronic devices.

• Effect of the Ortho Alkylation of Perylene Bisimides on the Alignment and Self-Assembly Properties,
  Debarshi Dasgupta, Amol M. Kendhale, Michael G. Debije, Jeroen ter Schiphorst, Ivelina. K. Shishmanova, Giuseppe Portale, Albertus P. H. J. Schenning,
  ChemistryOpen 2014, 3, 138–141.
  DOI: 10.1002/open.201402011