Perylene crystallochromy

Klebe, G., Graser, F., Hadicke, E. and Berndt, J. (1989). Crystallochromy as a solid state effect correlation of molecular conformation, crystal packing and colour in perylene-3,4 9,10-bis(carboximide) pigments. Acta Crystallogr. B, 45, 69-77. [263, 264]... 

Gisslen L, Scholz R (2009) Crystallochromy of perylene pigments interference between Frenkel excitons and charge-transfer states. Phys Rev B 80 23... 

HOMOs and LUMOs in organic semiconductors of common use have complex shapes with several nodal planes, and, consequently, the transfer integral between neighboring molecular orbitals is extremely sensitive to very small nuclear displacements. This sensitivity has been observed many times both theoretically and experimentally. An impressive experimental manifestation of this fact is the crystallochromy of perylene derivatives which was rationalized by Kazmaier and Hoffman in terms of the different intermolecular coupling between the perylene fragments using an extended Htickel computational approach [93]. A systematic study of Bredas and coworkers [132] quantified the importance of this effect for a series of tetracene derivatives. 

---