Anthracene and its simplest derivatives with electron-accepting (anthraquinone) and electron-donating (diaminoanthracene) properties in their anionic, neutral and cationic charge states are investigated using the density functional theory. The effect of addition and removal of the electron on the bond lengths, atomic charges, frontier orbitals, ionization potential (IP), electron affinity (EA) and reorganization energy is considered. The computed IP, EA and optical gaps are in rather good agreement with available experimental data.

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Polarized light absorption in photoalignment material induces anisotropic long-range interactions that orient liquid crystals. The main physical mechanisms behind anisotropic interactions are photocrosslinking and photodestruction of polymers, and photoisomerization and photorotation of azo dyes. Investigation of AtA-2 azo dye azimuthal anchoring versus exposure dose revealed the presence of an unusually strong anchoring peak at low doses, which is beyond our understanding of the known mechanisms. Here we explain these observations and demonstrate the existence of a photoalignment mechanism based on photoinduced hole dipole moments in the azo dye layer. Strong azimuthal anchoring energy > 2 × 1 0 − 4 J / m 2 is obtained with a <2007