Are UV–Vis and luminescence spectra of Alq3 [aluminum tris(8-hydroxy quinolinate)] δ-phase compatible with the presence of the fac-Alq3 isomer? A TD-DFT investigation

Recently a new crystalline phase of aluminium tris(8-hydroxyquinolinate) (Alq3) called δ-phase has been reported. On the basis of luminescence data, the presence of the facial isomer has been suggested. Using time dependent density functional theory calculations we compared the spectral features of meridianal and facial Alq3. Comparisons between the two isomers have been used to confirm the presence of facial Alq3 in δ-phase crystals. The interpretation of some characteristics of the more studied meridianal isomer has been suggested.