A matrix-isolation spectroscopic and theoretical investigation of tris(8-hydroxyquinolinato)aluminum(III) and tris(4-methyl-8-hydroxyquinolinato)aluminum(III)

Infrared and photoluminescence spectra of matrix-isolated and thin-film sam ples (both at 11 K) of tris(8-hydroxyquinolinato)aluminum(III) (Alq(3)) and tris(4-methyl-8-hydroxyquinolinato)aluminum (Almq(3)) were collected and c ompared to vibrational spectra generated by B3LYP based density functional calculations. The present infrared spectral results suggest that both Alq(3 ) and Almq(3) exist primarily in the meridional or C-1 isomeric form with l ittle or no spectral evidence for the presence of the alternate, facial (C- 3 symmetry) geometric isomer. In addition, photoluminescence spectra of the se molecules isolated in an argon matrix show vibronic structure in the emi ssion band associated with the S-1 --> S-0 transition.