Vibrational analysis of different crystalline phases of the organic electroluminescent material aluminium tris(quinoline-8-olate) (Alq(3))

M. Cölle, S. Forero-Lenger, J. Gmeiner, W. Brütting

erschienen 2003 Phys. Chem. Chem. Phys. 5, 2958–2963 (2003)
[DOI link]
DOI: 10.1039/b303689h

The isomerism of the Alq(3) molecule was investigated by applying infrared (IR) spectroscopy to two different crystalline phases of aluminium tris(quinoline-8-olate) (alpha-Alq(3) and delta-Alq(3)). Significant differences between the two phases were found in the IR spectra, which can be explained in terms of the different symmetries of the facial and meridional isomer. Additionally, intermolecular interactions of the Alq(3)-molecules due to crystallinity were taken into account. The results suggest that alpha-Alq(3) consists of the meridional isomer, while the recently discovered blue luminescent delta-phase is composed of the facial isomer of the Alq(3) molecule.