Configuration-specific synthesis of the facial and meridional isomers of tris(8-hydroxyquinolinate)aluminum (Alq3)

Treatment of AIO(OH) with 3 equiv of 8-hydroxyquinolinol in refluxing deionized water provided the meridional and facial isomers of tris(8-hydroxyquinolinate) aluminum (Alq(3)) with good yields as solid deposits after 1 and 90 h, respectively. X-ray diffraction and solid-state C-13 NMR studies revealed that mer-Alq(3) is formed in the early stage of the reaction and then gradually converts to fac-Alq(3), which is thermodynamically less stable, although no existence of a catalyst substance is implied.