Blue Emitting Pentacoordinated Al(III) Complexes Based on 2-Methyl-Quinolin-8-Olate and Substituted Phenolate Ligands. The Role of Phenolate Derivatives on Emission and Absorption Properties

This paper reports the synthesis, characterisation and photophysical investigation of the homologous series of blue-emitting pentacoordinated AlQ'L-2 complexes 1-6, where Q' is 2-methylquinolin-8-olate and L is a phenolate substituted in para to the oxygen donor atom. Both electron attracting and electron releasing substituents have been considered. Also binuclear complexes of formula Q'Al-2-L'-AlQ'(2), where L' = OC6H4C6H4O, OC6H4(CH2)(3)C6H4O and OC6H4C(CH3)(2)C6H4C(CH3)(2)C6H4O have been synthesised and characterised. These are interesting blue-emitting materials for OLED (organic light emitting diode) fabrication. A comparison between computational and experimental results allowed the description of the absorption and fluorescence processes. A study of the frontier orbitals involved in the electric conduction and fluorescence emission has been performed. Influences of the phenolate-based ligands on the compounds spectroscopy have been particularly taken into account.