Blue emitting pentacoordinated Al(iii) complexes based on 2-methylquinolin-8-olate and substituted phenolate ligands. The role of phenolate derivatives on emission and absorption properties

Abstract

This paper reports the synthesis, characterisation and photophysical investigation of the homologous series of blue-emitting pentacoordinated AlQ′₂L 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′₂Al–L′–AlQ′₂, where L′ = OC₆H₄C₆H₄O, OC₆H₄(CH₂)₃C₆H₄O and OC₆H₄C(CH₃)₂C₆H₄C(CH₃)₂C₆H₄O 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.