Synthesis and optical properties of aluminum and zinc quinolates through styryl subsituent in 2-position

Abstract 4-Methyl(methoxy or chloro)benzaldehyde reacted with 2-methyl-8-quinolinol to afford the corresponding substituted 2-styryl-8-quinolinol. The latter was used as chelating ligand to prepare aluminum and zinc complexes. The spectroscopic, thermal, thermomechanical and optical properties of these complexes were investigated. The thermal stability of the complexes was much higher than the reference complexes AlQ3 and ZnQ2. The char yield at 800 °C in N2 for typical complexes of Al and Zn was 49–64% whereas that for the reference complexes was 13–31%. The processability of the complexes was improved since they were soluble in common organic solvents such as THF, chloroform and acetonitrile. Solutions of complexes in THF emitted blue-green light with photoluminescence (PL) maximum at 513–576 nm that is considerably red-shifted relative to AlQ3 (514 nm) and ZnQ2 (535 nm). In addition, the PL maximum in THF of the synthesized Zn complexes was red-shifted as compared to the corresponding Al complexes. The nature of the styryl substituent (methyl, methoxy or chloro) of the chelating ligand influenced also the location of the PL maximum.