Zinc quinolates through styryl substitution in 2-position via acetoxy exchange reaction

2-Methyl-8-quinolinol reacted with salicylaldehyde to give the corresponding substituted 2-styryl-8-quinolinol. Two schemes were adopted in order to prepare zinc quinolates complex through styryl substitution in 2-position. In Scheme 1, four steps were used including hydrolysis of acetoxy, and single crystal of product of this step was acquired. For Scheme 2, acetoxy exchange reaction was directly used to give Zn complex from the styryl derivative a and Zn(OAc)2 in the presence of ethanol and triethylamine, which is a more facile synthesis method of zinc quinolates through styryl substitution in 2-position. The spectroscopic, thermal and optical properties of Zn complex were investigated. The thermal stability of Zn complex was higher than that of styryl derivative a. The residue yield at 800 °C in N2 for Zn complex was 64.3% whereas that for styryl derivative a was almost zero. Solutions of Zn complex in THF emitted yellow light with photoluminescence (PL) maximum at 551 nm, which is considerably red-shifted relative to Znq2 (535 nm) and Zn(2-Meq)2 (515 nm). The ground- and excited-state geometries, charge distributions, and excitation energies of Zn complex were evaluated by ab initio calculations.