Synthesis, Characterization and Analysis of Fluorescent Property of a Novel 8-Hydroxyquinolinate-Based Functional Molecule with Two Carboxylate Groups

A novel 8-hydroxyquinolinate-based functional molecule with two carboxylate groups (5,7-di(4-carboxylphenyl)-2-methyl-8-hydroxyquinoline) was synthesized in four steps with 8-hydroxyquinaldine as starting material. Based on the optimization of synthetic method and reaction conditions, the overall reaction yield of target molecule was increased up to 71.6%. The structure of target molecule was fully characterized and analyzed by ¹H and ¹³C NMR, and IR spectra. The luminescent properties of target molecule were explored by the UV-vis and fluorescence spectra. The results show that it has three obvious emission peaks between 380 and 440 nm in the solid state. Additionally, the emission wavelength and fluorescence intensity of target molecule can be tuned by different solvent molecules at room temperature.