Synthesis and luminescence properties of polymeric complexes of Cu(II), Zn(II) and Al(III) with 8-hydroxyquinoline side group-containing polystyrene

Three kinds of metalloquinolate-containing polystyrene were prepared via a polymer reaction and a coordination reaction. 5-Chloromethyl-8-hydroxyquinoline (CHQ) was first prepared through the chloromethylation reaction of 8-hydroxyquinoline (HQ) with 1,4-bichloromethoxy-butane as chloromethylation reagent. A polymer reaction, Friedel–Crafts alkylation reaction, was carried out between polystyrene (PS) and CHQ in the presence of Lewis catalyst, and HQ was bonded onto the side chains of PS, obtaining 8-hydroxyquinoline-functionalized Polystyrene, HQ-PS. And then, by using one-pot method with two-stage procedures, the coordination reaction of HQ–PS and small molecule HQ with metal ions including Al(III), Zn(II) and Cu(II) ions, was allowed to be carried out, and three polymeric metalloquinolates, AlQ3–PS, ZnQ2–PS and CuQ2–PS, were successfully prepared, respectively. In the chemical structures of these polymeric metalloquinolates, metalloquinolates were chemically attached onto the side chains of PS. HQ–PS and three polymeric metalloquinolates were fully characterized by FTIR, 1H NMR and TGA. The luminescence properties of the three polymeric metalloquinolates were mainly investigated by UV/Vis absorption spectra and fluorescence emission spectra in solutions and in solid film states. When excited by the ray at about 365 nm, the three polymeric metalloquinolates have blue-green luminescence, and the main emission peaks in the DMF solutions are located at 490, 482 and 502 nm for AlQ3–PS, ZnQ2–PS and CuQ2–PS, respectively. As compared with their emissions in solutions, the emissions in solid film states are red-shifted to some extent, and the main emission peaks are located at 500, 488 and 510 nm for AlQ3–PS, ZnQ2–PS and CuQ2–PS, respectively. Besides, these polymeric metalloquinolates have higher thermal stability than PS as polymeric skeleton.

► Functionalized polystyrene bearing 8-hydroxyquinoline side chain was prepared.
► Three luminescent polymeric metalloquinolates were prepared with one-pot method.
► Three polymeric metalloquinolates have blue-green luminescence.
► Their luminescence emissions in solid film states are red-shifted to some extent.