Luminescent Zinc(II) Complexes of Fluorinated Benzothiazol-2-yl Substituted Phenoxide and Enolate Ligands

Zn­(II) complexes of the following new, fluorine-containing, benzothiazole-derived ligands have been synthesized and characterized crystallographically: 2-(3,3,3-trifluoro-2-oxopropyl)­benzothiazole (3), 4,5,6,7-tetrafluoro-2-(3,3,3-trifluoro-2-oxopropyl)­benzothiazole (4), 4,5,6,7-tetrafluoro-2-(2-hydroxyphenyl)­benzothiazole (12), 2-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)-4,5,6,7-tetrafluorobenzothiazole (13), and 2-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)­benzothiazole (16); the Cu­(II) complex of ligand 4 is also reported. These are analogs of the important photo- and electroluminescent material [Zn­(BTZ)₂]₂, where H-BTZ = 2-(2-hydroxyphenyl)­benzothiazole. DFT calculations indicate that HOMO and LUMO energy levels in these materials are substantially lowered by fluorination. The fluorinated ZnL₂ complexes are mononuclear (in contrast to the dinuclear, nonfluorinated material [Zn­(BTZ)₂]₂). They easily sublime and show broad visible photoluminescence. A common crystallographic feature is the existence of pairs of fluorinated ZnL₂ molecules related by inversion centers, with their π systems facing one another.