Synthesis, crystal structure and fluorescence properties of two dinuclear zinc(II) complexes incorporating tridentate (NNO) Schiff bases

Reactions of hydrated zinc(II) trifluoroacetate and sodium azide with two tridentate Schiff bases HL1 (2-((E)-(2-(dimethylamino)ethylimino)methyl)-4-chlorophenol) and HL2 (2-((E)-(2-(dimethylamino)ethylimino)methyl)-4-bromophenol) under the same reaction conditions yielded two dinuclear isostructural zinc(II) complexes, Zn(L-1)(N-3)](2) (1) and Zn(L-2)(N-3)](2) (2), respectively. The complexes were characterized systematically by elemental analysis, UV-Vis, FT-IR, and H-1 NMR spectroscopic methods. Single-crystal X-ray diffraction studies reveal that each of the dinuclear complexes consists of two crystallographically independent zinc(II) ions connected by double bridging phenoxides. All zinc(II) ions in 1 and 2 are surrounded by similar donor sets and display distorted square-pyramidal coordination geometries. The ligands and complexes reveal intraligand (1)(*) flourescence. The enhancement of the fluorescence intensities for the complexes compared to the ligands indicates their potential to serve as photoactive materials. GRAPHICS]