A binuclear gadolinium complex of 8-hydroxyquinoline-2-carbaldehyde salicylhydrazone: structural characterisation and photoluminescence properties.

A dibasic tetradentate N3O3 Schiff base ligand {(Z)-2-hydroxy-N′-((8-hydroxyquinolin-2-yl)methylene)benzohydrazide}(H3L) and its binuclear phenoxido-bridged gadolinium complex, [Gd2(HL)2(NO3)2(DMF)4], were synthesised. The ligand was characterised by 1H-NMR, ESI-Mass, FT-IR, and UV–visible spectroscopic methods. The gadolinium complex was characterised by FT-IR, UV–visible spectroscopy, and single-crystal X-ray diffraction. The central gadolinium(III) ion is nine-coordinated, with a distorted tri-capped-trigonal-prismatic geometry. The equatorial coordination sites are satisfied by donor atoms such as phenolate oxygen in μ2 bridging modes, quinoline nitrogen, azomethine nitrogen from the 8-hydroxyquinoline-2-carbaldehyde and one carbonyl oxygen of salicyl moiety. In addition, two DMF molecules via their carbonyl oxygens and one nitrate in a bidentate fashion via O1 and O2 in the axial region complete the coordination. The gadolinium ions are separated by a distance of 4.04 Å in the complex. The Photoluminescence properties of the ligand and the gadolinium complex were studied in the solid-state at room temperature. [ABSTRACT FROM AUTHOR]