A new NiCe complex derived from ortho-vanillin: Structural characterization and luminescence properties

In this study, a new heteronuclear NiCe complex [NiL2Ce(NO3)2(OAc)(H2O)(X)]·1.25H2O (where L = ortovanillinato; X: H2O or CH3OH) was prepared and characterized by analytical and spectroscopic methods. Molecular structure of the complex was further characterised by single crystal X-ray diffraction study. In the structure of the complex, there are two geometrical isomers with only water as coordinated solvent at the Ni(II) centre, and two others with part water and part methanol at this site. In the structure of the complex, a NiL2 moiety is bound to the Ce(III) ion via two phenolic and two methoxy oxygen atoms of two ligands L. The coordination sphere of the Ce(III) ion is completed by the coordination of oxygen atoms of two bidentate nitrate anions, an acetate which bridges the two metal ions, and a water ligand. Hirshfeld surface analysis was performed to investigate the intermolecular contacts and their percentage contributions within the crystal packing. The complex molecules are linked by hydrogen bond contacts. The complex shows an emission band at 656 nm when excited at 317 nm with large stokes shift. The complex exhibits a reversible redox potential at –0.36 V due to the cerium-based oxidation/reduction process.