Synthesis, structure and tunable white-light emission of dinuclear Eu(III) Schiff base complex

The structures and photophysical properties of Ln(III) [europium(III), terbium(III) and gadolinium(III)] complexes with the Schiff base ligands L: (E)-N′-((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide have been investigated. Single crystal X-ray structure of the Eu(III) complex shows two unsymmetrical metal centers that are directly linked by three, near symmetrical phenoxo bridges. The complex exhibits extensive intramolecular stacking interactions between the naphthalene rings that lead to the formation of an excimer. By proper tuning of solvent's polarity and molecular aggregation, excitation of the Eu(III) complex in dichloromethane exhibits white emission expanding the visible region composed of blue (ligand), green (excimer) and red (sensitized Eu(III) centre) luminescence.