Syntheses, characterization, biological activity and fluorescence properties of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand and its lanthanide complexes

Eight new lanthanide metal complexes [LnL(NO3)2]NO3 {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand} were prepared. These complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), molar conductivity measurements and spectral studies (1H NMR, FT-IR, UV–vis, and luminescence). The Schiff base ligand coordinates to Ln(III) ion in a tetra-dentate manner through the phenolic oxygen and azomethine nitrogen atoms. The coordination number of eight is achieved by involving two bi-dentate nitrate groups in the coordination sphere. Sm, Tb and Dy complexes exhibit the characteristic luminescence emissions of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of the complexes exhibit antibacterial activity against a number of pathogenic bacteria.

Graphical abstractNew lanthanide metal complexes [LnL(NO3)2]NO3 {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, L = bis-(salicylaldehyde)-1,3-propylenediimine} are described and discussed. Luminescent spectra of Sm, Tb and Dy complexes exhibit characteristic metal-centered fluorescence.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights• Eight new complexes [LnL(NO3)2]NO3 {Ln = Nd, Dy, Sm, Pr, Gd, Tb, La, Er}are synthesized. • Sm, Tb and Dy complexes exhibit characteristic luminescence emissions of Ln(III) ions. • Most of the Ln(III) complexes exhibit good antibacterial activity.