Synthesis, density functional theory calculations and luminescence of lanthanide complexes with 2,6‐bis[(3‐methoxybenzylidene)hydrazinocarbonyl] pyridine Schiff base ligand

Abstract

A pyridine-diacylhydrazone Schiff base ligand, L = 2,6-bis [(3-methoxy benzylidene) hydrazinocarbonyl]pyridine was prepared and characterized by single crystal X-ray diffraction. homogeneous and heterogeneous catalysis. [16][17][18] Following our recently published work towards the complexation of lanthanide(III) nitrate salts with dimethyl pyridine-2,6-dicarboxylate, we were interested in the synthesis of a 2,6-bis [(3-methoxybenzylidene)hydrazine carbonyl]pyridine L ligand derived from dimethyl pyridine-2,6-dicarboxylate ligand. [19] In comparison with dimethyl pyridine-2,6-dicarboxylate ligand, the L ligand possesses more coordination sites that can bind and stabilize different lanthanide metal ions with high coordination numbers. Moreover it has flexible groups that can accommodate and protect lanthanide metal atoms from solvent molecules, which avoid non-radiative deactivation processes. [20] Moreover, L is efficient in the displacement of water molecules present in the coordination sphere of lanthanide ions that quenches the luminescence by absorption of the emitted radiation in the vibrational excitation processes via the vibrational levels of the O-H of water molecules. [21] This work reports the synthesis of the L ligand by a condensation reaction between 2-methoxybenzaldehyde and 2,6-bis(hydrazinocarbonyl)pyridine in ethanol and describes its crystal structure. Additionally the coordinating behavior of L with lanthanide metals (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er) has been investigated by elemental analysis, conductivity measurements, spectral analysis (IR, NMR, UV-Vis and mass) and thermal studies.The antioxidant activity and photoluminescence properties of L and Ln-L have been investigated.

A series of lanthanide complexes with 2‐fluoro‐N'‐(furan‐2‐ylmethylene) benzohydrazide ligand: Synthesis, characterization, luminescent properties and biological evaluation

“…This highest activity may be related to the fact that Dy (III) has the highest positively charged density because it has the smallest size in the series. It can quench the DPPH radical more efficiently than the other lanthanide ions …”

Probing the variations of synthesis, antimicrobial activity, and optical properties of new lanthanide and transition metal complexes of salicylaldehyde‐dipropylenetriamine ligand

“…Due to the importance that Schiff base derivatives possess, several Schiff‐base units and their corresponding metal complexes were synthesized and thermodynamically studied 30 . These findings highlight the broad spectrum of therapeutic possibilities offered by Schiff bases, driving continued interest and investigation into their pharmacological potential 31,32 . Schiff bases that contain additional electron‐donating groups, such as N, O, and S are playing a crucial role in metallo‐biomolecules 10 .…”

“…30 These findings highlight the broad spectrum of therapeutic possibilities offered by Schiff bases, driving continued interest and investigation into their pharmacological potential. 31,32 Schiff bases that contain additional electron-donating groups, such as N, O, and S are playing a crucial role in metallo-biomolecules. 10 It has been found that the coordination of Schiff base ligands through heteroatoms with lanthanide ions or transition metals enhances the biological activity 33,34 as well as the optical properties of these ligands, which has been attributed to the ion pairs on these atoms.…”

Lanthanide Complexes with N,N-Bis-(2-hydroxy-5-nitrobenzylidene)-1,2-phenylenediamine Schiff Base Ligand: Synthesis, Characterization, Photophysical Properties, and Biological Activity

“…In continuation of our research on synthesis of Schiff base ligands and their lanthanide complexes [29][30][31][32][33][34], herein we have focused on synthesis, characterization and luminescent properties of a series of lanthanide complexes with H 2 L ligand. Their biological activity has been tested against some clinical important bacteria.…”