Two new POM-based compounds modified by lanthanide-Schiff base complexes with interesting NLO properties.

Area of Science:

• Inorganic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polyoxometalates (POMs) are versatile inorganic clusters with diverse applications.
• Lanthanide complexes are explored for their unique optical and magnetic properties.
• Schiff base ligands offer tunable coordination environments for metal ions.

Purpose of the Study:

• To synthesize and characterize novel POM-based lanthanide-Schiff base complexes.
• To investigate the nonlinear optical properties, specifically two-photon absorption (TPA), of these new materials.
• To explore the supramolecular assembly and electrochemical behavior of the synthesized compounds.

Main Methods:

• Hydrothermal synthesis of lanthanide-Schiff base complexes with Keggin-type POMs.
• Single-crystal X-ray diffraction for structural elucidation.
• Infrared spectroscopy, thermogravimetric analysis, and powder X-ray diffraction for characterization.
• Two-photon absorption (TPA) measurements for nonlinear optical evaluation.
• Electrochemical studies to determine redox properties.

Main Results:

• Successful isolation of two POM-based lanthanide derivatives: a terbium(III) complex (1) and a dysprosium(III) analogue (2).
• Structural analysis revealed a distorted tricapped trigonal prismatic arrangement around the Ln(III) ion, coordinated by the Schiff base ligand, water molecules, and the POM cluster.
• Both compounds exhibited excellent third-order nonlinear optical (NLO) responses with significant two-photon absorption (TPA) values (2264 GM for 1 and 941 GM for 2).
• Hydrogen-bonding interactions led to the formation of a three-dimensional supramolecular structure.
• Electrochemical properties were systematically investigated.

Conclusions:

• The synthesized POM-based lanthanide-Schiff base complexes represent a new class of materials with promising nonlinear optical properties.
• These compounds are the first reported POM-based Ln-L(Schiff base) complexes demonstrating significant two-photon absorption.
• The findings highlight the potential of integrating POMs and lanthanide-Schiff base units for advanced NLO applications.