Crystal engineering of rare earth heteroleptic complexes: phosphine oxide ligand control, POM-directed assembly, and performance metrics

Abstract

This study explores crystal engineering strategies for rare earth heteroleptic complexes, focusing on ligand design, supramolecular control, and functional performance. Phosphine oxide ligands (TPPO) synergize steric/electronic effects to stabilize coordination geometries, while mixed-ligand systems (e.g., TPPO/phen) enhance Eu³⁺ luminescence (26.88% quantum yield). Polyoxometalates (POMs) template 3D architectures via hydrogen/charge interactions, enabling >95% photocatalytic dye degradation and >200 °C thermal stability. Rare earth-transition metal systems integrate 2D/3D topologies and multifunctionality (luminescence, gas adsorption) through electronic coupling. Additionally, carbon-based oxygen ligand systems (e.g., β-diketonates) demonstrate the applicability of these core strategies—leveraging synergistic N-donor coordination and supramolecular interactions to achieve advanced functionalities like temperature-responsive luminescence. Future work will prioritize flexible ligand engineering and stimuli-responsive designs for applications in clean energy and quantum technologies, establishing a roadmap for advanced rare earth materials.