LanthanidIons
Lanthanide ions, usually present as Ln3+ in solution, are the ionic forms of the lanthanide elements, which span atomic numbers 57 through 71. The chemistry is dominated by a pronounced and gradual lanthanide contraction: the ionic radii decrease steadily from La3+ to Lu3+, influencing complex stability and solubility. These ions are hard Lewis acids and preferentially bind oxygen- or fluorine-donor ligands. In aqueous solution they are highly hydrated, commonly existing as eight- or nine-coordinated aqua ions such as [Ln(H2O)9]3+; ligand binding often displaces water to form Ln–ligand complexes.
Chemically, the lanthanide ions show relatively similar behavior across the series due to shielding of the
Spectroscopically, lanthanide ions are known for sharp, line-like f–f transitions, producing characteristic emissions used in phosphors,
Occurrence and extraction: lanthanide ions are obtained from minerals such as monazite and bastnäsite, and their
Applications span lighting and displays, scintillators, catalysts, and analytical chemistry as tracers and luminescent probes. See