Syntheses, crystal structures and photoluminescence properties of erbium(III) complexes

We review our work on syntheses, crystal structure analyses, and photoluminescence properties of erbium mononuclear or dinuclear complexes. We have synthesized the erbium complexes from the reactions of erbium salt with two different chelating ligands, namely anthracene-9-carboxylic acid and pentaethylene glycol in the presence or in the absencence of picric acid. The photoluminescence properties of the complexes based on the crystal structure analyses and the electronic structures are discussed. The erbium complexes were found to crystallize into monoclinic P21/c space group, centered with metal ion being coordinated in eight or nine coordination number as usually observed in many erbium(III) complexes. The emission spectra are typical of broad band, with the center peak position being dependent on the attached ligands, consisting of 4f-4f emission transition of the erbium(III) ion and intraligand π*→ π transition of the aromatic system. In addition to erbium, the crystal structures and photoluminescence properties of other lanthanide(III) complexes are also discussed for comparison purposes.