What is it about?
The luminescence properties of lanthanide(III)dipicolinato compounds have been studied in great depth; however, our knowledge of SmIII with the dipicolinato ligand is rather limited. From mixtures of dipicolinato ligand and samarium(III)triflate solutions two different compounds were found to crystallise, with the amount present depending on the pH. Even though both samarium(III)diplicolinato compounds are nine-coordinated and were found to be best described by a tricapped trigonal prism (TTP) coordination geometry, the compounds exhibit different properties characterised by powder X-ray diffraction (PXRD) and luminescence spectra.
Why is it important?
The article is a cautionary tale about more than one compound being present, which without knowing about the speciation present, could easily lead to faulty interpretations from the luminescence spectra as these could give indications of only one compound from the crystal field splitting. We suggest that single crystal measurements are the only safe way of creating structure-property correlations for these compounds.