ИСТИНА

Luminescent lanthanide coordination compounds (LCCs) can find their application in many areas of research including organic light-emitting diode emission layers, biomarkers, etc. For this purpose, LCC must combine the efficient luminescence, long lifetime of the excited state and high stability, while biological applications require also a large Stokes shift, high aqueous solubility and non-toxicity. The search of appropriate LCC was carried out among lanthanide compounds with anions of halogen-substituted benzoic acids (carb)-. The choice of such ligands is due to the fact that lanthanide aromatic carboxylates are known for their high luminescence efficiency, while the introduction of a halogen will result in solubility increase. The goal of this work was to study the influence of the ligand fluorination degree on the structure and properties of lanthanide fluorobenzoates.More than 50 new lanthanide coordination compounds of general formula Ln2(carb)6(H2O)x (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were synthesized and fully characterized. According to X-ray analysis, the structural features of these LCCs were revealed depending on the number and position of the halogen substituent in the benzene ring and on the lanthanide ion. Particular attention in analyzing the structure and local structure of the complexes was given to XRD and PXRD analyses, 1H and 19F NMR spectroscopy, along with EXAFS-spectroscopy, allowing the local structure characterization of single crystals, as well as solutions and thin films. The studies of photophysical properties revealed that almost all the selected ligands, except nitro-derivative, are able to sensitize luminescence of europium and terbium, emitting in the visible range (with quantum yield of up to 70%), and neodymium, erbium and ytterbium, emitting in the near-IR range. Furthermore, the majority of the compounds obtained are water soluble and non-toxic – a key requirement for bioapplications.