Lanthanide complexes with β-diketones and coumarin derivates: synthesis, thermal behaviour, optical and pharmacological properties and immobilisation

The paper presents the results of the synthesis of complexes of the type Eu(DBM)3 and Eu(DBM)3·Q (DBM-dibenzoylmethane, Q-1,10-phenantroline or 4,7-diphenyl-1,10-phenantroline) and of Tb- and Nd-complexes with the newly-synthesised coumarin derivates 3,3′-[(4-chlorphenyl)methylene)bis(4-hydroxy-2H-chromen-2-one), 3,3′-[(3,5-dimethoxy-4-hydroxy)methylene)bis(4-hydroxy-2H-chromen- 2-one), etc. Elemental and thermogravimetric analysis, IR, UV, NMR and fluorescence spectroscopy and X-ray analysis were applied for characterisation of the complexes. Some peculiarities of the synthetic procedures for both types of complexes were discussed and the influence of the synthetic approach, pH of the reaction medium, temperature of synthesis and drying of the complexes on the composition, stability and optical properties was reported. The immobilisation of the complexes in thin films based on sol-gel produced SiO2 and on polymethylmethacrylate was studied. The optimal conditions for preparation of the matrices (composition of the starting system, temperature and time of sol aging, etc.) were recommended. The film morphology was evaluated by fluorescence, scanning electron and atomic force microscopy. The interaction of the lanthanide ions with the matrices and the influence of their nature, the effect of the in-situ polymerisation and other factors on photoluminescent excitation and emission spectra and excited state life-times of the complexes were followed. The effect of the second ligand on the photoluminescence properties of the immobilised diketonates was further elucidated. Processes involved in the thermal decomposition of the complexes and microcomposites produced on their base were proposed. Preliminary results on the pharmacological properties of the coumarin complexes reported showed unambiguously higher cytotoxicity of the Nd complex in comparison with that of the respective ligand.