ИСТИНА

The development of the methods of directional construction of molecular metalorganic structures is one of the fundamental tasks of the functional material science. The determination of relationship between the structure and the properties is necessary for successful creation of the materials with required characteristics. The present study is devoted to the investigation of structural and photoluminescent (PL) properties of novel binuclear carboxylate (pivalate) complexes with rare earth (RE) elements Eu, Sm, Tm, Tb and Gd, which are considered to be a prospective basis for organic light-emitting diodes. The main advantages of such metalorganic complexes as compared to other well-studied carboxylate compounds are: low cost and relative simplicity of the synthesis process, easiness of thin films formation by means of evaporation or from solution, opportunity of formation the complexes with multiple RE ions. Thus, it is possible to realize large-scale modifications of the PL properties of the metalorganic complexes by modifying its ligand structure, or by incorporation two or more different metallocenters. Five sets of samples with varied organic ligands – RE ions coordination environment – were synthesized. In addition, heterometallic complexes with two different RE ions were fabricated as well to investigate the opportunity of light emission with controllable spectral composition. X-ray structure analysis was used to clarify the elements composition of the molecular complexes, which are found to be of crystalline morphology. Typical structure refinement for the molecule with two Sm ions is shown in Fig. 1. The main feature of such compounds is that RE ions appear as the component of each molecule in the crystals, and not as a dopant, which allows one to reach high ions concentration (about 3X1021 cm 3) with no risk of their aggregation. In order to clarify the RE ions excitation mechanisms and energy transfer processes photoluminescence excitation spectra measurements were carried out by means of Perkin Elmer LS-55 Fluorescence Spectrometer. Ordinary PL spectra were obtained using both fluorescence lamp and different laser sources. Intensive photoluminescence characteristic for the specific RE ions was detected in visible spectral region.