ИСТИНА

Remarkable emission properties of the lanthanide complexes make for their wide use in light-emitting devices, displays, lasers, luminescence bioprobes, etc. Their emission efficiency depends on the relative positions of the excited levels in the emitting ion and in the ligands. Liquid-crystalline lanthanide complexes, due to their unique magnetic and spectroscopic properties as well as their possibility to align in an external electric or magnetic field, are promising luminescent materials with controlled polarization [1]. In this work ab initio XMCQDPT2/CASSCF approach [2] was used to calculate the energies of the ground and excited states of europium(III) complexes with β-diketonates and Lewis bases (2,2′-bipyrimidine and 1,10-phenantroline). In lanthanide complexes the central ion serves as an emitter and excitation energy is transferred to it through its ligands. Ligands usually absorb light in ultraviolet region and transfer energy from their triplet excited levels to the resonant levels of ion (”antenna effect”) whereat some radiative and nonradiative transitions occur. Therefore the thorough insight into the nature and main features of energy transfer in lanthanide complexes is essential in order to find the ligands that ensure the most efficient energy transfer to a particular lanthanide.