N. N. Bukov, L. I. Ivashchenko, V. Panyushkin
Apr 1, 2021
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Journal
Russian Journal of General Chemistry
Abstract
Complex compounds of 3-hydroxy-4-oxo-4H-pyran-2,6-dicarboxylic (meconic) acid (H3Mec) with europium(III), gadolinium(III), terbium(III), dysprosium(III), erbium(III), thulium(III) and ytterbium(III) ions were synthesized by the ion exchange method in aqueous solution. The hydrates of the complex compounds [Ln(HMec)(H2O)]·nH2O (n = 0‒4) are solid amorphous substances (Sm3+, Eu3+, Gd3+, and Tm3+ complexes) and fine crystalline substances (Tb3+, Dy3+, Er3+, and Yb3+ complexes) with colors characteristic of lanthanide ions. The region of thermal stability of the complexes was determined by the TG/DTG/DSC methods. The Ln3+ ions are coordinated monodentately to the ionized carboxyl groups and the oxygen atom O1 of the pyrone ring. The coordination of Ln3+ to the С3‒OH group and the С4=О ketogroup of the second ligand molecule leads to the formation of a polymer chain. The triplet level of the ligand (3T*) was determined from the phosphorescence spectrum of the Gd3+ complex compound (77 K). The spectral-luminescent properties of Sm3+, Eu3+, Tb3+, Dy3+, and Tm3+ complexes were studied.