SYNTHESIS OF RARE-EARTH GLYCOLATES AND HYDROXYGLYCOLATES

In recent years, there has been a growing interest in the REEs coordination compounds of different topologies with derivatives of carboxylate ligands - α-hydroxycarboxylate ligands, which have additional coordination capabilities with the participation of the α-hydroxyl group. In 2021 for the Y3+-OH-lactate system, it was demonstrated that, depending on the ratio of reagents, hydrothermal treatment can lead to the formation of three types of products: crystals of molecular yttrium lactate, gels of nanofibrous particles of yttrium hydroxolactate, and amorphous precipitates. The purpose of this study is to determine the structure, composition and physicochemical properties of REE glycolates (Tb-Lu and Y), as well as their composites with PVA, depending on the conditions of their preparation (pH and ratio of reagents). During this research work the crystalline glycolates of Tb-Lu and Y with composition Ln(C2H3O3)3∙2H2O formation conditions were established. By the methods of XRD, IR spectroscopy, CHN-analysis and TGA the isostructure of the obtained compounds was shown and the composition of [Ln(HOCH2COO)2(H2O)4][Ln(HOCH2COO)4], where Ln = Ho-Lu and Y, was clarified. For Yb(C2H3O3)3∙2H2O, the structure at 100 ℃ was solved for the first time. The Tb-Lu and Y hydroxoglycolates formation conditions were established, including Y and Tb hydroxoglycolates were obtained in the form of sols, and Er-Lu hydroxoglycolates were obtained in the form of nanofiber gels. For ytterbium hydroxoglycolate, the structure similarity with REE hydroxolactates is shown. A methodology for the preparation of composite material based on PVA, REE hydroxoglycolates and glycerol is also proposed. For lutetium hydroxoglycolate doped with terbium (0.5%), as well as for its composite with PVA, the quenching of terbium luminescence was demonstrated when the material was placed in aqueous solutions of Fe3+ and Cr3+, which can be used for their chemosensor detection.