Аннотация:Structural information on crystalline rare-earth lactates was virtually not reported despite the thermodynamic properties of rare-earth lactate complexes in aqueous solutions have been thoroughly studied since the 1960s [1]. Lactate belongs to the class of α-hydroxycarboxylates which have a great variety of coordination modes to metal centers. α-Hydroxycarboxylates (and lactates in particular) have potentially higher denticity in comparison with carboxylates. Moreover, they can form interligand hydrogen bonds. These features along with high coordination numbers of the rare earths make it difficult to obtain crystalline rare earth lactates. On the other hand, recent advances in the prediction and modeling of rare-earth lactate molecular complexes indicated that they could be obtained in the crystalline state [2]. In view of practical applications, rare-earth lactates are definitely of interest for the design of new luminescent and magnetic materials including biosensors or diluted magnets. Until recently, only few rare-earth lactate structures were solved, including [LnNa(rac-Lac)4]·2H2O (Ln = Sm, Eu) and [Ln(L-Lac)2](H2O)2·ClO4 (Ln = Eu, Tb), which possessed explicit luminescent and multiferroic properties being promising for creating sources of circularly polarized light, asymmetric catalysis, enantiomer-selective sensorics, and sorption [3]. In our report, a series of isostructural crystalline Y, Dy–Lu lactates as well as new nanocrystalline Y, Eu-Lu basic lactates were obtained using hydrothermal method. The compositions were for crystalline yttrium lactate as Y(C3H5O3)3·2H2O and for nanocrystalline yttrium basic lactate as Y4(OH)5(C3H5O3)7·6H2O. The unit cell volume of crystalline rare-earth lactates showed a linear dependence on the radius of a rare-earth cation. The nanocrystalline Y, Eu–Lu basic lactates have synthesized in the form of fibrous gels, the drying of these gels resulted in either corresponding aerogels or paper-like materials with essentially different microstructure as assessed using small-angle neutron scattering technique. The paper-like fibrous europium- and terbium-doped yttrium basic lactates have pronounced luminescent properties and can be used for the detection of benzene carboxylate anions or transition metal cations in aqueous media.