Multicomponent substitutional solid solutions with several ions with similar crystal-chemical properties in one site exhibit property characteristics significantly exceeding those of single-component compounds. Interest is currently focused on metal–organic frameworks (MOFs), which consist of cations connected by an organic linker. The aim is to synthesize and characterize new multicomponent MOFs, obtained using a hydrothermal method by mixing RE3+(NO3)3·xH2O (RE=La-Lu), H3BTC (benzene-1,3,5-tricarboxylic acid), and NaOH in distilled water.
XRPD showed that single-phase (Eu,Tb,Dy,Er)BTC, (Sm,Eu,Tb,Dy)BTC, and (Sm,Eu,Tb,Er)ВТС crystallize in MIL-78-type (sp.gr. C2/m, Z=4; [(4RE)BTC]) and two-phase samples (usually with adding RE=La-Pr) and have REBTC(Сс) (sp.gr. Сс, Z=4; [(4RE)BTC(H2O)6]) and MIL-78 structures. In diffraction patterns of (4RE)BTC, redistribution of the intensities of main peaks is observed, which is caused by the type and content of RE in (4RE)BTC.
IR spectra of [(4RE)BTC] and [(4RE)BTC(H2O)6] confirm their compositions: the weak band at ~3070 cm-1 and weak bands ~3480-~3230 cm-1 correspond to adsorbed water and water in the framework, respectively.
According to DSC, (Sm,Eu,Tb,Er)ВТС has the highest chemical stability (DН=8057.0 J/g), which is greater than the other components. However, the highest thermal stability (560.72°C) is observed in the SmBTC component of (Sm,Eu,Tb,Dy)BTC and (Sm,Eu,Tb,Er)ВТС, which may be due to a higher degree of amorphism in multicomponent phases compared to single-component ones.
Funding: This study was funded by the Ministry of Science and Higher Education of the Russian Federation, grant № FSFZ-2024-0003.
