Synthesis, properties, and magnetism–structure relationship of lanthanide-based metal–organic frameworks with (ethylenedithio)acetic acid

Abstract

A series of new lanthanide-based metal–organic frameworks were prepared by the reaction of H₂EDA ligand and Ln(NO₃)₃ (H₂EDA = (ethylenedithio)acetic acid, Ln = La (1, 5), Nd (2), Eu (3) and Gd (4)). 1–4 exhibit three-dimensional isomorphic structures, while 5 displays a different framework than 1–4. It was found that the structures of the lanthanide MOFs are easyly influenced by the reaction conditions and the metal ion radius. Moreover, the emission spectra revealed that 3 exhibits good luminescence properties. Magnetism measurements showed that 4 has ferromagnetic properties. Quantum Monte Carlo (QMC) simulations revealed that the coupling parameter between two Gd(III) ions is 0.03 cm⁻¹, suggesting a weak ferromagnetic exchange. Furthermore, under the consideration of strong correlations between localized f electrons, first principle density functional theory (DFT) calculations with the GGA + U approach showed that the magnetic properties of 4 are originated from the 4f electrons of Gd(III) propagating by a super-exchange pathway on two −/+/− spin nets of the carboxylate groups.