Self-assembly of three-dimensional oxalate-bridged alkali(i)–lanthanide(iii) heterometal–organic frameworks

Abstract

Three isostructural three-dimensional (3D) oxalate bridged alkali(I)–lanthanide(III) heterometal–organic frameworks with the general formula [Ln₈Na₄(ox)₁₀(μ₃-OH)₈]·MeOH·10H₂O (Ln = Tb (1), Dy (2), Er (3)) have been assembled from the solvothermal reactions of oxalic acid (H₂ox) with Ln(NO₃)₃ and Na₂CO₃. These compounds crystallize in the tetragonal I4/m space group and exhibit a 3D six-connected uninodal net of pcu alpha-Po primitive cubic type based on tetranuclear [Ln₄(μ₃-OH)₄] cubane clusters. Among them, compound 1 exhibits a multifunctional luminescent probe property for the detection of acetone, toluene, and Fe³⁺ ions based on fluorescence quenching mechanisms. The magnetic investigations of 1–3 indicate antiferromagnetic coupling between the spin centers Ln³⁺ ions. In addition, 1 and 3 show negligible adsorption capacity for carbon dioxide.