Novel 3D lanthanide-organic frameworks with an unusual infinite nanosized ribbon [Ln3(μ3–OH)2(–CO2)6]+n (Ln = Eu, Gd, Dy): syntheses, structures, luminescence, and magnetic properties

Abstract

Three novel lanthanide-organic frameworks, [Ln₃(μ₃–OH)₂L₂(HCO₂)₃(H₂O)₂]·H₂O (Ln = Eu (1), Gd (2), Dy (3); H₂L = 3,3′-dimethoxy-4,4′-biphenyldicarboxylic acid), have been prepared by the solvothermal reaction of Ln(NO₃)₃·6H₂O and H₂L in DMF/H₂O mixed solvent. Crystallographic data show that 1–3 are isomorphous and crystallize in the monoclinic space groupP2₁/c. Each complex contains a rare infinite nanosized ribbon [Ln₃(μ₃–OH)₂(–CO₂)₆]⁺_n with three crystallographically distinct Ln(III) ions: two nine-coordinated and one eight-coordinated. The nanosized ribbons are interconnected through HCO₂⁻ anions and L²⁻ linkers to yield a 3D framework. Furthermore, 1 exhibits strong red luminescence upon 343 nm excitation. The investigation of the magnetic properties shows the weak antiferromagnetic coupling between Gd(III) ions in 2 but ferromagnetic coupling between the Dy(III) ions in 3.