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

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.