Lanthanide coordination polymers based on 5-(2′-carboxylphenyl) nicotinate: syntheses, structure diversity, dehydration/hydration, luminescence and magnetic properties

Twelve lanthanide coordination polymers associated with the organic ligand 5-(2'-carboxylphenyl) nicotinic acid (H(2)cpna): {[Ln(Hcpna)(cpna)(phen)]center dot H2O} (n) (Ln = Sm (1), Tb (2), Ho (3), phen = 1,10-phenanthroline), {[Sm(Hcpna)(cpna)(phen)]center dot 2H(2)O}(n) (4), {[Ln(2)(cpna)(3)(H2O)(3)]center dot 4H(2)O}(n) (Ln = Y (5), Tb(6), Dy (7), Ho (8)), [Lu-2(cpna)(3)(H2O)(2)](n) (9), {[Y-2(cpna)(3)(phen) (2)(H2O)]center dot H2O}(n) (10), and [Ln(cpna)(phen)(NO3)](n) (Ln = Tm (11), Lu (12)) have been prepared by hydrothermal methods and structurally characterized. The structure analyses reveal that complexes 1-3 are isostructural and possess unique three-dimensional (3D) frameworks based on the dodecanuclear Sm/Tb/Ho macrocycles. Complex 4 exhibits a one-dimensional (1D) wheel-chain structure, which further builds three-dimensional (3D) supramolecular architecture via O-H center dot center dot center dot N hydrogen-bonding interactions. Complexes 5-8 are also isostructural and display three-dimensional (3D) open frameworks, which possess two types of channels along the a- and b-axis, respectively. Complexes 9 and 10 feature three-dimensional (3D) frameworks and are created from tetranuclear and dinuclear units, respectively. Complexes 11 and 12 are isostructural and demonstrate one-dimensional (1D) double chain structures, which further build three-dimensional (3D) supramolecular architecture via C-H center dot center dot center dot O hydrogen-bonding. The results show that the pH value of the reaction system, anion, auxiliary ligand and lanthanide contraction play a significant role in determining the structures of the complexes. In addition, the results of luminescent measurements for compounds 2 and 6 in the solid state at room temperature indicate that the different types of structures have a dissimilar influence on their characteristic luminescence. The magnetic properties of compounds 1, 3, 4, 7 and 11 have been investigated. Furthermore, thermal stabilities for 1-12 and the dehydration/hydration properties of compound 6 have also been studied.