Syntheses and characterizations of two lanthanide(III)–copper(II) coordination polymers constructed by pyridine-2,6-dicarboxylic acid

Two-Dimensional Layered Metal - Organic Frameworks of Lanthanum(III) Pyridine-2,6-dicarboxylate

Three two-dimensional (2D) LaIII metal–organic frameworks, {[La4(pda)6(H2O)8]·2H2O} n (1), {[La2(pda)3(H2O)4]·H2O} n (2), and {[La2(pda)2(H2O)5SO4]·2H2O} n (3) (pda = pyridine-2,6-dicarboxylate), have been synthesized under hydro(solvo)thermal conditions and characterized by means of X-ray single-crystal diffraction, X-ray powder diffraction, and IR spectroscopy. Complexes 1 and 2 crystallize in the same triclinic system of a P-1 space group, share the same composition, and 4·82 net topology, but have a different local coordination environment and symmetry for the LaIII ions, thus they form a pair of supramolecular isomers. Complex 3 contains two kinds of crystallographically independent LaIII ions and bis-chelating SO4 2– anions, to generate a 2D grid structure of (4, 4) topology. All three complexes display layered crystal packing in the crystal lattice. The thermogravimetric analyses indicate that the solvated and coordinated water molecules in all complexes can be removed upon heating, and the frameworks decompose above 400°C.

Synthesis, structure and fluorescent studies of novel uranium coordination polymers in the pyridinedicarboxylic acid system

Self-assembly under hydrothermal conditions has been employed to synthesize several novel uranium-containing polymeric materials in the pyridinedicarboxylic acid (pydc) system. Uranium containing coordination polymers were synthesized utilizing 2,3-pyridinedicarboxylic acid (2,3-pydc), 2,4-pyridinedicarboxylic acid (2,4-pydc) and 2,6-pyridinedicarboxylic acid (2,6-pydc) as the organic linker. Furthermore, several bimetallic compounds were also synthesized, U-M-2,6-pydc (M = Cu, Ag, Pb). A new secondary building unit for uranium(vi) compounds has also been realized in compound 4 [(UO(2))(2)(C(7)H(3)NO(4))(O)(H(2)O)] through tetramer building units edge shared to form one-dimensional chains. Presented herein will be the syntheses, crystal structures and fluorescent properties of these uranium-containing compounds.

Synthesis, Structure, and Magnetic Behavior of a Series of Trinuclear Schiff Base Complexes of 5f (UIV, ThIV) and 3d (CuII, ZnII) Ions

The reaction of [M(H(2)L(i))] (M = Cu, Zn) and U(acac)(4) in refluxing pyridine produced the trinuclear complexes [[ML(i)(py)(x)](2)U] [L(i) = N,N'-bis(3-hydroxysalicylidene)-R, R = 1,2-ethanediamine (i = 1), 2-methyl-1,2-propanediamine (i = 2), 1,2-cyclohexanediamine (i = 3), 1,2-phenylenediamine (i = 4), 4,5-dimethyl-1,2-phenylenediamine (i = 5), 1,3-propanediamine (i = 6), 2,2-dimethyl-1,3-propanediamine (i = 7), 2-amino-benzylamine (i = 8), or 1,4-butanediamine (i = 9); x = 0 or 1]. The crystal structures show that the central U(IV) ion adopts the same dodecahedral configuration in all of these compounds, while the Cu(II) ion coordination geometry and the Cu...U distance vary with the length of the diimino chain of the Schiff base ligand L(i). These geometrical parameters have a major influence on the magnetic properties of the complexes. For the smallest Cu...U distances (i = 1-5), the Cu-U coupling is antiferromagnetic and weak antiferromagnetic interactions are present between the Cu(II) ions, while for the largest Cu...U distances (i = 6-9), the Cu-U coupling is ferromagnetic and no interaction is observed between the Cu(II) ions. The magnetic behavior of the [[CuL(i)](2)Th] compounds (i = 1, 2), in which the Th(IV) ion is diamagnetic, confirms the presence of weak intramolecular antiferromagnetic coupling between the Cu(II) ions.