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The synthesis and characterization of various 3D porous cobalt-organic frameworks are studied. These compounds are shown to exhibit spin-canted antiferromagnetism and field-induced spin-flop transition.

Systematic syntheses, structures, visible luminescence and magnetic properties of a series of new lanthanide hybrids are described. The structures contain trigonal dodecahedral chains and clustered lanthanide oxide ring tunnels and 3D Ln-O-Ln connectivity.

By employment of a tripodal phosphoric carboxylate ligand, tris(4-carboxyl phenyl )phosphin e oxide (H,TPO), two novel porous metal--organic frameworks, namely, [Zn4(μ3OH)2(TPO)2(H2O)2] (l) and [Zn6(μ6-O)(TPO)2] (NO3)4-3H2O (2), have been synthesized by solvothermal methods. Complexes 1 and 2 exhibit three-dimensional microporous frameworks with flu and pyr topologies and possess rare butterfly-shaped Zn4(μ3-OH)2(CO2)6 and octahedral Zn6(μ6-O)(CO2)6 secondary building units, respectively. Large cavities and one-dimensional channels are observed in these two frameworks. Gas-sorption measurements indicate that complex 2 has a good H2 uptake capacity of 171.9 cm g-1 (1.53 wt %) at 77 K and 1.08 bar, and its ideal adsorbed solution theory calculation predicts highly selective adsorption of CO2 over N2 and CH4. Furthermore, complexes 1 and 2 exhibit excellent blue emission at room temperature. [ABSTRACT FROM AUTHOR]

Reaction of europium sulfate octahydrate with p-terphenyl-3,3'',5,5''-tetracarboxylic acid (H4ptptc) in a mixed solvent system has afforded three new coordination polymers formulated as {[Eu(ptptc)0.75(H2O)2]·0.5DMF·1.5H2O}n (1), {[Me2H2N] 2 [Eu2(ptptc)2(H2O)(DMF)]·1.5DMF·7H2O}n (2), and {[Eu(Hptptc)(H2O)4]·0.5DMF·H2O}n (3). Complex 1 exhibits a three-dimensional (3D) metal--organic framework based on {Eu2(μ 2-COO)2 (COO)4}n chains, complex 2 shows a 3D metal--organic framework constructed by [Eu2(μ 2-COO) 2(COO)6]2- dimetallic subunits, and complex 3 features a 2D layer architecture assembling to 3D framework through π···π interactions. All complexes exhibit the characteristic red luminescence of Eu(III) ion. The triplet state of ligand H4ptptc matches well with the emission level of Eu(III) ion, which allows the preparation of new optical materials with enhanced luminescence properties. The luminescence properties of these complexes are further studied in terms of their emission quantum yields, emission lifetimes, and the radiative/nonradiative rates. [ABSTRACT FROM AUTHOR]

Reactions of a tripodal ligand, N,N′,N″-tris(3-pyridinyl)phosphoric triamide (TPPA), and a series of transition-metal ions result in the assembly of five discrete M6L8 coordination cages [M6(TPPA)8(H2O)12](ClO4)12·57H2O [M = Ni2+ (1), Co2+ (2), Zn2+ (3), Cd2+ (4)] and [Pd6(TPPA)8]Cl12·22H2O (5). X-ray structural analyses reveal that the cages have large internal cavities and flexible windows. The flexible ligand TPPA adopts the syn conformation in cages 1-4, but it transforms to the anti conformation in cage 5. Because of the conformational transformation, the sizes of the windows and the volume of the internal cavity of cage 5 are increased. 1H NMR and electrospray mass spectrometric studies show that cage 5 maintains its structural integrity in solution. Additionally, compounds 3 and 4 exhibit strong blue fluorescent emissions, which are 1 order of magnitude higher than that of the free ligand. [ABSTRACT FROM AUTHOR]

Two 3D lanthanide frameworks, [Ln7(DPA)5(NA)3(μ3-OH)8(H2O)3]·2.5H2O [H2DPA = diphenic acid; HNA = nicotinic acid; Ln = Gd (1), Dy (2)], were synthesized and structurally characterized. They were rarely seen examples of 3D frameworks constructed from heptanuclear trigonal-antiprismatic lanthanide clusters with mixed H2DPA and HNA ligands. Both 1 and 2 show typical antiferromagnetic interactions. Additionally, complex 1 possesses a large magnetocaloric effect of 34.15 J kg-1 K-1. [ABSTRACT FROM AUTHOR]