Unprecedented nitronyl nitroxide bridged 3d-4f complexes: structure and magnetic properties.

Two novel 2p-3d-4f compounds, {Ln(hfac)3[Cu(hfac)2]3(NITPhPyrim)2} [Ln = Gd (1), Dy (2)], have been obtained by reacting phenyl pyrimidyl nitronyl nitroxide with Cu(hfac)2 and Ln(hfac)3. These two compounds are the first examples of two-dimensional 3d-4f complexes bridged by nitronyl nitroxide radicals. Overall ferromagnetic behaviors were observed in both compounds.

Syntheses, structures, and magnetic and luminescence properties of a new Dy(III)-based single-ion magnet.

Three new Ln(III) complexes based on 2,2'-bipyridine [Ln(hfac)3(bpy)] (Ln = Dy (1), Tb (2), or Ho (3); hfac = hexafluoroacetylacetonate; and bpy = 2,2'-bipyridine) have been synthesized and characterized structurally and magnetically. Single-crystal X-ray analysis shows that all these complexes contain one [Ln(hfac)3(bpy)] unit in which a center Ln(III) ion is surrounded with a slightly distorted square-antiprismatic LnO6N2 coordination sphere formed by three bischelate hfac anions and one bpy ligand. Both static and dynamic magnetic properties were studied for complex 1, which is proved to be a new single-ion magnet. The luminescence characterizations of complexes 1 and 2 are also studied in this paper.

Two novel cyanide-bridged bimetallic magnetic chains derived from manganese(III) Schiff bases and hexacyanochromate(III) building blocks.

Two novel complexes, [{Mn(salen)}(2){Mn(salen)(CH(3)OH)}{Cr(CN)(6)}](n)·2nCH(3)CN·nCH(3)OH (1) and [Mn(5-Clsalmen)(CH(3)OH)(H(2)O)](2n)[{Mn(5-Clsalmen)(µ-CN)}Cr(CN)(5)](n)·5.5nH(2)O (2) (salen(2-) = N,N'-ethylene-bis(salicylideneiminato) dianion; 5-Clsalmen(2-) = N,N'-(1-methylethylene)-bis(5-chlorosalicylideneiminato) dianion), were synthesized and structurally characterized by X-ray single-crystal diffraction. The structural analyses show that complex 1 consists of one-dimensional (1D) alternating chains formed by the [{Cr(CN)(6)}{Mn(salen)}(4){Mn(salen)(CH(3)OH)}(2)](3+) heptanuclear cations and [Cr(CN)(6)](3-) anions. While in complex 2, the hexacyanochromate(III) anion acts as a bis-monodentate ligand through two trans-cyano groups to bridge two [Mn(5-Clsalmen)](+) cations to form a straight chain. The magnetic analysis indicates that complex 1 shows three-dimensional (3D) antiferromagnetic ordering with the Néel temperature of 5.0 K, and it is a metamagnet displaying antiferromagnetic to ferromagnetic transition at a critical field of about 2.6 kOe at 2 K. Complex 2 behaves as a molecular magnet with Tc = 3.0 K.

Slow magnetic relaxation in novel Dy4 and Dy8 compounds.

Two novel dysprosium(III) clusters have been prepared and structurally characterized. One has a tetranuclear core with a rare zigzag arrangement, and the other is an unprecedented octanuclear cluster with six triangular Dy(3) units sharing vertices. Both dysprosium(III) clusters possess frequency-dependent on alternating-current magnetic susceptibilities, indicating possible single-molecule magnet behavior.

Slow magnetic relaxation in lanthanide complexes with chelating nitronyl nitroxide radical.

Two rare-earth radical complexes [Ln(hfac)(3)NIT-2Py].0.5C(7)H(16) [Ln = Tb (1), Dy (2)] have been synthesized and characterized structurally as well as magnetically. Both complexes are isomorphous, in which the NIT-2Py radical is coordinated to the Ln(III) ion in a chelating manner. Magnetic studies reveal that complex 1 shows a frequency-dependent, alternating-current magnetic susceptibility typical of a single-molecule magnet, whereas slow magnetic relaxation is observed in 2 under an applied direct-current field.

Bimetallic materials derived from manganese(III) Schiff base complexes and pentacyanidonitrosylferrate(II) precursor: structures and magnetic properties.

Three complexes, [Mn(salphen)(H(2)O)](2)[Fe(CN)(5)(NO)] x 2 CH(3)OH (1) (salphen = N,N'-phenylenebis(salicylideneiminato) dianion), [Mn(naphtmen)(CH(3)OH)](2)[Fe(CN)(5)(NO)] (2) (naphtmen = N,N'-(1,1,2,2-tetramethylethylene)bis(naphthylideneiminato) dianion), and {[Mn(salen)](2)[Fe(CN)(5)(NO)] x H(2)O}(n) (3) (salen = N,N'-ethylene-bis(salicylideneiminato) dianion), were synthesized and structurally characterized by X-ray single-crystal diffraction. The structural analyses show that complexes 1 and 2 consist of the discrete linear trinuclear [Mn(SB)](2)[Fe(CN)(5)(NO)] units (SB = salphen for 1, naphtmen for 2); in complex 3, the nitroprusside anion coordinates to the axial sites of the four [Mn(salen)](+) entities through its four cyano nitrogen atoms, providing a two-dimensional network. The magnetic analysis indicates that the nitroprusside bridging ligand propagates a very weak antiferromagnetic exchange and single-ion anisotropy (D) plays an important role in the overall magnetic properties. Different from complexes 2 and 3, complex 1 shows a typical spin-flop transition with a critical field of 20 kOe.

Spin canting and slow relaxation in a 3D pillared nickel-organic framework.

A 3D nickel-organic framework formulated as {[Ni(2)(fum)(2)(bpt)(2)(H(2)O)] x 3 H(2)O}(n) (1), built from a mixed fumaric ion (fum), 1H-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt), and nickel salt, has been hydrothermally synthesized and characterized. Compound 1, having a Ni-fum chain structure in which the chains are pillared by the bpt spacers in a 3D "brick-wall"-like architecture, exhibits canted antiferromagnetism at 5.0 K. Below this temperature, slow relaxation is observed from the alternating-current susceptibility measurements corresponding to the spin-glass-like behavior.

A porous 3D heterometal-organic framework containing both lanthanide and high-spin Fe(ii) ions.

The first porous 3D [Ln-Fe] heterometal-organic frameworks incorporating high-spin Fe(ii) ions were structurally characterized with fascinating 1D channels and higher thermal stability: the robust frameworks still keep intact on removing free H(2)O or adsorbing C(2)H(5)OH, and the luminescence of [Eu-Fe] complex displays selective detection of Mg(2+).

Four new lanthanide-nitronyl nitroxide (Ln(III) = Pr(III), Sm(III), Eu(III), Tm(III)) complexes and a Tb(III) complex exhibiting single-molecule magnet behavior.

Five new complexes based on rare-earth-radical [Ln(hfac)(3)(NIT-5-Br-3py)](2) (Ln = Pr (1), Sm (2), Eu (3), Tb (4), Tm (5); hfac = hexafluoroacetylacetonate; NIT-5-Br-3py = 2-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)-5-bromo-3-pyridine) have been synthesized and characterized by X-ray crystal diffraction. The single-crystal structures show that these complexes have similar structures, in which a NIT-5-Br-3py molecule acts as a bridging ligand linking two Ln(III) ions through the oxygen atom of the N-O group and nitrogen atom from the pyridine ring to form a four-spin system. Both static and dynamic magnetic properties were measured for complex 4, which exhibits single-molecule magnetism behavior.

The self-assembly and magnetic properties of a Ni(II)8(micro4-hydroxo)6 cube with micro2-pyrazolate as an exogeneous ancillary ligand.

A novel octanuclear hydroxonickel(II) complex possessing a unprecedented cube molecular structure with eight Ni(II) ions at each vertex, six micro4-OH- groups closing each face and twelve exo-bidentate pyrazolate ligands (micro2-pz) spanning each edge, has been synthesized and its magnetic properties investigated.

Template synthesis of lanthanide (Pr, Nd, Gd) coordination polymers with 2-hydroxynicotinic acid exhibiting ferro-/antiferromagnetic interaction.

Lanthanide coordination polymers were synthesized from Pr(III), Nd(III), and Gd(III) salts; 2-hydroxynicotinic acid (Hnica); and MnSO 4.H 2O under hydrothermal conditions. In the absence of (CH 3) 3CCOONa, 1D polymers with an infinite Ln(III)-O-Ln(III) chain structure, [Pr(Hnica)(H 2O) 2SO 4] n ( 1), [Nd(Hnica)(H 2O) 2SO 4] n ( 2), and [Gd(Hnica)(H 2O) 2SO 4] n ( 3), were generated. When (CH 3) 3CCOONa was added to the synthetic systems, 2D coordination polymers {[Pr 3(Hnica) 6(H 2O) 9].3H 2O.SO 4.NO 3} n ( 4), {[Nd 3(Hnica) 6(H 2O) 9].3H 2O.SO 4.NO 3} n ( 5), and {[Gd(Hnica) 2(H 2O) 2]ClO 4.H 2O} n ( 6) were obtained. Complexes 4 and 5 both exhibit Kagome lattice structure, while 6 displays a rhombic grid structure. All complexes were characterized by elemental analysis, IR spectra, UV-vis spectra, and X-ray single-crystal diffraction. The variable-temperature magnetic susceptibility studies reveal ferromagnetic interactions between gadolinium(III) ions in 3 and 6 and antiferromagnetic interactions in 1, 2, 4, and 5.

Structures and magnetic properties of ferromagnetic coupling 2D Ln-M heterometallic coordination polymers (Ln = Ho, Er; M = Mn, Zn).

Four new heterometallic coordination polymers have been successfully synthesized, namely, {[Ho(2)(HCAM)(6)Mn(3)(H(2)O)(12)].17.5H(2)O}(n) (1), {[Er(2)(HCAM)(6)Mn(3)(H(2)O)(12)].17.5H(2)O}(n) (2), {[Ho(2)(HCAM)(6)Zn(3)(H(2)O)(12)].26H(2)O}(n) (3), and {[Er(2)(HCAM)(6)Zn(3)(H(2)O)(12)].26H(2)O}(n) (4) (H(3)CAM = chelidamic acid). X-ray crystallographic studies reveal that coordination polymers 1-4 are isostructural and crystallized in the rhombohedral crystal system, space group R3. These compounds comprise a 2D honeycomb-type framework. A 2D water sheet is first found in 3 and 4, which exhibits a novel topological motif. The magnetic results for 1-4 show that ferromagnetic interactions take place between the Ho(3+)/Er(3+) and Mn(2+) ions within 1 and 2.

Bis{µ-2-[(2-oxidobenzyl-idene)amino-meth-yl]phenolato-κO,N,O'}bis-[(pyridine-κN)zinc(II)].

In the title centrosymmetric zinc(II) complex, [Zn(2)(C(4)H(13)NO(2))(2)(C(6)H(5)N)(2)], each Zn(II) atom is coordinated by two 2-[(2-oxidobenzyl-idene)amino-meth-yl]phenolate (L) ligands and one pyridine (py) mol-ecule in a distorted trigonal-bipyramidal geometry. Each L ligand behaves as a tridentate ligand and provides a phenolate oxygen bridge which links the two Zn(II) atoms. The ZnL(py) units are linked by π-π inter-actions between adjacent pyridine mol-ecules, with a centroid-centroid distance of 3.724 Å, resulting in a two-dimensional structure.

Synthesis, crystal structure, magnetic property and nuclease activity of a new binuclear cobalt(II) complex.

One new binuclear Co(II) complex of N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxyl-1,3-diaminopropane (HL), [Co(2)L(mu(2)-Cl)](ClO(4))(2) x 3CH(3)CN x C(2)H(5)OC(2)H(5) (1), has been synthesized and its crystal structure and magnetic properties are shown. In 1, each Co(II) atom has a distorted trigonal bipyramidal geometry with a N(3)OCl donor set. The central two Co(II) atoms are bridged by one alkoxo-O atom and one Cl atom with the Co1-Co2 separation of 3.239 A. Susceptibility data of 1 indicate strong intramolecular antiferromagnetic coupling of the high-spin Co(II) atoms. In this paper, the interaction with calf thymus DNA was investigated by UV absorption and fluorescent spectroscopy. Results show the complex binds to ct-DNA with a intercalative mode. The interaction between complex 1 and pBR322 DNA has also been investigated by submarine gel electrophoresis, noticeably, the complex exhibits effective DNA cleavage activity in the absence of any external agents.

Slow magnetic relaxation based on the anisotropic Ising-type magnetic coupling between the MoIII and MnII centers.

Three new complexes containing MnMoIII zigzag chains have been synthesized and structurally characterized. The crystal structure of complex 3 consists of two linkage isomers of the MoIIIMn chains, which correspond to 1 and 2, respectively. Both complex 1 and 3 show slow magnetic relaxation behavior with an energy barrier of Δ/kB = 69.5 K and 68.8 K, respectively, whereas complex 2 is a simple paramagnet. The linear apical MoIII-CN-MnII pairs provide the required magnetic anisotropy for the slow magnetic relaxation.

A novel 3D porous metal-organic framework based on trinuclear cadmium clusters as a promising luminescent material exhibiting tunable emissions between UV and visible wavelengths.

A novel 3D porous MOF built with trinuclear cadmium clusters exhibiting rhombohedral topology has been synthesized and characterized as a promising luminescent material that can give tunable emissions between UV and visible wavelengths by controlling the number of guest molecules.

Structure and magnetic properties of a new ferrimagnet containing a paramagnetic [Cr(CN)5(NO)]3- building block.

A new Prussian-blue type molecular magnet containing a paramagnetic [Cr(CN)5(NO)]3- building block has been synthesized and characterized; the observed magnetic behavior displays the nature of a ferrimagnet.

Two mononuclear single molecule magnets derived from dysprosium(III) and tmphen (tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline).

Two mononuclear Dy(III) complexes, [Dy(III)(hfac)3(tmphen)] (1) and [Dy(III)(acac)3(tmphen)]·2H2O (2) (tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline, hfac = hexafluoroacetylacetone, acac = acetylacetone) have been synthesized and structurally characterized by single crystal X-ray diffraction. Magnetic properties indicate that both of the complexes exhibit SMM behavior, and complex 1 is the first typical derivative of phenanthroline containing D2d-Dy(III) based mononuclear single molecule magnets. The energy barrier (Ueff/kB) of complex 2 (130.42 K) is much higher than that of complex 1 (35.09 K), indicating that the local symmetry of Dy(III) ions (D2d for 1, D4d for 2) plays an important role in magnetic behaviors.

First tetrameric NiII cluster with planar triangular topology exhibiting ferromagnetic pathways.

[Ni4L3(H2O)2](ClO4)2.2H2O 1, the first tetranuclear NiII cluster showing triangle planar geometry, formed with a new carboxylic-functionalized 1,5-diazacyclooctane bridging ligand has been presented; the global magnetic coupling is ferromagnetic and anisotropic calculations have been made.