Lanthanide(III)-cobalt(II) heterometallic coordination polymers with radical adsorption properties.

Two new coordination polymers {[Ln(2)(PDA)(6)Co(3)(H(2)O)(6)] x xH(2)O}(n) [Ln = Nd, x = 7 (1); Ln = Gd, x = 3.25 (2); H(2)PDA = pyridine-2,6-dicarboxylic acid] have been prepared under hydrothermal conditions with Ln(NO(3))(3) x 6H(2)O, CoO, and H(2)PDA in a molar ratio of 2:3:6. X-ray crystallographic analyses reveal that they crystallize in the hexagonal group P6/mcc and exhibit a nanotubular 3D framework. The adsorption experiment shows that 1 and 2 can adsorb radicals, which is proven by electron paramagnetic resonance spectra with the characteristic bands of the radicals at g = 2.006 and 2.005, respectively.

Heteronuclear complexes of macrocyclic oxamide with co-ligands: syntheses, crystal structures, and magnetic properties.

Four heteronuclear complexes Mn(CuL)2(SCN)2 (1), {[Mn(CuL)2(mu-dca)2].2H2O}n (2), Zn(CuL)2(SCN)2 (3), and [Fe(CuL)(N3)2]2 (4) incorporating macrocyclic oxamide ligands have been synthesized and structurally characterized. L is the dianion of diethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]-tetraazacyclotetradecine-13,18-dicarboxylate, and dca is the dicyanamide. The structure of 1 or 3 consists of oxamido-bridged trinuclear [MIICuII2] molecules (for 1, M is the manganese(II) ion, and for 3, M is the zinc(II) ion). Both of them consist of 1D supramolecuar chains via pi-pi interactions. The structure of 2 also has the oxamido-bridged trinuclear [MnIICuII2] structure units and consists of 2D layers formed by the linkage of copper(II) and manganese(II) atoms via the oxamido and mu1, 5-dca bridges. Complex 4 consists of oxamido-bridged tetranuclear [FeII2CuII2] molecules and arranges in 1D chains. Different co-ligands may result in different structures in this macrocyclic oxamide system. The variable-temperature magnetic susceptibility measurements (2-300 K) of 1 and 2 both show the pronounced antiferromagnetic interactions between the copper(II) and manganese(II) ions.

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.

Synthesis of a series of 4-pyridyl-1,2,4-triazole-containing cadmium(II) luminescent complexes.

Using two 4-substitued triazole ligands, 4-(pyrid-2-yl)-1,2,4-triazole (L(1)) and 4-(pyrid-3-yl)-1,2,4-triazole (L(2)), a series of novel triazole-cadmium(II) complexes varying from zero- to three-dimensional have been prepared and their crystal structures determined via single-crystal X-ray diffraction. [Cd(2)(micro(2)-L(1))(3)(L(1))(2)(NO(3))(mu(2)-NO(3))(H(2)O)(2)](NO(3))(2).1.75H(2)O (1) is a binuclear complex containing bidendate, monodedate and free nitrate anions. When the bridging anions SCN(-) and dca (dca = N(CN)(2)(-)) were added to the reaction system of 1, one-dimensional (1D) [Cd(L(1))(2)(NCS)(2)](n) (2) and two-dimensional (2D) [Cd(L(1))(2)(dca)(2)](n) (3) were isolated, respectively. When L(2) instead of L(1) was used, [Cd(L(2))(2)(NCS)(2)(H(2)O)(2)] (4) and 1D [Cd(L(2))(2)(dca)(2)](n) (5) were obtained. When the ratio of Cd to L(2) was changed from 1:2 to 1:1 in the reaction system of 5, three-dimensional (3D) {[Cd(3)(micro(2)-L(2))(3)(dca)(6)].0.75H(2)O}(n) (6) with 1D microporous channels along the a direction was isolated. Further investigations on other Cd(ii) salts and the L(2) ligand in a Cd to L(2) ratio of 1:1, an unexpected complex [Cd(mu(2)-L(2))(mu(3)-SO(4))(H(2)O)](n) (7) with a 3D open framework was obtained. All of the complexes exhibit strong blue fluorescence emission bands in the solid state at ambient temperature, of which the excitation and emission maxima are red-shifted to longer wavelength as compared to those in water. Powder X-ray diffraction and thermal studies were used to investigate the bulk nature of the 3D coordination polymers 6 and 7.

Structure of an I- x (H2O)6 anion cluster in a 3D anion crystal host [I x (H2O)6Fe(CN)6 x H2O]4-.

A planar structure of an anion cluster I- x (H2O)6 in a 3D supramolecular complex [Ru(bpy)3]2[I x (H2O)6Fe(CN)6 x H2O] has been determined by single-crystal X-ray analysis. In the supramolecule, the anion cluster I- x (H2O)6, together with the anion [Fe(CN)6 x H2O]2-, acts as a 3D crystal host, and the [Ru(bpy)3]2+ cations, as the guest molecules, occupy the vacancies of the 3D host framework. This is the first crystal example of the anion cluster I- x (H2O)6.

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.

A promising Mg(II)-ion-selective luminescent probe: structures and properties of Dy-Mn polymers with high symmetry.

Two Dy-Mn polymers, {[Dy(L1)3Mn(1.5)(H2O)3]3.125H2O}n (1, L1 = pyridine-2,6-dicarboxylic acid) and {[Dy(L2)3Mn(1.5)(H2O)6]8.25H2O}n (2, L2 = 4-hydroxylpyridine-2,6-dicarboxylic acid), with high symmetry (S6) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 A diameter, while 2 has a honeycomb-type 2D structure with the cavity of approximately 14.4 A diameter. In the construction of multidimensional porous polymers with 3d-4f mixed metals, it is the first observation that a ligand substituent effect leads to dramatic differences in the structures formed. Luminescent studies reveal that the emission intensities of 1 and 2 increase significantly upon the addition of Mg2+, whereas the introduction of other metal ions leaves the intensity unchanged or even weakens it; hence, both of them may serve as good candidates of Mg2+ luminescent probes. To our knowledge, complex 1 is also the first example of a 3d-4f metal-based nanoporous polymer to exhibit luminescent selectivity for Mg2+. Magnetic susceptibility measurements reveal a rather rare ferromagnetic interaction in 2. Thermal gravimetric analyses and powder X-ray diffraction investigations have also been performed, suggestive of high thermal stability of 1.

Synthesis, crystal structures, and properties of oxovanadium(IV)-lanthanide(III) heteronuclear complexes.

A new series of oxovanadium(IV)-lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)](3)21 H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)} 8.5 H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)}8.5 H2O (3), {[Eu(H2O)7][(VO)2(TTHA)](1.5)} 10.5 H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H(6)TTHA as structure-directing agent. X-ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2- unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2- ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2- ion. Compound 4 is an extended one-dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2- ions. For 5, the structure is further assembled into a three-dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV)-lanthanide(III) coordination polymers and thus enlarge the realm of 3d-4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions.

Effect of the semirigid capping ligand on the structure formation of cyano-bridged bimetallic assemblies: syntheses, crystal structures, and magnetic properties.

The syntheses, crystal structures, and magnetic properties of three novel cyano-bridged bimetallic assemblies, [Ni(bpm)(2)](3)[Co(CN)(6)](2)x3.5H(2)O (1), [Co(bpm)(2)][Fe(CN)(5)NO]x2H(2)O (2), and [Co(bpm)(2)][Ni(CN)(4)] (3) (bpm = bis(1-pyrazolyl)methane), are reported. Complex 1 crystallizes in the tetragonal space group P4(3)2(1)2 with a = 12.800(5) A, b = 12.800(5) A, c = 42.80(3) A, V = 7012(6) A(3), and Z = 8. Complex 2 crystallizes in the chiral trigonal space group P3(2)21 with a = 11.9961(19) A, b = 11.9961(19) A, c = 16.062(5) A, gamma = 120 degrees , V = 2001.7(8) A(3), and Z = 3. Complex 1 is a trigonal bipyramidal complex in which three [Ni(bpm)(2)](2+) units are situated in the equatorial plane and are connected to the two apical [Co(CN)(6)](3)(-) units via three N ends of the cyanide groups. Complex 2 possesses a triangular left-handed helical chain structure composed of [Co(bpm)(2)](2+) linked by [Fe(CN)(5)NO](2)(-); the shortest intramolecular Co...Fe distance is 5.162 A. To the best of our knowledge, this is the first observation of a heteronuclear helical chain structure based on pentacyanonitrosylferrate(II). The structure of complex 3 is roughly determined by X-ray crystallograhy analysis to be a 1D zigzag chain. These structure variations, from a discrete cluster to a 1D helical chain and a 1D zigzag chain, rely on the semirigidity of the capping ligand bpm. Magnetic susceptibility measurements indicate that complex 1 has an intramolecular ferromagnetic interaction (J = 4.06 cm(-)(1)) between the nickel(II) ions; this is further confirmed by the magnetization measurements. In complexes 2 and 3, the cobalt(II) ions are located in a moderately strong field.

Systematic investigation of the hydrothermal syntheses of Pr(III)-PDA (PDA = pyridine-2,6-dicarboxylate anion) metal-organic frameworks.

A series of novel two-dimensional (2D) and three-dimensional (3D) praseodymium coordination polymers, namely, {[Pr3(PDA)4(HPDA)(H2O)8] x 8H2O}n (2), {[Pr2(PDA)3(H2O)3] x H2O}n (3), {[Pr(PDA)(H2O)4] x ClO4}n (4), and { [Pr2(PDA)2(H2O)5SO4] x 2H2O}n (5) (PDA = pyridine-2,6-dicarboxylic anion), was designed and synthesized under hydrothermal conditions. Complexes 1-3 (chainlike polymer, {[Pr(PDA)(HPDA)(H2O)2] x 4H2O}n (1) was also obtained independently by us, although it has been reported recently by Ghosh et al.) were fabricated successfully by simply tuning the Pr/PDA ratio and exhibited various and intriguing topological structures from a 1D chain to a 3D network. While the synthetic strategy of 5 was triggered and further performed only after 1 was structurally characterized. The complexes were characterized by X-ray single-crystal determination, spectroscopic, and variable-temperature magnetic susceptibility analyses. In complex 2 an unusual nanosized square motif as a building block constructed by eight Pr ions was further assembled into a highly ordered 2D grid compound. In complex 3 the decanuclear Pr metal-based structure as a repeat unit interpenetrated to form a novel 3D polymer. Complex 4 was a 3D network polymer fabricated through a hexanuclear Pr ring as a building block, and ClO4- anions as guests were trapped in the cavity. In complex 5 six Pr atoms, two SO4(2-) anions, and carboxylic oxygen bridges constructed an intriguing rectangle structure as a repeat unit in the grid to form a 2D coordination polymer in which the unique bi-bidentate coordination mode of SO4(2-) anion was observed.

Coordination polymers containing 1D channels as selective luminescent probes.

Two 3d-4f heterometallic coordination polymers {[Ln(PDA)3Mn1.5(H2O)3].3.25H2O}infinity with 1D channels were synthesized under hydrothermal conditions (PDA = pyridine-2,6-dicarboxylic acid; Ln = Eu (1); Ln = Tb (2)). The emission intensities of 1 and 2 increased significantly upon addition of Zn2+, while the introduction of other metal ions caused the intensity to be either unchanged or weakened. The case implies that 1 and 2 may be used as luminescent probes of Zn2+.

[CoAu2(CN)4(NITpPy)2(H2O)2]n: a new 2-D interdigitating complex containing dicyanoaurate(I) anion, a radical, and cobalt(II) ion incorporating gold...gold and hydrogen bonding interactions.

A novel complex, [[CoAu2(CN)4(NITpPy)2(H2O)2]]n, 1, containing the cobalt(II) ion, dicyanoaurate(I) anion, and nitronyl nitroxide radical building blocks, has been prepared and structurally characterized by single-crystal X-ray analysis. The structure of complex 1 illustrates that aurophilicity and hydrogen bonding interactions increase dimensionality, generating a 2-D interdigitating system. The spectroscopic and magnetic properties have been investigated.

A Prussian-blue type ferrimagnet Na[MnCr(CN)6]: single crystal structure and magnetic properties.

A novel Prussian-blue type ferrimagnet Na[MnCr(CN)(6)] has been prepared and characterized by single crystal X-ray analysis and magnetic measurements. The complex has a face-centered cubic lattice and shows ferrimagnetic ordering below 60 K.

Spectroscopic properties, catalytic activities and mechanism studies of [(TpPh)Co(X)(CH3OH)m] . nCH3OH: bicarbonate dehydration in the presence of inhibitors.

Two inhibitor-containing 'half-sandwich' cobalt(II) complexes [(TpPh)Co(X)(CH3OH)m] x nCH3OH ((TpPh) = hydrotris (3-phenylpyrazolyl)borate; 1: X- = N3-, m = 1, n = 2; 2: X- = NCS-, m = 0, n = 0) have been synthesized and used as the catalysts in the bicarbonate dehydration reaction. The structures of 1 and 2 were determined by X-ray diffraction analysis, which shows that N3- and NCS- coordinate to the Co(II) ions of 1 and 2, respectively, with the Co-N bond lengths of 1.992(6) A and 1.901(3) A. The coordination geometries of the Co(II) complexes in solution are five-coordinated trigonal bipyramid as revealed by the spectroscopic measurements. The dehydration kinetic measurements of HCO3- are performed by the stopped-flow techniques at pH < 7.9. The apparent dehydration rate constant k(obs) varies linearly with Co(II) complex and H+ concentrations, respectively, and the catalytic activity of 2 is lower than that of 1. The aqua Co(II) complex must be the reactive catalytic species in the catalyzed dehydration reaction and the rate-determining step is the substitution of the labile water molecule by HCO3-. The k(obs) values increase with increasing reaction temperature, and the large negative entropy of activation also indicates the associative activation mode. The inhibition ability of NCS- is stronger than that of N3-, which can be rationalized by the decreases in the Co-N(N3-/NCS-) bond lengths and effective atomic charges of the Co(II) ions based on the X-ray crystallographic data and theoretical calculations in this work.

Novel triazole-bridged cadmium coordination polymers varying from zero- to three-dimensionality.

Cadmium salts with different triazole ligands have led to a series of novel triazole-cadmium compounds varying from zero- to three-dimensionality. [Cd(2)(deatrz)(2)(H(2)O)Br(4)] (1) (deatrz = 3,5-diethyl-4-amino-1,2,4-triazole) is a zero-dimensional complex which uses a triazole ligand together with micro-OH(2) as bridges to form a 1D chain via hydrogen-bonding contacts. [[Cd(3)(deatrz)(2)Cl(6)(H(2)O)(2)].2H(2)O](n) (2), [[Cd(dmtrz)Cl(2)].1.5H(2)O](n)(3) (dmtrz = 3,5-dimethyl-1,2,4-triazole), and [[Cd(3)(deatrz)(4)Cl(2)(SCN)(4)].2H(2)O](n)(4) are polymeric 1D chains. 2 and 4 were constructed via trinuclear cadmium units bridged by triazole ligands and chloride atoms, while 3 consists of micro(2)-Cl, micro(3)-Cl, and triazole bridges, cross-linked by hydrogen bonding to give a 3D framework. [[Cd(3)(dmatrz)(4)(SCN)(6)]](n)(5) (dmatrz = 3,5-dimethyl-4-amino-1,2,4-triazole) shows a two-dimensional structure whose fundamental units are trinuclear metal cations bridged via triazole ligands. The complex [[Cd(dmtrz)(SCN)(2)]](n)(6) is the first three-dimensional example in N1,N2-didentate-bridged triazole-metal compounds. Six complexes exhibit six types of bridging modes of N1,N2-triazole in combination with single-atom bridges. 2, 4, and 5 are the unprecedented examples of polymeric chains and planes constructed via trinuclear metal ion clusters, whereas 3 is the first example of the micro(3)-Cl bridging mode in triazole-metal complexes. We have briefly discussed the variety of dimensionalities based on the tuning of different organic ligands and anions.

3D porous and 3D interpenetrating triple framework structures constructed by aurophilicity-coordination interplay in [Mn[Au(CN)2]2(H2O)2]n and [KFe[Au(CN)2]3]n.

Two cyano-bridged heterobimetallic coordination polymers [Mn[Au(CN)2]2(H2O)2]n (1) and [KFe[Au(CN)2]3]n (2), have been synthesized from [Au(CN)2]- building blocks and structurally characterized. In both complexes aurophilicity play an important role in determining the 3D open microporous framework and the interpenetrating triple framework for 1 and 2, respectively. Both aqueous solutions of 1 and 2 display interesting luminescent properties.

The first azide(mu1,1)-bridged binuclear cobalt(II)-imino nitroxide complex with ferromagnetic behavior.

The first azide(mu1,1)-bridged binuclear cobalt(II) complex with a chelated imino nitroxide radical, [Co2(immepy)2(N3)(4)].2EtOH, was structurally and magnetically characterized, where immepy = 4,4,5,5-tetramethyl-2-(6'-methyl-2'-pyridyl) imidazoline-1-oxyl. Five nitrogen atoms complete the coordination sphere of the Co(II) ion, showing a distorted trigonal bipyramid geometry. Two N(3)(-) anions act as bridges between cobalt ions in the mu1,1 coordination mode, resulting in a binuclear structure with an inversion center. Magnetic studies show that ferromagnetic couplings occurred between the adjacent cobalt(II) ions through N3(-)(mu1,1)) bridges, and antiferromagnetic couplings between the cobalt(II) ions and organic radicals.

The first mu3-oxalato-bridged copper complex with tridentate Schiff base ligand N-ethyl-N'-salicylidene-1,2-diaminoethane: synthesis, structure, and magnetic properties.

The first mu(3)-oxalato-bridged copper(II) complex, [[Cu(3)(L)(3)(mu(3)-C(2)O(4))][Cu(L)(H(2)O)](ClO(4))(2)] x 0.5(H(2)O) x 0.5(CH(3)OH), where HL = N-ethyl-N'-salicylidene-1,2-diaminoethane, has been synthesized and characterized by variable-temperature magnetic susceptibility measurement. The complex exhibits ferromagnetic coupling between the oxalato-bridged copper atoms and antiferromagnetic coupling between the oxygen-bridged copper atoms.

Kinetic study of the effects of inhibitors on the catalyzed dehydration of HCO3- by copper(II) complexes [TpPh]CuX (X- = OH-, N3-, NCS-).

A series of half-sandwich copper(II) complexes [TpPh]CuX ([TpPh] = hydrotris(3-phenyl-pyrazolyl)borate; X- = OH- (1), N3- (2), NCS- (3)) have been synthesized as models for carbonic anhydrase. The structure of 3 was determined by X-ray diffraction analysis. Crystals of 3 (C37H30BCuN9S) are triclinic, space group P1 with a = 11.997(3) A, b = 12.116(3) A, c = 13.384(4) A, alpha = 81.088(5) degrees, beta = 79.289(6) degrees, gamma = 68.668(5) degrees, V = 1772.4(8) A3, and Z = 2. The dehydration kinetic measurements of HCO3- are performed by the stopped-flow techniques at pH < 7.9. The apparent dehydration rate constant kdobs varies linearly with total Cu(II) concentration, and the catalytic activity of the model complexes decreases in the order 1 > 2 > 3. The catalytic activity decreases with increasing pH indicating that the aqua model complex must be the reactive catalytic species in the catalyzed dehydration reaction and the rate-determining step is the substitution of the labile water molecule by HCO3-. The kdobs values increase with increasing reaction temperature, and the apparent activation energies of the model complexes with inhibitors are remarkably higher than that of the complex with no inhibitors, this being the origin of inhibition. The large negative entropy of activation also indicates an associative mode of activation in the rate-determining step. The inhibition ability of the inhibitor NCS- is stronger than that of the inhibitor N3-, which can be rationalized by the decrease in effective atomic charges of the Cu(II) ions as revealed by the theoretical calculations.

A ferromagnetically coupled CrCu3 tetramer and GdCu4 pentamer with a [15]N4 macrocylic ligand incorporating an oxamido bridge.

The synthesis and structural and magnetic properties of heteropolynuclear complexes [(L(3)Cu)(3)Cr](CH(3)CN)(3)(ClO(4))(3) (2) and [(L(3)Cu)(4)Gd.H(2)O](CH(3)OH)(H(2)O)(ClO(4))(3) (3) (H(2)L(3) ligand is 2,3-dioxo-5,6:14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,12-diene) and their precursor L(3)Cu (1) are presented. Complex 2 crystallizes in space group P2(1)/n with cell parameters a = 20.828(6) A, b = 18.321(5) A, c = 7.578(5) A, alpha = 90 degrees, beta = 91.990(8) degrees, gamma = 90 degrees, and Z = 4. The Cr(III) center is coordinated by six oxygen atoms from three Cu(II) precursors. The Cr-O bonds range over 1.948-1.982 A. The coordination environments of all the terminal Cu(II) ions change in comparison with their Cu(II) precursor. The ferromagnetic coupling (J = 16.48(1) cm(-)(1)) observed for 2 can be rationalized by symmetry considerations. For any pair of interacting magnetic orbitals, strict orthogonality is obeyed and the interaction is ferromagnetic. Complex 3 crystallizes in space group P1 with cell parameters a = 14.805(4) A, b = 16.882(5) A, c = 17.877(5) A, alpha = 75.403(5) degrees, beta = 83.317(6) degrees, gamma = 70.600(5) degrees, and Z = 2. The central Gd(III) assumes an 8 + 1 coordination environment, namely eight oxygen atoms from four Cu(II) precursors and one oxygen atom from H(2)O. The fit of the experimental data gives J = 0.27(2) cm(-)(1), g(Gd) = 1.98(1), and g(Cu) = 2.05(1). This small and positive J value shows weak ferromagnetic interaction between metal ions.