Synthesis, crystal structure and magnetic properties of a one-dimensional Mn2+ complex constructed from (+)-dibenzoyltartaric acid and 2,2'-bipyridine.

The self-assembly reaction of (+)-dibenzoyltartaric acid (D-H2DBTA) with 2,2'-bipyridine (bpy) and Mn(CH3CO2)2·4H2O yielded a new coordination polymer, namely, catena-poly[[[diaqua(2,2'-bipyridine-κ2N,N')manganese(II)]-µ-2,3-bis(benzoyloxy)butanedioato-κ2O2:O3] dihydrate], {[Mn(C18H12O8)(C10H8N2)(H2O)2]·2H2O}n or {[Mn(DBTA)(bpy)(H2O)2]·2H2O}n, (I). Complex (I) has been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA) and single-crystal and powder X-ray diffraction. It crystallizes in the orthorhombic space group P212121. In the complex, the Mn2+ cation displays a distorted octahedral {MnO4N2} geometry, formed from two carboxylate O atoms of two DBTA2- ligands, two cis-oriented N atoms from one chelating 2,2'-bipyridine ligand and two trans-oriented O atoms from coordinated water molecules. The polymer displays a 1D chain with an Mn...Mn distance of 9.428 (1) Å. Due to the presence of flexible polycarboxylate and rigid bipyridyl ligands in the molecular structure, a high thermal stability of the complex is attained. The magnetic properties of (I) were analyzed based on the mononuclear Mn2+ model due to the long intramolecular Mn...Mn distance. The zero field splitting (ZFS) contribution in the high-spin Mn2+ cation is almost negligible and there are weak antiferromagnetic couplings between 1D chains [zJ' = -0.062 (5) cm-1], corresponding to an intermolecular Mn...Mn distance of 7.860 (2) Å.

Synthesis, structure and magnetocaloric properties of a new two-dimensional gadolinium(III) coordination polymer based on azobenzene-2,2',3,3'-tetracarboxylic acid.

A new Gd3+ coordination polymer (CP), namely, poly[diaqua[µ4-1'-carboxy-3,3'-(diazene-1,2-diyl)dibenzene-1,2,2'-tricarboxylato]gadolinium(III)], [Gd(C16H7N2O8)(H2O)2]n, (I), has been synthesized hydrothermally from Gd(NO3)3·6H2O and azobenzene-2,2',3,3'-tetracarboxylic acid (H4abtc). The target solid has been characterized by single-crystal and powder X-ray diffraction, elemental analysis, IR spectroscopy and susceptibility measurements. CP (I) crystallizes in the monoclinic space group C2/c. The structure features a 4-connected topology in which Gd3+ ions are connected by carboxylate groups into a linear chain along the monoclinic symmetry direction. Adjacent one-dimensional aggregates are bridged by Habtc3- ligands to form a two-dimensional CP in the (10-1) plane. A very short hydrogen bond [O...O = 2.4393 (4) Å] links neighbouring layers into a three-dimensional network. A magnetic study revealed antiferromagnetic Gd...Gd coupling within the chain direction. CP (I) displays a significant magnetocaloric effect (MCE), with a maximum -ΔSm of 27.26 J kg-1 K-1 for ΔH = 7 T at 3.0 K. As the MCE in (I) exceeds that of the commercial magnetic refrigerant GGG (Gd3Ga5O12, -ΔSm = 24 J kg-1 K-1, ΔH = 30 kG), CP (I) can be regarded as a potential cryogenic material for low-temperature magnetic refrigeration.

An ultra-sensitive selective fluorescent sensor based on a 3D zinc-tetracarboxylic framework for the detection and enrichment of trace Cu2+ in aqueous media.

Herein, a novel and fluorescent zinc-organic framework sensor [Zn3(µ3-Hbptc)2(µ2-4,4'-bpy)2(H2O)4]n·2nH2O (1) (H4bptc = 2,3,3',4'-biphenyl tetracarboxylic acid, 4,4'-bpy = 4,4'-bipyridine) is synthesized and characterized, demonstrating its excellent fluorescence performance for Cu2+ detection and the enrichment of Cu2+ in aqueous media. The fluorescence intensity of 1 can be selectively quenched by Cu2+ in a linear range of Cu2+ concentrations of 0-0.7 µM. The limit of detection (LOD) value is as low as 32.4 nM, which is superior to those of most of the fluorescent sensors based on metal-organic frameworks (MOFs). It is also far below the maximum allowable concentration of Cu2+ in drinking water as defined by the U.S. Environmental Protection Agency (EPA) and the World Health Organization (WHO), so it is employed for the detection of Cu2+ in actual water samples. More importantly, the nature of the interaction between the active coordination site (COO-) of 1 and Cu2+ determines the quenching mechanism, that is Cu2+ in the analyte is captured by MOF 1, which has been investigated by ICP, luminescence, UV-vis, XPS, and lifetime studies. Besides, the chemosensor shows regeneration performance without the loss of performance in five consecutive cycles. So MOF 1 is a simple and convenient probe used not only for the rapid detection but also for the enrichment of trace amounts of Cu2+ in aqueous media, and the application can be further extended to a variety of environmental and biological analysis processes.

Luminescent and magnetic bifunctional coordination complex based on a chiral tartaric acid derivative and europium.

A new mononuclear europium complex incorporating the (+)-di-p-toluoyl-D-tartaric acid (D-H2DTTA) ligand, namely, catena-poly[tris{µ2-3-carboxy-2,3-bis[(4-methylphenyl)carbonyloxy]propanoato}tris(methanol)europium(III)], [Eu(C20H17O8)3(CH3OH)3]n, (I), has been synthesized and characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction and single-crystal X-ray diffraction analysis. The structure analysis indicates that complex (I) crystallizes in the trigonal space group R3 and exhibits an infinite one-dimensional chain structure, in which the Eu3+ ion is surrounded by six O atoms from six D-HDTTA- ligands and three O atoms from three coordinated methanol molecules, thus forming a tricapped trigonal prism geometry. The D-H2DTTA ligand is partially deprotonated and adopts a µ1,6-coordination mode via two carboxylate groups to link adjacent Eu3+ ions, affording an infinite one-dimensional propeller-shaped coordination polymer chain along the c axis, with an Eu...Eu distance of 7.622 (1) Å. Moreover, C-H...π interactions lead to the formation of helical chains running along the c axis and the whole structure displays a snowflake pattern in the ab plane. The circular dichroism spectrum confirms the chirality of complex (I). The solid-state photoluminescence properties were also investigated at room temperature and (I) exhibits characteristic red emission bands derived from the Eu3+ ion (CIE 0.63, 0.32), with a reasonably long lifetime of 0.394 ms, indicating effective energy transfer from the ligand to the metal centre. In addition, a magnetic investigation reveals single-ion magnetic behaviour. The spin-orbit coupling parameter (λ) between the ground and excited states is fitted to be 360 (2) cm-1 through Zeeman perturbation. Therefore, complex (I) may be regarded as a chiral optical-magneto bifunctional material.

Inhibition of MSK1 Promotes Inflammation and Apoptosis and Inhibits Functional Recovery After Spinal Cord Injury.

Mitogen- and stress-activated kinase (MSK) 1 is a nuclear serine/threonine kinase. In the central nervous system, it plays an important role in regulating cell proliferation and neuronal survival; it is also involved in astrocyte inflammation and the inhibition of inflammatory cytokine production. However, its specific role in spinal cord injury is not clear. Here, we aimed to elucidate this role using an in vivo animal model. In this study, we found that MSK1 is gradually decreased, starting 1 day after spinal cord injury and to its lowest level 3 days post-injury, after which it gradually increased. To further investigate the possible function of MSK1 in spinal cord injury, we interfered with its expression by utilizing a small interfering RNA (siRNA)-encoding lentivirus, which was injected into the injured spinal cord to inhibit local expression. After MSK1 inhibition, we found that the expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1ß were increased. Moreover, the expression of IL-10 was decreased. In addition, neuronal apoptotic cells were increased significantly and expression of the apoptosis-related protein caspase-3 was also increased. Ultrastructural analysis of nerve cells also revealed typical neuronal apoptosis and severe neuronal damage. Finally, we found that hindlimb motor function decreased significantly with MSK1 knockdown. Therefore, our findings suggest that the inhibition of this protein promotes inflammatory responses and apoptosis and suppresses functional recovery after spinal cord injury. MSK1 might thus play an important role in repair after spinal cord injury by regulating inflammation and apoptosis.

Three chiral one-dimensional lanthanide-ditoluoyl-tartrate bifunctional polymers exhibiting luminescence and magnetic behaviors.

Since Ln-CPs have excellent optical properties (higher color purity, longer fluorescence lifetime and higher quantum yield) and magnetic properties, it is of great significance to prepare dual magneto-optical materials based on Ln(iii). Herein, we obtained three versatile Ln-CPs, [Ln(HDTTA)3(CH3OH)3] n , derived from reactions of lanthanide salts (Ln = Tb 1, Dy 2, Ho 3) and a chiral and flexible ligand, namely, (+)-di-p-toluoyl-d-tartaric acid (d-H2DTTA) in a methanol-water solution, at room temperature and pressure. The structures of these compounds have been characterized by single crystal and powder X-ray diffraction, infrared spectroscopy, elemental analyses and thermogravimetric analyses. Complexes 1-3 are isomorphic, crystallizing in the chiral trigonal R3 space group with the linkage of Ln3+ ions and featuring 1D propeller chain structures. The circular dichroism spectra confirm that the complexes maintain the chirality from the ligands. Furthermore, the luminescent and magnetic properties have been investigated, relying on intrinsic properties of the lanthanide ions. The photoluminescence measurements indicate that 1, 2 and 3 show strong green, white and blue emission bands with CIE chromaticity coordinates of (0.32, 0.56), (0.29, 0.26) and (0.21, 0.12), respectively. The decay lifetime curve of 1 shows the exponential decay with long lifetime of 1.169 ms and the relative quantum yield for 1 was 19.31%. In addition, the magnetic properties of complexes 1-3 have been investigated by measuring the magnetic susceptibility in the temperature range of 2-300 K. They are all dominated by spin-orbit coupling and ligand field perturbation, and the exchange coupling between Ln3+ ions is almost negligible. Therefore, complexes 1-3 are promising chiral, optical and magnetic multifunctional materials.

Irreversible solvent-assisted structural transformation in 3D metal-organic frameworks: Structural modification and enhanced iodine-adsorption properties.

In this work, we demonstrate a solvent-assisted structural transformation between two 3D metal-organic frameworks (MOFs) ([Zn4(α-bptc)2(H2O)3]n (1) → {[Zn2(α-bptc)(H2O)4]·(pra)}n (2)) (α-H4bptc = 2,3,3',4'-biphenyl tetra-carboxylic acid and pra = pyridin-2-amine) at room temperature by immersing complex 1 in a mother solution. The structural transformation involves not only solvent exchange but also the cleavage and formation of coordination bonds, which is confirmed by infrared spectroscopy, single-crystal X-ray diffraction analysis, powder X-ray diffraction patterns, and thermogravimetric analysis. Structural analyses revealed that significant modifications occurred during the transformation including the changes in lattice parameters, unit cell volume, space group, coordination number, secondary building units, and topological type. In the case of drastic structural transitions, significant changes in properties were also observed. Complex 2 displayed the interesting uptake and release of iodine with the changes in visible color, UV and fluorescence spectra, and fully reversible I2 uptake of 8.5 mg g-1, which further suggested about its future application as iodine absorbing material.

A two-dimensional mixed-valence Cu(II)/Cu(I) coordination polymer constructed from 2-(pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate.

Coordination polymers are a thriving class of functional solid-state materials and there have been noticeable efforts and progress toward designing periodic functional structures with desired geometrical attributes and chemical properties for targeted applications. Self-assembly of metal ions and organic ligands is one of the most efficient and widely utilized methods for the construction of CPs under hydro(solvo)thermal conditions. 2-(Pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate (HPIDC(2-)) has been proven to be an excellent multidentate ligand due to its multiple deprotonation and coordination modes. Crystals of poly[aquabis[µ3-5-carboxy-2-(pyridin-3-yl)-1H-imidazole-4-carboxylato-κ(5)N(1),O(5):N(3),O(4):N(2)]copper(II)dicopper(I)], [Cu(II)Cu(I)2(C10H5N3O4)2(H2O)]n, (I), were obtained from 2-(pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic acid (H3PIDC) and copper(II) chloride under hydrothermal conditions. The asymmetric unit consists of one independent Cu(II) ion, two Cu(I) ions, two HPIDC(2-) ligands and one coordinated water molecule. The Cu(II) centre displays a square-pyramidal geometry (CuN2O3), with two N,O-chelating HPIDC(2-) ligands occupying the basal plane in a trans geometry and one O atom from a coordinated water molecule in the axial position. The Cu(I) atoms adopt three-coordinated Y-shaped coordinations. In each [CuN2O] unit, deprotonated HPIDC(2-) acts as an N,O-chelating ligand, and a symmetry-equivalent HPIDC(2-) ligand acts as an N-atom donor via the pyridine group. The HPIDC(2-) ligands in the polymer serve as T-shaped 3-connectors and adopt a µ3-κ(2)N,O:κ(2)N',O':κN''-coordination mode, linking one Cu(II) and two Cu(I) cations. The Cu cations are arranged in one-dimensional -Cu1-Cu2-Cu3- chains along the [001] direction. Further crosslinking of these chains by HPIDC(2-) ligands along the b axis in a -Cu2-HPIDC(2-)-Cu3-HPIDC(2-)-Cu1- sequence results in a two-dimensional polymer in the (100) plane. The resulting (2,3)-connected net has a (12(3))2(12)3 topology. Powder X-ray diffraction confirmed the phase purity for (I), and susceptibilty measurements indicated a very weak ferromagnetic behaviour. A thermogravimetric analysis shows the loss of the apical aqua ligand before decomposition of the title compound.

A new family of 1D, 2D and 3D frameworks aggregated from Ni5, Ni4 and Ni7 building units: synthesis, structure, and magnetism.

Three new Ni(ii)-clusters based on a Y-shaped ligand (biphenyl-3,4',5-tricarboxylate, H3BPT), [Ni5(HBPT)4(OH)2(H2O)12]n (), [Ni4(BPT)2(OH)2(H2O)6]n·4nH2O (), and [Ni7(BPT)2(1,4-bib)2(OH)6(HCO2)2]n·3nH2O () (1,4-bib = 1,4-bi(1H-imidazol-1-yl)benzene), have been synthesized under solvothermal conditions. They were studied by infrared spectroscopy (IR), single crystal X-ray diffraction, thermogravimetric analysis (TGA), and magnetochemistry. The complexes contain low nuclear Ni-clusters as building units (BUs). Structurally, in , the cluster BUs of [Ni5(µ3-OH)2](8+) can be viewed as two reverse triangles sharing a common vertex, which are connected by the partially deprotonated µ2-η(1):η(1)-HBPT(2-) forming 1D chains. The BUs of [Ni4(µ3-OH)2](6+) clusters in can be considered as two reverse triangles sharing a common edge and extended by deprotonated µ6-η(1):η(1):η(1):η(1):η(2)-BPT(3-) constructing a 2D framework. The 3D framework of complex consists of a [Ni7(µ3-OH)4(R-COO)7(HCO2)3] cluster BUs with fully deprotonated µ5-η(1):η(1):η(1):η(1):η(1):η(1)-BPT(3-) and 1,4-bib ligands. In addition, TGA reveals that the complexes are stable in the range of 293-548 K. Magnetostructural analyses indicate ferromagnetic coupling of J1 = 1.85(3) and J2 = 2.25(4) cm(-1) in and J = 5.76(6) cm(-1) in , whereas magnetic parameters J1 = -2.64(3), J2 = -23.22(19) and J3 = 12.02(5) cm(-1) indicate an alternating magnetic chain (AF/F) in .

2-[(E)-(4-Bromo-phenyl)imino-methyl]-4-chloro-phenol.

In the title compound, C13H9BrClNO, the dihedral angle between the substituted benzene rings is 44.25 (11)°. There are strong intra-molecular O-H⋯N hydrogen bonds, which generate S(6) rings, and also inter-molecular Cl⋯Cl [3.431 (3) Å] and Br⋯ Br [3.846 (1) Å] contacts. The crystal packing a C-H⋯O and C-H⋯π inter-actions.

Bis(2,4,6-triamino-1,3,5-triazin-1-ium) hydrogen phosphate trihydrate.

In the title hydrated mol-ecular salt, 2C(3)H(7)N(6) (+)·HPO(4) (2-)·3H(2)O, three of the O atoms of the hydrogen phosphate anion are disordered over two positions, with relative occupancies of 0.763 (1) and 0.237 (1). In the crystal, the components are linked by N-H⋯N, N-H⋯O and O-H⋯O hydrogen bonds.

trans-Dichlorotetrabenzimidazolecadmium(II) tetrabenzimidazole: a three-dimensional supramolecular structure built from C-H...pi, N-H...Cl and N-H...N hydrogen bonds.

The title compound, [CdCl2(C7H6N2)4].4C7H6N2, consists of a Cd(Bzim)4Cl2 complex (Bzim is benzimidazole) lying on a fourfold rotation axis in the space group P4nc, and four benzimidazole molecules which are linked to the coordinated benzimidazole unit by N-H...N hydrogen bonds. One N-H...Cl and three C-H...pi hydrogen bonds link these units into a three-dimensional supramolecular structure.

cis-Dichloro[tris(2-benzimidazolylmethyl)amine]iron(III) chloride ethanol dihydrate: hydrogen bonding changing the arrangement of tapes built from pi-pi and C-H...pi interactions.

The title compound, [FeCl2(C24H21N7)]Cl.C2H5OH.2H2O, comprises an [FeCl2(C24H21N7)]+ cation, a Cl- anion, an ethanol molecule and two water molecules. The cations are linked by pi-pi and C-H...pi interactions into one-dimensional tapes, and hydrogen bonding between the cations, Cl- anions, and ethanol and water molecules links these tapes into a three-dimensional network.

Bis(mu-1,10-phenanthrolin-2-olato-kappa3N,N':O)dicopper(I)(Cu-Cu) monohydrate.

The crystal structure of the title compound, [Cu(2)(C(12)H(7)N(2)O)(2)].H(2)O, shows that this dinuclear complex has shorter Cu-N, Cu-O and Cu-Cu distances within the coordination sphere than similar reported complexes. The complex molecule is located on a centre of symmetry and the water molecule is on a twofold axis of the space group C2/c. The discrete complex molecules are extended into a two-dimensional supramolecular array via pi-pi stacking interactions, intermolecular Cu.Cu interactions and C-H.O hydrogen bonds.