An organically templated Co(ii) sulfate with the kagome lattice

Mixed Kagomé and Triangular Lattices in Transition Metal Sulfate Compounds M7(SO4)3(OH)8 (M = Co, Ni, Cu)

A series of transition metal sulfate compounds, M7(SO4)3(OH)8 (M = Co, Ni, Cu), have been hydrothermally synthesized and exhibit unique topological spin lattices composed of mixed kagomé and triangular motifs. Co7(SO4)3(OH)8 and Ni7(SO4)3(OH)8 feature alternating kagomé and triangular layers along the c-axis, while Cu7(SO4)3(OH)8 shows merged kagomé and triangular motifs extending along the a-axis due to greater octahedral distortion. Magnetic measurements reveal that Co7(SO4)3(OH)8 exhibits a ferrimagnetic transition at ∼6.5 K with strong frustration, while Ni7(SO4)3(OH)8 undergoes long-range magnetic order at ∼24 K and exhibits spin-glass behavior at ∼2.5 K.

Structure and magnetic properties of an amine-templated one-dimensional cobalt-fluoro-sulfate containing Co4F4 cubane and hydrogen evolution reaction (HER) performance of its derived carbon-wrapped CoSe2 nanorods

Amine-templated 1D cobalt fluoro sulfate of the composition [(CH₃)₂NH₂]₂[Co₄F₄(SO₄)₃(C₃N₂H₄)₄], consisting of Co₄F₄ cubane-type secondary building unit, has been synthesized under solvothermal condition. The magnetic properties of the Co₄F₄ cubane chain exhibited a low-temperature magnetic ordering below 17 K (T_c) attributed to intra-cluster ferromagnetic coupling and did not show spin-glass freezing. The selenylation of the Co₄F₄ cubane chain leads to the formation of sphere-like CoSe₂ in the hydrothermal route (CoSe₂@HT). At the same time, nanorods of CoSe₂ encapsulated with carbon matrix were obtained in a sealed tube method (CoSe₂@ST). Moreover, CoSe₂@ST exhibited a higher hydrogen evolution reaction (HER) activity than CoSe₂@HT in an acidic medium with 177 mV overpotential to achieve the benchmark current density of 10 mA cm^-2. The promising HER performance of derived CoSe₂@ST could be attributed to an increase in the geometrical and specific activity due to the encapsulation of N-doped carbon matrix over the CoSe₂ nanorods that facilitate faster charge transfer at the electrode-electrolyte interface and higher electrochemical conductivity than the derived CoSe₂@HT. This work demonstrates a low-temperature, solvent- and reducing agent-free new synthetic approach for synthesizing framework-derived materials.

Synthesis and characterization of layered metal sulfates containing M(μ3-OH/F)2(M = Mg, Co) diamond chains

Cobalt and magnesium sulfates of the compositions, [C₄N₂H₁₂]₂[Co₃F₂(SO₄)₃(H₂O)₂], (1) and [NH₄]₂[Mg₃(OH)₂(SO₄)₃(H₂O)₂], (2), respectively, have been synthesized under hydro/solvothermal conditions, and are characterized by IR spectra, elemental analysis, powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and X-ray single-crystal diffraction. 1 and 2 crystallized in the orthorhombic space groups Pnma and Cmc2 respectively. While 1 is templated by the organic piperazinium cation, 2 is obtained in the presence of ammonium ions. The layered structures are formed by the diamond chains comprising of M₃(μ₃-OH/F)₂ units (M = Co: 1, Mg: 2). Magnetic studies of 1 reveal its ferromagnetic nature with a transition at 10.8 K and show it does not exhibit spin-glass freezing. Isothermal magnetization shows a hysteresis loop at 2.5 K with a coercive field of 1200 Oe and remnant magnetization of 0.1μ_B. A sharp λ-like anomaly is also seen in the heat capacity curve, favoring long range magnetic ordering below T_c.

Kagome-type isostructural 3D-transition metal fluorosulfates with spin 3/2 and 1: synthesis, structure and characterization

Two isostructural transition metal fluorosulfates based on Co and Ni metal ions with the molecular composition of [H₃O][M(SO₄)F] (where M = Co^(II) for 1 and Ni^(II) for 2) were synthesized under solvothermal conditions and structurally characterized by single crystal X-ray analysis. The materials were further characterized by complementary techniques like TGA, FTIR and PXRD. The 3D-crystal lattice consists of a kagome-type entity where sulfate groups replaced one of the metal nodes when compared with true kagome structures. Magnetic studies of the complexes were also performed which showed that the interactions at the metal center are antiferromagnetic in nature. The proton conductivity increases with the increase in humidity and was found to be 7.9 × 10^-6 S cm^-1 for 2 at RH = 98%.

The first organically templated open-framework metal-sulfites with layered and three-dimensional diamondoid structures

The crystallographic signatures and characterization data of two novel organically templated open-framework zinc-sulfite (NH₃CH₂CH₂NH₃)[Zn₃(SO₃)₄], 1 and (CN₃H₆)₂[Zn(SO₃)₂], 2 are reported for the first time using different amines to generate 2D (for 1) and 3D (for 2) assemblies with 4, 6, 8 and 12-membered rings.

Ionothermal synthesis of open-framework metal phosphates with a Kagomé lattice network exhibiting canted anti-ferromagnetism†Electronic supplementary information (ESI) available: Cif files, atomic parameters, X-ray diffraction patterns, IR spectra, TG curves, and thermal ellipsoid plot and atomic label schemes of compound . See DOI: 10.1039/c4tc00290cClick here for additional data file

Four open-framework transition-metal phosphates; (NH4)2Co3(HPO4)2F4 (1), (NH4)Co3(HPO4)2(H2PO4)F2 (2), KCo3(HPO4)2(H2PO4)F2 (3), and KFe3(HPO4)2(H2PO4)F2 (4); are prepared by ionothermal synthesis using pyridinium hexafluorophosphate as the ionic liquid. Single-crystal X-ray diffraction analyses reveal that the four compounds contain cobalt/iron-oxygen/fluoride layers with Kagomé topology composed of interlinked face-sharing MO3F3/MO4F2 octahedra. PO3OH pseudo-tetrahedral groups augment the [M3O6F4] (1)/[M3O8F2] layers on both sides to give M3(HPO4)2F4 (1) and M3(HPO4)2F2 (2-4) layers. These layers are stacked along the a axis in a sequence AA…, resulting in the formation of a layer structure for (NH4)2Co3(HPO4)2F4(1). In NH4Co3(HPO4)2(H2PO4)F2 and KM3(HPO4)2(H2PO4)F2, the M3(HPO4)2F2 layers are stacked along the a axis in a sequence AA i … and are connected by [PO3(OH)] tetrahedra, giving rise to a 3-D open framework structure with 10-ring channels along the [001] direction. The negative charges of the inorganic framework are balanced by K+/NH4+ ions located within the channels. The magnetic transition metal cations themselves form layers with stair-case Kagomé topology. Magnetic susceptibility and magnetization measurements reveal that all four compounds exhibit a canted anti-ferromagnetic ground state (Tc = 10 or 13 K for Co and Tc = 27 K for Fe) with different canting angles. The full orbital moment is observed for both Co2+ and Fe2+.

Synthesis and characterization of robust three-dimensional chiral metal sulfates

Chiral three-dimensional Mg(ii) and Mn(ii) sulfates have been synthesized, well characterized and studied from first-principles calculations. High temperature X-ray diffraction, thermogravimetric analysis and DFT calculations reveal that the structures of both the compounds remain intact even after the thermal decomposition of the ammonium ion.

Coordination compounds of bis(5-tetrazolyl)amine with manganese(II), zinc(II) and cadmium(II): synthesis, structure and magnetic properties

Six coordination compounds of bis(5-tetrazolyl)amine (H2bta) with different metal ions, M{M3(mu3-X)(bta)3(H2O)6}2] (X = OH for M = Mn(II) 1, and Cd(II) 2; X = F for M = Mn(II) 3), [Mn(bta)(H2O)3].0.5H2O (4), [Zn(bta)(NH3)2]0.5H2O (5) and [Zn(Hbta)2(H2O)2]H2O (6) have been described. The compounds were synthesized using one-pot hydrothermal methods involving the in situ generation of the ligand from dicyanamide and azide (1-4, 6), or by the methods using the pre-synthesized H2bta ligand (4, 5). The bta ligand in 1-3 assumes the mu3 tetradentate mode with both 1,2- and 1,4-tetrazole bridges, generating an unusual 2D layer, in which [M3(mu3-X)] triangular motifs act as three-connecting nodes and the mononuclear motifs acting as six-connecting nodes that are inter-linked by the ligands. The 2D layer in 1 and 3 represents a novel type of a geometrically spin-frustrated lattice. Both 4 and 5 consist of co-crystallized binuclear motifs and 1D polymeric chain motifs, which arise from two different mu2 tridentate bridging modes of bta with 1,2- and 1,4-tetrazole bridges, respectively. In 6, the mono-anionic Hbta ligands chelate Zn in the non-bridging bidentate mode to generate mononuclear molecules, which are assembled through extended hydrogen bonds to generate a 3D architecture with a ten-connected net topology. Magnetic investigations revealed that interactions through the different bridges in 3 and 4 are all antiferromagnetic, and also confirmed that 3 is a geometrically-frustrated antiferromagnet (T(N) = 2.5 K).

Structure and properties of [Cr(III)F(NCMe)5](BF4)2.MeCN: a nonaqueous source of Cr(III)F2+ and a building block for new Prussian-blue-like magnetic materials

[Cr (III)F(NCMe) 5](BF 4) 2.MeCN ( 1) was synthesized from a prolonged dissolution of [Cr (III)(NCMe) 6](BF 4) 3 in MeCN via fluoride abstraction from BF 4 (-). Complex 1 exhibits a crystal field splitting, Delta o, of 17 470 cm (-1) and is a nonaqueous source of Cr (III)F (2+). The reaction of 1 with (NEt 4) 3[Cr (III)(CN) 6] formed a new Prussian-blue-like magnetic material of (NEt 4) 0.04[Cr (III)F] 1.54[Cr (III)(CN) 6](BF 4) 0.12.0.10(MeCN) ( 2) composition. Complex 2 magnetically orders at a critical temperature, T c, of 85 K and at 2 K exhibits magnetic hysteresis with a coercive field, H cr, of 60 Oe and a remanent magnetization, M rem, of 1880 emuOe/mol.

Structural and magnetic modulation of a purely organic open framework by selective guest inclusion

Solvent inclusion/evacuation caused variations in the structural and magnetic characteristics of the purely organic porous magnet based on the tricarboxylic-substituted PTMTC radical. Whereas no inclusion is observed for nonpolar solvents, the exposure of crystals of the alpha-phase of PTMTC to vapors of polar organic solvents with hydrogen acceptor and/or donor functionalities, such as, ethanol, benzoic alcohol, n-decanol, THF, and DMSO results in the inclusion of these solvents in the highly polar tubular channels of the alpha-phase. The resulting inclusion compounds of formula PTMTC.x(guest) show several structural rearrangements, as confirmed by IR and XRPD (X-ray powder diffraction) measurements. The crystal transformations have been studied for a specific case: the PTMTC.EtOH adduct. The crystal structure reveals that included guest solvent molecules participate in the formation of new hydrogen bonds with the carboxylic groups of PTMTC radicals, inducing the disruption of several direct hydrogen bonds among these radicals. As expected, the interruption of direct hydrogen bonds between PTMTC radicals induces large transformations in the magnetic properties. From the ferromagnetic behavior of the alpha-phase, predominant antiferromagnetic interactions are observed for the inclusion adducts. Interestingly, both structural and magnetic changes are reversible after removal of guest solvent molecules.

Organic–inorganic hybrid materials constructed from inorganic lanthanide sulfate skeletons and organic 4,5-imidazoledicarboxylic acid

Five different types of the lanthanide sulfate-carboxylates family, [La(2)(SO(4))(Himdc)(2)(H2O)2] , [Gd(2)(SO(4))(2)(Himdc)(H2O)3].H2O , [Ln(2)(SO(4))(2)(Himdc)(H2O)(3)].H2O (Ln = Gd3a, Eu3b), [Eu(6)Cu(SO(4))(6)(Himdc)(4)(H2O)(14)] , and [Ln(Himc)(SO(4))(H2O)] (Ln = Eu5a, Gd5b, Tb5c, Dy5d, Er5e); H(2)imc = 4-imidazolecarboxylic acid, H(3)imdc = 4,5-imidazoledicarboxylic acid) have been obtained by hydrothermal reactions of Ln(2)O(3), transition metal sulfates and H(3)imdc at 170 degrees C and characterized by means of elemental analyses, IR, TG analysis, luminescence spectroscopy and single crystal X-ray diffraction. The 3D structure of 1 is constructed from alternately linkages of organic {La(Himdc)} layers and inorganic {La(2)O(2)(SO(4))} layers, with the La atoms as hinges. 2 and 3a/3b both contain alternately arranged 1D left- and right-handed helical {Ln(imdc)} chains bridged by SO(4)(2-) anions to form a 3D framework with 1D rectangle-like channels along the b axis. The structural differences of 2 and 3a/3b lie in the linkages of the SO(4)(2-) anions. Complex 4 consists of 2D tubular Eu-sulfate layers pillared by {Cu(Himdc)(2)} units to generate a 3D network. Complexes 5a-5e possess 2D bamboo-raft-like layer structures based on helical tubes. Interestingly, H(2)imc comes from the in-situ decarboxylation of H(3)imdc in the hydrothermal reactions. The luminescence properties of the complexes 3a, 4, 5a 5c, 5d were investigated in solid state at room temperature.

Synthesis, structure and magnetic properties of an amine-templated Mn2+ (S = 5/2) sulfate with the Kagome structure

In pursuit of a compound with the Kagome structure, formed by a non-Fe(3+) transitional metal ion with a spin of 5/2, we have synthesized an amine-templated Mn(2+) sulfate under solvothermal conditions. This compound with a perfect Kagome structure shows evidence for antiferromagnetic interactions with no long-range order.

Old materials with new tricks: multifunctional open-framework materials

The literature on open-framework materials has shown numerous examples of porous solids with additional structural, chemical, or physical properties. These materials show promise for applications ranging from sensing, catalysis and separation to multifunctional materials. This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids. For this, a detailed revision of the different examples so far reported will be presented, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications. (413 references.)

Novel frustrated magnetic lattice based on triangular [Mn3(μ3-F)] clusters with tetrazole ligands

Unprecedented [Mn(II)(3)(micro(3)-F)(micro-N-N)(3)] triangular clusters with tetrazole ligands are linked by Mn(II) ions to generate a novel spin-frustrated 2D lattice exhibiting antiferromagnetic ordering.