A three-dimensional coordination polymer featuring effective ferrimagnetic hydroxide-bridged manganese(II) chains

A three-dimensional coordination polymer, [Mn3(OH)2Na2(3-cnba)6]n (1) (3-Hcnba = 3-cyanobenzoic acid), has been synthesized by the reaction of MnCl2, NaN3, and 3-Hcnba in water. Its crystal structure was determined by single-crystal X-ray diffraction. Magnetic studies show that the complex behaves as a three-dimensional metamagnet built from effective ferrimagnetic Mn(II) chains in which spin moments are linked by interactions in an AF-F-AF (F = ferromagnetic and AF = antiferromagnetic) sequence in the triangular magnetic repeating unit.     

New hydrazine sensors based on electropolymerized meso-tetra(4-sulphonatephenyl)porphyrinate manganese(III)/silver nanomaterial

A new electrocatalytic active porphyrin nanocomposite material was obtained by electropolymerization of meso-tetra(4-sulphonatephenyl)porphyrinate manganese(III) complex (MnTPPS) in alkaline solutions containing sub-micromolar concentrations of silver chloride. The modified glassy carbon electrodes efficiently oxidize hydrazine at 10mV versus Ag/AgCl, dramatically decreasing the overpotential of conventional carbon electrodes. The analytical characteristics of this amperometric sensor coupled with batch injection analysis (BIA) technique were explored. Wide linear dynamic range (2.5x10(-7) to 2.5x10(-4)molL(-1)), good repeatability (R.S.D.=0.84%, n=30) and low detection (3.1x10(-8)molL(-1)) and quantification (1.0x10(-7)molL(-1)) limits, as well as very fast sampling frequency (60 determinations per hour) were achieved.     

A one‐dimensional manganese(III)–porphyrin coordination polymer: crystal structure and photophysical properties

A novel manganese(III)–porphyrin complex, namely, catena‐poly[[chloridomanganese(III)]‐μ₂‐5,10,15,20‐tetrakis(pyridin‐3‐yl)‐21H,23H‐porphinato(2?)‐κ⁵N²¹,N²²,N²³,N²⁴:N⁵], [MnCl(C₄₀H₂₄N₈)]_n, 1 , was prepared by the hydrothermal reaction of manganese chloride with 5,10,15,20‐tetrakis(pyridin‐3‐yl)‐21H,23H‐porphine. The crystal structure was determined by single‐crystal X‐ray diffraction. The porphyrin macrocycle exhibits a saddle‐like distortion geometry. The Mn^III atom has a six‐coordination geometry. Each porphyrin unit links to two neighbouring units to yield a one‐dimensional coordination polymer. These chains are further interlinked by hydrogen bonds to form a two‐dimensional network. The complex shows red photoluminescence emission bands in ethanol solution, which can be attributed to ligand‐to‐ligand charge transfer (LLCT) accompanied by partial metal‐to‐ligand charge transfer (MLCT), as revealed by TDDFT calculations.     

Structure and properties of cobalt(III) porphyrinate molecular complexes

By combined calculation and spectral methods the structure and properties of the molecular complexes of cobaltoctaalkylporphyrin in benzene were studied. Geometric and energy characteristics of the optimized molecules of cobalt porphyrinate and its molecular complexes were calculated. Their stability and degree of deformation were evaluated. It was established that the process of axial coordination is accompanied by the reduction of cobalt. Interrelation between the stability of the cobalt porphyrinate complexes and the nature of the base was noted. A change in the degree of deformation of the porphyrin ligand in the course of reaction was shown. Correlations between the calculation data and the value of the equilibrium constant of the axial coordination reaction were obtained.     

A 3D chiral porous In(III) coordination polymer with PtS topological net

The solvothermal reaction of In(III) and 1,2,4,5-benzeneteracarboxylic acid with the presence of piperazine leads to the generation of a novel 3D chiral porous coordination polymer with PtS topological net. Interestingly, the resulting crystals were not a racemic mixture but enantiomeric excess, which was confirmed by the measurement of optical rotation of bulk samples using solid vibrational circular dichroism (VCD) spectra and the solid circular dichroism (CD) spectra based on large crystals from one crystallization. High-pressure CO(2) and CH(4) adsorption measurement at 298 K reveals that activated 1 can absorb 45.8 cm(3) (STP)/g CO(2) at 22 atm and 22.5 cm(3) (STP)/g CH(4) at 25 atm.     

A SHG-active manganese coordination polymer with noncentrosymmetric structure based on achiral carboxyphosphinate ligand

The hydrothermal reaction of MnSO₄ with the achiral 2-carboxyethyl(phenyl)phosphinate ligand (H₂L) afforded a 2?D coordination polymer manganese phosphinate, [Mn(HL)₂]_n (1) (H₂L?=?2-carboxyethyl(phenyl) phosphinic acid). It contains two types of dimeric ring motifs, which can generate a layer structure through edge-sharing. The interlayer stacking by C-H…π interactions between the C-H groups of the phenyl rings of HL^- and the phenyl rings of the adjacent layers results in its crystallization in a noncentrosymmetric crystal structure with (4³)₂(4⁶·6⁶·8³) topology. Compound 1 shows a second harmonic generation response that is 0.8 times that of urea. The luminescence spectrum indicates an emission maximum at 457?nm, attributed to an intra-ligand emission state.     

A rare ferromagnetic manganese(III) 'cube'

A {Mn(III)4} distorted cube has been synthesized that possesses an S = 8 ground state and single-molecule magnetism behaviour.     

Uranyl sensitization of samarium(III) luminescence in a two-dimensional coordination polymer

Heterometallic carboxyphosphonates UO(2)(2+)/Ln(3+) have been prepared from the hydrothermal reaction of uranyl nitrate, lanthanide nitrate (Ln = Sm, Tb, Er, Yb), and phosphonoacetic acid (H(3)PPA). Compound 1, (UO(2))(2)(PPA)(HPPA)(2)Sm(H(2)O)·2H(2)O (1) adopts a two-dimensional structure in which the UO(2)(2+) metal ions bind exclusively to the phosphonate moiety, whereas the Ln(3+) ions are coordinated by both phosphonate and carboxylate functionalities. Luminescence studies of 1 show very bright visible and near-IR samarium(III)-centered emission upon direct excitation of the uranyl moiety. The Sm(3+) emissive state exhibits a double-exponential decay with lifetimes of 67.2 ± 6.5 and 9.0 ± 1.3 μs as measured at 594 nm, after excitation at both 365 and 420 nm. No emission is observed in the region typical of the uranyl cation, indicating that all energy is either transferred to the Sm(3+) center or lost to nonradiative processes. Herein we report the synthesis, crystal structure, and luminescent behavior of 1, as well as those of the isostructural terbium, erbium, and ytterbium analogues.     

A three‐dimensional (3D) manganese (II) coordination polymer: Synthesis,structure and catalytic activities

A new Mn (II)‐containing coordination polymer, [Mn₆(Ipa)₆(ad)?6H₂O] ( 1 ; Ipa = isophthalate ligand; ad = adenine), was synthesized by reacting hydrated manganese nitrate with isophthalic acid and adenine under solvothermal reaction conditions. Polymer 1 was characterized using single‐crystal X‐ray diffraction analysis and other techniques such as Fourier transform infrared spectroscopy, elemental analyses and powder X‐ray diffraction. The solid‐state structure of 1 confirmed the formation of a three‐dimensional framework structure based on Mn₆ secondary building units. Phase purity of bulk 1 and its thermal stability were investigated. Polymer 1 was evaluated for its performance as a heterogeneous catalyst for the Henry (nitroaldol) reaction of nitromethane with several aldehydes. The recyclability of 1 and heterogeneity of the reaction were also explored. A plausible mechanism for such reaction is proposed. To the best of our knowledge, polymer 1 represents the first example of a Mn (II)‐ and adenine‐containing coordination polymer as well as the first example of a Mn (II)‐containing coordination polymer that has been employed for the Henry reaction.     

A manganese(II) coordination polymer with mixed pyrimidine-2-carboxylate and oxalate bridges: synthesis, structure, and magnetism

A new two-dimensional (2D) coordination polymer with mixed pyrimidine-2-carboxylate (pymca) and oxalate (ox) bridges, [Mn(2)(pymca)(2)(ox)(H(2)O)(2)](n) (1), was synthesized by a hydrothermal reaction involving the in situ formation of the pymca and ox ligands from 2-cyanopyrimidine (pymCN), and its structure and magnetic properties were characterized. The dianionic ox and monoanionic pymca ligands are both potentially bis(chelating) and have been used to construct anionic and cationic 2D honeycomb networks [(6,3) net], respectively. In the present compound, ox assumes the usual bis(chelating) bridging mode, but pymca serves as a tridentate bridge with one of the pyrimidyl nitrogens uncoordinated. The two different bridges collaborate to generate a highly undulated 2D layer with the (6,3) net topology, and the layers are closely packed in parallel through pi-pi interactions between pyrimidyl rings and hydrogen bonds involving coordinated water molecules, oxalate oxygens, and uncoordinated pyrimidyl nitrogens. Magnetic measurements reveal that the compound is a spin-canted antiferromagnet with weak ferromagnetic transition below T(c) = 2.4 K.     

A 3D porous indium(III) coordination polymer involving in-situ ligand synthesis

The hydrothermal reaction of In³⁺ and 1,2,4-benzenetricarboxylic acid with the presence of piperazine leads to the generation of a novel 3D porous coordination polymer, [H₃O][In₂(btc)(bdc)(OH)₂]·5.5H₂O (1), (btc=1,2,4-benzenetricarboxylate, bdc=1,4-benzenedicarboxylate). Compound 1 crystallizes in orthorhombic space group Pbca with a=16.216(7) Å, b=13.437(6) Å, c=31.277(14) Å, and Z=8. It is interesting to find that the in-situ decarboxylation reaction of 1,2,4-benzenetricarboxylate (btc) partially transformed into 1,4-benzenedicarboxylate (bdc) occurs. The 16 indium(III) centers were linked by four btc, four bdc and two μ₂-OH ligands to form a box-girder. The adjacent box-girders are further connected by the bdc and btc ligands to generate a novel porous metal–organic framework containing nanotubular open channel with a cross-section of approximately 11.5×11.3 Å². The micropores are occupied by lattice water molecules, and the solvent-accessible volume of the unit cell was estimated to be 3658.6 Å³, which is approximately 53.7% of the unit-cell volume (6815.4 Å³).     

New 3-D La(III)-Cu(II)-containing coordination polymer with a high potential porosity

A new 3-D coordination polymer containing both 3d and 4f ions has been designed. Its chemical formula is La2[Cu(pba)]3(H2O)8 . 8H2O. It crystallizes in the quadratic system, space group I41/a with a = 42.4947(9) Angstrom, c = 16.3378(3) Angstrom, and Z = 16. Its crystal structure can be described as a 3-D molecular framework exhibiting a complex network of interconnected zigzaglike channels. Once crystallization water molecules are removed, this compound presents a high potential porosity and a low density. The porosity has been evaluated using Connolly's algorithm.     

A manganese(II) coordination polymer with a 3D porous structure: Synthesis,structure, and spectroscopic and magnetic behaviour

A manganese(II) complex with N,N′-bis(carboxymethyl)dithiooxamide (H₄GLYDTO), [Mn(H₂GLYDTO)(H₂O)₂]_n, has been synthesized and characterized by elemental analysis and thermogravimetric analysis, as well as by infrared, electronic and EPR spectroscopy and magnetic susceptibility measurements. The crystal and molecular structure of this complex was determined by single-crystal X-ray structure analysis. The compound shows a 3D porous framework with alternate left- and right-handed helical channels where the manganese(II) ions have an octahedral environment. Variable temperature magnetic measurements reveal the existence of very weak antiferromagnetic interactions through the syn-anti carboxylate bridge, with an exchange parameter of J/k = −0.12 K.     

Tris(salicylhydroxamato)manganese(III)

Summary Hydroxamic acids show a degree of selectivity towards transition metal ions having symmetrical d-electron configuration, e.g. vanadium(V) (d⁰) and iron(III) (d⁶⁵). Hydroxamato complexes of metal ions having unsymmetrical d-electron distribution are rare. Thus for manganese(III) (d⁴) only some thiohydroxamato complexes⁽¹⁾ have been characterised so far. In this communication we report on the first synthesis of a salicylhydroxamato complex of manganese(III). Such investigations are of interest because these higher valent manganese complexes are potentially models for the water-splitting complex present in photosystem II⁽²).     

Structure and photoluminescent property of a three-dimensional pillared-layer La(III)-Cu(I) heterometallic coordination polymer

A three-dimensional (3D) pillared-layer La(III)-Cu(I) heterometallic coordination polymer (HCP) formulated as [La₂Cu₄I₃(Hina)₇(H₂O)] _n (1) (Hina = isonicotinic acid), is synthesized by a hydrothermal reaction of La₂O₃, CuI, and ina. The crystal structure is determined by single crystal X-ray diffraction. HCP 1 crystallizes in the monoclinic space group P2₁/c with unit cell parameters: a = 17.0147(3) Å, b = 18.4431(3) Å, c = 16.7487(3) Å, β = 102.469(2)°, V = 5131.84(15) ų, Z = 4. It features a 3D pillared-layer heterometallic organic framework, where Ln-ina layers are pillared by discrete [Cu₈I₆(ina)₁₂] units along the direction of the a axis. In addition, the solid-state photoluminescent property is investigated.