One-dimensional Manganese Research Articles

Sonochemical synthesis and characterization of new one-dimensional manganese(II) coordination polymer nanostructures

A new Mn(II) coordination polymer, [Mn (L1)2(NCS)2]n (1) [L1=3,4-bis(4-pyridyl)-5-(2-pyridyl)-1,2,4-triazole] was synthesized by the reaction of ligand L1 and mixtures of manganese(II) acetate and potassium thiocyanate using the heat gradient method. Compound 1 has been characterized by IR spectroscopy, elemental analyses and X-ray crystallography. The crystal structure of compound 1 was determined by single-crystal X-ray diffraction and shows a new interesting one-dimensional coordination polymer. Nanostructures of compound 1 have been synthesized by sonochemical method. The products were characterized by X-ray powder diffraction, scanning electron microscopy (SEM), and IR spectroscopy. The thermal stability of nano particles of compound 1 was studied by thermal gravimetric and differential thermal analyses.

Synthesis, characterization, and supercapacitor studies of manganese (IV) oxide nanowires

One-dimensional manganese (IV) oxide (MnO2) (∼20nm in average diameter) were synthesized by cathodic electrodeposition and heat treatment. The mechanism of electrodeposition and nanowire formation were discussed. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR). Nanowires with varying lengths and diameters were found in TEM and SEM images of the sample. The results of N2 adsorption–desorption analysis indicated that the BET surface area of the MnO2 nanowires was 157m2g−1 and the pore size distributions were 2.5 and 4.5nm. The electrochemical performances of the prepared MnO2 as an electrode material for supercapacitors were evaluated by cyclic voltammetry and galvanostatic charge/discharge measurements in a solution of 0.5M Na2SO4. The higher specific capacitance of 318Fg−1 and good capacity retention of 86% were achieved after 1000 charge–discharge cycles had been observed for the MnO2 nanowires electrode.

One-dimensional manganese oxide nanostructures as radical scavenger to improve membrane electrolyte assembly durability of proton exchange membrane fuel cells

One-dimensional manganese oxide (MnO2) scavengers are proposed to minimize the radical degradation of membrane electrode assembly (MEA) in fuel cells. The synthesized MnO2 nanotubes and MnO2 nanowires are ca. 5–8 nm in diameter and more than 100 nm in length, respectively. Water retention of the hydrophilic MnO2 reduces the humidity sensitivity of the fuel cells. At 75 RH% humidify levels of inlet gas at 60 °C, single cells assembled by catalyst layer with MnO2 nanotubes and nanowires as the cathodes have peak power densities of 599.3 and 536.8 mW cm−2, respectively. Radical scavenger MnO2 in the cathode catalyst is effective in minimizing the radical degradation in proton exchange membrane (PEM) fuel cells. After the OCV degradation, the hydrogen crossover of cell assembled by catalyst layer with MnO2 nanowires or MnO2 nanotubes in anode and traditional catalyst layer in cathode are about 5.3 and 4.9 mA cm−2, respectively. As a comparison, single cell with conventional catalyst layer in both anode and cathode, the hydrogen crossover through the MEA is increased to 14.7 mA cm−2.

Synthesis, crystal structure and magnetic characterization of two Mn(III) chains with Schiff-base ligands

Two new one-dimensional manganese(III) complexes [Mn2III(L1)4(piv)2] (1) and [MnIII(L2)(bix)]·2H2O⋅ClO4 (2) (H2L1=N-(2-hydroxyethyl)-3-methoxysalicylaldimine, H2L2=N,N′-bis(salicylidene)phenylenediamine, bix=1,4-bis-(imidazol-1-ylmethyl)benzene, piv=pivalate) have been synthesized and characterized by X-ray crystallography and magnetic measurements. Crystal structure studies reveal that complex 1 consists one-dimensional manganese(III) chains linked by L12- ligand in η1:η1:η1:μ2 mode. In complex 2, the Mn(III) ion is coordinated by the tetradentate L22- ligand in the equatorial plane, whereas bix ligand acts as bridge in the axial direction. Magnetic studies show that both complexes exhibit weak antiferromagnetic exchange coupling between Mn(III) ions.

Electrochemical Property of Manganese Oxide Nanobelt Bundles with Layered Structure

AbstractOne‐dimensional manganese oxide nanobelt bundles with birnessite‐type structure have been synthesized by a hydrothermal process in a NaOH solution employing K‐type layered manganese oxide as a precursor. The obtained manganese oxide nanobelt bundles exhibit excellent discharge properties and cycle stability. The initial capacity is 376 mAh·g−1 and the reversible capacity of 243 mAh·g−1 is maintained after the 50th cycle at a current density of 20 mA·g−1. Meanwhile, the manganese oxide nanobelt bundles show an excellent cycle performance even if at relative high current density.

Synthesis and crystal structure of one-dimensional azide-bridged Mn(III) polymer [Mn(BrSal2MePn)(μ1,3-N3)] n (BrSaI2MePn = N,N′-bis(salicylidene)-1,2-propanediamine)

A new one-dimensional manganese(III) Schiff base complex [Mn(BrSal2MeĐn)(μ1,3-N3)] n (I) was synthesized by the reaction of MnCl2 · 6H2O with the Schiff base ligand H2BrSal2MeĐn condensed from 2,2-dimethylpropylenediamine with 5-bromosalicylaldehyde and was characterized by elemental analyses and FT-IR spectroscopy. The molecular structure of I has been determined from single-crystal X-ray diffraction analysis. In this structure, the Mn3+ ion is in a distorted octahedral geometry with an obvious Jahn-Teller effect, where the deprotonated tetradentate Schiff-base ligand BrSal2MePn2− is bound in the equatorial plane and the N 3 − anions show μ1,3-bridging mode in the axial direction.

Controlled Morphology of One-Dimensional Manganese Dioxide with Dramatic Enhancing Removal Efficiency to Heavy Metal Ions in Aqueous Solution

To examine the effects of morphologies of one-dimentional metal oxides on their surface properties, two typical morphologies of manganese dioxide (one is nanorod, the other is nanofiber) as a model of metal oxide were prepared with hydrothermal approach under similar conditions. The adsorption properties of Pb2+ in aqueous solution were carried out by using surface active group of MnO2 with different morphologies. The results indicated that the sorption capacities for Pb2+ were dramaticly increased via tailoring the morphology of MnO2. The products were characterized with SEM (Scanning Electron Microscopy), XRD (X-ray Diffraction), FTIR (Fourier-Transform Infrared), atomic absorption spectrophotometer, and so on. These results illustrated that it was feasible to improve the removal efficiency of heavy metal ions dramatically in aqueous solution by tailoring the morphology of nanostructured MnO2.

Synthesis and crystal structure of one-dimensional azide-bridged Mn(III) polymer [Mn(Sal2-1,2Pn)(N3)] n (Sal2-1,2Pn = N,N′-bis(salicylidene)-1,2-propanediamine)

The new one-dimensional azide-bridged manganese(III) polymer, [Mn(Sal2-1,2Pn)(N3)]n (I), where Sal2-1,2 Pn = N, N,N′-bis(salicylidene)-1,2-propanediamine, was prepared from a reaction mixture containing Sal2-1,2 Pn, MnCl2 · 2H2O and NaN3 (2: 1: 8 molar ratio) in methanol-chloroform (v/v 2: 1) and has been characterized by elemental analyses, FT-IR spectroscopy, and X-ray single-crystal diffraction. In the structure of I, Mn3+ ion is in a distorted octahedral geometry with an obvious Jahn-Teller distortion. The quadridentate Schiff-base ligand Sal2-1,2Pn is located in the equatorial plane. The azide ion acts as an end-to-end bridge to form the one-dimensional manganese(III) polymer.

Preparation and capacitive property of manganese oxide nanobelt bundles with birnessite-type structure

One-dimensional manganese oxide nanobelt bundles with layered structure have been synthesized by hydrothermally treating the precursor, K-type layered manganese oxide in a NaOH solution of 6.0 mol L −1 at 150 °C for 30 h. The obtained material is characterized by XRD, SEM, TEM and BET analysis. The manganese oxide nanobelt bundles are more than 50 μm long and 20–50 nm wide, and the specific surface area is about 160 m 2 g −1. The electrochemical property of the synthesized manganese oxide nanobelt bundles has been studied using cyclic voltammetry in a mild aqueous electrolyte. The manganese oxide nanobelt bundle exhibits good capacitive behavior and cycling stability in a neutral electrolyte system, and its initial capacitance value is 268 F g −1.

Mononuclear and one-dimensional manganese(II) complexes constructed by dithioethers: Effect of flexibility and positional isomerism

Interactions of dithioether ligands L 2, L 4 and L 5 (L 2 = 1,3-bis(4-(3-pyridyl) pyrimidin-2-ylthio) propane; L 4 = 1,3-bis[4-(3-pyridyl) pyrimidinyl thiomethyl]benzene; L 5 = 1,4-bis[4-(3-pyridyl)pyrimidinylthiomethyl] benzene) with Mn(II) ions and NH 4SCN in an analogous way led to the formation of two discrete mononuclear complexes and a one-dimensional chain, respectively, which may be attributed to the different flexibility and positional isomerism of the ligands.

Synthesis, Structure, and Magnetic Properties of Na3LnMn3O3(AsO4)3(Ln = La, Sm, and Gd): A New 3d-4f Series Exhibiting One-Dimensional Manganese(III) Oxide Chains Connected via LnO9Units

In attempts to synthesize compounds containing mixed lanthanide and transition metal oxide magnetic nanostructures, a new 3d-4f arsenate phase, Na(3)GdMn(3)O(3)(AsO(4))(3), was isolated using high-temperature, molten-salt methods. The X-ray single-crystal structure analysis shows that Na(3)GdMn(3)O(3)(AsO(4))(3) crystallizes in a hexagonal space group with a = 11.091(2) A, c = 5.954(1) A, and V = 634.2(2) A(3); P6(3)/m (No.176); Z = 2. The structure has been refined by full-matrix, least-squares methods to a final solution with R1 = 0.0466, wR2 = 0.1318 and GOF = 1.101. This new three-dimensional framework consists of ferromagnetic one-dimensional [MnO(4)](infinity) chains, composed of edge-shared MnO(6) units propagating along c. The GdO(9) polyhedra connect three neighboring [MnO(4)](infinity) chains via oxygen atoms. Na(3)LaMn(3)O(3)(AsO(4))(3) (1), and Na(3)SmMn(3)O(3)(AsO(4))(3) (2), the isostructural derivatives of Na(3)GdMn(3)O(3)(AsO(4))(3) (3), were synthesized to acquire additional insight into the 3d-4f magnetic couplings. The Na(3)LnMn(3)O(3)(AsO(4))(3) series reveals an increase in chiT at low temperatures upon substitution of smaller Ln(3+) ions ranging from La(3+) to Gd(3+). The increase in chiT is likely due to the magnetic nature and size of the lanthanide ions present. It was expected that the Mn-O-Mn ferromagnetic interactions would dominate as 3d-4f magnetic interactions are generally weak. The magnetic data shows that the paramagnetic Ln(3+) ions in 2 (Sm) and 3 (Gd) do significantly enhance the bulk ferromagnetism compared to that of 1 (La), suggesting sizable contributions from the 4f magnetic ions.

Synthesis, crystal structure and magnetic properties of a one-dimensional Mn(III) Schiff-base complex bridged by derivative of tetracyano- p-quinodimethane

A new one-dimensional manganese(III) Schiff-base complex [Mn(III)(salophen) (MeOTCNQ)] · CH 3CN 1 (salophen = N,N′-bis(salicylidene)phenylenediamine) bridged by 7-methoxy-7,7,8,8-tetra-cyano- p-quinodimethane (MeOTCNQ), has been synthesized and characterized by X-ray crystallography and magnetic studies. Crystal structure study reveals that complex 1 has a 1D manganese(III) chain bridged by MeOTCNQ ligand which was obtained unexpectedly from tetracyano- p-quinodimethane (TCNQ) reacting with methanol. Noticeably, MeOTCNQ molecules in complex 1 adopt an unusual cis– syn coordination mode. The analysis of magnetic data indicates that a weak intrachain antiferromagnetic interaction exists in complex 1.

One-Dimensional Manganese Coordination Polymers Composed of Polynuclear Cluster Blocks and Polypyridyl Linkers: Structures and Properties

The synthesis, crystal structures and magnetic properties of five new manganese compounds are reported. These include a linear trinuclear cluster [Mn(II)(3)(O(2)CCHMe(2))(6)(dpa)(2)].2MeCN (1) (dpa = 2,2'-dipyridylamine), a tetranuclear cluster [Mn(II)(2)Mn(III)(2)O(2)(O(2)CCMe(3))(6)(bpy)(2)] (3) (bpy = 2,2'-bipyridine), and chain coordination polymers composed of cluster blocks such as Mn(3), Mn(3)O, and Mn(4)O(2) bridged by 2,2'-bipyrimidine (bpm) or hexamethylentetramine (hmta) ligands to give ([Mn(II)(3)(O(2)CCHMe(2))(6)(bpm)].2EtOH)(n) (2), [Mn(II)(2)Mn(III)(2)O(2)(O(2)CCHMe(2))(6)(bpm)(EtOH)(4)](n) (4), and (([Mn(II)Mn(III)(2)O(O(2)CCHMe(2))(6)(hmta)(2)].EtOH)(n) (5). The magnetic analysis of the compounds was achieved using a combination of vector coupling and full-matrix diagonalization methods. Susceptibility data for compound 1 was fitted using a vector coupling model to give g = 2.02(1) and 2J/k(B) = -5.38(2) K. To model the trimer chain, we used vector coupling for initial values of J(1) and then diagonalization techniques to estimate J(2) to give g = 1.98(1), 2J(1)/k(B) = -3.3(1) K and 2J(2)/k(B) = -1.0(1) K by approximating the system to a dimer of trimers. The analysis of 3 was made difficult by the mixture of polymorphs and the difficulties of a three-J model, while for 4 an analysis was not possible because of the size of the computation and the relative magnitudes of the three couplings. Compound 5 was modeled using the same techniques as 2 to give g = 1.99(1), 2J(1)/k(B) = +32.5(2) K, 2J(2)/k(B) = -16.8(1) K, and 2J(3)/k(B) = +0.4(1) K. The combination of techniques has worked well for compounds 2 and 5 and thus opens up a method of modeling complex chains.

Morphology Control of Cryptomelane Type MnO2 Nanowires by Soft Chemistry. Growth Mechanisms in Aqueous Medium

Nanowires of one-dimensional manganese oxide (cryptomelane) have been synthesized using reaction between MnII (MnSO4) and MnVII (KMnO4) in water by a low-temperature route at 60 °C and 95 °C. Characterization of the nanoparticles was carried out using powder X-ray diffraction, transmission electron microscopy, electron diffraction, and nitrogen adsorption−desorption. Two synthesis methods were developed depending whether the pH was initially adjusted or fixed all along the solid formation. Both methods exhibited variation of the nanowire morphology with diameter, length, and specific area varying in the 15−40 nm, 0.1−1.1 μm, and 35−110 m2·g-1 ranges, respectively, depending on the growth conditions (acidity and temperature). The growth mechanism of the nanowires was proved to proceed by oriented attachment of primary 10 nm width nanorods for the lateral direction and dissolution−crystallization for the longitudinal direction. The diameter variation with acidic conditions was interpreted in terms of electrostatic interactions between primary nanorods.

An Unusual 1D Manganese Azido Complex with Novel EO/EO/EO/EE Coordination Mode: Synthesis, Structure, and Magnetic Properties

A novel one-dimensional manganese(II) azido complex, [Mn2(N3)4(phen)2]n (1), in which the azido bridging ligands take on an unusual new type of combination with the metal center as the sign of [-EO-EO-EO-EE-]n, has been hydrothermally synthesized, and its magnetic properties have been studied.

One-dimensional manganese(II) complex with only end-to-end azide ligands: Crystal structure and magnetic characterization

A novel one-dimensional azido-bridged manganese(II) complex of formula [Mn(L) 2(N 3)](ClO 4) 1 has been synthesized and characterized crystallographically and magnetically, where L is the bidentate Schiff base obtained from the condensation of pyridine-2-carbaldehyde with 4-methoxyl aniline. Complex 1 is of one-dimensional chain structure with single end-to-end azido bridges. Magnetic analysis reveals that the weak antiferromagnetic interaction is mediated by the single end-to-end azido bridge with the exchange parameter J = −6.60 cm −1.

Catena-Poly[[tetraaquamanganese(II)]-μ-4-(carboxylatomethylsulfanyl)phenoxyacetato

The title compound, [Mn(C10H8O5S)(H2O)4]n, a one-dimensional manganese(II) complex comprising helical chains bridged by 4-(carboxylatomethylsulfanyl)phenoxyacetate ligands has been characterized by single-crystal X-ray diffraction analysis. Hydrogen-bonding interactions between adjacent chains extend the complex into a three-dimensional supramolecular architecture.

One-Dimensional Nanostructures from Layered Manganese Oxide

In this paper, we report the preparation of one-dimensional (1D) nanostructures from layered compounds (2D). γ-MnOOH nanorods were successfully prepared from platelike layered Na-birnessite by simple hydro(solvo)thermal treatment at low temperature. It was observed that the reaction medium plays an important role in the phase and morphology modifications. The γ-MnOOH was thermally treated under different conditions of atmosphere (inert or oxidizing) and temperature, which led to several phases of manganese oxide nanorods, such as MnO2 (pyrollusite), Mn2O3 (bixbyite), and Mn3O4 (hausmannite). Indeed, the achievement of such phase tuning was possible because of the outstanding structural flexibility of manganese oxides. Considering the simplicity, reproducibility, and high yield of these methods, they may be employed for low-cost large-scale production of one-dimensional manganese oxide nanostructures.

Synthesis of [NH4]MnCl2(OAc) and [NH4]2MnCl4(H2O)2 by Solvothermal Dehydration and Structure/Property Correlations in a One-Dimensional Antiferromagnet

The utility of the solvothermal dehydration strategy whereby superheated acetonitrile reacts with water of hydration to form ammonium acetate is demonstrated in the synthesis of [NH(4)]MnCl(2)(OAc), I, and [NH(4)](2)MnCl(4)(H(2)O)(2), II, from MnCl(2).4H(2)O. The structure of I is shown to crystallize in the monoclinic space group C2/c (No. 15) with a = 15.191(6) A, b = 7.044(2) A, c = 13.603(6) A, beta = 107.31 degrees, V = 1389.7(9) cm(-)(1), and Z = 8. The structure of II crystallizes in the space group I4/mmm (No. 139) with a = 7.5250(5) A, b = 8.276(2) A, V = 468.6(1) cm(-)(1), and Z = 2. Both structures exhibit extensive hydrogen bonding that controls both local Mn-Cl bonding and the interchain organization. I is shown to be a one-dimensional Heisenberg antiferromagnet with an intrachain exchange constant J/k = -2.39 K. This structure exhibits exchange coupling intermediate between the well-studied triply and doubly chloride-bridged one-dimensional manganese Heisenberg antiferromagnets. The structure/property correlation demonstrates a linear dependence of the exchange constant on the Mn-Cl-Mn bond angle, alpha, for alpha < 94 degrees.

Synthesis, crystal structure and magnetic properties of a novel manganese (II)-nitronyl nitroxide-azido (m1,1 and m1,3) one-dimensional complex

A novel one-dimensional manganese(II) complex containing nitronyl nitroxide radical [Mn2(IM2-py)2(Ac)2(μ1,1-N3)(μ1,3-N3) · EtOH]n was synthesized and characterized structurally and magnetically. It crystallizes in the monoclinic space group p21/n. Each Mn(II) ion is six-coordinated in a distorted octahedral environment. The two N atoms of the nitronyl nitroxide radical and the two O atoms of acetate ligands are in the equatorial plane, whereas the two different azido bridging ligands are in trans axial position. Mn(II) ions are linked by nitrogen atom of μ1,1-azido and oxygen atoms of two carboxy groups to form a Mn-Mn unit. Mn-Mn units are linked by azido ligands through μ1,3 bridging style to form a one-dimensional chain. The compound is connected by the coordination bonds, π-π interactions and hydrogen bonds as a three-dimensional structure. Magnetic susceptibility data support that there are stronger antiferromagnetic interactions between the radical and Mn(II) ion, weak antiferromagnetic interactions between the Mn-R units, and very weak antiferromagnetic interactions between the R-Mn-Mn-R units.