Mn Salts Research Articles

Transition metal salt catalysed green synthesis of mesoporous silica nanoparticles

Conventionally, mesoporous silica nanoparticles are prepared by catalysing silicon alkoxides using acids or bases and are highly important in storage, delivery, and catalysis. Here, for the first time, we demonstrate that a transition metal ion (such as Ni(II), Co(II), and Mn(II)) also catalyses the hydrolysis and condensation reactions of silicon alkoxides in aqueous media without any additional acid or base to synthesize mesostructured and micro/mesostructured silica nanoparticles. An aqueous solution of a transition metal salt (specifically, nitrate salts of Ni(II), Co(II), or Mn(II), or chloride and sulphate salts of Ni(II)), 10-Lauryl ether (C12H25(OCH2CH2)10OH, C12E10) and cetyltrimethylammonium bromide (C16H33N(CH3)3Br, CTAB), and tetramethyl orthosilicate (TMOS) undergoes a precipitation reaction at room temperature, yielding ultra-small ordered mesostructured silica nanoparticles. These nanoparticles are subsequently calcined to produce mesoporous silica (meso-SiO2) with a high surface area (680–871 m2/g), large pore-volume (2.2–3.71 cm3/g), and small pore-size (1.2–3.0 nm). Moreover, the counter anions of the salts play an important role in the assembly process to obtain nanoparticles with an additional well-defined secondary pore (7.5–33.4 nm or larger). Coordinated water of the metal ion and methoxy group of the silica source react to produce a complex in which two hydroxy sides are in close vicinity to speed up the condensation reaction. We propose a hydrolysis and condensation reaction mechanism for TMOS to highlight the role of the metal ion as a catalyst.

Manganese Nanoparticles: Synthesis, Mechanisms of Influence on Plant Resistance to Stress, and Prospects for Application in Agricultural Chemistry.

Manganese (Mn) is an important microelement for the mineral nutrition of plants, but it is not effectively absorbed from the soil and mineral salts added thereto and can also be toxic in high concentrations. Mn nanoparticles (NPs) are less toxic, more effective, and economical than Mn salts due to their nanosize. This article critically reviews the current publications on Mn NPs, focusing on their effects on plant health, growth, and stress tolerance, and explaining possible mechanisms of their effects. This review also provides basic information and examples of chemical, physical, and ecological ("green") methods for the synthesis of Mn NPs. It has been shown that the protective effect of Mn NPs is associated with their antioxidant activity, activation of systemic acquired resistance (SAR), and pronounced antimicrobial activity against phytopathogens. In conclusion, Mn NPs are promising agents for agriculture, but their effects on gene expression and plant microbiome require further research.

Ternary oxides of MnCuNi nanocomposite for enhanced supercapacitor applications

MnO2/CuO/NiO nanocomposites were synthesized at 180 °C via a straightforward hydrothermal approach. The aqueous solutions of Mn, Cu, and Ni salts were combined with KMnO4 to produce these nanomaterials. The same molar ratios were explored to achieve mixed-oxide active materials. The resultant nanocomposites exhibited a phase blend comprising tetragonal -MnO2, monoclinic -CuO, and cubic -NiO. Specifically, the Mn:Cu:Ni nanocomposite with a 1:1:1 ratio showed an impressive specific capacitance of 754.61Fg-1 at a scan rate of 5 mVs−1 and maintained 74 % of its capacity after 5000 cycles, indicating its excellent cyclic stability. This composite electrode surpassed all individual electrodes tested, highlighting its potential as a superior electrode material for supercapacitors. Regarding its performance metrics, the areal capacitance was recorded at 108.79 mFcm−2, while the areal energy and power densities were 0.0283 mWhcm-2 and 0.315 mWcm−2, respectively. These findings signify a significant stride in the development of advanced electrode materials for supercapacitors, suggesting potential applications in other transition-metal-oxide-based electrode innovations.

Complexation of drug amifampridine with Cu(II), Zn(II) and Cd(II) ions, and its dimerization with the magic of Mn(II) salts. Potential anti-COVID-19 and anticancer activities.

The different behaviors of the drug amifampridine (AMP) against Mn(II), Cu(II), Zn(II) and Cd(II) metal ions, in the presence and absence of tris(2-aminoethyl)amine (tren) was studied. The results showed that AMP successfully coordinates with Cu(II), Zn(II) and Cd(II) metal ions, but interestingly it undergoes an unexpected dimerization through a C-H activation in the presence of different Mn(II) salts. A four-coordinate complex of zinc(II), [Zn(AMP)2Cl2] (1), a binuclear complex of cadmium(II), [Cd2(AMP)2Cl4] (2), three five-coordinate tren-based metal complexes, [Cu(tren)(AMP)](ClO4)2 (8), [Zn(tren)(AMP)]Cl2 (9) and [Cd(tren)(AMP)](ClO4)2 (10), three pyridinium salts, [AmpDimer]X (X = Cl-, NO3-, ClO4-; (3, 4 & 5)), and also two four-coordinate metal complexes with this pyridinium cation, [Zn(AmpDimer)Cl3] (6) and [Cd(AmpDimer)Cl3] (7), were synthesized. All new compounds were characterized by elemental analysis and IR spectroscopy, and by 1H- and 13C-NMR spectroscopy (for 1, 2, 3, 6, 7, 9 & 10) and by X-ray crystal structure determinations (for 1, 3, 4, 5, 7, 8 & 10). Theoretical studies showed that the [M(tren)(AMP)]2+ cations act as pH-sensitive drug carriers of AMP and release it upon protonation. The molecular docking studies on the interaction of AMP and the above complexes/salts with DNA and the proteins of SARS-CoV-2 showed that the synthesized complexes/salts have greater anticancer and anti-covid-19 activities than AMP alone.

Chemical CO2 fixation using a cyanido bridged heterometallic Zn(II)-Mn(II) 2D coordination polymer.

A new cyanido bridged Zn(II)-Mn(II) mixed-metal coordination polymer, {[Zn(μ-L)(μ-CN)2Mn0.5]·(CH3OH)}n (1), has been synthesized by the reaction of Zn(CN)2, Mn(II) salts and a hydrazone ligand (HL = (E)-N'-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide) in methanol. Compound 1 was characterized using various analytical methods (including elemental analysis, photoluminescence, FT-IR, XRD, SEM, and EDX analyses, and TGA), and its structure was determined by X-ray analysis. These analyses confirmed the formation of a mixed metal Zn(II)-Mn(II) coordination polymer containing both cyanide and hydrazone bridging ligands. This mixed metal coordination polymer exhibits interesting emission spectra by having several emissions via excitation at 230, 270, 375 and 385 nm. The catalytic activity of compound 1 in chemical CO2 fixation was investigated in the presence of epoxides, and the effects of various parameters on its catalytic performance were evaluated. The results of catalytic studies show that compound 1 can efficiently catalyze the chemical CO2 fixation reaction under mild conditions. The amount of co-catalyst, temperature of the reaction, nature of the solvent and also the substituent connected to the epoxide ring are some of the important parameters that have considerable effects on the catalytic activity of 1.

Role of aurone ligands in microwave enhanced Mn (II) and Co (II) catalyzed dehydrogenative coupling reaction: An efficient ligand for the synthesis of quinoline, pyridine, and pyrrole

AbstractThe role of new series of phosphine‐free aurone ligands have been investigated in microwave‐enhanced Mn (II) and Co (II) dehydrogenative coupling reactions. Various heterocyclic compounds such as Quinoline, pyridine, and pyrrole have been synthesized and characterized by NMR spectroscopy. The synthesized ligands (L1–L4) with Mn(II) and Co (II) salt showed excellent catalytic activity and proved to be very effective for the dehydrogenative coupling reaction. This synthetic method involves the in‐situ formation of a metal ligand complex that was analyzed by mass spectrometry. A broad range of substrates including aliphatic ketone, heterocycles, and sterically hindered Ketone coupling partners are well tolerated in the developed protocol.

Intermetallic compounds as oxygen evolving anodes for metal electrowinning: Electrochemical dealloying and effects of scale in practical electrochemistry

Electrochemical dealloying has recently been highlighted as a promising technique for developing active electrodes for water electrosplitting. Intermetallic compounds of a base metal with passive film-forming element are effective oxygen evolution anodes for metal electrowinning. Cobalt- manganese-silicon alloys and titanium-nickel intermetallics are demonstrated as examples and related to the proposed paradigm of electrochemical dealloying. These systems illustrate the effects of scale in practical electrochemistry, where ‘scale’ has multiple meanings: the transition to practise; formation of surface deposits; and the evolution of the interface in extended use. In the case of cobalt-silicon-manganese alloys, the microstructure of the metal is critical. A highly porous surface layer is developed, within which the active phase is ‘nanostrands’ of cobalt metal in ‘nanoconfinement’ within a slowly-dissolving silicide matrix. Within the confined environment, a saturated solution of cobalt salt causes a salt film over the cobalt metal under which an oxygen-evolving cobalt anodic oxide is stabilised. In the case of TiNi, a nickel-rich surface forms over a thin titanium anodic oxide. Oxygen evolution occurs by field-assisted electron tunnelling to the surface nickel titanium oxide states. Field-driven ion migration both leads to these active states and leads to a slow dissolution of the metal. There is a useful range of composition between 51 and 55 wt% Ni (46 – 50 at%) which balances ductility against dissolution rate: excess titanium leading to a continuous phase of Ti2Ni results in a very brittle material; separation of TiNi3 leads to more rapid dissolution. In practise however, intrusion of oxygen during casting of large plates segregated Ti as the oxide Ti4Ni2O leading to separation of TiNi3 . The more rapid dissolution of this phase, in association with formation of MnO2 from Mn salts present in plant electrolyte, led in association with oxidation of cobalt salts to deposition of an adherent surface scale under which the solution became strongly acidic. The accelerated anode dissolution led to an under-scale of TiO2 which further increased acidification. Impractically rapid destruction of the anode resulted. The work illustrates how mass-transport and microstructure in the evolving interphase between electrode and electrolyte can interact in subtle ways important for practical application.

Novel synthesis of nickel-based bimetallic compounds using ammonium tetrafluoroborate and ammonium bifluoride as structure directing agents for energy storage application

Nickel-based compounds are widely applied as the active material for energy storage devices, owing to high theoretical capacity and easy-fabricated process. Bimetallic compounds having multiple redox states can provide abundant redox reactions for charge storage. Structure directing agent (SDA) can promote the preferable growth of active materials and to enhance energy storage abilities. In this work, NH4BF4 and NH4HF2 are firstly used as SDA to synthesize nickel-based compounds along with 2-methylmidozole in the one-step solution process for energy storage applications. The bimetallic compounds are synthesized by incorporating Al, Mn, Co, Cu and Zn salts in the precursor solution including the Ni salt. The system with Al, Cu or Zn possesses single metal compound and barely nickel compound. Mn and Co-incorporated systems present clear bimetallic components with nickel hydroxide. The highest specific capacitance (CF) of 1336.3 F/g (297.0 mAh/g) are achieved at 20 mV/s for the NiCo-based electrode, owing to the bimetallic feature and favorable two-dimensional sheet-like structures. An energy storage device is assembled using the NiCo-based compound and reduced graphene oxide electrodes. The maximum energy density of 10.5 Wh/kg at 0.3 kW/kg, and the CF retention of 78.5% and Coulombic efficiency of 85.2% are achieved after 10,000 times charge/discharge cycles.

Cation Adaptive Structures Based on Manganese Cyanide Prussian Blue Analogues: Application of Powder Diffraction Data to Solve Complex, Unprecedented Stoichiometries and New Structure Types.

A Mn(II) salt and A+ CN- under anaerobic conditions react to form 2-D and 3-D extended structured compounds of Am MnII n (CN)m+2n stoichiometry. Here, the creation and characterization of this large family of compounds, for example AMnII 3 (CN)7 , A2 MnII 3 (CN)8 , A2 MnII 5 (CN)12 , A3 MnII 5 (CN)13 , and A2 MnII [MnII (CN)6 ], where A represents alkali and tetraalkylammonium cations, is reviewed. Cs2 MnII [MnII (CN)6 ] has the typical Prussian blue face centered cubic unit cell. However, the other alkali salts are monoclinic or rhombohedral. This is in accord with smaller alkali cation radii creating void space that is minimized by increasing the van der Waals stabilization energy by reducing ∠Mn-N≡C, which, strengthens the magnetic coupling and increases the magnetic ordering temperatures. This is attributed to the non-rigidity of the framework structure due the significant ionic character associated with the high-spin MnII sites. For larger tetraalkylammonium cations, the high-spin Mn sites lack sufficient electrostatic A+ ⋅⋅⋅NC stabilization and form unexpected 4- and 5-coordinated Mn sites within a flexible, extended framework around the cation; hence, the size, shape, and charge of the cation dictate the unprecedented stoichio-metry and unpredictable cation adaptive structures. Antiferromagnetic coupling between adjacent MnII sites leads to ferrimagnetic ordering, but in some cases antiferromagnetic coupling of ferrimagnetic layers are compensated and synthetic antiferromagnets are observed. The magnetic ordering temperatures for ferrimagnetic A2 MnII [MnII (CN)6 ] with both octahedral high- and low-spin MnII sites increase with decreasing ∠Mn-N≡C. The crystal structures for all of the extended structured materials were obtained by powder diffraction.

Isolation and Characterization of Rhizospheric Soil Bacteria Present in Shivrajpur Mn Mine Site

Due to the obvious potential hazards it poses to the environment, animals, and human health, Mn (II) contamination has become worrisome. The broad aim of the study was to examine the contamination levels of soil in the Shivrajpur Mn mine site, physicochemical tests such as pH and heavy metal analyses were done. Later 16S rRNA sequencing was used to characterize bacterial species isolated from different colonizer plant samples. The bacterial strains recovered from Mn mine rhizospheric soil exemplified morphological and molecular diversity. It was discovered that all seven bacterial isolates could survive Mn salt concentrations up to 2000 mg/l, whereas only one, Staphylococcus capitis (GenBank OP861008), could withstand concentrations up to 10,000 mg/l. The three isolates, Staphylococcus capitis, Bacillus albus (GenBank OP861099), Bacillus tequilensis (GenBank OQ135205), have the ability to sustain the Mn tolerance as the agar wells were surrounded by growth expanse. The findings imply that the Staphylococcus capitis could be used to create a biosorbent that is both effective and environmentally benign, and it can aid in the bioremediation of contaminated soil.

Trace metals from microbial growth media form in situ electro-catalysts

Most microbial electrosynthesis systems depend heavily on the availability of hydrogen as electron carrier. To improve hydrogen availability in microbial processes, in situ hydrogen production is required with a catalyst that is compatible under microbial conditions (near-neutral pH, mesophilic temperature, aquous electrolyte). Here, we demonstrate the use of trace metal compounds from microbial medium as hydrogen evolution reaction (HER) electro-catalyst under microbial compatible conditions. Concentrated mixtures (10 vol%) of the metal compounds present in the microbial medium (trace metal mix medium; containing Co, Cu, Fe, Mn, Mo, Ni and Zn salts and ethylenediaminetetraacetic acid (EDTA)) were added to electrochemical reactors (controlled at -1.06 V vs Ag/AgCl and flushed with CO2/N2). After addition of the concentrated trace metal mix, the cathodic current increased up to 15 times with high electron recovery into hydrogen (70–100%). The formed HER catalyst performance was also measured in microbial growth medium (with ammonium and 0.1 vol% trace metal mix), showing similar performance rates compared to the concentrated trace metal mix medium. Further identification of the active compounds within the mix emphasized the role of Cu and Mo, a mix with Cu and Mo showed the same catalyst performance as the trace metal mix with all previously mentioned compounds. Moreover, the performance of the trace metal mix without EDTA showed the highest increased current (7 times higher up to -240 A/m2 or -80 kA/m3), decreased hydrogen overpotential (55 mV at -10 A/m2) and increased exchange current density (1.36 mA/m2). Integration of the discovered HER catalyst in biological systems will allow in situ hydrogen production in bio-electrochemical and fermentation systems.

Mn(acac)3 as a Remarkably Efficient Oxidant: Mediation of the Radical Addition/Cyclization Cascade of Boronic Acids with Isocyanides

AbstractA remarkably efficient protocol for the mediation of Mn(III) to the radical addition/cyclization cascade of boronic acids with isocyanides leading to 3‐aminoquinoline derivatives is established. A reasonable explanation to the high reactivity of the Mn(III) salt was suggested. Application of the synthetic method to the late‐stage modification of drug molecules was also presented.

Sequential Assembly and Stabilization of Cu6S6 Octahedral Clusters in NaCl-, NiAs-, and CdI2-Related Structures and Their Utility toward Thermochromism and Multicomponent Hantzsch Reaction.

Seven new inorganic-organic coordination polymer compounds have been synthesized and their structures are determined by single-crystal structure determination. The compounds were prepared by the sequential assembly of a [Cu6(mna)6]6- moiety in the presence of a Mn salt and a secondary amine ligand. Of the seven compounds, [{Cu6(mna)6}Mn3(H2O)(H2O)1.5]·5.5H2O (I), [{Cu6(mna)6}Mn3(H2O)(Im)1.5]·3.5H2O (Ia), [{Cu6(mna)6}{Mn(BPY)(H2O)}2{Mn(H2O)4}]·2H2O (III), and [{Cu6(mna)6}{Mn(BPE)0.5(H2O)2}2{Mn(BPE)(H2O)2}] (IV) have a three-dimensional structure, whereas [{Cu6(mna)4.5(Hmna)1.5}{Mn(BPA)(H2O)2}{Mn(H2O)}]{Mn0.25(H2O)3}·7H2O (II), [{Cu6(mna)6}{Mn(4-BPDB)0.5H2O}{Mn(H2O)2}].{Mn(H2O)6}·6H2O (V), and [{Cu6(mna)4(Hmna)2}·{Mn(H2O)3}2]·(4-APY)2·6H2O (VI) have a two-dimensional structure. Some of the prepared compounds exhibit structures that closely resemble the classical inorganic structures, such as NaCl (Ia, III), NiAs (I), and CdI2 (IV and VI). The stabilization of such simple structures from the assembly of octahedral Cu6S6 clusters and different Mn species and aromatic nitrogen-containing ligands suggests the subtle interplay between the constituent reactants. The compounds were examined for the multicomponent Hantzsch reaction, which gave the product in good yields. The compounds, II and VI, on heating to 70 °C change color reversibly from pale yellow to deep red, which suggests the possible use of these compounds as thermochromic materials. The present study suggests that the Cu6S6 octahedral clusters can be assembled into structures that resemble classical inorganic structures.

MOF-Based Co and Mn Embedded in Nitrogen-Doped Microporous Carbon as an Efficient Catalyst for Oxygen Reduction Reaction in Anion Exchange Membrane Fuel Cell

Developing a low-price, high catalytic activity, and strong durability electrocatalyst for alkaline oxygen reduction reaction (ORR) is significantly important for anion exchange membrane fuel cell (AEMFC). Herein, Co and Mn salts were added into ZIF-8 to obtain CoMn-ZIF-Ac-2. Co and Mn embedded in nitrogen-doped microporous carbon (CoMn-N-C-Ac-2-Ts, T = 700 , 800, 900, and 1000°C) were obtained by carbonizing CoMn-ZIF-Ac-2 at various temperature. The influence of various pyrolysis temperature and molar ratios between Co and Mn toward ORR catalytic activity was researched. For CoMn-N-C-Ac-2-Ts, CoMn-N-C-Ac-2-800 had the highest ORR catalytic activity with the half-wave potential of 0.875 V in 0.1 M KOH, only 5 mV lower than that of 20 wt % Pt/C. Besides, high 4e- selectivity, excellent stability (retaining 100% for 20 h at 0.6 V vs. RHE), and methanol tolerance are also exhibited. In addition, CoMn-N-C-Ac-2-800 exhibited better ORR activity than Mn-N-C-Ac-800 and Co-N-C-Ac-800, which was attributed to more Co-N4, more MnIII species, and higher surface area. Moreover, the AEMFC based on the CoMn-N-C-Ac-2-800 cathode catalyst obtained a maximal power density of 291 mW·cm-2, which was 78% of the P max achieved with 20 wt % Pt/C (375 mW·cm-2). The highest ORR performance for CoMn-N-C-Ac-2-800 was contributed by the highest defect degree, the most amounts of Co/Mn-N4 active site, the maximum BET surface area, and micropore structure.

The Formation and Transformation of Manganese Oxide Minerals on the Surface of Kaolinite

AbstractThe formation of manganese (Mn) oxides is influenced by environmental conditions and, in some red soils, Mn oxides occur as coatings on the surface of kaolinite particles in the form of colloidal films or fine particles. The present study aimed to explore the types of formation mechanisms of Mn oxide minerals on the surface of kaolinite. Mn oxide minerals synthesized by reducing the Mn in KMnO4 with a divalent Mn salt (MnSO4) were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of various initial molar ratios of Mn2+/Mn7+ (R = 1:0.67, 1:1, 1:2, and 1:4), cationic species (Na+ or Mg2+), synthesis temperatures (30, 60, and 110°C), and amount of added kaolinite (0.25, 0.5, 1.0, 2.0, and 5.0 g) on the formation of Mn oxides were studied. The results showed that Mn oxide mineral types were affected by the initial R value and the background cation. With decreases in the initial R value, the synthesized minerals transformed from cryptomelane to birnessite. The relative mass ratios of kaolinite to Mn oxide were calculated as 1:0.92, 1:0.63, 1:1.15, and 1:1.63. The sodium cation (Na+) had a greater role than Mg2+ in promoting the dissolution–recrystallization of birnessite to cryptomelane. The synthesis temperature had no effect on mineral types, but Mn content increased as temperature increased. When the amount of added kaolinite was increased from 0.25 to 5.0 g, Mn oxide minerals formed gradually and transformed from birnessite to cryptomelane. This work revealed a possible formation process and reaction mechanism on the surface of kaolinite particles in some red soils.

Effects of Mn(II) salt anions on MnO@C composites derived from manganese-based aerogels and their lithium storage properties

Effects of Mn(II) salt anions on MnO@C composites derived from manganese-based aerogels and their lithium storage properties

Formation of inorganic liquid gallium particle-manganese oxide composites.

Gallium (Ga) is a low melting point post-transition metal that, under mild mechanical agitation, can form micron and submicron-sized particles with combined fluid-like and metallic properties. In this work, an inorganic network of Ga liquid metal particles was synthesised via spontaneous formation of manganese (Mn) oxide species on their liquid metallic surfaces forming an all-inorganic composite. The micron-sized Ga particles formed by sonication were connected together by Mn oxide nanostructures spontaneously established from the reduction of a Mn salt in aqueous solution slightly above the melting point of Ga. The formed Mn oxide nanostructures were found to coalesce from the surface of the Ga particles into a continuous inorganic network. The morphology of the composites could be altered by varying the Mn salt concentration and by performing post-treatment annealing. The composites presented a shell of various Mn oxide nanostructures including wrinkled sheets, rods and nanoneedles, around spherical liquid Ga particles, and a liquid metal core. The photoelectric and optical properties of the composites were thoroughly characterised, which revealed decreasing bandgaps and valence band edge characteristics as a function of increased Mn oxide coverage. The photoluminescence properties of the composites could be also engineered by increasing the Mn oxide coverage. The all-inorganic liquid Ga composite could be formed via a straightforward reduction reaction of a Mn-rich salt at the surface of liquid Ga particles with tunable surface properties for future optoelectronic applications.

Tetra-, tetradeca- and octadecametallic clusters of Mn.

Reaction of equimolar amounts of MnBr2·4H2O and HL1 ((3,5-dimethyl-1H-pyrazol-1-yl)methanol) in a basic MeCN solution leads to the formation of [MnII4(L1)4Br4(H2O)4] (1), whose metallic skeleton is a [MnII4] tetrahedron and cluster core a [MnII4(μ3-O)4] cubane. Replacing MnBr2·4H2O with Mn(O2CMe)2·4H2O affords [MnIII2MnII12O2(L1)4(OAc)22] (2) which is best described as a series of edge-sharing [Mn4] tetrahedra that have self-assembled into a linear array in which each [Mn2] pair is 'twisted' with respect to its neighbours in a corkscrew-like manner. Employment of the triangle [MnIII3O(OAc)6(py)3](ClO4) as a reactant instead of a MnII salt results in the formation of [MnIII14MnII4O14(L1)4(HL1)2(OAc)18(H2O)2] (3) whose core is comprised of three vertex-sharing [MnIII4] butterflies flanked on either side by one [MnIII4] cubane and one [MnIII2MnII2] tetrahedron. Dc magnetic susceptibility and magnetisation measurements of polycrystalline samples of 1-3 reveal the predominance of antiferromagnetic exchange interactions. For [Mn4] (1) this leads to a diamagnetic ground state, while for [Mn18] (3) competing exchange interactions result in Single-Molecule Magnet (SMM) behaviour with Ueff = 22 K.

A novel 3D bacterial cellulose network as cathodic scaffold and hydrogel electrolyte for zinc-ion batteries

Aqueous zinc-ion batteries (ZIB) have been subject to intensive research, motivated by the high theoretical specific capacity and relatively low cost of metallic zinc. Nevertheless, cathode dissolution and structural instability result in slow Zn-ion migration dynamics and severe electrode degradation, impeding the development of ZIB. Herein, to our best knowledge, this is the first time a novel 3D bacterial cellulose (BC) network is successfully used as cathodic scaffold to provide sufficient ion pathways and stabilize the host material. Meanwhile, BC hydrogel electrolyte with high ionic conductivity and flexibility enables the use of ZIB in wearable applications. Carbon nanofibers (CNFs)@Mn3O4 are obtained through carbonization of BC network and pre-absorption of Mn salt. The CNFs@Mn3O4/BC electrolyte/Zn full cell possesses a low inner resistance and thus delivers a high capacity of 415.2 mAh g−1 at 0.1 A g−1. Further, the full cell shows excellent coulombic efficiency above 99% and capacity retention of 88.2% after 1000 cycles at high current density of 2 A g−1. The charge storage mechanism and stability of assembled batteries, unveiled via ex-situ characterization, confirm the reversible diffusion of Zn2+. A flexible ZIB fabricated via facile lamination shows an outstanding energy density of 179 mAh g−1 at 1 A g−1, illustrating potential in wearable applications.

Syntheses and Antioxidant Activity of 1-Isonicotinoyl-4-phenylthiosemicarbazide and Crystal Structures of N-Phenyl-5-(pyridin-4-yl)-1,3,4-oxadiazol-2-amine Hydrochloride and 4-Phenyl-3-(pyridin-4-yl)-1H-1,2,4-triazole-5(4H)-thione derived from 1 Isonicotinoyl-4-phenylthiosemicarbazide

The title compound C13H12N4OS (I) is synthetized from isonicotinic hydrazide and isothiocynate. Compounds C13H11N4OCl (II) and C13H10N4S (III) where obtained upon reaction of (I) with Fe(II) or Mn(II) salts. Compound (II) is heterocyclic 1,3,4-oxadiazole while compound (III) is heterocyclic 1,2,4-triazole. The 1,3,4-oxadiazol derivative is almost planar with dihedral angle of 2.66 (8) and 5.14 (8)° between 1,3,4-oxadiazole ring and phenyl and pyridinium rings respectively; the dihedral angle between the phenyl and pyridinium rings is 3.92 (8)°. The 1,2,4-triazole derivative is non-planar. The phenyl and pyridyl rings form dihedral angles of 58.35 (5) and 58.33 (5)°, respectively, with the 1,2,4-triazole ring; the dihedral angle between the phenyl and pyridyl rings is 36.85 (4)°. In the compound (II) intramolecular hydrogen bonds of type N—H···Cl, C—H···N and C—H···Cl resulting in S(6) ring stabilize the structure. Intermolecular hydrogen bonds of type N—H···N, C—H···N, C—4···Cl link the molecule thus forming a three-dimensional network. In the structure of compound (III), intermolecular hydrogen bonds of type N—H···N, C—H···N, C—H···S1,link the monomer in a three-dimensional network.