Enhanced electrochemical performance of Ce-MOF/h-CeO2 composites for high-capacitance energy storage applications.

The escalating demand for energy storage underscores the significance of supercapacitors as devices with extended lifespans, high energy densities, and rapid charge-discharge capabilities. Ceria (CeO2), known for its exceptional properties and dual oxidation states, emerges as a potent material for supercapacitor electrodes. This study enhances its capacitance by integrating it with Metal-Organic Frameworks (MOFs), carbon-rich compounds noted for their good conductivity. In our research, hollow ceria (h-ceria) is synthesized via hydrothermal methods and amalgamated with Ce-MOF, employing 2,6-dinaphthalene dicarboxylic acid as a ligand, to fabricate Ce-MOF@h-CeO2 composites. The structural and morphological characteristics of the composite are methodically examined using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), and Fourier-Transform Infrared (FT-IR) spectroscopy. The band gap of the materials is ascertained through UV-Diffuse Reflectance Spectroscopy (UV-DRS). Electrochemical behavior and redox properties of the Ce-MOF composites are explored using Cyclic Voltammetry (CV), Galvanostatic Charge and Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS), providing insights into the material's stability. Electrochemical characterization of the composite reveals maximum specific capacitance, energy density and power density are 2643.78 F g-1 at a scan rate of 10 mV s-1, 249.22 W h kg-1, and 7.9 kW kg-1, respectively. Additionally, the specific capacitance of Ce-MOF synthesized with a 2,6-dinaphthalene dicarboxylic acid (NDC) ligand reaches 995.59 F g-1, surpassing that of Ce-MOF synthesized using a 1,3,5-tricarboxylic acid (H3BTC) ligand. These findings highlight the promising economic potential of high-performance, environmentally sustainable, and cost-effective energy storage devices. The innovative Ce-MOF@h-CeO2 composite materials at the core of this research pave the way for advancing the field of energy storage solutions.

An organic coprecipitation route to synthesize high voltage LiNi0.5Mn1.5O4.

High-voltage cathode material LiNi0.5Mn1.5O4 has been prepared with a novel organic coprecipitation route. The as-prepared sample was compared with samples produced through traditional solid state method and hydroxide coprecipitation method. The morphology was observed by scanning electron microscopy, and the spinel structures were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. Besides the ordered/disordered distribution of Ni/Mn on octahedral sites, the confusion between Li and transition metal is pointed out to be another important factor responsible for the corresponding performance, which is worthy further investigation. Galvanostatic cycles, cyclic voltammetry, and electrochemical impedance spectroscopy are employed to characterize the electrochemical properties. The organic coprecipitation route produced sample shows superior rate capability and stable structure during cycling.

Lithium cobalt(II) pyrophosphate, Li(1.86)CoP(2)O(7), from synchrotron X-ray powder data.

Structure refinement of high-resolution X-ray powder diffraction data of the title compound gave the composition Li(1.865)CoP(2)O(7), which is also verified by the ICP measurement. Two Co sites exist in the structure: one is a CoO(5) square pyramid and the other is a CoO(6) octa-hedron. They share edges and are further inter-connected through P(2)O(7) groups, forming a three-dimensional framework, which exhibits different kinds of inter-secting tunnels containing Li cations and could be of great inter-est in Li ion battery chemistry. The structure also exhibits cation disorder with 13.5% Co residing at the lithium (Li1) site. Co seems to have an average oxidation state of 2.135, as obtained from the strutural stochiometry that closely supports the magnetic susceptibility findings.

Electrochemical performances of LiMnPO4 synthesized from non-stoichiometric Li/Mn ratio.

In this paper, the influences of the lithium content in the starting materials on the final performances of as-prepared Li(x)MnPO(4) (x hereafter represents the starting Li content in the synthesis step which does not necessarily mean that Li(x)MnPO(4) is a single phase solid solution in this work.) are systematically investigated. It has been revealed that Mn(2)P(2)O(7) is the main impurity when Li < 1.0 while Li(3)PO(4) begins to form once x > 1.0. The interactions between Mn(2)P(2)O(7) or Li(3)PO(4) impurities and LiMnPO(4) are studied in terms of the structural, electrochemical, and magnetic properties. At a slow rate of C/50, the reversible capacity of both Li(0.5)MnPO(4) and Li(0.8)MnPO(4) increases with cycling. This indicates a gradual activation of more sites to accommodate a reversible diffusion of Li(+) ions that may be related to the interaction between Mn(2)P(2)O(7) and LiMnPO(4) nanoparticles. Among all of the different compositions, Li(1.1)MnPO(4) exhibits the most stable cycling ability probably because of the existence of a trace amount of Li(3)PO(4) impurity that functions as a solid-state electrolyte on the surface. The magnetic properties and X-ray absorption spectroscopy (XAS) of the MnPO(4)·H(2)O precursor, pure and carbon-coated Li(x)MnPO(4) are also investigated to identify the key steps involved in preparing a high-performance LiMnPO(4).

A novel lithium copper iron phosphate with idealized formula Li(5)Cu(2)Fe(PO(4))(4): crystal structure and distribution of defects.

Gray-green single crystals were obtained under high-pressure, high-temperature hydro-thermal conditions. A refinement of atom occupancies gave the composition Li(3.68)Cu(2+)Fe(3+)(Cu(0.55)Li(0.45))(2)Fe(2+) (0.15)(PO(4))(4). The structure is built from triplets of edge-sharing (Cu,Li)O(5)-FeO(6)-(Cu,Li)O(5) polyhedra, CuO(4) quadrilaterals and PO(4) tetra-hedra. In the (Cu,Li)O(5) polyhedra the Cu and Li positions are statistically occupied in a 0.551 (2):0.449 (2) ratio. Both FeO(6) and CuO(4) polyhedra exhibit [Formula: see text] symmetry. The positions of additional Li atoms with vacancy defects are in the inter-stices of the framework.

Cobalt complex as building blocks: synthesis, characterization, and catalytic applications of {Cd2+-Co3+-Cd2+} and {Hg2+-Co3+-Hg2+} heterobimetallic complexes.

The present work demonstrates the utilization of the Co(3+) complex of pyridine-amide ligand as building blocks for the assembly of heterobimetallic complexes. These Co(3+)-centered building blocks orient the tethered pyridine groups to a preorganized cleft that successively coordinates to the Cd(2+) and Hg(2+) ions in the periphery. Both {Cd(2+)-Co(3+)-Cd(2+)} and {Hg(2+)-Co(3+)-Hg(2+)} heterobimetallic complexes have been thoroughly characterized, including crystal structures depicting interesting weak interactions in the solid state. The {Cd(2+)-Co(3+)-Cd(2+)} and {Hg(2+)-Co(3+)-Hg(2+)} heterobimetallic complexes have been further used for the catalytic cyanosilylation of imines and ring-opening reactions of oxiranes and thiiranes. The results suggest peripheral metal-selective catalytic reactions.

Design, synthesis, and self-assembling properties of novel triazolophanes.

A series of novel triazolophanes containing peptidic and nonpeptidic backbones is reported. The crystal structure of one such macrocycle displays self-assembly through nonconventional hydrogen-bonding interactions.

Cobalt coordination induced functionalized molecular clefts: isolation of {Co(III)-Zn(II)} heterometallic complexes and their applications in Beckmann rearrangement reactions.

The present work shows that the Co3+ coordination to the deprotonated pyridine-amide ligands orients the noncoordinated or hanging pyridine rings, thus furnishing a cleft in which Zn2+ ions coordinate. The building block approach points out a strategy to incorporate a Lewis acidic metal center in the periphery. This strategy has been used to synthesize Co3+-centered-Zn2+-peripheral heterobimetallic complexes. These heterobimetallic complexes have been thoroughly characterized including structural studies and have been successfully shown to catalyze the Beckmann rearrangement of the aldoximes and ketoxime to their respective amides.

1-Phenyl-3-{4-[4-(4-undecyl-oxybenzoyl-oxy)phenyl-oxycarbon-yl]phen-yl}triazene 1-oxide.

The X-ray crystallographic study of the title compound, C(37)H(41)N(3)O(6), at 150 K establishes the N-oxide form of the triazene 1-oxide unit. There is one intra-molecular N-H⋯O hydrogen-bonding inter-action and the crystal packing is stabilized by one N-H⋯O, three C-H⋯O and three C-H⋯π inter-molecular inter-actions. The dihedral angles between pairs of adjacent benzene rings are 14.9 (3), 56.3 (1) and 56.0 (1)°

Expanding the scope of sulfur-centered Arbuzov rearrangement in diethyl/di-n-propyl sulfite for the synthesis of mixed-ligand di-n-butyltin alkanesulfonates.

A one-pot reaction between di-n-butyltin oxide and diethyl/di-n-propyl sulfite in the presence of an equimolar amount of alkyl iodide proceeds via sulfur-centered Arbuzov rearrangement to afford the corresponding di-n-butyltin (alkoxy)alkanesulfonates n-Bu2Sn(OR')OS(O)2R [R = R' = Et (1), n-Pr (2); R = Me, R' = Et (3), n-Pr (4)]. The compounds 1 and 3 react with methylphosphonic acid under mild conditions to give [n-Bu2Sn(OS(O)2R)OP(O)(OH)Me]n [R = Et (5), Me (6), respectively].

Synthesis and characterization of novel fluorophosphazene-derived cobaltacyclopentadienyl metallacycles: reagents for assembly of aryl-bridged fluorophosphazenes.

Reaction of (beta-phenylethynyl)pentafluorocyclotriphosphazene, F5P3N3C identical with CPh, with in situ generated eta5-(MeOC(O)C5H4)Co(PPh3)2 resulted in the formation of two isomers of cobaltacyclopentadienylmetallacycles, (eta(5)-carbomethoxycyclopentadienyl)(triphenylphosphine)-2,5-bis(pentafluorocyclotriphosphazenyl)-3,4-diphenyl cobaltacyclopentadiene (1) and (eta5-carbomethoxycyclopentadienyl)(triphenylphosphine)-2,4-bis(pentafluorocyclotriphosphazenyl)-3,5-diphenyl cobaltacyclopentadiene (2), along with the sandwich compound [eta5-carbomethoxycyclopentadienyl]-[eta4-1,3-bis(pentafluorocyclotriphosphazenyl)-2,4-diphenylcyclobutadiene]cobalt (3). Formation of cobaltacyclopentadienylmetallacycles or cyclobutadienylmetallocene having two fluorophosphazene units on vicinal carbon atoms of the rings was not observed in this reaction. Reaction of 1 with diphenylacetylene resulted in the formation of a novel aryl-bridged fluorophosphazene, 1,4-bis(pentafluorocyclotriphosphazenyl)-2,3,5,6-tetraphenyl benzene (4), and the conversion of cobaltametallacycle to the sandwich compound, [eta5-(MeOC(O)C5H4]Co(eta4-C4Ph4) (5). Reaction of 1 with phenylacetylene resulted in the formation of aryl-bridged fluorophosphazene, 1,4-bis(pentafluorophosphazenyl)-2,3,5,-triphenyl benzene (6). New compounds 1-4 were structurally characterized. In compound 1, the two fluorophosphazene units were oriented in gauche form with respect to each other. However, in compounds 2 and 3, they were eclipsed to each other, and in compound 4, they were oriented anti to each other.

Convenient direct synthesis of bisformylated calix[4]arenes via ipso substitution.

[reaction: see text] A facile synthesis of bisformylated calix[4]arenes via ipso substitution of p-tert-butylcalix[4]arenes through treatment with hexamethylenetetramine/trifluoroacetic acid is described. Under identical conditions, p-tert-butylcalix[4]arene tetramethyl ether 4 gives proximally substituted bisformylated derivative 4a in a pinched cone conformation.

Novel bile acid-based cyclic bisimidazolium receptors for anion recognition.

[structure: see text] Novel deoxycholic acid-based cyclic receptors, 3 and 4, containing two imidazolium groups and m-xylene and p-xylene as spacers have been synthesized. These receptors bind anions through hydrogen bonds utilizing two imidazolium (C-H)(+) and inwardly directed methylene hydrogens of both acetyl groups. Receptor 3 shows a moderate selectivity for fluoride ion whereas receptor 4 shows high affinity and selectivity for chloride ion in CDCl(3).