Xn:Harmful;
1307-96-6Relevant articles and documents
Magneto-structural study of an oxamato-bridged PdIICo II chain: X-ray crystallographic evidence of a single-crystal-to- single-crystal phase transition
Oliveira, Willian X. C.,Ribeiro, Marcos A.,Pinheiro, Carlos B.,Nunes, Wallace C.,Julve, Miguel,Journaux, Yves,Stumpf, Humberto O.,Pereira, Cynthia L. M.
, p. 5685 - 5693 (2012)
Two new mononuclear oxamato-containing palladium(II) complexes of formula K2[Pd(opba)]·2H2O (1) and (PPh4) 2[Pd(opba)]·2H2O (2) and the heterodimetallic palladium(II)-cobalt(II) chain {[Co(H2O)2Pd(opba)] ·dmso}n (3) [opba = 1,2-phenylenebis(oxamate), PPh 4+ = tetraphenylphosphonium cation and dmso = dimethyl sulfoxide] have been prepared, and the structures of two of them (compounds 2 and 3) were determined by X-ray diffraction analysis of single crystals. The structure of 2 consists of discrete anions of [Pd(opba)2] 2- and PPh4+ cations. Each PdII ion in 2 is surrounded by two oxamate nitrogen atoms and two carboxylate oxygen atoms in a square-planar surrounding. Compound 3 is a neutral chain with regular alternating PdII and CoII ions, the [Pd(opba)] 2- entity acting as a bis(bidentate) ligand towards trans-diaquacobalt(II) fragments, and dmso molecules of crystallization. Compound 3 exhibits a single-crystal-to-single-crystal phase transition between monoclinic C2/c (α phase) and triclinic P1 (β phase) space groups. Within the α phase the dmso molecule of crystallization is disordered, but it becomes ordered below 215 K in the β phase. The ordering process of the dmso molecule is followed by a reduction in the unit cell volume. The magnetic properties of 3 are barely affected by the structural phase transition, and they indicate an important spin-orbit coupling of the high-spin octahedral CoII ion [α = 1.245, λ =-151 cm -1, Δ = 494 cm-1, the spin Hamiltonian being defined as H =-αλLS + Δ(Lz2-2/3) + βH(-αL + geS)] with an almost negligible intra- [through the diamagnetic square-planar PdII centre] and interchain antiferromagnetic interactions (θ =-0.32 K).
Na10Co4O10, an oligooxocobaltate(II, III) with unusual magnetic properties
Sofin, Mikhail,Guedel, Hans-Ulrich,Bircher, Roland,Peters, Eva-Maria,Jansen, Martin
, p. 3527 - 3529 (2003)
The novel mixed-valent oligooxocobaltate can be synthesized through a direct reaction by the azide/nitrate route. The magnetic properties of the compound are characterized by the strongly distinct hierarchy in the magnetic exchange interactions within the complex anion (see picture).
Enhancing the electrocatalytic activity of CoO for the oxidation of 5-hydroxymethylfurfural by introducing oxygen vacancies
Huang, Xin,Song, Jinliang,Hua, Manli,Xie, Zhenbing,Liu, Shuaishuai,Wu, Tianbin,Yang, Guanying,Han, Buxing
, p. 843 - 849 (2020)
The electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a highly attractive strategy to generate valuable biomass-based oxygenated chemicals. Robust, stable and inexpensive electrocatalysts are crucial for this interesting reaction. In this work, we found that the electrocatalytic performance of cobalt oxide (CoO) could be significantly improved by introducing oxygen vacancies via Se doping. The resulting CoO-CoSe2 with a CoO/CoSe2 molar ratio of 23?:?1 showed excellent performance and stability for the electro-oxidation of HMF to FDCA, and a FDCA yield of 99% could be achieved with a faradaic efficiency of 97.9% at a potential of 1.43 V vs. RHE. A systematic study indicates that the introduction of rich oxygen vacancies could enhance the catalytic activity and the selectivity to FDCA by increasing the electrochemical surface area and reducing charge transfer resistance. As far as we know, this is the first work to develop a highly stable metal oxide as the active component for this reaction.
Crystalline nanoflowers with different chemical compositions and physical properties grown by limited ligand protection
Narayanaswamy, Arun,Xu, Huifang,Pradhan, Narayan,Peng, Xiaogang
, p. 5361 - 5364 (2006)
(Figure Presented) A varied bouquet: Crystalline nanoflowers (see picture) of compounds with different chemical and physical properties, for example, In2O3, ZnO, CoO, MnO, and ZnSe, are grown by a new approach, limited ligand protection (LLP). LLP destabilizes the primary nanoparticles and promotes their three-dimensionally oriented attachment into complex nanostructures.
Oxygen reduction reaction over (Ba,Sr)6RE2Co4O15-Ba(Ce,Pr,Y)O3composite cathodes for proton-conducting ceramic fuel cells
Eguchi, Koichi,Kamiuchi, Naoto,Kunimoto, Naoki,Manriki, Kohei,Matsui, Toshiaki,Miyazaki, Kazunari,Muroyama, Hiroki
, p. 15199 - 15206 (2021)
In this study, the effect of elemental substitution, especially the Ba/Sr ratio and rare-earth elements, in (Ba,Sr)6RE2Co4O15(RE = La, Pr, Nd, Sm, Gd) and the composite effect with BaCe0.5Pr0.3/
Environmentally benign benzyl alcohol oxidation and C-C coupling catalysed by amide functionalized 3D Co(II) and Zn(II) metal organic frameworks
Guedes da Silva, M. Fátima C.,Karmakar, Anirban,Kuznetsov, Maxim L.,Martins, Luísa M. D. R. S.,Novikov, Alexander S.,Paul, Anup,Pombeiro, Armando J. L.
, p. 324 - 337 (2020)
The new 3D metal-organic frameworks (MOFs) [Co(1κN;2κOO′-μ-L)2]n.4n(DMF).1.5n(H2O) (1) and [Zn2(1κN;2κO-μ-L)2(κO4-μ4-BTC)]n.3n(DMF).2n(H2O) (2) [L = 4-(pyridin-4-ylcarbamoyl)benzoate; BTC = benzene-1,3,5-tricarboxylate] have been synthesized from the pyridyl amide functionalized benzoic acid (HL). They were characterized by elemental, FT-IR, powder X-ray and single crystal X-ray diffraction analyses. Topological analysis of 1 discloses a 2,3,7-connected trinodal net with a 4-connected uninodal net with 2-fold interpenetrating networks, whereas that of 2 shows a dia topology. The solid-state photoluminescent properties of HL and 2 were also investigated. The heterogeneous catalytic activity of 1 and 2, under eco-friendly conditions, was assessed in benzyl alcohol oxidation and C-C bond formation model reactions. 1 has good activity in the solvent-free microwave-assisted oxidation of benzyl alcohol to benzaldehyde using tert-butyl hydroperoxide (tBuOOH, TBHP) as oxidizing agent (yields up to 89%). Although with a lower activity, MOF 2 with a redox inactive Zn(II) site, also catalyses such alcohol oxidation, which is explained by DFT calculations according to a mechanism of a similar type to that followed by the peroxidative alkane oxidation. 2 is the most active one in the ambient temperature sonochemical Knoevenagel condensation of benzaldehyde and malononitrile (yields up to 94%) and in the ambient temperature Henry C-C coupling reaction of benzaldehyde with nitroethane in water (yields > 99%), showing appreciable diastereoselectivity towards the syn isomer. The recyclability of catalysts 1 and 2 was evaluated.
Thermal behaviour of malonic acid, sodium malonate and its compounds with some bivalent transition metal ions
Caires,Lima,Carvalho,Giagio,Ionashiro
, p. 35 - 40 (2010)
Characterization, thermal stability and thermal decomposition of transition metal malonates, MCH2C2O4·nH2O (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), as well as, the thermal behaviour of malonic acid (C3H4O4) and its sodium salt (Na2CH2C2O4·H2O) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry. The dehydration, as well as, the thermal decomposition of the anhydrous compounds occurs in a single step. For the sodium malonate the final residue up to 700 °C is sodium carbonate, while the transition metal malonates the final residue up to 335 °C (Mn), 400 °C (Fe), 340 °C (Co), 350 °C (Ni), 520 °C (Cu) and 450 °C (Zn) is Mn3O4, Fe2O3, Co3O4, NiO, CuO and ZnO, respectively. The results also provided information concerning the ligand's denticity, thermal behaviour and identification of some gaseous products evolved during the thermal decomposition of these compounds.
Non-isothermal decomposition of cobalt acetate tetrahydrate
Mohamed,Halawy,Ebrahim
, p. 387 - 404 (1994)
The non-isothermal decomposition of cobalt acetate tetrahydrate was studied up to 500°C by means of THE, DTG, DTA and DSC techniques in different atmospheres of N2, H2 and in air. The complete course of the decomposition is described on the basis of six thermal events. Two intermediate compounds (i.e.acetyl cobalt acetate and cobalt acetate hydroxide) were found to participate in the decomposition reaction. IR spectroscopy, mass spectrometry and X-ray diffraction analysis were used to identify the solid products of calcination at different temperatures and in different atmospheres. CoO was identified as the final solid product in N2, and Co3 O4 was produced in air. A hydrogen atmosphere, on the other hand, produces cobalt metal. Scanning electron microscopy was used to investigate the solid decomposition products at different stages of the reaction. Identification of the volatile gaseous products (in nitrogen and in oxygen) was performed using gas chromatography. The main products were: acetone, acetic acid, CO2 and acetaldehyde. The proportions of these products varied with the decomposition temperature and the prevailing atmosphere. Kinetic parameters (e.g. E and In A) together with thermodynamic functions (e.g.ΔH, Cp and ΔS) were calculated for the different decomposition steps.
Oxidation of CoO studied with the perturbed angular correlation method
Wegner,Inglot,Lieb
, p. 1 - 7 (1990)
The substages of the oxidation of CoO have been investigated with the PAC method during isochronal and isothermal annealings at low oxygen activity (10-9 atm). The successive trapping of cation vacancies at the 111In probe atoms up to the formation of spinel-like microclusters has been observed. The results of the PAC experiments are compared with those of X-ray diffraction and RBS analyses and confirmed by a PAC experiment for 111In in Co3O4. A quantitative analysis of the oxidation kinetics in terms of first order rate equations yields an activation enthalpy of ΔH = 0.27(4) eV. It is found that the absorption of oxygen and the formation of vacancies at the surface are the rate controlling processes in this experiment.
A Cobalt-Based Metal–Organic Framework as Cocatalyst on BiVO4 Photoanode for Enhanced Photoelectrochemical Water Oxidation
Zhang, Wang,Li, Rui,Zhao, Xin,Chen, Zhong,Law, Adrian Wing-Keung,Zhou, Kun
, p. 2710 - 2716 (2018)
A metal–organic framework (MOF)-modified bismuth vanadate (BiVO4) photoanode is fabricated by an ultrathin sheet-induced growth strategy, where ultrathin cobalt oxide sheets act as a metal source for the in situ synthesis of Co-based MOF poly[Co2(benzimidazole)4] (denoted [Co2(bim)4]) nanoparticles on the surface of BiVO4. [Co2(bim)4] with small particle size and high dispersion can serve as a promising cocatalyst to accept holes transferred from BiVO4 and boost surface reaction kinetics for photoelectrochemical (PEC) water oxidation. The photocurrent density of a [Co2(bim)4]-modified BiVO4 photoanode can achieve 3.1 mA cm?2 under AM 1.5G illumination at 1.23 V versus the reversible hydrogen electrode (RHE), which is better than those of pristine and cobalt-based inorganic materials-modified BiVO4 photoanodes. [Co2(bim)4], with porosity and abundant metal sites, exhibits a high surface charge-separation efficiency (83 % at 1.2 V versus RHE), leading to the enhanced PEC activity. This work will bring new insight into the development of MOF materials as competent cocatalysts for PEC water splitting applications.
A cobalt (II)-based semiconductor complex with two-channel slow magnetic relaxation
?i?már, Erik,Hchicha, Khouloud,Kliuikov, Andrii,Korb, Marcus,Na?li, Houcine
, (2021)
The hydrothermal reaction of 2-methylimidazole (hereafter abbreviated as 2-mim) with cobalt (II) sulfate heptahydrate in methanol affords a novel sulfate cobalt (II) complex with formula [Co(C4H6N2)4](SO4)?(H2O) (1). Its crystal structure was refined from X-ray diffraction data, complemented with the structural information derived from spectroscopic (IR and UV–Vis), thermal data and magnetic measurements. The crystal structure of 1 is made up of isolated [Co(2-mim)4]2+ cations, (SO4)2- anions and lattice water molecules. An extensive network of hydrogen bonds ensures the interconnection of the different entities. Greater knowledge on these interactions has been provided based on the Hirshfeld surface analysis and 2D fingerprint plots. Heating of 1 above 97 °C initiates gradual decomposition stages, which lead to the metal oxide as a final product at 710 °C, as proven by TGA/DSC analysis. A UV–Vis spectroscopy study confirms the tetrahedral environment around the metal. The determined bandgap energy Eg = 2.6 eV from the UV–Vis spectra indicate the interesting semiconducting behavior of our compound. Static magnetic measurements and EPR study revealed the presence of the easy-axis anisotropy with axial term D = –5.45 cm?1 and very small rhombicity, confirmed by the first-principle calculations. Complex 1 behaves as a field-induced single-ion magnet with two relaxation channels. The high-frequency relaxation can be described by the interplay of the two-phonon Orbach and Raman process, the relaxation barrier Ueff = 11.4 cm?1 agrees well with the difference between the two lowest Kramer's doublets.
Moore, T. E.,Watt, G. W.
, p. 2772 - 2775 (1942)
CoO microspheres and metallic Co evolved from hexagonal α-Co(OH)2 plates in a hydrothermal process for lithium storage and magnetic applications
Ma, Keyuan,Liu,Yuan,Liu,Wang, Jun,Xie,Cheng
, p. 595 - 604 (2017)
CoO microspheres and metallic Co could be successfully synthesized by simply reacting cobalt acetate with a mixture solvent of ethylene glycol and deionized water in a hydrothermal process for different times. As the reaction proceeded, α-Co(OH)2, CoO and metallic Co were produced. To understand the phase evolution processes from α-Co(OH)2 to CoO and then metallic Co, a range of time-dependent experiments were carried out, and the intermediate products obtained at different reaction times were investigated in detail. The investigation revealed that CoO microspheres were actually evolved from α-Co(OH)2 as a precursor. Just elongating the reaction time, CoO microspheres could be further reduced to metallic Co. With a pure ethylene glycol medium for the same reaction, only α-Co(OH)2 could be generated, indicating an important role of water. When the obtained CoO microspheres were used as anode materials for lithium-ion batteries, they delivered a specific capacity of 803 mA h g-1 at 0.1 A g-1 with a retention of 453 mA h g-1 after 70 cycles. Meanwhile, the magnetic properties of the obtained CoO microspheres and metallic Co were investigated, with the CoO microspheres showing an antiferromagnetic behavior and the metallic Co exhibiting ferromagnetic characteristics. This study suggested a novel method for synthesizing CoO with a uniform microsphere morphology and bulk metallic Co easily.
A thermal decomposition study on cobalt(II) complexes of 1,2-di(imino-4′-antipyrinyl)ethane
Madhu,Radhakrishnan,Grunert, Matthias,Weinberger, Peter,Linert, Wolfgang
, p. 29 - 36 (2003)
The phenomenological, kinetic and mechanistic aspects of thermal decomposition of perchlorate, nitrate, chloride, bromide and iodide complexes of cobalt(II) with the Schiff base 1,2-di(imino-4′-antipyrinyl)ethane (GA) have been studied by TG and DTG analyses. The kinetic parameters like the activation energy, pre-exponential factor and entropy of activation were calculated. The decomposition reactions follow random nucleation with one nucleus on each particle - Mampel model .
Thermal, spectral and magnetic properties of 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II)
Ferenc, Wieslawa,Walkow-Dziewulska, Agnieszka,Sadowski
, p. 365 - 371 (2005)
The complexes of 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) have been synthesized as hydrated polycrystalline solids and characterized by elemental analysis, IR, FIR and electronic spectroscopy, magnetic studies and X-ray diffraction measurements. They possess colours typical of the M(II) ions: Cu-blue, Ni-green, Co-pink. The carboxylate groups bind as monodentate or a symmetrical, bidentate chelating or bridging ligands. The thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which are decomposed to the oxides of respective metals. The magnetic susceptibilities of the complexes were measured over the range 77-300 K and the magnetic moments were calculated. The results reveal the complexes of Ni(II) and Co(II) to be high-spin complexes and that of Cu(II) to form dimer.
Mesoporous CoO-supported palladium nanocatalysts with high performance for: O -xylene combustion
Xie, Shaohua,Liu, Yuxi,Deng, Jiguang,Yang, Jun,Zhao, Xingtian,Han, Zhuo,Zhang, Kunfeng,Wang, Yuan,Arandiyan, Hamidreza,Dai, Hongxing
, p. 806 - 816 (2018)
The Pd-based catalysts have been widely studied for the combustion of volatile organic compounds, in which the roles of the Pd and the support are still not known clearly. In this study, mesoporous Co3O4 and CoO (i.e., meso-Co3O4 and meso-CoO) were prepared and used as support for the loading of Pd nanoparticles (NPs). The supported Pd samples performed much better than the supports for o-xylene combustion, in which the Pd/meso-CoO sample showed the best catalytic activity (T90% = 173 °C), giving rise to reaction rates at 170 °C 3.5 and 84 times higher than those over the Pd/meso-Co3O4 and meso-CoO samples, respectively. It has been established that the meso-CoO sample possessed strong ability to activate oxygen molecules to the active oxygen species, the loaded Pd NPs in a metallic Pd phase was beneficial for o-xylene adsorption, and the adsorbed o-xylene species could immediately react with the active oxygen species at the interface between Pd NPs and meso-CoO. Therefore, we conclude that the excellent catalytic performance of the Pd/meso-CoO sample was associated with its highly active Pd-CoO interface.
Atomically-thin non-layered cobalt oxide porous sheets for highly efficient oxygen-evolving electrocatalysts
Sun, Yongfu,Gao, Shan,Lei, Fengcai,Liu, Jiawei,Liang, Liang,Xie, Yi
, p. 3976 - 3982 (2014)
Water electrolysis for hydrogen production requires better catalysts to lower the kinetic barrier of the oxygen evolution reaction. Herein, conceptually-new, noble-metal-free, porous, atomically-thick sheets are first put forward as an excellent platform to promote the oxygen evolution activity through affording abundant catalytically active sites and enhanced two-dimensional conductivity. As an example, the synthetic porous Co 3O4 atomically-thick sheets with a thickness of 0.43 nm and about 30% pore occupancy afford low-coordinated Co3+ atoms to serve as the catalytically active sites, while the obviously increased density of states at the valence band and conduction band edge facilitate fast electron transport along their two-dimensional conducting paths. As a result, the porous, atomically-thick Co3O4 sheets exhibit an electrocatalytic current up to 341.7 mA cm-2, roughly 50-times larger than that of the bulk counterpart and even more strikingly higher than that of most existing reports under similar conditions. This work holds great promise for triggering breakthroughs in the field of electrocatalysis.
Reversible single-crystal-to-single-crystal transformation and highly selective adsorption property of three-dimensional cobalt(II) frameworks
Su, Zhi,Chen, Min,Okamura, Taka-Aki,Chen, Man-Sheng,Chen, Shui-Sheng,Sun, Wei-Yin
, p. 985 - 991 (2011)
A three-dimensional (3D) coordination polymer, [Co3(L) 2(BTEC)(H2O)2] · 2H2O [1, HL = 3,5-di(imidazol-1-yl)benzoic acid, H4BTEC = 1,2,4,5- benzenetetracarboxylic acid], with tfz-d topology has been hydrothermally synthesized. The framework of 1 has high thermal stability and exhibits single-crystal-to-single-crystal (SCSC) transformations upon removing and rebinding the noncoordinated and coordinated water molecules. X-ray crystallographic analyses revealed that the coordination geometry of Co(II) changes from octahedral to square pyramid upon dehydration, accompanying the appearance of one-dimensional (1D) open channels with dimensions of 2.0 × 2.8 A. The dehydrated form [Co3(L)2(BTEC)] (2) exhibits highly selective adsorption of water molecules over N2,CH 3OH, and CH3Ch2OH, which could be used as sensors for water molecules. Furthermore, the magnetic properties of 1 and 2 were investigated, showing the existence of ferromagnetic interaction between the Co(II) atoms within the trinuclear subunit.
Cation distribution in manganese cobaltite spinels Co3-x Mn x O4 (0 ≤ x ≤ 1) determined by thermal analysis
Bordeneuve,Rousset,Tenailleau,Guillemet-Fritsch
, p. 137 - 142 (2010)
Thermogravimetric analysis was used in order to study the reduction in air of submicronic powders of Co3-x Mn x O4 spinels, with 0 ≤ x ≤ 1. For x = 0 (i.e. Co3O4), cation reduction occurred in a single step. It involved the CoIII ions at the octahedral sites, which were reduced to Co2+ on producing CoO. For 0 III ions and the second was attributed to the reduction of octahedral Mn4+ ions to Mn3+. From the individual weight losses and the electrical neutrality of the lattice, the CoIII and Mn4+ ion concentrations were calculated. The distribution of cobalt and manganese ions present on each crystallographic site of the spinel was determined. In contrast to most previous studies that took into account either CoIII and Mn3+ or Co2+, CoIII and Mn4+ only, our thermal analysis study showed that Co2+/CoIII and Mn3+/Mn4+ pairs occupy the octahedral sites. These results were used to explain the resistivity measurements carried out on dense ceramics prepared from our powders sintered at low temperature (700-750 °C) in a Spark Plasma Sintering apparatus.
Heroun, E. F.
, p. 872 - 881 (1934)
Hexagonal nanoplates of NiO/CoO/Fe2O3 composite acting as an efficient photocatalytic and electrocatalytic water oxidation catalyst
Zhao, Yukun,Zhang, Yan,Ding, Yong,Chen, Mindong
, p. 15628 - 15635 (2015)
A unique hexagonal sheet-shaped NiO/CoO/Fe2O3 composite with irregularly shaped nanoparticles was fabricated for the first time through a simple co-precipitation and hydrothermal method. The NiO/CoO/Fe2O3 composite was characterized by numerous techniques (TEM, HRTEM, PXRD, EDX, ICP-AES, BET, and XPS) to confirm its structure and composition. This structure of the NiO/CoO/Fe2O3 composite may enhance the photocatalytic and electrocatalytic performance for water oxidation. Compared with NiO, CoO and Fe2O3, the NiO/CoO/Fe2O3 composite exhibits a lower overpotential and a much smaller Tafel slope of 49 mV dec-1 for water oxidation. At the same time, the composite possesses beneficial ferromagnetic properties and superior stability; thus, it can be used repeatedly without any loss in activity.
TG-MS and TG-FTIR studies of imidazole-substituted coordination compounds: Co(II) and Ni(II)-complexes of bis(1-methylimidazol-2-yl)ketone
Materazzi,Vecchio,Wo,De Angelis Curtis
, p. 183 - 187 (2012)
Co(II) and Ni(II) coordination compounds with bis(1-methylimidazol-2-yl) ketone (BIK) of general formula M(BIK)2X2 (M = Co or Ni; X = Cl or NO3) were synthesized and characterized by elemental analysis, by UV-vis and FTIR spectroscopies. Following our previous thermoanalytical studies on imidazole-substituted coordination compounds, the thermal behavior of the synthesized complexes was investigated by TG and DTG techniques: the thermal profile is always characterized by three substantial consecutive releasing steps for all the three complexes and the releasing supposed behavior is confirmed by EGA analysis (TG-MS and TG-FTIR). In particular, the first step is ascribed to the release of the two anions, followed by the loss of four methyl groups (side chains of the ligand) and two bridge-carbonyl groups. The residual Cobalt or Nickel tetra-imidazole complex decomposes in a final step to give the metal oxide as the final residue.
Redox reaction and gas phase precipitation in the system In/Mn/O
Moeller, Angela,Schmidt, Peer,Fastje, Oliver
, p. 1654 - 1658 (2007)
The oxidation of manganese metal with In2O3 occurs at approximately 973 K in evacuated silica ampoules. Thereby, the vapour transport species In2O(g) is being formed, which decomposes to indium metal and In2O3 at lower temperatures. Thermodynamic data as well as a description of the transport mechanism is given.
Cytotoxic effects, microbiological analysis and inhibitory properties on carbonic anhydrase isozyme activities of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its Cu(II), Co(II), Zn(II) and Mn(II) complexes
Ucar, Asuman,Findik, Mukerrem,Kuzu, Muslum,Pehlivanoglu, Suray,Sayin, Ulku,Sayin, Zafer,Akgemci, Emine Guler
, p. 533 - 550 (2021)
Metal complexes of thiosemicarbazones have been receiving considerable attention in biological applications such as antimicrobial and anticancer therapies. In this work, Co(II), Zn(II) and Mn(II) complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone (HMAT) were synthesized for the first time and characterized by EPR, FT-IR, NMR, UV–Vis spectroscopies, TG/DSC and elemental analysis. X-ray powder diffraction analysis was carried out for Zn(II) complex. HMAT and its Cu(II), Co(II), Zn(II) and Mn(II) complexes were tested as enzyme inhibitory agents. All compounds are effective inhibitor of cytosolic carbonic anhydrase I and II isoforms (hCA I and II) enzymes. IC50 values of HMAT and its Cu(II), Co(II), Zn(II) and Mn(II) complexes were determined as 93.35, 324.46, 25.67, 1.06 and 22.36?μM for CA I isozyme and 99.02, 86.64, 57.76, 10.34 and 36.48?μM for CA II isozyme, respectively. The evaluation of potential cytotoxic effects of the compounds was performed against normal epithelial breast mammary gland CRL-4010, estrogen-positive low metastatic MCF-7 and triple negative highly metastatic MDA-MB-231 breast adenocarcinoma cell lines by MTT assay. The results showed that the tested metal complexes have high cytotoxic effects than their ligand molecule. In particular, the Cu(II) complex displayed preciously high cytotoxic properties different from the others. Given these facts, the Cu(II) complex could be debated as potential chemotherapeutic molecule against drug-resistant breast cancer cells. Minimum inhibitory concentrations of the compounds against the test organisms were also detected for the microbiological analysis.
Three new coordination compounds based on 2-phenyl-4-quinolinecarboxylic acid and nitrogenous neutral ligands: Syntheses, structural features, and properties
Hou, Xiang-Yang,Wang, Xiao,Fu, Feng,Wang, Ji-Jiang,Tang, Long
, p. 1254 - 1260 (2013)
Solvothermal reactions of 2-phenyl-4-quinolinecarboxylic acid (Hpqba) with CdII, CoII, ZnII and/or 4,4′-bipyridyl (4,4′-bipy), 1,4-bis(imidazol-1-ylmethyl)benzene (biyb), 2,2′-bipyridyl (2,2′-bipy) afford three new coordination compounds of stoichiometries [Cd(pqba)2(4,4′-bipy)] (1), [Zn(pqba) 2biyb] (2), and [Co3(pqba)6-(2,2′-bipy) 2] (3). Compounds 1-3 were characterized by elements analysis, IR spectroscopy, thermogravimetry, and single-crystal X-ray diffraction study. Compound 1 has a two-dimensional structure, whereas compound 2 consists of a one-dimensional (1D) network, which is further expanded by π·· ·π stacking interactions to form a 3D supramolecular structure. Complex 3 also exhibits a 3D supramolecular structure completely based on π···π stacking interactions. The pqba ligands adopt μ1-k1,k1, μ1-k1, μ2-k1,k1, and μ2-k 1,k2 coordination modes for compounds 1, 2, and 3. The fluorescence properties were examined on compounds 1 and 2 in the solid state at room temperature. Magnetic susceptibility measurements indicate that in complex 3 antiferromagnetic coupling between adjacent CoII ions exist. Copyright
Antibacterial and anticorrosion behavior of bioactive complexes of selected transition metal ions with new 2-acetylpyridine Schiff base
Ashmawy, Ashraf M.,Deghadi, Reem G.,Elsharkawy, Ahmed E.,Mohamed, Gehad G.
, (2022/01/19)
Successful preparation of Schiff base 4-(4-aminophenoxy)-N-(1-(pyridin-2-yl)ethylidene)aniline derived from refluxing of 4,4-oxydianniline with 2-acetylpyridine within 2?h in 1:1 molar ratio was performed. Different transition metal complexes were synthesized by reacting metal chlorides with the formed ligand in 1:1 molar ratio. Structural features of the complexes were obtained from different tools such as infrared (IR), 1H-nuclear magnetic resonance (1H-NMR), ultraviolet–visible (UV-vis), molar conductivity, thermogravimetric (TG)/differential thermogravimetric (DTG), microanalysis, and mass spectrometry. All complexes had an octahedral structure and Schiff base acted as a neutral bidentate ligand that linked to metal centers via N-azomethine and N-pyridine atoms. Cr(III), Fe(III), and Ni(II) complexes were electrolytes while other complexes were nonelectrolytes. The molecular structure of Schiff base was optimized theoretically and its HOMO and LUMO energies were dictated by B3LYP/DFT calculations. The in vitro antibacterial activity versus some selected bacteria species showed that all prepared compounds were biologically active except Fe(III) complex against certain species and Co(II) complex had the highest biological activity values. Molecular docking was used to determine effective binding modes between ligand and its [Co(L)(H2O)2Cl2]·4H2O complex with active sites of 4WJ3, 4ME7, 4K3V, and 3T88 receptors. The strongest binding of Co(II) complex was with the 4ME7 receptor with lowest binding energy value ?25.4?kcal mol?1. Schiff base as corrosion inhibitors for mild steel in 1.0-M HCl had been investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP), and electrochemical frequency modulation (EFM). The results showed that the inhibitor acts as a mixed-type inhibitor. The inhibition efficiency increases with increasing inhibitor concentration to its maximum of 97.5% at 1?×?10?3?M solution. The adsorption model obeys the Langmuir isotherm, and Gibbs free energy was around ?40 kJ/mol, indicating that it is spontaneously and chemically adsorbed on the surface. SEM/EDX results proved the sticking of a barrier film on the mild steel sample.
Theoretical and Experimental Evaluation of the Reduction Potential of Straight-Chain Alcohols for the Designed Synthesis of Bimetallic Nanostructures
Ishijima, Masanao,Matsumoto, Takatoshi,Cuya Huaman, Jhon L.,Shinoda, Kozo,Uchikoshi, Masahito,Matsuo, Kohei,Suzuki, Kazumasa,Miyamura, Hiroshi,Balachandran, Jeyadevan
, p. 9432 - 9441 (2021/05/06)
Recently, the development of bimetallic nanoparticles with functional properties has been attempted extensively but with limited control over their morphological and structural properties. The reason was the inability to control the kinetics of the reduction reaction in most liquid-phase syntheses. However, the alcohol reduction technique has demonstrated the possibility of controlling the reduction reaction and facilitating the incorporation of other phenomena such as diffusion, etching, and galvanic replacement during nanostructure synthesis. In this study, the reduction potential of straight-chain alcohols has been investigated using molecular orbital calculations and experimentally verified by reducing transition metals. The alcohols with a longer chain exhibited higher reduction potential, and 1-octanol was found to be the strongest among alcohols considered. Furthermore, the experimental evaluation carried out via the synthesis of metallic Cu, Ni, and Co particles was consistent with the theoretical predictions. The reaction mechanism of metallic particle formation was also studied in detail in the Ni-1-octanol system, and the metal ions were confirmed to be reduced via the formation of nickel alkoxide. The results of this investigation were successfully implemented to synthesize Cu-Ni bimetallic nanostructures (core-shell, wire, and tube) via the incorporation of diffusion and etching besides the reduction reaction. These results suggest that the designed synthesis of a wide range of bimetallic nanostructures with more refined control has become possible.
Enhancement of propane combustion activity over CoO: Xcatalysts by introducing C2-C5diols
Liu, Zhao,Cheng, Lijun,Zhangxue, Shiyun,Huang, Min,Zeng, Jia,Yuan, Shanliang,Bo, Qifei,Zhang, Biao,Jiang, Yi
, p. 8795 - 8805 (2021/05/25)
A series of nanocrystalline CoOx catalysts were synthesized by a citric acid complexation strategy. The effects of C2-C5 diols (including ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentadiol) on catalyst structure and propane combustion performance were investigated. The results showed that the structure of CoOx transformed from pure Co3O4 to mixed-phase CoO-Co3O4 with a larger surface area and smaller crystallite size after the introduction of diol compounds. Importantly, diol compounds effectively weaken the Co-O bond strength in nanocrystalline CoOx and enhance the activity of oxygen species, thus effectively degrading propane. Due to the weakest Co-O bond strength, excellent oxygen species activity, abundant oxygen vacancies, and the strongest redox ability, the catalyst prepared by adding 1,3-propanediol (Co-PDO) exhibited the best catalytic activity (T90 = 227 °C). Moreover, the increase in pore size, surface Co2+ and oxygen vacancy content of Co-PDO in the 40 h stability test can compensate for the loss of activity caused by the decrease in specific surface area, thereby maintaining stable catalytic activity.
