Xn:Harmful;
7440-48-4Relevant articles and documents
Synthesis, characterisation and catalytic performance of nanocrystalline Co3O4 for gas-phase chlorinated VOC abatement
De Rivas, Beatriz,Lopez-Fonseca, Ruben,Jimenez-Gonzalez, Cristina,Gutierrez-Ortiz, Jose I.
, p. 88 - 97 (2011)
Several nanocrystalline Co3O4 catalysts were investigated for their activity and selectivity during the oxidation of 1,2-dichloroethane, which was selected as a model chlorinated volatile organic compound. A wide number of synthesis routes starting from cobalt(II) nitrate were examined, namely calcination of the precursor salt, solid-state reaction, precipitation and sol-gel. The catalysts prepared by precipitation decomposed the chlorinated feed at the lowest temperatures. Activity was observed to be chiefly governed by a small crystallite size which may give rise to more easily accessible active sites (oxygen -O- or O2-- species), which were not present on the more highly crystalline Co3O 4 catalysts. Additionally, surface Lewis acidity played a relevant catalytic role. Interestingly, the behaviour of some of the nanocrystalline oxides was superior to that of supported noble metal catalysts and other bulk oxide catalysts. Conversion to deep oxidation products was complete (CO 2, HCl and Cl2), and no appreciable deactivation with time on stream was noticed.
Carr, B.
, p. 488 - 488 (1921)
Electrochemical deposition of co under the influence of high magnetic fields
Uhlemann,Krause,Chopart,Gebert
, p. C817-C826 (2005)
The effect of uniform, vertically oriented high magnetic fields up to 13 T on the electrodeposition of Co has been investigated in dependence on the cell and electrode geometry as well as the orientation and strength of the magnetic flux density by means of cyclic voltammetry, chronoamperometric measurements, and atomic force microscopy investigations. In the majority of cases, the limiting current density ilim increases with increasing magnetic flux densities independent of the cell geometry and orientation. The current efficiency of Co increases with increasing magnetic flux densities only in magnetic fields aligned parallel to the electrodes due to the magnetohydrodynamic (MHD) effect. The morphology of the deposits exhibits randomly oriented round-shaped grains. The electrochemical behavior of horizontal electrodes with magnetic fields oriented perpendicular to the surface is strongly dependent on the electrode geometry. The current efficiency of the Co deposition on flat electrodes increases for low magnetic flux densities and keeps constant for high magnetic fields. In contrast, for wall electrodes the current efficiency decreases strongly even for low magnetic fields. These results are caused by overlapping effects of two types of convection, macro-MHD- and micro-magneto convection due to gradients of the concentration and the magnetic susceptibility. This leads to a modified morphology.
Synthesis, characterization, and tunable optical properties of hollow gold nanospheres
Schwartzberg, Adam M.,Olson, Tammy Y.,Talley, Chad E.,Zhang, Jin Z.
, p. 19935 - 19944 (2006)
Nearly monodisperse hollow gold nanospheres (HGNs) with tunable interior and exterior diameters have been synthesized by sacrificial galvanic replacement of cobalt nanoparticles. It is possible to tune the peak of the surface plasmon band absorption betwe
Effect of temperature on Co electrodeposition in the presence of boric acid
Santos,Matos,Trivinho-Strixino,Pereira
, p. 644 - 649 (2007)
The electrodeposition of cobalt from sulphate solutions containing boric acid was investigated using EQCM technique coupled with potentiostatic measurements. The boric acid was added to electrolyte as a buffer to avoid the local pH rise caused by parallel hydrogen evolution reaction (HER). The results showed that the buffer contribution of boric acid is effective in the cobalt electrodeposition at 25 °C; however, cobalt hydroxide is formed simultaneously with cobalt deposition at 48 °C. The M/z values calculated using the Sauerbrey equation and the Faraday Law showed that in the initial stages of deposition at 48 °C, only cobalt deposits were detected, but after 2 s, an important amount of Co(OH)2 started to be formed.
Preparation and Properties of Cobalt(II) Hydroxide-(Sodium Fluoride Tetrasilicic Mica) Intercalation Complexes and of Highly Dispersed Cobalt on Mica
Ohtsuka, Kunio,Koga, Johji,Suda, Mitsuru,Ono, Mikiya,Takahashi, Minoru
, p. 2843 - 2848 (1987)
Cobalt(II) hydroxide-(sodium fluoride tetrasilicic mica) intercalation complexes were prepared by titrating cobalt(II) nitrate solutions in the presence of mica with sodium hydroxide under oxygen-free conditions.These complexes were characterized by chemical analysis, XRD, DTA-TGA, IR, and surface area measurements.These confirmed that the brucite-like cobalt(II) hydroxyde sheet developed within the interlayer of the silicate.Cobalt atoms reduced at 400-700 deg C by H2 migrated from the interlayer of the silicate to the external surface of these where highly dispersed cobalt particles were formed.Ultra-fine cobalt metals (50-200 Angstroem) with a hexagonal close-packed form were prepared at 400 deg C by H2.The degree of reduction and the grain diameter of cobalt increased with an increase of the reducing temperature and/or the reducing time.
Preparation and magnetic properties of anisotropic (Sm,Pr)Co5/Co composite particles
Wang, Xiaoliang,He, Huanlong,Wang, Fengqing,Chen, Yan,Xu, Lei,Li, Xiaohong,Zhang, Xiangyi
, p. 889 - 892 (2012)
Anisotropic (Sm,Pr)Co5/Co nanocomposite particles have been fabricated by chemical coating the 2 h ball milled (Sm,Pr)Co5 flakes with Co nanoparticles. The Co nanoparticles were synthesized with mean particle sizes in the range of 2050 nm. The nanocomposite particles present [0 0 1] out-of-plane texture and improved magnetic properties, e.g., an enhanced remanent magnetization of 72 emu/g for (Sm,Pr)Co5/Co and 66 emu/g for (Sm,Pr)Co5. In addition, by using the 8 h ball milled powders (much smaller than the 2 h ball milled powders) as the starting materials, Co nanoparticles can also be successfully coated on the surface of the flakes. A plausible mechanism for the formation of Co nanoparticles on the surface of (Sm,Pr)Co5 flakes is discussed.
Highly conformal deposition of pure Co films by MOCVD using Co2 (CO)8 as a precursor
Lee,Yang,Lee,Kim,Nam,Shin,Ko,Lee,Lee,Kim
, p. G539-G542 (2006)
Highly conformal Co thin films were deposited on Si O2 trenches with an aspect ratio of 13 by metallorganic chemical vapor deposition (MOCVD) using Co2 (CO)8 as a precursor in a low-temperature regime of 50-70°C where the growth rate was 3.5-7.0 nmmin. Lowering the pressure of the process reduces the number of collisions in the gas phase and, thus, widens the temperature regime in which the surface reaction controls the growth rate. A processing pressure of 26.7 Pa (0.2 Torr) allows for conformal deposition only at 50°C, whereas deposition at a reduced pressure of 4.0 Pa (0.03 Torr) widens the temperature regime (50-70°C) in which excellent conformality can be obtained. The conformal Co thin film, produced at 50°C and 4.0 Pa, showed a resistivity of 10-12 μ cm and contained 1.0 atom % oxygen and less than 1.0 atom % carbon. After annealing this film at 600°C, its resistivity was reduced to 6 μ cm, which is close to the bulk resistivity (5.7 μ cm) of Co. Therefore, this low-temperature process, which allows for the excellent conformal deposition of pure Co films, can be utilized to produce silicided contacts for advanced devices which require a low contact resistance and good electrical performance.
Synthesis of Co submicrospheres self-assembled by Co nanosheets via a complexant-assisted hydrothermal approach
Li, Hao,Jin, Zhen,Song, Huiyu,Liao, Shijun
, p. 30 - 35 (2010)
Co submicrospheres with the typical diameter of ca. 500 nm, and possessing beautiful morphologies composed of dense Co nanosheets ca. 10 nm thick, were synthesized by a facile and low-cost complexant-assisted hydrothermal approach. Magnetic measurement at room temperature indicated the coercivity of the submicrospheres reached 268 Oe, which was much higher than that of bulk Co and of some microstructure cobalt materials reported previously. Hexagonal close-packed (hcp) and face-centered cubic (fcc) cobalt phases in the materials were identified by X-ray diffractometer (XRD). It was revealed that the addition of the complexant sodium tartrate played a crucial role in the formation of the hierarchical architectures of the Co submicrospheres. We believe that the high coercivity of the synthesized submicrospheres may result from their special nano-micro structure, and we suggest that this low-cost and facile synthesis approach can be used for large-scale production of Co magnetic materials with special structures and morphologies, as well as excellent magnetic properties.
Magnetic and microwave absorbing properties of Co-Fe thin films plated on hollow ceramic microspheres of low density
Kim, Sung-Soo,Kim, Seon-Tae,Ahn, Joon-Mo,Kim, Keun-Hong
, p. 39 - 45 (2004)
Conductive and magnetic microspheres are fabricated by plating of Co-Fe alloy thin films on hollow ceramic microspheres of low density for the application to lightweight microwave absorbers. Metal plating was carried out in a two-step electroless plating process (pre-treatment of sensitizing and subsequent plating). Uniform coating of the film with about 2μm thickness was identified by SEM. High-frequency magnetic and microwave absorbing properties were determined in the rubber composites containing the metal-coated microspheres. Due to the conductive and ferromagnetic behavior of the Co-Fe thin films, high dielectric constant and magnetic loss can be obtained in the microwave frequencies. In particular, the magnetic loss increases with Fe content in the alloy films and its frequency dispersion can be explained by ferromagnetic resonance theory. Due to the electromagnetic properties, high absorption rate and thin matching thickness are predicted in the composite layers containing the metal-coated microspheres of low density (about 0.8g/cc) for the electromagnetic radiation in microwave frequencies.
Surfactant-assisted hydrothermal synthesis of chains self-assembled by cobalt microspheres
Zhang,Ma,Li,Wang,Zhang
, p. 1957 - 1965 (2008)
Magnetic cobalt chains, self-assembled by microspheres of hexagonal-phase cobalt, have been synthesized at 100 °C via a hydrothermal reduction route in the presence of cobalt chloride, the surfactant sodium dodecylsulfate (SDS) (or cetyltrimethylammonium bromide CTAB) and the complex reagent sodium tartrate. As-synthesized, the chains are 100-300 μm in length and the cobalt microspheres, which consist of nanosheets with an average thickness of about 60 nm, are 5-10 μm in diameter. The magnetic hysteresis loops at 5 K and 300 K of the chains of microspheres show ferromagnetic characteristics. The morphologies of the microspheres can be controlled by adjusting the concentrations of the surfactant and the complex reagent and also the reaction temperature.
Kersten, H.
, p. 178 - 180 (1932)
Redox energetics and enthalpy increments of GdBaCo2O6-δ
Tsvetkov,Sednev-Lugovets,Sereda,Malyshkin,Ivanov,Zuev, A.Yu
, (2020)
The enthalpy increments for the GdBaCo2O6-δ double perovskite were determined by means of drop calorimetry in air in the temperature range between 365.4 K and 1272.4 K. The heats of orthorhombic I→orthorhombic II phase transition at 347.2 K and orthorhombic II→tetragonal transition at 745.8 K are equal to (2.95 ± 0.07) kJ·mol?1 and (2.40 ± 0.09) kJ·mol?1, respectively, as measured with differential scanning calorimetry for GdBaCo2O6-δ. These calorimetric data were used to determine the heat capacity of GdBaCo2O6-δ and the high-temperature ‘chemical’ contribution to the enthalpy increments, caused by the oxygen exchange. The differentiation of the ‘chemical’ contribution with respect to oxygen nonstoichiometry yielded the partial molar enthalpy of oxygen in the GdBaCo2O6-δ, which agrees well with the previously reported results. The enthalpy increment data of nonstoichiometric oxides have proven itself as a valuable source of redox energetics information.
Preparation of large Co nanosheets with enhanced coercivity by a magnetic-field-assisted solvothermal approach free of surfactants, complexants or templates
Li, Hao,Liao, Shijun
, p. 2566 - 2570 (2009)
We presented a magnetic-field-assisted solvothermal route to prepare hexagonal close-packed (hcp) large Co nanosheets free of any surfactants, complexants or templates. Scanning electron microscope (SEM) images showed that the typical size and thickness o
Synthesis of "solid solution" and "core-shell" type cobalt-platinum magnetic nanoparticles via transmetalation reactions
Park,Cheon
, p. 5743 - 5746 (2001)
In this article, we report the synthesis of "solid solution" and "core-shell" types of well-defined Co-Pt nanoalloys smaller than 10 nm. The formation of these alloys is driven by redox transmetalation reactions between the reagents without the need for a
The origin of triple conductivity and water uptake in layered double perovskites: A case study on lanthanum-substituted GdBaCo2O6?δ
Ivanov, Ivan,Malyshkin, Dmitry,Novikov, Andrey,Sereda, Vladimir,Tsvetkov, Dmitry,Zuev, Andrey
, (2020)
Some layered double perovskite cobaltites have been shown recently to absorb water and exhibit increasing electrical conductivity in humid atmospheres. However, the assumptions that their crystal lattice is capable of proton uptake, and that these oxides really possess triple (oxide ion, protonic and electronic) conductivity, have already been brought into question. We investigated in detail the crystal structure and phase composition of various lanthanum-substituted GdBaCo2O6?δ and came to several important conclusions. Firstly, in oxidative conditions (e.g. in air), the substitution of La for either only Gd or only Ba in GdBaCo2O6?δ results in formation of multiphase materials. For example, BaCo1–xGdxO3?δ exsolves from Gd1–xLaxBaCo2O6?δ due to the redistribution of La between Gd and Ba sites in Gd1–xLaxBaCo2O6?δ lattice. Secondly, a single-phase double perovskite can be synthesized in air only by simultaneously substituting, within certain limits, both Gd and Ba in GdBaCo2O6?δ with La. Finally, using Gd0.8La0.2Ba0.95La0.05Co2O6?δ and BaCo0.8Gd0.2O3?δ as examples, we demonstrated that while single-phase double perovskite does not hydrate, in the same conditions, the cubic perovskite BaCo0.8Gd0.2O3?δ (BaCo1–xGdxO3?δ is encountered in Gd1–xLaxBaCo2O6?δ as an impurity) absorbs significant amount of water. Thus, the water uptake by lanthanum-substituted GdBaCo2O6?δ is most likely to occur due to the impurities, and not the main double perovskite phase.
Magnetic properties and structure of electrodeposited ZnCo alloys granular thin films
Vlad,Pascariu,Tanase,Pinzaru,Dobromir,Nica,Georgescu
, p. 1481 - 1487 (2011)
We present several results concerning the preparation by means of electrolysis and characterization of ZnCo alloys thin films. Films of Zn, Co and ZnCo with various compositions (816 at% Co) were prepared in sulfate baths, using potentiostatic control, envisaging applications in the domain of corrosion resistant magnetic sensors. The effects of applied voltage on the magnetic properties, microstructure and phase content of the electrodeposited ZnCo films were investigated. The applied voltage significantly influenced the film composition and their magnetic properties. These films, when deposited at an applied voltage of 4.5 V exhibited multiphase behavior due to the inclusion of new phases (cobalt hydroxide), whereas at 3.0 V, only ZnCo alloys were deposited. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM).
Designed synthesis of cobalt and its alloys by polyol process
Joseyphus,Matsumoto,Takahashi,Kodama,Tohji,Jeyadevan
, p. 3008 - 3018 (2007)
The role of polyol, precursor and reaction promoting agents in the synthesis of metal and alloy nanoparticles using polyol process has been investigated by analyzing the reaction steps involved in the synthesis of cobalt in Co ion-polyol-[OH-] ion system in detail. The reducing potential of polyols and the easiness with which any metal salt can react to form reducible complexes has been evaluated using the orbital molecular theory and the results were experimentally verified. The reduction limit of polyol and their extension using reaction promoting agents such as [OH-] ions is also explained. The reduction of cobalt is preceded by various reaction stages of complex/compound formation, which has been fully identified. Furthermore, the reducing form of cobalt has been identified as either cobalt alkoxide or cobalt hydroxide. The results confirmed that the complex forming reactions that take place prior to the formation of the precursor, which finally get reduced to metal, play a decisive role in determining the physical properties of the nanoparticles. The approach can be extended to reduce any metals or alloys using polyol process.
Characterization and testing of silica-supported cobalt-palladium catalysts for conversion of syngas to oxygenates
Kumar, Nitin,Smith, Miranda L.,Spivey
, p. 218 - 226 (2012)
Silica-supported Co-Pd catalysts were prepared by co-impregnation using 2 wt% Pd and two different cobalt loadings: 2 wt% (2Co-2Pd) and 10 wt% (10Co-2Pd). They were characterized by ICP-OES, H2-TPR, in situ XRD, DRIFTS, and activity/selectivity
Surface modification of metallic Co nanoparticles
Matoussevitch, Nina,Gorschinski, Angelika,Habicht, Wilhelm,Bolle, Jens,Dinjus, Eckhard,B?nnemann, Helmut,Behrens, Silke
, p. 92 - 96 (2007)
Monodisperse Co nanoparticles were synthesized by thermal decomposition in the presence of aluminium alkyls yielding air-stable Co nanoparticles after surface passivation. Several procedures for surface modification of these pre-stabilized, metallic Co nanoparticles are presented, including direct anchoring of surface-active functional groups and biocompatible dextran layers as well as silica and polymer coatings. As a result, individually coated nanoparticles as well as microspheres can be obtained.
Reactive deposition of ultrafine cobalt powders part I electrochemical investigation
Cui,Tseung
, p. 461 - 468 (1993)
During the reactive deposition of cobalt powders, Co(OH)2 colloidal layers are formed at the electrode surface; the individual cobalt crystals are isolated by the Co(OH)2 colloid around the grain boundaries so that growth is inhibite
Phase equilibria, structure and properties of intermediate phases in the Sm2O3 – Fe2O3 – CoO and Sm2O3 – CaO – CoO systems
Galayda,Volkova,Gavrilova, L. Ya.,Balymov,Cherepanov
, p. 288 - 297 (2017)
Phase equilibria in the Sm2O3 – Fe2O3 – CoO and Sm2O3 – CaO – CoO systems were systematically studied at 1100 °C in air. The following solid solutions: SmFe1-xCoxOsub
Rethinking Co(CO3)0.5(OH)·0.11H2O: A new property for highly selective electrochemical reduction of carbon dioxide to methanol in aqueous solution
Huang, Jianzhi,Hu, Qiong,Guo, Xinrong,Zeng, Qiang,Wang, Lishi
, p. 2967 - 2972 (2018)
Co(CO3)0.5(OH)·0.11H2O is usually acknowledged and used as a precursor to synthesize other nanomaterials. However, some important properties of Co(CO3)0.5(OH)·0.11H2O have not been discovered yet. Herein, we report an important new property of hollow urchin-like Co(CO3)0.5(OH)·0.11H2O for highly selective electrochemical reduction of carbon dioxide to methanol in NaHCO3 aqueous solution at -0.98 V versus saturated calomel electrode (SCE) with Faradaic efficiency of up to 97.0% under ambient conditions, which is superior to most of the electrocatalysts reported to date. Finally, this low-cost electrocatalyst shows great potential in CO2 conversion industry for practical application in the future.
Kinetic features of thermal decomposition of cobalt acetylacetonate and development of catalysts for the oxidation of carbon monoxide, based on the decomposition products
Tsyganova,Didenkulova,Shekunova,Faerman,Aleksandrov
, p. 1646 - 1650 (2004)
The kinetic features of thermal decomposition of cobalt acetylacetonate in a vacuum were elucidated, and the volatile thermolysis products were identified. The homogeneous-heterogeneous character of the process was shown. Catalysts for the oxidation of CO to CO2 were developed on the basis of cobalt acetylacetonate decomposition products and synthetic cellular ceramics, and the kinetic and activation parameters of the oxidation were determined. 2004 MAIK Nauka/Interperiodica .
Magnetism of single-crystalline Co nanorods
Soulantica,Wetz,Maynadi,Falqui,Tan,Blon,Chaudret,Respaud
, (2009)
We report on the synthesis and preparation of oriented nanomaterials of single crystalline metallic Co nanorods of 6 nm in diameters and two different aspect ratios (7 and 15). They display optimized magnetic properties, with a spontaneous magnetization j
Effect of spark plasma sintering temperature on microstructure and thermoelectric properties of the cermet composites consisting of Bi2Te2.1Se0.9 matrix and Co@CoTe2 inclusions
Ivanov, Oleg,Novikov, Vseslav,Vasil'ev, Alexei,Yaprintsev, Maxim,Zhezhu, Marina
, (2021/11/08)
Novel cermet Bi2Te2.1Se0.9+0.33 ?wt% Co composite has been prepared via spark plasma sintering (SPS) the starting Bi2Te2.1Se0.9 and Co powders at different SPS-temperatures (TS ?= ?598, 623, 648 and 673 ?K). During the sintering, initial Co inclusions transform into final filler Co@CoTe2 (“core”-“shell”) inclusions, randomly distributed inside textured grained Bi2Te2.1Se0.9 matrix. Forming these inclusions is originated from high-temperature chemical interaction between Bi2Te2.1Se0.9 and Co. Main features in microstructure and thermoelectric properties of the cermet composite found with increasing TS are: (i) a texturing degree of grained Bi2Te2.1Se0.9 matrix gradually decreases that is attributed to reducing in ability of initial nanometer Co particles to act as lubricant; (ii) a fraction of the Co core decreases, and a fraction of the CoTe2 shell increases that is related to acceleration of Co→CoTe2 reaction at higher temperatures; (iii) the specific electrical resistivity and the Seebeck coefficient reduce, whereas the total thermal conductivity increases that can be originated from growth of electron concentration due to local Co doping. Highest value of the thermoelectric figure-of-merit equal to ～0.8 was observed for the composite, SPS-treated at 673 ?K.
In Situ Study of Reduction of MnxCo3- xO4Mixed Oxides: The Role of Manganese Content
Bulavchenko, Olga A.,Afonasenko, Tatyana N.,Ivanchikova, Anastasya V.,Murzin, Vadim Yu.,Kremneva, Anna M.,Saraev, Andrey A.,Kaichev, Vasily V.,Tsybulya, Sergey V.
, p. 16518 - 16528 (2021/11/04)
A series of Mn-Co mixed oxides with a gradual variation of the Mn/Co molar ratio were prepared by coprecipitation of cobalt and manganese nitrates. The structure, chemistry, and reducibility of the oxides were studied by X-ray diffraction (XRD), X-ray absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction (TPR). It was found that at concentrations of Mn below 37 atom %, a solid solution with a cubic spinel structure is formed. At concentrations above 63 atom %, a solid solution is formed on the basis of a tetragonal spinel, while at concentrations in a range of 37-63 atom %, a two-phase system, which contains tetragonal and cubic oxides, is formed. To elucidate the reduction route of mixed oxides, two approaches were used. The first was based on a gradual change in the chemical composition of Mn-Co oxides, illustrating slow changes in the TPR profiles. The second approach consisted in a combination of in situ XRD and pseudo-in situ XPS techniques, which made it possible to directly determine the structure and chemistry of the oxides under reductive conditions. It was shown that the reduction of Mn-Co mixed oxides proceeds via two stages. During the first stage, (Mn, Co)3O4 is reduced to (Mn, Co)O. During the second stage, the solid solution (Mn, Co)O is transformed into metallic cobalt and MnO. The introduction of manganese cations into the structure of cobalt oxide leads to a decrease in the rate of both reduction stages. However, the influence of additional cations on the second reduction stage is more noticeable. This is due to crystallographic peculiarities of the compounds: the conversion from the initial oxide (Mn, Co)3O4 into the intermediate oxide (Mn, Co)O requires only a small displacement of cations, whereas the formation of metallic cobalt from (Mn, Co)O requires a rearrangement of the entire structure.
Synthesis, spectral characterization, density functional theory studies, and biological screening of some transition metal complexes of a novel hydrazide–hydrazone ligand of isonicotinic acid
El-Nahas, Ahmed M.,Kashar, Tahani I.,Tolan, Dina A.,Yoshizawa, Kazunari
, (2021/03/16)
Novel Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) complexes (1–7) of hydrazide–hydrazone ligand (H2L) derived from the condensation of isonicotinic acid hydrazide with (Z)-N′-(2-nitrobenzylidene)-3-oxobutanehydrazide have been prepared. The ligand and its chelates were characterized based on elemental analysis, spectral, thermal analysis, molar conductance, and magnetic moment measurements. Besides, density functional theory (DFT) computations have been conducted to study structures and energetics of the ligand and its complexes. The IR spectra showed that the ligand was chelated with the metal ion in a monobasic tridentate manner using ONO donors in all complexes except Zn(II) complex (5) where the ligand binds with Zn(II) ion as a dibasic tridentate utilizing ONO donors. The magnetic moment and electronic spectral data revealed octahedral and square pyramidal geometries for complexes (1, 7) and (2, 4, 5), respectively, whereas a square planar geometry was suggested for 3. DFT studies show that the Cd(II) center reveals interesting structural deviations from regular octahedral geometry in the resulting hexa-coordinated complex [Cd(H2L)2].2H2O (6) assumes a trigonal prismatic (TP) structure for this complex. The antibacterial and antifungal activities of the ligand and its complexes have been investigated with different bacterial and fungal strains. The data revealed that Hg(II) complex (7) demonstrated a very good antibacterial and antifungal activity than others. Highlights: A new hydrazide–hydrazone ligand of isonicotinic acid was synthesized. Seven mononuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) complexes of the new ligand were prepared and characterized by different tools. DFT studies have been carried out to study the structure of the ligand and its complexes. Antimicrobial activities of the ligand and its complexes were studied against a variety of bacterial and fungal strains by using disk diffusion method and results were compared with standard drugs.
