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The discharge characteristics of a heat activated battery containing NiCl2–CoCl2 mixtures as a positive electrode are studied. The battery cell discharge temperature is found to decrease when the mixtures are used instead of individual nickel(II) and cobalt(II) chlorides. The minimum temperature at which a stable discharge plateau is detected is 480°C. The maximum capacity of the discharge plateau is 0.33 A h g–1. The optimum composition of the cathode mixture contains 20 wt % CoCl2. The composition and morphology of the reduction products of the cathodic materials are determined. The initial nickel and cobalt chlorides are reduced to metals during battery cell discharge. The reduction process is accompanied by the diffusion of lithium halides from the separator to the cathodic space. The reduced metals (Ni, Co) form a network of branched dendrites covered with a salt film based on lithium chloride. The density and morphology of the dendritic deposit is determined by the composition of the initial cathodic mixture. The salt film consists of solid solutions and peritectics of the Li, Co, Ni||Cl, Br, F system. The reduction of M2+ (where M = Ni, Co) to the M0 metal is shown to proceed via a melt mechanism in the diffusion kinetics mode.

Despite gingival derived mesenchymal stem cells (GDMSCs) are unique and have numerous advantages for regenerative dentistry, the hypoxia preconditioning of GDMSCs may be essential prior to the transplantation. The aim of this study is to examine whether CoCl2 can enhance HIF-1α in GDMSCs in vitro. GDMSCs of Rabbit (Oryctolagus cuniculus) were obtained from laboratory stock. The sample for this study was randomly selected and divided into 4 groups; GDMSC normoxia (24 hours and 48 hours) groups and GDMSC hypoxia (24 hours and 48 hours) groups respectively (N=20/n=5). To stimulate the hypoxia condition, the final concentration of 100μM Cobalt (II) Chloride (CoCl2) was used in this study. The examination of Hypoxia Inducible Factor-1α (HIF-1α) stimulated with CoCl2 in the GDMSCs utilized immunocytochemistry methods with Fluorescein isothiocyanate antibody labelling. The Tukey Honest Significant Different (HSD) test was conducted to compare the significant difference in HIF-1α expression between groups (p

The discharge characteristics of the batteries of thermally activated chemical current sources containing CoCl2–CoF2 mixtures as positive electrodes are studied. The compositions and morphologies of the reduction products of the cathodic materials are determined. The use of the mixtures instead of individual cobalt halides makes it possible to stabilize the discharge characteristics and to decrease the discharge temperature of the current source battery. The reduction of Co2+ to metallic Co0 occurs under diffusion-controlled conditions.

A new CO2 absorber is reported in this paper. When CoCl3 is mixed with propylenediamine at room temperature and atmospheric ambient pressure, the extremely low concentration of CO2 in the air can be absorbed to form a stable metal complex [Co(PPD)2CO3]Cl·H2O (PPD = 1,3-propylenediamine). The CO2 capture capacity can reach 23.6 wt. %. Although Co is relatively expensive, the practical use of cobalt metal complexes produced still needs to be developed. This study provides an idea of capturing CO2 at low concentration under normal conditions. Through the structural characterization and performance study of complex [Co(PPD)2CO3]Cl·H2O, a new method for CO2 capture was explored. Thermogravimetric analysis data show that the compound [Co(PPD)2CO3]Cl·H2O has the ability to desorption CO2 and H2O at 160-220 ºC, and the ability to adsorb CO2 or regenerate CO2 is being explored. The electrochemical property of compound [Co(PPD)2CO3]Cl·H2O were also investigated.

© 2019 Elsevier B.V. In this paper thermochromic features of cobalt(II) were investigated in the binary mixture containing inorganic salt (ammonium nitrate) and molecular solvent (N-methylformamide) in order to find responsive thermochromic medium for possible application in a greenhouses for auto-regulated shading and solar protection. Absorption spectra of cobalt(II) in the NH 4 NO 3 + zNMF (z = 3, 4, 5, 6 and 20) binary mixtures were recorded in the visible wavelength range in the presence of different cobalt(II) and chloride concentrations at five selected temperatures: 308.15; 318.15; 328.15; 338.15 and 348.15 K. From the obtained spectra, geometry, composition and speciation of the complexes were discussed. Influences of the temperature and mixture composition on the absorption spectra were also analysed. From an analysis of the spectra using two computer programs, it was concluded that the following complexes were formed: [Co(NO 3 ) 4 (NMF) 2 ] 2− , [CoCl 3 (NO 3 )(NMF) 2 ] 2− and [CoCl 4 ] 2− . For these complexes stability constants were determined at all temperatures. Thermodynamic parameters were also calculated using the temperature dependence of calculated stability constants.

In this paper, we introduce a new Co precursor for the atomic layer deposition (ALD) of Co metal and other Co containing materials. CoCl2(TMEDA) (TMEDA = N,N,N ',N '-tetramethylethylenediamine) is a diamine adduct of cobalt(II) chloride that is inexpensive and easy to synthesize, making it an industrially viable precursor. Furthermore, CoCl2(TMEDA) shows good volatility at reasonably low temperatures and is thermally stable up to a temperature of, similar to 300 degrees C. We also present a full ALD study for the deposition of CoO thin films using CoCl2(TMEDA) and water as precursors. The process was investigated within a temperature range of 225-300 degrees C. Saturation of the film growth with respect to both precursor pulse lengths was verified. According to X-ray diffraction, the films were a mixture of hexagonal and cubic CoO. No reflections corresponding to Co3O4 were detected. The hexagonal phase is characteristic to nanomaterials only and is not seen in bulk CoO. The crystal structure of the films could be tuned by temperature, water pulse lengths, and type of substrate material. The films deposited at 275 degrees C exhibited 1:1 Co:O stoichiometry and very high purity. The CoO films could be reduced to Co metal at an exceptionally low temperature of 250 degrees C in 10% forming gas. Continuity of the reduced Co films was improved when the CoO film was deposited on TiN instead of native oxide terminated Si. The Co content of a 50 nm reduced metal film was as high as 95 at. %, with negligible amounts of oxygen and hydrogen.

This paper reports an effective synthesis, for the first time, of cobalt (II) chloride (CoCl2)-doped graphene quantum dots (cobalt (II) chloride–GQDs). Excellent results were obtained by using cobalt (II) chloride powder and graphene oxide as source materials in a facile hydrothermal process. The prepared materials were characterized by using high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction and photoluminescence (PL). HRTEM images suggest that the diameter of the majority of the cobalt (II) chloride–GQDs is in the narrow range of 2·5–7 nm, much smaller than that of GQDs, which are approximately 15 nm. By using different excitation energies in PL, the appearance of a peak introduces an additional energy level between π and π*, reinforcing the cobalt (II) chloride doping process. The authors observed that cobalt (II) chloride electrodes can exhibit a reversible redox reaction of Co2+ ↔ Co4+ and show specific pseudocapacitance of ∼300 F/g. The new charge storage mechanism using cobalt (II) chloride electrodes is easily scalable and highly economical for future pseudocapacitors and can be extended to a large variety of commercial inorganic salt electrodes.

A facile cobalt-catalyzed N-alkylation of amines with alcohols using inexpensive, commercially available CoCl2·6H2O is reported. Employing this readily available cobalt catalyst, a variety of amines with wide functional group tolerance were selectively alkylated under benign conditions.

Cobalt is an essential metal that is required for the generation of vitamin B12. However, exposure to excess cobalt for a prolonged period may adversely affect the human body, causing hepatotoxicity, pulmonary fibrosis, and neurotoxicity. 3-Aminotriazole (3-AT) is a catalase inhibitor that is often used to examine the cellular role of catalase. In the present study, we showed that 3-AT treatment significantly reduced cobalt (II) chloride (CoCl2)-induced cytotoxicity in HepG2 cells by suppressing the expression and activation of apoptotic markers, caspase-3 and poly adenosine diphosphate ribose polymerase (PARP). Mechanistically, 3-AT treatment attenuated CoCl2-induced accumulation of reactive oxygen species (ROS) and expression of RO S-responsive genes. Furthermore, the CoCl2-induced mitochondrial membrane potential (Δψm) shift and mitochondrial damage were attenuated by 3-AT. Taken together, these findings suggest that 3-AT alleviates CoCl2-induced cytotoxicity by reducing ROS generation and protecting against mitochondrial damage.

High-spin cobalt(II) complexes are considered useful building blocks for the synthesis of single-molecule magnets (SMM) because of their intrinsic magnetic anisotropy. In this work, three new cobalt(II) chloride adducts with labile ligands have been synthesized from anhydrous CoCl2, to be subsequently employed as starting materials for heterobimetallic compounds. The products were characterized by elemental, spectroscopic (EPR and FT–IR) and single-crystal X-ray diffraction analyses.trans-Tetrakis(acetonitrile-κN)bis(tetrahydrofuran-κO)cobalt(II) bis[(acetonitrile-κN)trichloridocobaltate(II)], [Co(C2H3N)4(C4H8O)2][CoCl3(C2H3N)]2, (1), comprises mononuclear ions and contains both acetonitrile and tetrahydrofuran (thf) ligands, The coordination polymercatena-poly[[tetrakis(propan-2-ol-κO)cobalt(II)]-μ-chlorido-[dichloridocobalt(II)]-μ-chlorido], [Co2Cl4(C3H8O)4], (2′), was prepared by direct reaction between anhydrous CoCl2and propan-2-ol in an attempt to rationalize the formation of the CoCl2–alcohol adduct (2), probably CoCl2(HOiPr)m. The binuclear complex di-μ-chlorido-1:2κ4Cl:Cl-dichlorido-2κ2Cl-tetrakis(tetrahydrofuran-1κO)dicobalt(II), [Co2Cl4(C4H8O)4], (3), was obtained from (2) after recrystallization from tetrahydrofuran. All three products present cobalt(II) centres in both octahedral and tetrahedral environments, the former usually less distorted than the latter, regardless of the nature of the neutral ligand. Product (2′) is stabilized by an intramolecular hydrogen-bond network that appears to favour atransarrangement of the chloride ligands in the octahedral moiety; this differs from thecisdisposition found in (3). The expected easy displacement of the bound solvent molecules from the metal coordination sphere makes the three compounds good candidates for suitable starting materials in a number of synthetic applications.

The reaction of the Δ4-alkenols with PhSeX can follow three possible reaction pathways: two pathways lead to the formation of two regioisomeric cyclic ether products through the process of intramolecular cyclization, while the third represents the addition of the reagent to the double bond of an alkenol. As there are relatively few literature data on the kinetics of these reactions, we have chosen 6-methyl-hept-5-en-2-ol as a substrate of interest in order to obtain valuable results that will enable better understanding of the mechanism of phenylselenoetherification reactions. 6-Methyl-hept-5-en-2-ol is a particularly interesting model-substrate due to its substitution pattern of functional groups involved in the cyclization process. In this research, through synthetic and kinetic studies, we aimed to resolve key questions concerning the influence on kinetics, chemo- and regioselectivity of the reagent's counter ion, steric hindrances in substrate functional groups and the presence of additives.

Effect of a modifying cobalt(II) chloride additive on the selectivity of adsorbents and liquid stationary phases used in gas chromatography for the separation of volatile organic substances (VOSs) of different chemical nature is considered. It is found that the specified additive leads to a drastic increase in the retention parameters of oxygen-containing VOSs, first of all, aliphatic alcohols, and relatively weakly affects the retention of other VOSs, including nucleophilic nitrogen-containing compounds. In particular, the addition of cobalt chloride to Carbowax increases the retention parameters of methanol and ethanol and reduces the corresponding parameters for analytes from the other VOS classes.

The determination of cholesterol concentration in the blood is an important characteristic of the state of health. Modern methods for the detection of cholesterol involve the use of enzymes or expensive and complicated equipment. In this study, an enzymeless electrochemical method for the quantitative determination of cholesterol using cobalt (II) chloride as an electrocatalyst has been proposed. An analytical signal was peak current of cobalt (II) chloride faradaic oxidation on a platinum disk electrode in acetonitrile media in the presence of cholesterol via linear sweep voltammetry. A possible path of the electrocatalytic oxidation of cholesterol on the electrode surface was proposed. The catalytic constant kcat and the Michaelis constant Km calculated for the electrocatalytic oxidation process of cholesterol on the electrode surface are comparable in magnitude to the natural enzyme cholesterol oxidase, indicating the high efficiency of CoCl2 as an electrocatalyst for oxidation and, therefore, the determination of cholesterol. The highest value and the best reproducibility of analytical signal are reached at a CoCl2 concentration of 25 mM and a scan rate of 100 mV·s− 1. The linear region of the calibration curve “current-cholesterol concentration” obtained using a developed method in a solution of 0.1 M LiClO4 and 25 mM CoCl2 in acetonitrile is 25–200 μM (R2 = 0.971) with a detection limit of 2 μM.

Fibrinopeptide B (GluFib) is one of the factors of thrombosis. Normal soluble blood protein, fibrinogen (fibrinopeptide A and fibrinopeptide B), is transformed into the insoluble fibrin, which in the form of filaments adheres to the vessel wall at the site of injury, forming a grid. In the literature, it is noted that a violation of blood coagulation under the influence of cobalt and lanthanides compounds has been established. It is possible that the reason is the change in the structure of the molecules of fibrin fibers under the influence of cobalt and lanthanides influences. In this paper the spatial structure of GluFib was investigated with manganese (II) chloride, cobalt (II) chloride and gadolinium (III) chloride by NMR spectroscopy. The spatial structures were obtained by applying 1D and 2D 1H–1H NMR spectroscopy (TOCSY, ROESY). The chemical shifts of some 1H NMR signals of GluFib in complex with cobalt and gadolinium salts have changed. The changing chemical shifts belong to betta-group atoms of 7 and 8 glutamic acid. Analyzing spectra, it was found that ions of cobalt and gadolinium interact with GluFib, integrating between the amino acid residues of the seventh and eighth glutamic acids. Manganese ions don’t interact with fibrinopeptide B molecule. In our work we were received the spatial structure of GluFib peptide in aqueous solution in complex with cobalt (II) chloride and gadolinium (III) chloride. The interaction of the peptide with the ions of these metals leads to backbone bending.

Dengue virus (DENV) serotypes DENV-1 to DENV-4 are enveloped viruses that belong to the genus Flavivirus of the Flaviviridae. Dengue vaccine or antiviral has not yet been clinically approved for humans, even though there have been great efforts toward this end. Antiviral activity against DENV is needed to develop to be an alternative drug for DENV virus. Cobalt(II) chloride have been used in the treatment and prevention of diseases of humans since ancient times. The aim of this study is to investigate the antiviral effects and Cytotoxicity of Cobalt(II) chloride. This compound was further investigated for its inhibitory effect on the replication of DENV-1 in Vero cells. Antiviral activity and Cytotoxicity measured by WST-1 assay. The IC 50 value of the Cobalt(II) chloride for DENV-1 was 0.38 μg/ml. The cytotoxicity of Cobalt(II) chloride to Vero cell suggest that the CC 50 value was 2.91 µg/ml The results of this study demonstrate the anti-dengue serotype 1 inhibitory activity of Cobalt(II) chloride was a high toxic compound.

Cobalt(II)-Nicotinamide had been synthesized mole ratio in 1 : 2 of metal to the ligand in methanol. The complex was characterized by atomic absorption spectrophotometer (AAS), conductometer, UV-Vis spectrophotometer, MSB (magnetic susceptibility balance) and FT-IR spectrophotometer. The result of AAS showed that cobalt(II) in the complex was 14,40%. The molar conductivity showed that the complex was 2 to 1 electrolyte. UV-Vis spectra appeared a transition peak of third transition 4T1g(F) → 4T1g(P). The momen magnetic showed that the complex was paramagnetic. The infrared spectral indicate that groups of primary N-H and carbonyl were coordinated to the center ion of Co(II). The complex formula was estimated as [Co(Nicotinamide)2(H2O)2]Cl2 and probably octahedral.

The new [Co(btmgn)Cl 2] complex and the 1,8-bis(tetramethylguanidino)naphthalene (btmgn) ligand were synthesized and characterized. The X-ray single crystal investigation showed distorted tetrahedral geometry around the Co(II) ion. The geometry of the btmgn and [Co(btmgn)Cl 2] complex was optimized using the B3LYP/6–311G(d,p) method. The calculated geometric parameters at the optimized structure of the [Co(btmgn)Cl 2] complex showed good agreement with our reported X-ray structure. The two tetramethylguanidino groups are in a cis-type position to the naphthalene ring plane both in the free and coordinated btmgn. The large red shift of the υ C=N mode upon coordination indicates the strong ligand–metal interactions. The calculated natural charges using natural bond orbital (NBO) analysis at the two coordinated Cl-atoms are not equivalent. Also the two LP(4)Cl →LP*(3)Co intramolecular charge transfer interaction energies (E (2)) are 29.00 and 39.17 kcal/mol, respectively. The two Co-Cl bonds are not equivalent where the longer Co-Cl bond has more electronegative chlorine atom than the shorter one. Molecular electrostatic potential (MEP) study of the btmgn ligand showed that the N4 and N7 atoms are the most reactive nucleophilic centers for the coordination with the Co 2+ ion. The [Co(btmgn)Cl 2] complex has higher polarizability (α 0), first hyperpolarizability (β 0) and lower energy gap (ΔE) than the free ligand. The TD-DFT calculations predicted the transition bands at 337.2 nm (f =0.2299, H →L) and 342.6 nm (f =0.1465, H-2/H →L) for the btmgn and [Co(btmgn)Cl 2], respectively.

Solution-casting technique was employed for the preparation of solid polymer electrolyte based polyethylene oxide (PEO) with 0, 1, 3 and 5 weight percentage cobalt chloride (CoCl 2 ) films were characterized by X-ray Diffractometry (XRD), Differrential Scanning Calorimetry (DSC), Scanning Electron Microscope (SEM) and Ultra Violet-Visible (UV-Vis.) Spectroscopy methods. The optical band gaps, absorption band edges and Urbach energy shows decrease with increasing of Co +2 ion concentration in the polymer matrix because of the formation of free radicals or cluster. The Thermogravimetry (TG) and Derivative Thermogravimetry (DTG) were used to examine the thermal stability of the film and it was found that the stability of the complexes is higher than that of the pure PEO due to the addition of CoCl 2 . The wavelength position of a fluorescence emission band varied by increasing of a dopant wt % of salt.

A series of 2-(1-(arylimino)ethyl)-7-arylimino-6,6-dimethylcyclopentapyridine derivatives (L1-L5) was synthesized, and individually reacted with cobalt(II) chloride to form the corresponding cobalt chloride complexes (C1-C4). These compounds were characterized, and the single crystal X-ray diffraction for two representative cobalt complexes was carried out. The molecular structures indicate that 2,7-bis(arylimino)cyclopentapyridines act as tridentate ligands; however, one of the Co-N coordinative bonds is weak due to the spatial separation of nitrogen atoms. Upon activation with either MAO or MMAO, all cobalt complexes exhibit catalytic activities toward ethylene. Polymerization takes place in the presence of MAO with activities of approximately 10(4) g of PE per (mol of Co) per h, but oligomerization occurs in the presence of MMAO with the activities higher by one order of magnitude. The resultant products, either polyethylenes or oligomers, display high linearity. Relatively low activities observed for cobalt complexes discussed reflect the importance of the appropriate spatial arrangement of the three donor nitrogen atoms.

Cobalt(II) chloride (10mol%) was found to be an efficient catalyst for one pot synthesis of variety of 2-substituted-4(3H)quinazolinones by condensation of anthranilamide and aldehydes and synthesis of 3-substituted-4(3H)quinazolinones by condensation of anthranilic acid, orthoester, primary amines at reflux giving good to excellent yields (75-95%).

Cobalt(II) chloride hexahydrate and primary aromatic amines were reacted by co-grinding in 1:2 metal salt to ligand ratio under solvent-free environment at room temperature. Out of 16 solid state reactions, seven cobalt-amine complexes could be established as solid coordination compounds by elemental analysis, TGA, IR, PXRD, magnetic susceptibility etc., in addition to visual observation of the color change of reaction mixture. Based on investigation of reaction and analysis of products, conclusions with outlook could be made as follows: On top of the —NH2 group on primary aromatic amines an additional substituent group should better be at para or meta positions and not at ortho position in order to realize the solid coordination compounds. On the other hand, an electron withdrawing substituent or an extra aromatic ring is negative towards formation of the solid coordination compounds. The solid coordination Co(II)-compounds are labile in solution.

Because of its use in on-board hydrogen portable hydrogen-air fuel cell, hydrogen generation based on the reaction between aluminum and water was evaluated. In the present work, the effect of CoCl2 and NiCl2 on aluminum–water reaction was studied. The amount of hydrogen generated linearly increased with increasing NiCl2 concentration from 1 M to 2.5 M, and reached the maximum with 1–1.5 M CoCl2. However, it dramatically decreased with further increase in CoCl2 and NiCl2 concentration. The formation of Co/Al and Ni/Al galvanic cell, the decrease in pH, and the permeation of chloride in the oxide layer supported hydrogen generation. Besides these factors, amorphous Co with higher specific surface area acted as the catalyst to hasten hydrogen generation. The hydrogen evolution in 1 M CoCl2 increased from 30 °C to 45 °C, and then it obviously decreased at 60 °C. The hydrogen generation in NiCl2 showed similar behavior. The by-product Co or Ni could be easily separated by use of a magnetic stirring bar and reused in subsequent rounds of aluminum–water reaction.

A new analytical method for determining cobalt (Co) species in human serum by size exclusion chromatography with inductively coupled plasma mass spectrometry (SEC-ICP-MS) was applied to serum samples collected from 12 human volunteers who participated in a Co(II) chloride supplement study involving ingestion of 1 mg Co/day for up to 90 consecutive days. The study protocol included determination of serum total Co by acid digestion followed by ICP-MS. Co speciation assay measurements were conducted for up to 13 time points per individual spanning from one to two weeks before dosing began to two weeks after dosing ceased. The Co speciation assay showed good recovery >91% relative to total Co measurements. Undiluted serum demonstrated uniform fractions of large molecular Co defined as Co bound to albumin and other proteins >50 kDa at 96% and the residual as small molecular Co defined as free Co(II) and

The Co(III) complex of 3,6,9,15-tetra-azabicyclo[9.3.1]penta-deca-1,11,13-triene (L1) has been synthesized in DMF and isolated as a blue solid (1) ([L1CoIIIClX]n+, X = Cl− or DMF, n = 1 or 2). Complex 1 exhibits solution behavior similar to the classic cobalt(II) chloride equilibrium. When 1 is dissolved in water, the solution is pink and this complex exists as 1a, which consists of a cobalt(III) bound to L1 and two cis-chlorides with a perchlorate counter-ion to balance the complex charge ([L1CoIIICl2][ClO4]). In contrast, when 1 is dissolved in DMF or other organic solvents the solution is blue and is observed as 1b. The 1b complex salt contains two cobalt centers. One cobalt(III) is bound to L1, Cl−, and DMF. Charge balance is accomplished by the second cobalt center: [CoIICl4]2−, thus making 1b (L1CoIIICl(DMF)][CoIICl4]). This equilibrium was confirmed using UV–visible spectroscopy, EPR, and X-ray crystallography.

A new triazene, 1-[(2-methoxy)benzene]-3-[benzothiazole] triazene (HL), has been synthesized and charaterized. In the presence of Et3N, the reaction of HL and CuCl2·2H2O or CoCl2·6H2O gives the triazenide complexes [Cu4L′4(μ-OMe)4] 1 (L′ 1-[benzothiazole]triazene ion) and [Co2L4] 2, respectively. The X-ray crystal structures of both complexes have been obtained. Magnetic studies indicate significant antiferromagnetic coupling between the copper(II) centers or cobalt(II) centers for complexes 1 and 2, with coupling constants (J) of –587 cm−1 for 1 and –147 cm−1 for 2. Complex 2 shows one reversible one-electron redox wave at –0.835 V, and one irreversible oxidation at –0.193 V, which are in accord with the redox potentials of [CoIII-CoII]/[CoII-CoII] and [CoIII-CoIII]/[CoII-CoII] couples, respectively.

The cobalt(II)–chloride association equilibria in ammonium nitrate–dimethyl sulfoxide (DMSO) melts of the type NH4NO3·xDMSO at five different compositions in the range 1.0 ≤ x ≤ 5.0 have been investigated by the spectrophotometric method. Absorption spectra of cobalt(II) chloride solutions containing variable amounts of ammonium chloride at different temperatures from 35 to 65 °C have been recorded in the wavelength range of 400–800 nm. In the absence of chloride, the solutions show spectra typical for octahedral coordination of cobalt(II). Addition of chloride changed the absorption spectra to a tetrahedral or severely distorted octahedral coordination. Stability constants for the complexes [Co(NO3)2(DMSO)2], [Co(NO3)2X2]2− and [CoCl4]2−, and the species spectra for all complexes are reported. The effect of varying the DMSO/NH4NO3 mole ratio is discussed. A sharp increase of the stability constants around x = 2 is correlated to the competition between the solvent molecules or ions and the cobalt(II) ions for the ligand and to the solvation of NH4+ with two DMSO.

Solvent free, highly efficient method has been developed using ecofriendly, heterogeneous reusable cobalt chloride catalyst at ambient reaction conditions for the O-acylation of various alcohols and phenols with acetyl chloride in excellent yield in a short reaction time. The catalyst is recycled several times without loss of catalytic activity.

The reaction of cobalt(ii) chloride with bis(benzo)bispidinoaza-14-crown-4 (L) containing two α-pyridyl substituents affords complex [Co(L)(H2O)][CoCl4] (1). The structure of complex 1 was determined by X-ray diffraction analysis. In structure 1, molecule L is coordinated to the neutral Co(1) atoms as an N, N, N, N-tetradentate-chelating ligand. The tetrachlorocobaltate dianion acts as a counterion. The coordination polyhedron of the Co atom in complex 1 is an octahedron, and that of the Co(2) atom in the anion is a tetrahedron. The coordination polyhedra of the Co atoms in complex 1 are linked by the bridging chlorine atom. In the octahedron of the Co(1) atom, two five-membered and two six-membered nonplanar chelate metallocycles, which are conjugated with each other along the Co(1)-N(1) and Co(1)-N(2) bonds, undergo ring closure. All bond lengths of the Co(1) atom with the N atoms range from 2.098(4) to 2.228(5) A, and the Co(2)-Cl bond lengths change from 2.233(2) to 2.331(2) A. The longest Co(1)-Cl(4) bond (2.558(2) A) is that with the metal ion. A molecule of complex 1 is stabilized by strong intramolecular hydrogen bonds involving the crown ether fragment.

A simple, efficient, and general method has been developed for the one-pot, three-component synthesis of α-aminophosphonates from condensation reaction of trimethyl phosphite, aryl aldehydes and aryl amines in the presence of CoCl 2 ·6H 2 O under solvent-free conditions. Thus α -aminophosphonates were synthesized relatively quickly in good yields at room temperature.

In this paper the spectral behaviour at different temperatures of solutions of anhydrous CoCl2 in water, methanol, ethanol, 1-propanol, 2-propanol, and acetone is reported and discussed. The work was initiated by the striking colour changes observed in some of these solvents when the temperature is lowered well below room temperature. The effects are interpreted in terms of octahedral-tetrahedral configurational changes of solvated Co2+ complexes. A number of earlier observations, which are relevant to the ones reported here and most of which support the interpretation given, are briefly reviewed and discussed.

The reactions of CoCl2·6H2O, dppm (bis(diphenylphosphino)methane) and TCNQ (7,7,8,8-tetracyanoquinodimethane), with different ratios of the components, provided three new compounds, [Co(dppmdo)3][TCNQ]2 1 (dppmdo = P,P′-dioxo-bis(diphenylphosphinyl)methane), [Co(dppmdo)3][(μ-TCNQ)-CoCl3] 2, and [Co(dppmdo)3][(μ-DCBE)-CoCl3] 3 (DCBE = p-dicyanomethyl-benzoic ethyl ester). These products were characterized by IR, UV–Vis and UV–Vis-NIR spectra, X-ray crystallography, magnetic susceptibility measurements and cyclic voltammograms. 1 and 2 reveal low-energy transitions in the near-infrared region, which can be attributed to intra-ligand transitions involving radical anions (TCNQ/TCNQ−). It is interesting to note that, except for the redox potentials which are anodically shifted, indicating that it is easier to reduce TCNQ in 1 and 2 than the free TCNQ molecule, the electrochemistry of compounds 1 and 2 resemble that of the independent organic acceptor TCNQ. The magnetic properties suggest that an amount of electron transfer has occurred from the CoII complex, [Co(dppmdo)3]2+, to the TCNQ− anions in 1; an amount of electron transfer also has occurred from the CoII cation to the TCNQ− anion via a cyanide-bridge in 2; there is a mixture of spin transition of CoII ions and antiferromagnetic coupling between CoII ions in 3.

Influence of solvent composition, i.e. the salt mole fraction and water content on absorption spectra of cobalt(II) chloride and nitrate in x Ca(NO 3 ) 2 · z H 2 O–(1 − x )NH 4 NO 3 systems was investigated by spectrophotometric method in the wavelength range 400–800 nm at 55 °C. On the basis of absorption spectra of cobalt(II) chloride and nitrate complexes and overall molar absorption coefficients obtained in 13 investigated systems, the geometry of the complexes formed was studied. Comparing of these spectra with those obtained in anhydrous melts and aqueous solutions, possible coordination of water molecules with cobalt(II) and formation of mixed complexes was considered.

Acrylonitrile-butadiene rubber (NBR) composites filled with Cobalt (II) Chloride (CoCl2) particles were prepared by a solvent dispersion method. Acetone was selected as solvent for NBR and CoCl2. To directly enhance the interaction between NBR and CoCl2, a coordination reaction was generated by hot pressing at 200 °C. Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV–vis), and x-ray photoelectron spectroscopy (XPS) were employed to investigate the coordination reaction. Results showed that the coordination reaction occurred between the nitrile groups (−CN) of NBR and cobalt ions (Co2+) of CoCl2. Compared with the properties of pure NBR, the tensile strength of NBR/CoCl2 composites filled with 10 parts per hundreds of rubber (phr) CoCl2 increased 2200%. Scanning electron microscopy (SEM) indicated that the CoCl2 particles were dispersed in the NBR matrix homogeneously. The indistinguishable interface between CoCl2 particles and NBR matrix indicated good compatibility. Additionally, thermogravimetric analysis (TGA) showed that coordination reaction improved heat resistance of NBR matrix.

The well-known fact that cobalt(II) halide complexes in various media undergo changes in coordination, absorbance, and color with increasing temperature was combined with the high latent heat of fusion of new materials suitable for simultaneous control of temperature, light intensity, and heat storage. Hence, the increase in absorbance with temperature acts as an autoregulated shading protection from overheating. Several binary mixtures of calcium nitrate tetrahydrate and ammonium nitrate, xCa(NO3)2 · 4H2O + (1 - x)NH4NO3, with low melting points were studied as suitable solvents for the formation of cobalt(II) chloride complexes. The temperature dependence of the densities of these melts has been measured. Absorption spectra in the visible spectral range [(400 to 800) nm] have also been investigated. The overall stability constants of [Co(NO3)4] 2- , [Co(NO3)2Cl2] 2- , and [CoCl4] 2- complexes at different temperatures were calculated using a nonlinear regression program. On the basis of these stability constants, the thermodynamic data (i.e., enthalpy, entropy, and free-energy changes) were calculated for the corresponding complexation reactions. Also, the dependence of the enthalpy and entropy changes on the solvent composition has been analyzed.

The complex of cobalt(II) chloride with bi-1,1′-(3,3-dimethyl-3,4-dihydroisoquinoline) (L), [CoLCl2] (I), is synthesized and studied by X-ray diffraction, electronic spectroscopy, and IR spectroscopy. In the structure of complex I, ligand L performs a bidentate-chelating function, adding to the cobalt atom through the nitrogen atoms. The coordination polyhedron of the cobalt atom is a tetrahedron (2N, 2Cl) with ordinary Co-N (2.00(1)–2.07(1) A) and Co-Cl (2.216(6)–2.226(6) A) bond lengths. The noncentrosymmetric orthorhombic unit cell of crystal I contains two independent molecules of the complex (1 and 1′) joined by C-H=Cl hydrogen bonds into a pseudocentrosymmetric dimer. Ligands Lc and Lc′ exist in the same cisoid isomeric form (torsion angle N(1)-C(1)-C(12)-N(2) is 19.2° in Lc and 26.6° in Lc′).

A simple and efficient method for the convenient synthesis of 2-arylbenzimidazole has been described on reaction with o-phenylenediamine and various aromatic aldehydes using cobalt(II) chloride hexahydrate as a catalyst. The method is cost-effective, high-yielding, clean, and selective.

Cobalt(II) chloride catalyses the conversion of a variety of aldoximes, including salicylaldoxime and substituted salicylaldoximes, into corresponding nitriles in the presence of an inorganic base in acetonitrile. The reaction proceeds under mild conditions and the yields are generally very good to excellent.

Primary and secondary benzylic alcohols were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H 2 O 2 catalyzed by montmorillonite K-10 supported cobalt(II) chloride.

Oximes were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H 2 O 2 catalyzed by montmorillonite K-10 supported cobalt(II) chloride.

We present the kinetic and temperature dependences of the optical absorption of thermochromic films of polyvinyl alcohol with added CoCl2. Based on the data obtained, we have analyzed the possibility that tetrahedral cobalt complexes are formed from octahedral complexes.

In this work, the absorption spectral characteristics and color-change reaction mechanism of cobalt(II) chloride(COCl2) in alcohol organic solvents has been investigated in the presence of water, and then the optimum conditions for determining the water content in the solvents were selected. Results indicated that the absorption spectra Of COCl2 in alcohols decreased with the increment of water content. At the maximum absorption wavelength of 656 nm, there were good linear relationships between the logarithm of the absorbance and the water content in organic solvents such as ethanol, n-propanol, iso-propanol and n-butanol with related coefficients in the range of 0.9996 similar to 0.9998. For determining water content in organic solvents, this method is simple, rapid, sensitive, reproducible and environmentally friendly. Furthermore, the linear range cannot restrict determination of the water content in organic solvents. This method had been applied to determine the water content in ethanol and n-butanol with satisfactory recovery of water in n-butanol between 98.41%-101.29%.

A series of S-alkylated derivatives of 2-thiohydantoins, containing two 5-(3-pyridylmethylene)-3,5-dihydro-4H-imiazole-4-one fragments joined by polymethylene bridges with different numbers of carbon atoms, was synthesized. The title (5Z,5′Z)-2,2′-(alkane-α,ω-diylsulfanyldiyl)bis(5-(3-pyridylmethylene)-3,5-dihydro-4H-imidazol-4-ones) (L) were obtained by alkylation of 5-(3-pyridylmethylene)-3-phenyl-2-thiohydantoine by 1,2-dibromoethane, 1,6-dibromohexane or 1,10-dibromodecane in DMF in the presence of potassium carbonate. The complexes of ligands L with CoCl2 · 6H2O have been synthesized. It is shown that, regardless of the L:CoCl2 ratio, complexes with LCoCl2 composition are obtained in all cases. The structure of the cobalt(II) chloride complex with (5Z,5′Z)-2,2′-(ethane-1,2-diyldisulfanyldiyl)bis(5-(3-pyridylmethylene)-3-phenyl-3,5-dihydro-4H-imidazol-4-one) was determined by means of the RSA method. The cobalt atom in this complex has a tetrahedral ligand environment and it is coordinated by two chloride anions and two nitrogen atoms of pyridine fragments, forming a 19-membered metallocycle. Electrochemical investigations of the synthesized ligands and complexes have been made by CVA and RDE methods. It is established that the first stage of reduction for the complexes takes place on the metal, whereas the first stage of oxidation takes place on the coordinated chloride-anions.

Heterogeneous hydrogenation of the styrene and stilbene chromium tricarbonyl complexes by molecular hydrogen on skeletal nickel and palladium on carbon as catalysts was studied. As compared to styrene and stilbene, their arene chromium tricarbonyl analogs are hydrogenated considerably more slowly, which is related, most likely, to strong adsorption of the π-complexes on the catalyst surface. For the homogeneous hydrogenation of these complexes using a H2PtCl6-SnCl2-LiBr system, styrene and η6-styrene chromium tricarbonyl are reduced with a high rate, whereas stilbene and its chromium tricarbonyl complex are hydrogenated very slowly. A possibility of reduction of the unsaturated arene chromium tricarbonyl complexes by sodium borohydride in the presence of cobalt(II) chloride as a catalyst was shown.

The structure of tris-chloro[2,6-bis(2′-pyridyl)-4-(2′-pyridinium)-1,3,5-triazine]cobalt(II) monohydrate, [Co(C18H13N6)Cl3]·H2O (C2/c (No. 15), a=7.783(11), b=22.42(3), c=11.001(15) A, β=90.05(2)°), crystallized from the open air reaction of CoCl2 and 2,4,6-tri(2-pyridyl)-1,3,5-triazine in the ionic liquid, N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide is reported. The structure consists of six coordinate cobalt in an octahedral geometry bonded to the tridentate tptz ligand and three chlorines. The non-coordinating pyridyl group in the tptz ligand is protonated (with the protonated nitrogen crystallographically disordered over two possible sites), providing overall charge neutrality for the complex.

A novel probe, tetraphenyl porphyrin Cobalt(II)chloride (CoTPPCl), was first developed for the determination of nucleic acids at a nanogram level by a resonance light scattering (RLS) technique. Under optimum conditions, the weak RLS signal of CoTPPCl was enhanced greatly by nucleic acids at 444.0 nm; the enhanced RLS intensity is proportional to the concentration of nucleic acids in the range of 0.05–3.5 mg L−1 for calf thymus DNA and 0.03–4.2 mg L−1 for fish sperm DNA. The detection limits (3δ) are 3.5 ng mL−1 for calf thymus DNA and 4.5 ng mL−1 for fish sperm DNA, respectively. The results show that determination of nucleic acids with CoTPPCl as a probe is much more sensitive than with α, β, γ, δ‐ tetrakis[4‐(trimethylammoniumyl)phenyl]porphine (TAPP). Synthetic samples and plasmid DNA extracted from K‐12‐HB101 colt were determined with satisfactory results.

A monofunctional phosphine oxide containing endcapping reagent, 4-carboxyphenyl biphenyl phosphine oxide, was synthesized for the preparation of telechelic polyester oligomers. The chemical structure of the endcapping reagent was verified using NMR spectroscopy, mass spectroscopy, and elemental analysis. Phosphine oxide telechelic polyesters were prepared for the first time via copolymerization of a low molar mass polyester oligomer precursor and the phosphine oxide endcapping reagent in the melt state. The quantitative incorporation of telechelic phosphine oxide functionality was confirmed using 1H NMR spectroscopy and elemental analysis. The corresponding complexes of phosphine oxide terminated polyesters and cobalt(II) chloride were prepared via charging the cobalt salt at the onset of melt polymerization. 31P {1H} NMR spectroscopy, FT-IR spectroscopy, and UV–vis spectroscopy indicated that the cobalt(II) ion preferentially coordinated with the phosphine oxide end groups. The complexes exhibited higher melt viscosity than their salt-free analogues due to the formation of coordinated polymers. The presence of the telechelic phosphine oxide end groups also aided in the homogeneous dispersion of the cobalt salt in a poly(ethylene terephthalate) (PET) matrix.

A series of S-alkylated 2-thiohydantoin derivatives containing two 5-(2-pyridylmethylene)-2-sulfanyl-3,5-dihydro-4H-imidazol-4-one moieties linked through a polymethylene bridge with different numbers of carbon atoms was synthesized for the first time. These compounds were obtained by the alkylation of 3-phenyl-5-(2-pyridylmethylene)-2-thiohydantoin or 3-methyl-5-(2-pyridylmethylene)-2-thiohydantoin with different α,ω-dibromoalkanes in acetone or DMF in the presence of potassium carbonate. Complexes of these compounds (L) with CoCl2 were synthesized. In all cases, the complexes L(CoCl2)2 were formed regardless of the ratio of L and inorganic salt introduced into the reaction. According to electronic spectroscopic data, the cobalt atom in the complexes has a tetrahedral coordination environment. The synthesized ligands and complexes were electrochemically studied by cyclic voltammetry.

The complex formation between cobalt(II) and chloride ions in molten NH4NO3・2.61H2O, NH4NO3・CH3CONH2・1.61H2O and NH4NO3・2.61CH3CONH2 has been investigated. Absorption spectra of cobalt(II) chloride containing variable amounts of ammonium chloride were recorded at 45 to 60 °C. In the absence of chloride, the solutions show spectra typical for octahedral co-ordination of cobalt(II). Addition of chloride caused a shift of the absorption maximum toward lower energies and an increase of the molar absorption coefficient with increasing chloride concentration. The position of the absorption maximum and the intensity of the absorption indicate tetrahedral or severely distorted octahedral co-ordination. The stability constants for [Co(NO3)4]2−, [Co(NO3)2Cl2]2− and [CoCl4]2− complex formation in NH4NO3・2.61CH3CONH2 are reported.

Cobalt(II) chloride hexahydrate (CoCl2·6H2O) efficiently catalyzes the acetylation of alcohols with AcOH in high yields. This protocol is also effective with other carboxylic acids, trifluoroacetic acid, propanoic acid, phenylacetic acid and benzoic acid, affording the corresponding acylated products in moderate to good yields. Removal of water is not necessary in these reactions. The catalyst can be filtered and recycled without loss of activity.

The absorption spectra of Co(II) chloride complexes, containing variable concentrations of chloride ligand, in a molten mixture of 80 mol% acetamide-20 mol% calcium nitrate tetrahydrate, were studied at 313, 333, 353, and 363 K, in the wavelength range 400-800 nm. The melt contains three possible ligands (CH3CONH2, H2O, and NO3-) for competition with added chloride ligand. Addition of chloride caused a shift of the absorption maximum of octahedral cobalt( II) nitrate towards lower energies and pronounced changes in the shape of the initial spectrum of cobalt( II) nitrate. The effect of temperature changes on the molar absorption coefficient of the Co( II) species was dependent on the chloride concentration and was attributed to the structural changes occurring in the cobalt( II) species. The STAR and STAR FA programs were applied to identify the complex ionic species and to calculate the stability constants of Co( II) complexes formed in this solvent. The results indicate the highest probability of formation of the following complex species: Co(NO3)(4)(2-), Co(NO3)(2)Cl-2(2-), and CoCl42-. Stability constants of each complex were presented for the equilibria occurring at 313, 333, 353, and 363 K. Distribution of the Co( II) species was also calculated over the ranges of chloride concentration and temperature investigated.