An assumption as to formation of polynuclear complexes does not agree with the result of , where formal standard potentials of Cr(III)/Cr(II) and Cr(II)/Cr were determined in alkali chloride melts, and no deviations from the Nernst law were observed. This assumption contradicts the data of electron spectroscopy  that exclude formation of polynuclear chromium complexes in NaCl–KCl, KCl, CsCl melts. In [16, 17], the reference electrode was the Ag/NaCl–KCl–AgCl electrode (2 wt.%) with a porcelain or alundum tube. We established interaction of these materials with the NaCl–KCl– CrCl 3 melt . After two hours of the conditioning of the reference electrode in the chloride melt,
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ability to selectively attach oxygen atom to olefins and other organic substrates. Recently metal catalyst of various organic oxidations effectively promoted chromium complexes acting via. their oxidation states, presumably chromium(III) has been reported 9-13 . Schiff base ligands 14 are able to
The values of these parameters (Table 4) are comparable to those observed for chromium complexes involv- ing similar set of chromophore . However, it may be pointed out that these parameters are not standardised and thus require modifications. To overcome the shortcoming of various parameters of the classical Hamiltonian for tetragonal complexes, Lever et al.   had advanced the theory of a Normalised Spherical Harmonic (NSH) Hamiltonian. The NSH parameters DQ, DS, DT, DQ xy , and DQ z are fully capitalized to relate them to the corresponding crystal field parameters. Yet emphasize their distinction. The NSH classical parameters are re- lated by,
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The continuous demand for new chemotherapeutic agents indicates that new approaches are critically needed. The current study was under taken to examine the effect of the two novel antitumor complexes namely cobalt and chromium complexes of bis-(4-bromobenzaldehydeiminoacetophenone), BBIA-Co and BBIA-Cr, on liver, kidney and heart of Ehrlich ascites carcinoma (EAC) bearing male albino mice. The effect of the two complexes on antioxidant status of the animals and histopathological examination of liver, kidney and heart tissues were also examined. Results indicated that treatment with either BBIA-Co or BBIA-Cr had ameliorated to some extent the changes in liver function exerted by EAC inoculation. Both complexes had no significant effect on kidney function, while they induced cardiac toxicity to animals. The study also showed no significant changes in the antioxidant status of EAC inoculated mice treated with BBIA-Co compared to normal animals, which was not indicated after BBIA-Cr treatment. The biochemical data results were further supported by histopathological examination.
Chapter 1 presents the synthesis and characterization of a series of bis(diphenylphosphino)amine ligands and their corresponding chromium(III) trichloride complexes. The isolated chromium complexes are precursors to highly active catalysts for the selective oligomerization of ethylene to 1-hexene and 1-octene. The unique feature of the ligands presented herein is the presence of coordinating functionalities tethered to the nitrogen backbone. These act as hemilabile donors, which stabilize the active species and/or transition states during catalysis. This increased stability leads to more productive catalysts. Furthermore, important solvent and additive effects have been investigated. While reactions in non-polar solvents exhibit poor activity at lower ethylene pressures, those in more polar solvents are highly active and generate very little undesired polymer. Varying the solvent has a significant impact on 1-hexene/1-octene selectivity as well. Experiments with potentially coordinating additives result in a higher tendency for 1-octene formation. An investigation of catalyst decomposition is also discussed.
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Pyridine dicarboxylic acids are peculiar ligands.They shows different co-ordination modes. Therefore they may react differently with metals in different conditions. This has aroused a considerable interest in their studies. Different ways of synthesis of the complexes are also possible. Due to this reason we have made an effort to interpret the spectra of the chromium complexes. Interpretation of electronic spectra of chromium- pyridinedicarboxylate complexes indicates that they have either octahedral or distorted octahedral geometries.
ABSTRACT: Background: Hyperglycemia may induce endothelial dysfunction. Chromium Supplementation enhances endothelial relaxation and may improve endothelial dysfunction. Present study was planned to evaluate effect of proprietary chromium complex(PPC) and its individual components on endothelial dysfunction and lipid profile in type 2diabetics. Methodology: Study was done in two parts. In part I, PPC 400mcg produced significant improvement in endothelial function compared to PPC 200mcg and placebo. In part II, 96 eligible subjects were randomized to chromium chloride 400mcg, Phyllanthus emblica 6mg and Shilajit 6mg, chromium picolinate 400mcg, chromium polynicotinate 400mcg and chromium dinicocysteinate 400mcg and compared to PPC 400mcg. Efficacy parameters were change in endothelial function(>6% change in reflection index(RI), biomarkers of oxidative stress and lipid profile after 12weeks treatment. Laboratory safety parameters were measured at baseline and post treatment. Results: Total 96 subjects completed the study. PPC 400mcg produced better improvement in reflection index (−3.34%±1.00% to −7.23%±1.88% (p<0.001) compared to chromium chloride 400mcg (-3.79%±0.82 to-3.22%±0.85), Phyllanthus emblica 6mg and Shilajit 6mg (-1.44%±0.58 to-5.67%±0.54), chromium picolinate 400mcg (- 4.68%±1.24 to -2.46%±0.90), chromium polynicotinate 400mcg (-4.3%±1.2to- 3.71%±1.1), chromium dinicocysteinate 400mcg (-4.85%±0.74 to-3.82%±0.74). Further, PPC 400 mcg produced significant improvement of biomarkers of oxidative stress and lipid profile compared to other groups. All treatments were well tolerated. Conclusion: PPC 400 mcg showed significant improvement in endothelial function, lipid profile and biomarkers of oxidative stress in type 2 diabetics, followed by the combination of Phyllanthus emblica and Shilajit extracts, chromium picolinate, chromium polynicotinate, chromium dinicocysteinate and chromium chloride. Further, it can be inferred that PPC 400 mcg has significant synergistic activity .
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The UV-Vis absorption spectra of complexes in mixed solution (ethanol and water) is shown in Fig. 1a-b. The spectra exhibit characteristic π→π* and n→π* (phenanthrolin and terpyridine) in the 263 and 309 nm. As observed in the fig, the peak at 570 nm is attributed to the charge transfer of Cr 22-24 .
This paper incorporates the preparation, characterization and biochemical screening of the biologically potent ligands and their complexes with chromium (III). The ligands used in these studies are hydrazinecarboxamides. These ligands and their corresponding metal complexes were synthesized by two synthetic procedures, i.e., microwave as well as the conventional heating. A comparison has been made between these two synthetic methods on the basis of the yield of the products, refluxing time and the solvent consumed. The structural deductions were made on the basis of magnetic measurements, electronic, infrared, ESR, and NMR spectral studies. The four complexes of chromium (III) with hydrazincarboxamides have been synthesized.The bonding pattern of the ligands and the geometry of their chromium (III)complexes have been deduced on the basis of UV, IR, 1 H NMR, 13 C NMR spectral and X-ray diffraction studies. Some selected metal complexes and their parent ligands have been screened for their antifungal activities and the observed results have been explained.
After the regeneration process, the once used caustic soda is used rather than the fresh caustic soda. The once used caustic soda solution is passed through the cation and anion resin, the concentration of alkaline chromium is about the 26g/l in the alkaline chromium tank. The solution from the alkaline chromium tank is passed to the cartridge filter to remove the suspended particle, so that it helps to proper working of cation resin. In alkaline chromium we need only chromium, so this solution passed through the resin bed. In the Drag-out water collection tank, is used to collect then fed to the bottom of the vacuum evaporation chamber. When the volume reaches about the 170lites the titanium coil starts get heat and the solution get started to evaporate and is then collected at copper coil. The condensed water in the copper coil water is collected in distil water collection chamber and which is used in the process. The concentrated chromium tank is used to collect the chromium concentration which is further used in the chromium plating process or the concentrated chromium solution produced during regeneration is added to the chromium plating bath when needed.
Cr(VI) complexes are considered as a very important class of organic compounds because of their oxidizing properties. Cr(VI) reagents have a wide spectrum of application in synthetic organic chemistry. Here we have made an effort to compile most of these oxidation processes using these reagents which are reported in recent years. However, there is still a need to explore several areas of these transition metal complexes and to synthesize new ones with more properties.
There has been growing interest in the formation of mixed ligand chelates involving ligands containing different functional groups and transition metals of different oxidation states. Transition metal complexes of pyruvic acid semicarbazone shows remarkable antitumor, antiviral, anticancer, anti-malarial, anti-fungal, anti-bacterial and catalytic activities. In view of these applications, we have carried out synthesis and characterization and biochemical study of mixed ligand complexes chromium(III) with pyruvic acid semicarbazone and L 2 =
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----------------------------------------------------------------------------***-------------------------------------------------------------------------- Abstract - Chromium oxide nanomaterials are well known for its sensing and antibacterial property. In this paper the precipitation method involves precipitation of the precursor salt solution with precipitants. This method has a good control of factors such as chemical composition, homogeneity, crystalline, particle size and morphology. In a chemical route method different precursor such chromium sulphate and chromium chloride were used with liquor ammonia as precipitating agent. The prepared samples were characterized by using XRD and UV-Vis Spectrophotometer to analyze its structural and optical properties. The material was confirmed to be chromium oxide using XRD analysis having hexagonal structure. Almost the single phase of all the nanomaterial has been achieved with fewer impurity peak. Thus chromium oxide nanoparticle prepared by chemical route has been used for studying the antibacterial effect on E. Coli bacteria. It has been found that the zone of incubation has been developed which confirms the effect of chromium oxide for degrading the activity of E. Coli bacteria. Thus chromium oxide nanoparticles have been prepared by precipitation method using different reducing agent and its properties has been analyzed and discussed.
In this research paper the main focus is on the factors like pH and temperature, which affects the formation of chromium oxide nanoparticles . Nanosized chromium oxide can be synthesized using different methods such as precipitation, co- precipitation, sol-gel, hydrothermal, gel citrate, mechanochemical process, urea-assited homogenous precipitation, gas condesnation, microwave plasma, sonochemical etc. [1,2,5]. In this present work chemical precipitation method have been selected which involves the reduction of salt with base. Transition metal oxides have evolved to play a prominent role in antibacterial activity. C. Ramesh et. al discussed the effect of chromium oxide nanoparticle against E.coli bacteria which reveals it be an effective bactericide .
This paper establishes a high discharge of Cr(VI) to the environmental matrices from various industries and mining activities and also puts light on the environmental fate and transport of chromium including exposure pathway to human. The population residing near and the workers of the industries may experience various health problems due to the exposure of hexavalent chromium contamination. Due to high mobility of Cr in soil and high solubility in water the concentration of chromium in soil decreases and in water it increases. The reason behind this was leaching of chromium from the wastes. The risk in the contaminated water was also due to salinity and sodicity of chromium compounds. This makes the water unsuitable for drinking and irrigation purpose. A comprehensive health effect and environmental impact assessment in prior to setting up of chromite ore mines or tannery industries and steel industries can review discharges to the environment and potential pathways of exposure for workers and to public. Specific mitigation and control strategies can be employed to ensure that objective related to protection to human and environment are met.
(Fig. 2), and complex III in the triclinic space group P1 (Fig. 3), each with one molecule per asymmetric unit. A benzene molecule was found co-crystallized and located on an inver- sion center in the structure of I. In each complex, the coord- ination geometry around the chromium(0) atom is distorted octahedral, with the midpoints of the three formal fulvene double bonds and the three carbonyl carbons describing the six verticies of the octahedra. Analysis of the fulvene bond lengths when compared to the previously reported uncom- plexed fulvenes reveals nearly unchanged C—C single bonds (C1—C5, C4—C5, and C2—C3) with slight elongation of the C C double bonds (C1 C2, C3 C4, and C5 C6) (Table 1). This double-bond elongation is typical upon - coordination to a metal atom. Based upon the alternating short and long bond distances, the coordination mode of the fulvene to the chromium atom is best described as – 2 :– 2: – 2
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Chromium(III) porphyrin and its derivative have been synthesized by bromination and demetallation of copper tetra phenyl porphyrin.All the complexes were characterized on the basis of their elemental analysis, UV-vis spectra and magnetic moment properties.The magnetic moment suggested that the complex in the range 3.79 BM indicating an octahedral structure. The comparison of the UV- vis spectra of the free base show that substitution of Br atom at -pyrrole position lead to greater shift than substitution of electronegative group in the phenyl ring.
The indifferent cations effect was verified at fixed pH, ligand and chromium (VI) and NH 4 Cl- NH 4 OH concentrations. In this study, sodium, alkali chlorides, lithium and calcium were used. The existence of these ions reduces the CHSs as shown in Fig. 7-8. The obtained results suggested that the calcium has stronger supressing effect on the CHSs compared to other ions. The CHSs drops constantly with increase in chloride ions concentration. The sodium chloride effect was lower than potassium chloride, with lithium chloride and calcium chloride peak height decrease highly. In all cases, with increase in chloride concentration potential of the CHSs shifted to more negative potentials. The decrease in CHSs due to indifferent ions suggested the adsorption properties of chromium(VI)-CDT complexes on the electrode surface 30, 32 .
Among oxo derivatives of variable valence metals , Chromium compound play the most important role , in oxidative reaction .A number of Chromium reagents are readily available . Almost every oxidisable fuctional group may undergo Chromium oxidation .Chromium ( VI ) containing reagents include Chromium acid , dichromate ion , Chromyl chloride , chromyl acetate , t – butyl Chromate , Chromylnitrate and Co – ordination complexes of Chromium trioxide . 1-2
Chromium ( VI oxidations are usually performed under acidic condition . Co – solvents like ( Jone’s reagent ) benzene , methylenechloride ( Two Phase system ) are often added in order to deal with water insoluble organic complexes . The oxidation rate is generally high under acid catalysed conditions , however the low pH of the reaction medium and the presence of water favouring hydrolytic condition exclude the use of this class of reagents for the oxidation of molecules containing acid sensitive groups.