Cr Complexes Research Articles

Synthesis, spectroscopic characterization, antimicrobial and antitumor studies of mono-, bi- and tri-nuclear metal complexes of a new Schiff base ligand derived from o-acetoacetylphenol

New mono-, bi- and trinuclear metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO2(VI) with a new Schiff base ligand H3L; ((E)-2-hydroxy-N′-(4-(2-hydroxyphenyl)-4-oxobutan-2-ylidene)) benzohydrazide (H3L) have been synthesized. The ligand and its metal complexes were characterized by elemental analyses, IR, 1H NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. The metal complexes exhibited octahedral and tetrahedral geometrical arrangements. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages have been evaluated using Coats–Redfern equations. Structural parameters of the synthesized compounds were calculated on the basis of DFT level implemented in the Gaussian 09 program and Hyperchem 7.52 and correlated with the experimental data. The antimicrobial activity of the present compounds was screened against Gram–positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram–negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). The antitumor activity of the ligand and its Ni(II) and Cu(II) complexes was investigated against HepG2 cell line.

Elaborated spectral, modeling, QSAR, docking, thermal, antimicrobial and anticancer activity studies for new nanosized metal ion complexes derived from sulfamerazine azodye

New azodye ligand (H2L) and its relative Cr(III)-, Mn(II)-, Fe(III)-, Co(II)-, Ni(II)-, Cu(II)-, Zn(II)- and Cd(II)-nanosized complexes were prepared. A new synthesized compounds were characterized using spectral (mass, IR, UV–Vis, XRD, and ESR) and analytical (elemental, molar conductance, thermal and magnetic moment measurements) tools. Infrared spectra showed that the ligand behaves as a monobasic bidentate, coordinating with central atoms through carbonyl oxygen and α-hydroxyl group. The geometrical structures of Cr(III) and Fe(III) complexes were found to be in octahedral configuration, whereas Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes have tetrahedral forms. XRD patterns reflect an amorphous appearance of all investigated complexes. TEM images showed nanosized particles and identical distribution over the complex surface. Molecular modeling for the drug ligand and its metal ion complexes were performed using Gaussian09 program to assert on their structural formulae. Some essential parameters were extracted using HOMO and LUMO energies. AutoDock tools 4.2 was used to simulate the interaction process with infected cell proteins to expect the experimental pathway. The inhibition activity of drug ligand and its metal ion complexes was evaluated towards different types of bacteria and fungi through in vitro antimicrobial activities. The antitumor activities of all compounds are straightened towards human liver carcinoma (HEPG2) cell lines. Fe(III) and Co(II) complexes exhibited IC50 of 2.90 and 4.23 µg mL−1, respectively, which means they are more potent anticancer drug than the standard (doxorubicin, IC50 = 4.73 µg mL−1). Therefore, the two complexes may consider promising anticancer drugs.

Carcinogenicity of chromium and chemoprevention: a brief update.

Chromium has two main valence states: hexavalent chromium (Cr[VI]) and trivalent chromium (Cr[III]). Cr(VI), a well-established human carcinogen, can enter cells by way of a sulfate/phosphate anion-transport system, and then be reduced to lower-valence intermediates consisting of pentavalent chromium (Cr[V]), tetravalent chromium (Cr[IV]) or Cr(III) via cellular reductants. These intermediates may directly or indirectly result in DNA damage or DNA–protein cross-links. Although Cr(III) complexes cannot pass easily through cell membranes, they have the ability to accumulate around cells to induce cell-surface morphological alteration and result in cell-membrane lipid injuries via disruption of cellular functions and integrity, and finally to cause DNA damage. In recent years, more research, including in vitro, in vivo, and epidemiological studies, has been conducted to evaluate the genotoxicity/carcinogenicity induced by Cr(VI) and/or Cr(III) compounds. At the same time, various therapeutic agents, especially antioxidants, have been explored through in vitro and in vivo studies for preventing chromium-induced genotoxicity/carcinogenesis. This review aims to provide a brief update on the carcinogenicity of Cr(VI) and Cr(III) and chemoprevention with different antioxidants.

Design and nonlinear optical properties (NLO) using DFT approach of new Cr(III), VO(II), and Ni(II) chelates incorporating tri-dentate imine ligand for DNA interaction, antimicrobial, anticancer activities and molecular docking studies

In recent years, metals based antitumor complexes have played a vital role in chemotherapy. Therefore, in this study, some new imine Cr(III), VO(II) and Ni(II) complexes incorporating ESAP imine ligand (2-Ethoxy-6-((2-hydroxy-phenylimino)-methyl)-phenol were designed and synthesized. The investigated complexes were fully characterized by micro analysis, infrared, electronic spectra, thermal analysis (TGA), conductivity as well as magnetic susceptibility measurements. Moreover, the stability constants of the prepared complexes were determined spectrophotometrically. The results suggest that the titled ESAP imine ligand serves as tri-dentate moiety through deprotonated two phenolic oxygen and azomethene nitrogen atoms for coordination to Cr(III) in octahedral geometry, tetrahedral to Ni(II) and distorted square pyramidal to VO(II). The electronic structure and nonlinear optical parameters NLO of the newly synthesized complexes are investigated theoretically at the B3LYP/GEN level of theory. The studied complexes show promising optical properties. Indeed, the prepared compounds were evaluated for antimicrobial effect against some types of bacteria and fungi. The investigated complexes exhibit a stronger antimicrobial efficiency compared to its ligand. Moreover, the interaction of the complexes with CT-DNA was monitored using spectral studies, viscosity and gel electrophoreses measurements. Furthermore, the cytotoxic activity of the prepared imine complexes on human colon carcinoma cells, hepatic cellular carcinoma cells and breast carcinoma cells have shown promising results and enhancement of the anti-proliferative activity compared to its ligand. The molecular docking into TRK (PDB: 1t46) was done for the optimization of the investigated compounds as potential TRK inhibitors.

Chromium(III) complexes of dimethyl diphenyldithiophosphates: Synthesis, characterization, and antibacterial studies

GRAPHICAL ABSTRACT

Ethylene oligomerization in zeolite-grafted Cr(III)-diphosphinoamine catalysts using triisobutylaluminium as cocatalyst: Change from dimerization to trimerization due to confinement effect

Zeolite-supported Cr(III)-diphosphinoamine (Cr(III)-PNP) catalysts were prepared through grafting PNP on HY and NaY zeolites followed by complexing with CrCl3(THF)3 for ethylene oligomerization. The structure of supported Cr(III)-PNP catalysts was characterized by scanning electron microscopy, X-ray diffraction, nitrogen adsorption and desorption, thermogravimetric analyses and Fourier transform infrared, and the influence of the supported pattern on reactivity for ethylene oligomerization were investigated. The results revealed that the complex of Cr(III)-PNP was grafted on silicon hydroxyls in the pore channel of HY zeolite to decrease pore size but to maintain pore structure. Comparing with homogeneous Cr(III)-PNP producing 1-butene as main product, HY-supported catalyst had higher activity and selectivity toward 1-hexene increased from 4.07% to 73.24% using triisobutylaluminium as cocatalyst. The increase is attributed to confinement effect of the pore channel, which increases the stability of the chromacycloheptane intermediate to 1-hexene. The confinement effect for ethylene oligomerization was revealed in experiment.

Solventless Coupling of Epoxides and CO2 in Compressed Medium Catalysed by Fluorinated Metalloporphyrins

Metal complexes of meso-arylporphyrins (Cr(III), Fe(III), and Zn(II)) were evaluated in the coupling reaction of cyclohexene oxide (CHO) with CO2 in compressed medium, where the Cr complexes were demonstrated to be the most active systems, leading predominantly to copolymerisation products. It is noteworthy that no addition of solvent was required. To improve the catalytic activity, and to simultaneously increase the solubility in compressed CO2, a new fluorinated catalyst, tetrakis(4-trifluoromethylphenyl)porphyrinatochromium(III) chloride (CrCl-pCF3TPP), was applied to this reaction. The alternating copolymerisation of CHO with CO2, using the Cr(III) fluorinated porphyrin catalyst, required the use of a co-catalyst, bis(triphenylphosphine)iminium chloride (PPNCl), with the best yields of copolymers being obtained at 80 °C, and CO2 pressures in the range of 50–110 bar, over a period of 24 h, with a low catalyst/substrate molar ratio (0.07%). The polycarbonate’s structure was analysed by 1H NMR, 13C NMR, and MALDI-TOF spectroscopy, which demonstrated high carbonate incorporations (98–99%). Gel permeation chromatography revealed number-average molecular weights (Mn) in the range of 4800–12,800 and narrow molecular weight distributions (Mw/Mn ≤ 1.63).

Relativistic Approximations to Paramagnetic NMR Chemical Shift and Shielding Anisotropy in Transition Metal Systems.

We apply approximate relativistic methods to calculate the magnetic property tensors, i.e., the g-tensor, zero-field splitting (ZFS) tensor (D), and hyperfine coupling (HFC) tensors, for the purpose of constructing paramagnetic nuclear magnetic resonance (pNMR) shielding tensors. The chemical shift and shielding anisotropy are calculated by applying a modern implementation of the classic Kurland-McGarvey theory ( J. Magn. Reson. 1970 , 2 , 286 ), which formulates the shielding tensor in terms of the g- and HFC tensors obtained for the ground multiplet, in the case of higher than doublet multiplicity defined by the ZFS interaction. The g- and ZFS tensors are calculated by ab initio complete active space self-consistent field and N-electron valence-state perturbation theory methods with spin-orbit (SO) effects treated via quasidegenerate perturbation theory. Results obtained with the scalar relativistic (SR) Douglas-Kroll-Hess Hamiltonian used for the g- and ZFS tensor calculations are compared with nonrelativistically based computations. The HFC tensors computed using the fully relativistic four-component matrix Dirac-Kohn-Sham approach are contrasted against perturbationally SO-corrected nonrelativistic results in the density functional theory framework. These approximations are applied on paramagnetic metallocenes (MCp2) (M = Ni, Cr, V, Mn, Co, Rh, Ir), a Co(II) pyrazolylborate complex, and a Cr(III) complex. SR effects are found to be small for g and D in these systems. The HFCs are found to be more influenced by relativistic effects for the 3d systems. However, for some of the 3d complexes, nonrelativistic calculations give a reasonable agreement with the experimental chemical shift and shielding anisotropy. The influence of scalar relativity is strong for the 5d IrCp2 system. This mixed ab initio/DFT technique, with a fully relativistic method used for the critical HFC tensor, should be useful for the treatment of both electron correlation and relativistic effects at a reasonable computational cost to compute the pNMR shielding tensors in transition metal systems.

Biospeciation of Cr(III) Nutritional Supplements in Biological Fluids

Metal ion speciation in various biological systems has been extensively studied to elucidate its biological role and the toxicity of the element of interest. In the present study, chromium speciation was performed by reacting Cr(III) nutritional supplement s [Cr(pic) 3 ], where pic = 2 pyridinecarboxylato( - ), and a Cr(III) propionate complex, [Cr 3 O(OCOEt) 6 (OH 2 ) 3 ]) + , in calf serum. Cr(III) complexes in serum were fractionated using size-exclusion chromatography, and the Cr(III) concentrations in each fraction were determined using graphite furnace atomic absorption spectroscopy. The results showed that Cr(III) bound to both high- and low-molecular weight serum fractions. While Cr(III) was mainly bound to albumin or transferrin, unknown low-molecular-weight serum fractions were also important in Cr binding. The Cr(III) distribution in serum fractions was found to be time-dependent.

Green synthesis and spectroscopic studies of some complexes compounds as pigments and their applications in paints

PurposeThe purpose of this study to investigate the synthesis of new Cr(III), Fe(III), Ni(II) and Cu(II) Schiff base complexes by a simple technique (microwave technique). The evaluation of the prepared complexes as pigments as corrosion resistant was also explored.Design/methodology/approachThe Schiff base complexes were prepared by using microwave method (green chemistry), and then, the physico-chemical requirements according to standards for the synthesised pigments were investigate.FindingsThe prepared complexes exhibit good physical, mechanical and corrosion properties as pigments in paint formulations.Research limitations/implicationsThe simple technique used for synthesis of metal complex pigments will significantly increase the cost saving for the manufacturing of such pigments category. Also, the used technique is considered a green method (eco-friendly), as there no organic solvent was used.Practical implicationsThe evaluation of the prepared complex pigments as corrosion resistants was also studied.Originality/valueIt is a simple technique, green synthesis (no solvent used) is involved and high yield is obtained.

Chromium(III) Bis-Arylterpyridyl Complexes with Enhanced Visible Absorption via Incorporation of Intraligand Charge-Transfer Transitions.

A series of chromium(III) bis-arylterpyridyl complexes containing intraligand charge-transfer (ILCT) excited states were prepared and characterized. These complexes show significant absorption in the visible region due to the ILCT bands. The ILCT bands are tunable across the UV and visible spectrum via incorporation of electron-withdrawing and electron-donating groups on the aryl ring. The absorption of Cr(4'-(4-methoxyphenyl)-2,2':6',2″-terpyridine)23+ (4) in particular is much stronger in the visible region (ε = 11 900 M-1 cm-1 at 450 nm and ε = 5090 M-1 cm-1 at 500 nm) than that of the parent complex Cr(tpy)23+ (tpy = 2,2':6',2″-terpyridine; ε = 2160 M-1 cm-1 at 450 nm, and ε = 170 M-1 cm-1 at 500 nm). Emission experiments on this series reveal Cr(III)-based phosphorescence with lifetimes from 140 to 600 ns upon excitation into the ILCT bands, which indicates funneling of the excitation energy from ligand-localized excited states to Cr(III)-based excited states. Cyclic voltammograms exhibit at least three reversible ligand-based reductions. The first reduction shows shifts of up to -160 mV compared to Cr(tpy)23+. The excited-state reduction potential of these complexes ranges from +0.95 to +1.04 V vs the ferrocene/ferrocenium couple, making them potent photooxidants.

SYNTHESIS, SPECTRAL STUDIES, STRUCTURAL EVALUATION AND ANTIMICROBIAL ACTIVITY OF SOME NOVEL C R(III) COMPLEXES CONTAINING TETRADENTATE MACROCYCLIC LIGANDS

A string of novel coordination compounds of Cr(III) complexes have been derived and characterized from the macrocyclic ligands (L 1 -L 2 ) carried out by condensation reaction between ligands and the subsequent metal salt. The chemical composition of ligand was determined by analytical and spectral techniques i.e. elemental analysis, IR and Mass spectrocopy. Spectral techniques revealed tetradentate [N 4 ] the nature of ligand and its coordination mode to metal ion through nitrogen donor atoms. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, ePR studies. The geometry of these complexes was ascertained by molecular modelling study by using Gaussian 09 program. All metal complexes were found to exhibit octahedral geometry around the metal ion. The newly synthesized macrocyclic ligands and metal complexes were subjected for antimicrobial screening to determine the inhibition and control against tested microorganisms, bacteria ( S.lutea , S.aureus, S.albus and E.coli ) and fungi ( A.fulviceps, U . hordei, A. niger and P.catinus ) by using disc diffusion method and agar plate technique, respectively. The experimental results suggest that metal complexes exhibit enhanced inhibition zone than free macrocyclic ligand.

Electrosynthesis and pseudocapacitance performance of ionic liquid – Cr (η6-C6H5) complex functionalized reduced graphene oxide/poly ortho aminophenol nanocomposite film

In present work, RGO/IL-Cr composites were synthesized via chemical routes. The structural and valance state of the prepared samples was characterized by X-ray diffraction, X-ray photoelectron spectroscopy. For improving the electrochemical performance of conductive polymer, POAP/RGO/IL-Cr composite films have been fabricated by POAP electropolymerization in the presence of RGO/IL-Cr as active electrodes for electrochemical supercapacitors. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. The supercapacity behavior of the composite film was attributed to the i) high active surface area of the composite, ii) charge transfer along the polymer chain due to the conjugation form of the polymer and finally iii) synergism effect between conductive polymer and RGO/IL-Cr.

Mechanistic Study for the Photochemical Reactions of d6 M(CO)5(CS) (M = Cr, Mo, and W) Complexes.

The mechanisms of photoextrusion reactions are determined theoretically for the model system of six-coordinated M(CO)5(CS) (M = Cr, Mo, and W), using both CASSCF and MP2-CAS methods and the Def2-SVPD basis set. Three types of elimination reaction pathways (i.e., path I, path II, and path III for axial CO extrusion, equatorial CO extrusion, and CS ligand extrusion, respectively) are considered in this study. Theoretical findings show that the photoextrusion mechanism for Cr and Mo complexes proceeds as follows: M-S0-Rea + hν → M-S1-FC → M-CI → M-Pro + CO. This study shows that when the reactant, M(CO)5(CS) (M-S0-Rea), is photoirradiated by UV light, it is excited vertically to many low-lying singlet excited states. It then relaxes to the first singlet excited state from the Franck–Condon point (M-S1-FC). After passing through a conical intersection point (M-CI), this species eliminates a CO group to yield a five-coordinated product, M(CO)4(CS) (M-S0-Pro). However, for the W analogue, the photolysis mechanism is represented as W-S0-Rea + hν → W-T1-Min → W-T1-TS → W-T1/S0 → W-S0-Pro + CO. That is to say, when the reactant, W(CO)5(CS) (W-S0-Rea), absorbs UV light, it is excited to its several low-lying excited states by a vertical excitation. This species may then return to an intermediate at the first triplet excited state (W-T1-Min) by means of intersystem crossings or conical intersections. After passing through a triplet transition state (W-T1-TS) and a subsequent intersystem crossing (W-T1/S0), this molecule finally loses a CO ligand to produce a photoproduct at the ground singlet state (W-S0-Pro). In other words, conical intersections and intersystem crossings play a decisive role in these photoextrusion reactions for M(CO)5(CS). Theoretical evidence from a kinetic viewpoint strongly supports the theory that the photolysis of M(CO)5(CS) only produces CO-loss photoproducts rather than the CS-loss photoproduct. Theoretical analysis using the results of this study allows a good interpretation of the available experimental observations.

Spectroscopic characterization, thermal, antimicrobial and molecular docking studies on nano-size mixed ligand complexes based on sudan III azodye and 1,10-phenanthroline

In this study, new ternary complexes of sudan III azodye as primary ligand and 1,10-phenanthroline (1,10-phen) as secondary ligand with different transition metal ions as Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) were synthesized. The chelates have been characterized using different spectroscopic techniques (UV–Vis, FT-IR, 1H NMR, mass spectra, solid reflectance and ESR), elemental analysis (C, H, N and metal content), XRD, magnetic susceptibility, conductivity measurement and thermal studies (TG and DTG). The magnetic moment and spectral measurements suggested an octahedral geometry. The thermal behaviour of the complexes was studied within the temperature range of 30–1000 °C under nitrogen atmosphere and 10 °C min−1 heating rate. The complexes were found to be non-ionic in nature except Cr(III), Mn(II), Fe(III) and Cd(II) chelates. The complexes have been found to posses 1:1:1 (M: sudan III azodye:1,10-phen) stoichiometry. The XRD spectra concluded that the prepared Cr(III), Fe(III), Co(II), Ni(II) and Cu(II) complexes were amorphous while, sudan III and its Mn(II), Zn(II) and Cd(II) complexes had crystalline character. The average crystallite size (ξ) was calculated from the XRD pattern according to Debye–Scherrer equation and found to be 11.55, 23.2, 23.6 and 8.79 nm for sudan III, Mn(II), Zn(II) and Cd(II) complexes. The bioefficacy of the ligands and ternary complexes have been examined against the growth of bacteria in vitro to evaluate their antimicrobial potential against several microorganisms like: Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Streptococcus pneumonia. The results showed that some of these compounds had good antibacterial activity more than the parent azo dye ligand. Molecular docking was used to predict the binding between azo dye ligand and ternary complexes with the 3hb5-oxidoreductase, crystal structure of S. aureus (3q8u) and human-DNA-Topo I complex (1SC7).

Synthesis, structure, chemical and bioactivity behavior of eight chromium(III) picolinate derivatives Cr(R-pic)3

The worldwide use of chromium(III) picolinate Cr(pic)3 as nutrition additives has aroused more and more controversies. To reevaluate thesafety and validity of Cr(pic)3, seven new derivatives Cr(R-pic)3 (pic=picolinic acid, R=H (1), 5-Br (2), 5-CF3 (3), 4-Cl (4), 5-COOH (5), 3-CH3 (6), 5-OH (7), 3-OH (8)) were synthesized and characterized by X-ray crystal diffraction, ESI-MS, IR and elemental analysis. It was found that different substituent group affected physicochemical activities of the complex such as the Fenton-like reaction and oxidation reaction. Especially, –OH group derivatives lose their hydroxyl radical-generation and Cr(VI)-generation abilities comparing with halogen group in tube experiment. Even so, these differences in chemistry properties may be ignored in live cells and animal tests: no obvious cellulardamage (MTT assay) and tissue injury (acute toxicity study) were observed for both Cr(pic)3 and its derivatives. In addition, hypoglycemic activity study indicated that these Cr(III) complexes have no significant influence than CrCl3 salt on the blood glucose, serum insulin, total cholesterol, triglyceride, high density lipoprotein and low density lipoprotein of diabetic mice through two months’ study. Therefore, these substituent group is unable to improve the biological activities of Cr(pic)3 obviously and the validity of Cr(pic)3 used as a nutrition additives is doubted.

Characterization of Product and Potential Mechanism of Cr(VI) Reduction by Anaerobic Activated Sludge in a Sequencing Batch Reactor

Bioremediation of Cr(VI) and nitrate is considered as a promising and cost-effective alternative to chemical and physical methods. However, organo-Cr(III) complexes in effluent generally causes environmental concerns due to second-pollution. Here, Cr(VI) reduction and immobilization efficiencies of anaerobic activated sludge were investigated. Anaerobic activated sludge showed strong reduction ability of Cr(VI) and possessed a great potential of Cr(III) immobilization. Almost 100.0 mg l−1 Cr(VI) could be completely reduced and immobilized by anaerobic activated sludge in a sequencing batch reactor in 24 h. And most generated Cr(III) was accumulated outside of sludge cells. Extracellular polymeric substances (EPS) could bind to Cr(VI) and form EPS-Cr(VI) interaction to reduce the toxic effect of Cr(VI) and promote the Cr(VI) reduction. Protein-like and humic-like substances were responsible for binding with Cr(VI), meanwhile the process was a thermodynamically favorable binding reaction. Then Cr(VI) was reduced to Cr(III) by membrane-associated chromate reductase of sludge. Eventually, the generated Cr(III) might exist as poly-nuclear Cr(III) complexes adhered to sludge surfaces.

Chromium in Agricultural Soils and Crops: A Review

The mobility and distribution of metals in the environment is related not only to their concentration but also to their availability in the environment. Most chromium (Cr) exists in oxidation states ranging from 0 to VI in soils but the most stable and common forms are Cr(0), Cr(III), and Cr(VI) species. Chromium can have positive and negative effects on health, according to the dose, exposure time, and its oxidation state. The last is highly soluble; mobile; and toxic to humans, animals, and plants. On the contrary, Cr(III) has relatively low toxicity and mobility and it is one of the micronutrients needed by humans. In addition, Cr(III) can be absorbed on the surface of clay minerals in precipitates or complexes. Thus, the approaches converting Cr(VI) to Cr(III) in soils and waters have received considerable attention. The Cr(III) compounds are sparingly soluble in water and may be found in water bodies as soluble Cr(III) complexes, while the Cr(VI) compounds are readily soluble in water. Chromium is absorbed by plants through carriers of essential ions such as sulfate. Chromium uptake, accumulation, and translocation, depend on its speciation. Chromium shortage can cause cardiac problems, metabolic dysfunctions, and diabetes. Symptoms of Cr toxicity in plants comprise decrease of germination, reduction of growth, inhibition of enzymatic activities, impairment of photosynthesis and oxidative imbalances. This review provides an overview of the chemical characteristics of Cr, its behavior in the environment, the relationships with plants and aspects of the use of fertilizers.

Spectral and cyclic voltammetric studies of glyceryl guaiacolate drug in pure form and in situ chelation with some different transition metals

An equimolar series of binary complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with guaifenesin (glyceryl guaiacolate) (H2L or Gf) have been synthesized. The Gf ligand is deprotonated and coordinated to the metal ion with both oxygen's donor atoms with 1:1 (metal:Gf) ratio and it is determined by micro-analytical technique. The resulting metal chelates of Gf were characterized using the conductivity measurements, FT-IR, Laser Raman, electronic solid reactance, magnetic susceptibility calculation, 1H NMR, TGA and ESR spectral studies. The conductivity measurements confirm that all the metal complexes were non-electrolytic in DMSO except for chromium and iron(III) complexes have an electrolytic behavior. Based on spectral and analytical data octahedral geometry is assigned to the Cr(III), Mn(II), Fe(III), Co(II) and Ni(II) complexes with four coordinated water molecules, but the copper and zinc(II) complexes have square planner molecular geometry with two coordinated water molecules. The general molecular formula of the solid Gf complexes has been found as [M(Gf)(H2O)n]·x·yH2O, where M=Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II), n=2 or 4, x=Cl− for (Fe and Cr(III) complexes) and y=3 for (Cr(III) and Ni(II) complexes). The electrochemical reduction of Gf and its complexes were realized on a platinum wire electrode in Britton–Robinson (BR) buffer using the cyclic voltammetric (CV) technique. The effect of functional groups on reduction potential of the Gf was investigated. A general electrochemical reduction mechanism of the compounds is suggested.

DNA interaction, antimicrobial, anticancer activities and molecular docking study of some new VO(II), Cr(III), Mn(II) and Ni(II) mononuclear chelates encompassing quaridentate imine ligand

The present study was conducted to synthesis of some new imine Cr(III), VO(II), Mn(II) and Ni(II) complexes derived from the condensation of 2-amino phenol with 2-hydroxynapthaldehyde were synthesized. The prepared HNPN imine ligand was analyzed by its melting point, IR, 1H NMR and 13C NMR spectroscopies. The investigated HNPN imine complexes were characterized by elemental analysis, FT IR, UV–vis and thermal analysis (TGA) under nitrogen atmosphere from ambient temperature to 750°C. The experimental results revealed that the investigated complexes contain hydrated water molecules. The molar conductance values of complexes are relatively low, indicating the non-electrolytic nature of these complexes. Magnetic susceptibility measurements show that the investigated complexes are paramagnetic. Moreover, the stability constants of the preparing complexes were determined spectrophotometrically. All the complexes were found to be monomeric 1:1 (M:L) stoichiometry in nature with octahedral geometry for Cr(III), tetrahedral for Mn(II), square planner for Ni(II) and square pyramidal for VO(II). Moreover, the prepared HNPN imine ligand and its complexes were evaluated for antimicrobial effect against some types of bacteria such as Bacillus subtilis (+ve), Escherichia coli(−ve) and Staphylococcus aureus (+ve) and some types of fungi such as Aspergillusniger, Candida glabrata and Trichophyton rubrum. The results of these studies indicate that the metal complexes exhibit a stronger antibacterial and antifungal efficiency compared to their corresponding imine ligand. Moreover, the interaction of the investigated complexes with CT-DNA was checked using spectral studies, viscosity measurements and gel electrophoreses. The absorption titration studies revealed that each of these complexes is an avid binder to calf thymus-DNA. Also, there was appreciable changes in the relative viscosity of DNA, which is consistent with enhanced hydrophobic interaction of the aromatic rings and intercalation mode of binding. In addition to, the cytotoxic activity of the prepared imine complexes on human colon carcinoma cells, (HCT-116 cell line), hepatic cellular carcinoma cells, (HepG-2 cell line) and breast carcinoma cells (MCF-7 cell line) has cytotoxicity effect against growth of carcinoma cells compared to the clinically used Vinblastine standard. Furthermore, the molecular docking into TRK (PDB: 1t46) was done for the optimization of the investigated compounds as potential TRK inhibitors.