Cr Complexes Research Articles

Synthesis, Characterization, and Thermal Analysis of a New Acidicazo Ligand's Metal Complexes

The researchers wanted to make a new azo imidazole as a follow-up to their previous work. The ligand 4-[(2-Amino-4-phenylazo)-methyl]-cyclohexane carboxylic acid as a derivative of trans-4-(aminomethyl) cyclohexane carboxylic acid diazonium salt, and synthesis a series of its chelate complexes with metalions, characterized these compounds using a variety technique, including elemental analysis, FTIR, LC-Mass, 1H-NMRand UV-Vis spectral process as well TGA, conductivity and magnetic quantifications. Analytical data showed that the Co (II) complex out to 1:1 metal-ligand ratio with square planner and tetrahedral geometry, respectively while 1:2 metal-ligand ratio in the Cu(II), Cr(III), Mn(II), Zn(II), Ru(III)and Rh(III)complexes with octahedral geometry except Mn complex has tetrahedral geometry. The Ligand functions as a neutral tridentate ligand in all complex investigations, coordinating Cr(III), Zn(II), Ru(III), and Rh(III) ions via the N atom of amine and azo groups, as well as the O phenolic OH group. When coordinated with the Cu(II), Co(II), and Mn(II) ions via the two N atoms of the amine and azo groups, this Ligand functions as a neutral bidentate.

Microwave-Assisted Synthesis, Spectral and Biopotential Characterization of Cr(III), Cu(II) and Zn(II) Complexes with 4-Aminothiophenol and Benzoate Ion

Bioactive metal complexes of Cr(III), Cu(II), and Zn(II) were synthesized with 4-aminothiophenol and benzoate ion under microwave irradiation. The synthesized metal chelates were characterized by physical, spectral, biological studies. The geometry and magnetism of all the complexes were monitored by electronic spectra and magnetic studies. The metal complexes possess the metal-ligand ratios is in the order of 1:3:3 metal:ligand1:ligand2 for Cr(III), 1:2:2 metal: ligand1:ligand2 for Cu(II) and Zn(II) complexes were predicted based on the elemental analysis and metal estimation. The synthesized metal chelates are monomeric and neutral in nature and they show well redox properties based on the results of conductivity and electrochemical studies. Octahedral geometry of Cr(III), tetragonal geometry of Cu(II) and square planar geometry of Zn(II) complexes confirmed by IR, far-IR, NMR and EPR spectral studies. The crystalline nature and lattice parameters of Zn(II) complex were predicted by using the X-ray diffraction powder method. Biopotential activities of 4-aminothiophenol compared with metal chelates and standard drug namely chloramphenicol for bacterial and fluconazole for fungal strain by Agar disc diffusion method using Streptococci, Shigella and C. albicans. The results of DNA cleavage of pBR322 DNA and binding nature of ct-DNA to Cr(III) complex possess the binding and cleavage nature of them by predicting the binding constant of the metal complex.

Effective corrosion inhibition of mild steel in hydrochloric acid by newly synthesized Schiff base nano Co(ii) and Cr(iii) complexes: spectral, thermal, electrochemical and DFT (FMO, NBO) studies.

Two new cobalt(ii) and chromium(iii) complexes were synthesized and characterized by FT-IR, 1HNMR, UV, elemental analysis, TGA, conductivity, XRD, SEM, and magnetic susceptibility measurements. Structural analysis revealed a bi-dentate chelation and octahedral geometry for the synthesized complexes. The optical band gap of the Co(ii)-L and Cr(iii)-L complexes was found to be 3.00 and 3.25 eV, respectively revealing semiconducting properties. The X-ray diffraction patterns showed nano-crystalline particles for the obtained complexes. In addition, the synthesized metal complexes were examined as corrosion inhibitors for mild steel in HCl solution. The electrochemical investigations showed a maximum inhibition efficiency of 96.60% for Co(ii)-L and 95.45% for Cr(iii)-L where both complexes acted as mixed-type inhibitors. Frontier Molecular orbital (FMO) and Natural bond orbital (NBO) computations showed good tendency of the ligand to donate electrons to the metal through nitrogen atoms while the resultant complexes tended to donate electrons to mild steel more effectively through oxygen atoms and phenyl groups. A comparison between experimental and theoretical findings was considered through the discussion.

6,8-(1,3-Diaminoguanidine) luteolin and its Cr complex show hypoglycemic activities and alter intestinal microbiota composition in type 2 diabetes mice.

Flavonoid compounds such as luteolin exhibit hypolipidemic effects, and there are few reports on the hypoglycemic activity of luteolin derivatives. In this research, 6,8-(1,3-diaminoguanidine) luteolin (DAGL) and its Cr complex (DAGL·Cr) were obtained as a result of structural modifications to luteolin, and the hypoglycemic activities and the composition of intestinal microbiota in T2DM mice were investigated. This study found that DAGL and DAGL·Cr could significantly restore body weight, FBG, OGTT, AUC, and GSP in T2DM mice. Moreover, the pancreatic islet function index and the biochemical indicators of serum and the liver were also significantly improved. The histopathological results also showed that DAGL and DAGL·Cr had a stronger repair ability in the liver and the pancreas. It was also revealed that the potential hypoglycemic mechanism of DAGL and DAGL·Cr was involved in the simultaneous regulation of PI3K/AKT-1/GSK-3β/GLUT-4 and PI3K/AKT-1/mTOR/S6K1/IRS-1. Furthermore, DAGL and DAGL·Cr could also regulate the structure of the intestinal microbiota and increase the content of SCFA to relieve the symptoms of hyperglycemia in T2DM mice. This included a significant reduction in the ratio of Firmicutes and Bacteroidetes (F/B), and at the genus level, an increase in the relative abundance of Alistipe and Ruminiclostridium, and improvement in the content of SCFA in the feces of T2DM mice. In conclusion, in this study, DAGL and DAGL·Cr were found to improve hyperglycemia in T2DM mice by improving the pancreatic islet function index, regulating the biochemical indicators of serum and the liver, repairing damaged tissues, and regulating the PI3K/AKT-1 signaling pathway as well as reducing F/B, increasing the relative abundance of intestinal beneficial microbiota, and the content of SCFA in the feces. The hypoglycemic effect of DAGL·Cr on the body weight, serum IL-10, serum IL-6, and pancreatic islet function index was significantly better than that of DAGL.

Bioremediation Trends on Mitigation of As(III), Cr(VI) and Organic Dyes From Aqueous Medium using Plant and Microbial Biomass: An Overview

Arsenic, chromium and organic dyes are the prominent carcinogenic agents, posing a serious health hazard. In current scenario, groundwater as well as surface water mostly contaminated by chemical complexes of As (III), Cr (VI) and organic dyes, these are leading hazardous threat to eco-system. Several mitigation techniques of As (III), Cr (VI) and organic dyes are available but efforts are going on to devise a novel method of removal of these toxicants. This review takes into account all the recent advances in the detoxification of contaminated water exploring removal mechanism by biosorption and bioaccumulation. The possibility of the removal of toxic heavy metals from an aqueous medium by plant and bacterial biomass has been discussed. Now a days, bioaccumulation and biosorption from plants and microbial sources has emerged as simple, effective and eco-friendly techniques for decontamination of these chemical compounds from water resources at very low cost. Many agricultural products and solid wastes have also been found suitable decontaminant of toxic heavy metals and dyes. A wide spectrum of medicinal and aromatic plants as well as aquatic plants available in abundance may also be utilized as potential remover of As (III), Cr (VI) and organic dyes. This article explained mechanism and application on detail aspects of bioremediation technology including conventional techniques with recent development. This review shows the trends and development of mitigation stretagies by bioremediation with latest updates.

Determination of Stability Constant of The Complexes of Metal Ion Fe(III), Mn(II) And Cr(III) With Some Substituted 2-Oxo-2H-Chromene-3-Carbohydrazide Derivatives at 0.1 M Ionic Strength at 42oC

Proton ligand and metal ligand stability constant are measured for Fe(III) and 1, 2-dihydroxy benzene and 1, 5-disulphonic acid complexes . Determination of stability constant of substituted of pyrazoles with rare earth metals form complexes are reported . Effect of temperature on formation constants of 2 acetylpyridine(N benzoyl)glycine hydrazone with lanthanide(III) ions at different ionic strengths are reported. Irving and Rossotti, Herson and Gilbert , Wilkins and Lewis and Rossotti and Rossotti have determined stability constant by Bjerrum-Calvin titration technique . Kabadi , Jahagirdar and Narwade have determined pK values of salicylaldehyde, salicylic acid and sulphonic acid respectively by similar procedure. The metal ligand stability constant of some β-diketones are reported . Stability constants have investigated for some substituted pyrazolines, isoxalline and diketone . The method most frequently applied for study of complex equilibria is pH-metric titration technique . Stepwise formation of mononuclear binary complexes is described by set of equilibrium constants. For pH-metric measurements an electrode must be selected. According to Bjerrum, Martell and Calvin , the formation of complex MLN is stepwise process and one has to deal with a series of equilibria of the type: Irving and Rossotti, Herson and Gilbert , Wilkins and Lewis and Rossotti and Rossotti have determined stability constant by Calvin-Bjerrum titration technique . The value of nA,n, pK, log K1 and log K2 are evaluated by Irving and Rossotti's equation. The stability constant and thermodynamic parameters of complexes containing lighter lanthanides , copper(II) , calcium and magnesium are reported. It is also important in environmental studies , medicinal and industrial chemistry . Effects of transition metal on stability constant of complexes have studied by pH metric method . Bendi , Janrao and Ramteke have studied stability constant of ligands with lanthanide metals complexes.The present work involves pH metric study of substituted 2-oxo-2H-chromene-3-carbohydrazide derivatives with metal ions Fe(III), Mn(II), Cr(III) and Ti(III) at temperature42oC. The Bjerrum-Calvin titration technique as modified by Irving and Rossotti has been employed in the present study. The following three sets of titrations are carried out in sequence.

Development of Chromium(III) Selective Potentiometric Sensors for Its Determination in Petroleum Water Samples Using Synthesized Nano Schiff Base Complex as an Ionophore.

Many analytical techniques, such as X-ray fluorescence spectrometry, inductively coupled plasma-atomic emission spectrometry, and even traditional spectroscopic and fluorimetric methods, are used for the measurement of Cr(III) ions. These methods are sophisticated and very expensive, so thecheapest and low-cost ion selective electrodes were used. The quantification of Cr(III) ions in various samples of petroleum water using ion selective electrodes was suggested. Nano chromium modified carbon paste sensor (MCPE) and nano chromium modified screen printed sensor (MSPE) based on Schiff base Cr(III) complex are developed. The developed nano Cr(III) Schiff base chelate was characterized using elemental, spectroscopic, and thermal analysis techniques. The proposed nano Cr(III) has good properties for antibacterial and antifungal activity. The modified carbon paste and screen-printed sensors were fabricated for determination of Cr(III) ion. The proposed MCPE (sensor I) and MSPE (sensor II) obeys Nernstian equation upon incorporating nano Cr(III) ionophore in the paste at 25°C with a trivalent cationic slope of 18.8 ± 0.2 and 20.0 ± 0.4 mV/decade. They have showed fast response time around 8 and 5 s, and they may be used for at least 98 and 240 days without significant changes in MCPE and MSPE potential, respectively. The sensors I and II showed good selectivity for Cr(III) ion toward a wide variety of metal ions or anions as confirmed by potentiometric selectivity coefficients values. The detection and quantification limits were defined alongside the other process validation parameters. The results have been compared well to those obtained by atomic absorption spectrometry (AAS), and the data of F- and t-test indicated no significant difference between the proposed and AAS methods. These sensors have been used to determine Cr(III) ions in genuine spiked different petroleum well water samples with satisfactory percentage recoveries, low standard, and relative standard deviation values using direct potentiometric and standard addition methods. The proposed method of producing nano Cr(III) complex as a sensor material possesses the distinct advantages of being simple, easily reproducible, appropriate for operation, and highly selective and sensitive. Modified carbon paste and screen-printed electrodes were fabricated based on nano Cr(III) complex as ionophore. The electrodes follow Nernstian behavior, and they optimized according to IUPAC recommendation. They showed a high selectivity for Cr(III) ion over many bi- or trivalent metal ions and anions. The results obtained compared well with those obtained using AAS. They successfully applied for determination of Cr(III) in petroleum water samples.

Nano‐synthesis, solid‐state structural characterization, and antimicrobial and anticancer assessment of new sulfafurazole azo dye‐based metal complexes for further pharmacological applications

AbstractA new azo dye ligand (abbreviated as H3L) derived from coupling of sulfafurazole diazonium salt with 2,4‐dihydroxybenzaldehyde was prepared and characterized applying different spectroscopic and analytical techniques. The novel nanosized trivalent Cr and Fe alongside with divalent Mn, Co, Ni, and Cd complexes with H3L have been synthesized for further promising pharmaceutical uses. All complexes were totally characterized by investigating various analytical and spectral tools such as microanalysis, FT‐IR, 1H NMR, UV‐Vis, powder XRD, and TEM spectra as well as magnetic moment and molar conductance measurements. Microanalysis, TGA, and conductance studies confirmed the formation of all metal complexes in 1:1 (L: M) molar ratio with covalent mode. The FT‐IR and 1H NMR investigation asserted the chelation of H3L to different metal ions through azo nitrogen and phenolic deprotonated hydroxy oxygen in the o‐position. UV‐Vis, ESR, and magnetic moment studies revealed octahedral geometry around Cr and Fe ions, whereas Mn, Co, Ni, and Cd complexes displayed tetrahedral configurations. XRD patterns and TEM images proved homogeneous distribution over the chelates surfaces and nanometric size of complexes particles. Molecular modeling was used to optimize the complexes' geometric structure showing good harmonity with the experimental results. The antifungal and antibacterial efficiencies were strongly enhanced upon complex formation. Cr(III) and Ni(II) complexes showed the strongest and promising anticancer activities (IC50 = 7.64 and 6.99 μg/ml) among the tested compounds, whereas Cd(II) complex showed moderate anticancer efficiency (IC50 = 12.10 μg/ml), compared with the 5‐fluorouracil (applied standard drug) with IC50 = 6.44 μg/ ml.

Synthesizing, Structuring, and Characterizing Bioactivities of .Cr(III), La(III), and Ce(III) .Complexes with Nitrogen, Oxygen .and Sulpher donor bidentate Schiff base ligands

Two Schiff bases, namely, 3-(benzylidene amino) -2-thioxo-6-methyl 2,5-dihydropyrimidine-4(3H)-one (LS])and 3-(benzylidene amino)-6-methyl pyrimidine 4(3H, 5H)-dione(LA)as chelating ligands), were used to prepare some complexes of Cr(III), La(III), and Ce(III)] ions. Standard physico-chemical procedures including metal analysis M%, element microanalysis (C.H.N.S) , magnetic susceptibility, conductometric measurements, FT-IR and UV-visible Spectra were used to identify Metal (III) complexes and Schiff bases (LS) and (LA). According to findings, a [Cr(III) complex] showed six coordinated octahedral geometry, while [La(III), and Ce(III) complexes]were structured with coordination number seven. Schiff's bases and mineral complexes were examined in vitro to investigate potential inhibition against Gram-positive bacteria such as Pseudonomous aerugionosa and Gram-negative bacteria such as Staphylococcus aureus. The low concentration for inhibition has been also determined by studying the minimal inhibitory concentrations MIC .Antibiotics (Ampicillin, Amoxicillin) have been chosen to contrast their activity. Furthermore, Anti-fungal activity against two types of fungi ʺAspergillus flavusʺ and ʺPenicillum Spp.ʺ was studied for these compounds. The results of the antibacterial activity were better compared to the standard drugs.

Magnetic resonance spectroscopy features of the thalamus and the cerebellum and their association with clinical features in children with autism spectrum disorder: a prospective study.

To study the changes in biochemical metabolites in the thalamus and the cerebellum and their association with clinical features in children with autism spectrum disorder (ASD). In this prospective study, magnetic resonance spectroscopy (MRS) with point-resolved spatial selection was used to analyze the thalamus and the cerebellum at both sides in 50 children with ASD aged 2-6 years. Creatine (Cr) was as the internal standard to measure the relative values of N-acetylaspartate (NAA)/Cr, choline (Cho)/Cr, myoinositol (MI)/Cr, and glutamine and glutamate complex (Glx)/Cr, and the differences in metabolites and their association with clinical symptoms were compared. In the children with ASD, NAA/Cr in the left thalamus was positively correlated with the scores of hearing-language and hand-eye coordination in the Griffiths Development Scales-Chinese (P<0.05). Cho/Cr in the right cerebellum was positively correlated with the scores of personal-social competence, hearing-language, and hand-eye coordination (P<0.05). NAA/Cr and Glx/Cr in the left thalamus were positively correlated with those in the left cerebellum (P<0.05). There was no significant difference in metabolites between the left and right sides of the thalamus and the cerebellum in the children with ASD (P>0.05). There are metabolic disorders in the cerebellum and the thalamus in children with ASD, and there is a correlation between the changes of metabolites in the left cerebellum and the left thalamus. Some metabolic indexes are related to the clinical symptoms of ASD. MRS may reveal the pathological basis of ASD and provide a basis for diagnosis and prognosis assessment of ASD as a noninvasive and quantitative detection method.

CO2 Cleavage Reaction Driven by Alkylidyne Complexes of Group 6 Metals and Uranium: A Density Functional Theory Study on Energetics, Reaction Mechanism, and Structural/Bonding Properties.

Designing novel catalysts is essential for the efficient conversion of metal alkylidyne into metal oxo ketene complexes in the presence of CO2, which to some extent resolves the environmental concerns of the ever-increasing carbon emission. In this regard, a series of metal alkylidyne complexes, [b-ONO]M≡CCH3(THF)2 ([b-ONO] = {(C6H4[C(CF3)2O])2N}3-; M = Cr, Mo, W, and U), have been comprehensively studied by relativistic density functional theory calculations. The calculated thermodynamics and kinetics unravel that the tungsten complex is capable of catalyzing the CO2 cleavage reaction, agreeing with the experimental findings for its analogue. Interestingly, the uranium complex shows superior catalytic performance because of the associated considerably lower energy barrier and larger reaction rate constant. The M≡C moiety in the complexes turns out to be the active site for the [2 + 2] cyclic addition. In contrast, complexes of Cr and Mo could not offer good catalytic performance. Along the reaction coordinate, the M-C (M = Cr, Mo, W, and U) bond regularly transforms from triple to double to single bonds; concomitantly, the newly formed M-O in the product is identified to have a triple-bond character. The catalytic reactions have been extensively explained and addressed by geometric/electronic structures and bonding analyses.

Metal ion recovery from electrodialysis-concentrated plating wastewater via pilot-scale sequential electrowinning/chemical precipitation

Metal recovery from industrial wastewater can be achieved by electrowinning (EW) and chemical precipitation (CP), but this is challenging because of the low concentration of metal ions in the wastewater, especially that from metal plating plants, as well as the presence of other organic and anionic species. However, electrodialysis (ED) is a promising method for concentrating the metal species in wastewater. Therefore, in this study, we developed and operated a pilot-scale ED system for the treatment of real plating wastewater, obtaining ED-concentrated plating wastewater in the concentration compartment for the selective recovery of Cu and other metals using pilot-scale EW and CP processes, respectively. The ED process was run at 200 V (13.3 V/cell-pair) and produced plating wastewater having metal concentrations up to two orders of magnitude greater than that of the input wastewater. A cell voltage of 2.0 V was selected for EW because it yielded an appropriate current density and the selective recovery of Cu as Cu(0) and Cu2O without producing metallic sludge. We obtained almost 93%–96% Cu-selective recovery (initial [Cu] = 790–1145 mg/L) from the ED-concentrated plating wastewater samples via our pilot-scale EW process, which had a specific energy consumption of 3.5–5.3 kWh/kgCu. In the CP process, we found that hydroxide precipitation allowed the selective recovery of amorphous Fe(OH)3/Fe–Cr complexes at pH 4–5 and β-Ni(OH)2/λ-Zn(OH)2 at pH values exceeding 7. Thus, the sequential EW/CP system is suitable for the treatment of ED-concentrated plating wastewater and the recovery of valuable metals.

Discrete versus 1D Compounds based on Pentagonal Bipyramid Coordination Geometries: A Matter of Solubility?

AbstractA series of heterometallic compounds based on the association of trans‐dicyanido Cr(III) complex [Cr(L)(CN)2]K ⋅ 2H2O and several divalent [MnII(H2Ln)Cl2] heptacoordinated complexes, where Ln stands for pentadentate ligands featuring a planar N3O2 coordination pocket and various substituents (NH2, cyclohexyl, S,S‐mandelic), is described. A dinuclear compound [Cr(L)(CN)2M(H2L2)] and 1D coordination polymers of general formula [Cr(L)(CN)2M(H2Ln)]X (X=PF6− or [Cr(L)(CN)2]−) were rationally prepared by a simple adjustment of the Cr : M stoichiometry for R=NH2 or tuning the solvent mixtures to promote the crystallization of discrete complexes or chains. The crystal structures, phase purities and magnetic properties of all the compounds are reported.

Coordination compounds of pyrazolone‐based ligand: Design, characterization, biological evaluation, antitumor efficiency, and DNA binding evaluation supported by in silico studies

AbstractCu (II), Ni (II), Mn (II), and Cr (III) chelates of the organic ligand named 3‐(furan‐2‐yl)‐5‐oxo‐N,1‐diphenyl‐4,5‐dihydro‐1H‐pyrazole‐4‐carbothioamide ligand (abbreviated as H2L) have been obtained. Successful structure elucidation of the ligand and its chelates has been managed by applying alternative spectral and analytical techniques including elemental analysis, inductively coupled plasma (ICP), NMR, mass, and FTIR spectra in addition to molar conductance and TGA technique which all joint confirmed the formation of the metal complexes in the molar ratio 1:2 (M:L) for Cu (II) and Mn (II) chelates, while 1:1 for the rest of complexes. The applied techniques also confirmed the metal complexes to be formulated as [Cu (HL)2(H2O)2]‧0.5H2O, [Ni (HL)(H2O)Cl]‧0.5H2O, [Mn (HL)2(H2O)2]‧2H2O and [Cr (HL)(H2O)2(CH3COO)2]‧2.5H2O, where HL is the organic ligand. UV–Vis spectra and μeff values of the metal chelates assured the geometry around the metal ion center to be octahedral for both Cu (II), Mn (II), and Cr (III) complexes. For the Ni (II) complex, tetrahedral arrangement has been concluded. The in vitro antimicrobial efficacy applied on several microorganisms and the antioxidant activity showed biological activities in relation to employed standard reported compounds with enhanced activity of the Cr (III) complex compared with the other tested compounds. The antitumor activity was examined upon four carcinoma cell lines that are HePG‐2 MCF‐7, HCT‐116, and HeP‐2 demonstrated that the Cr (III) complex to has the highest activity against the four tested carcinoma cell lines relative to the other tested compounds. The binding mode of the ligand and its complexes with SS‐DNA have been examined applying UV–Vis spectral titration and viscosity measurements, assuring groove binding interactions, which were supported theoretically through the docking studies.

EDAS and TOPSIS based Estimation of Oxidation of Methionine by Cr(VI) Reagents

Objectives: To find the suitable solvent for the oxidation of methionine by Cr(VI) reagents using EDAS and TOPSIS method. Methods: When methionine oxidized by Cr(VI) complexes i.e. tetrakis(pyridine)silver dichromate (TPSD), quinolinium bromochromate (QBC), tetraethylammonium chlorochromate (TEACC) and quonilinium chlorochromate (QCC) formation of corresponding sulfoxide take place. Reaction performed in chloroform (CF), 1,2- dichloroethane (DCE), dichloromethane (DCM), dimethylsulphoxide (DMSO) and acetone solvents. Findings: Reaction is fastest in DMSO and slowest in acetone for the oxidation of methionine in the following- DMSO, DCE, DCM, acetone, CF. Novelty: Solvent effect is investigated using the rate constant k2; by EDAS and TOPSIS methods. Keywords: Methionine; Oxidation; Solvent effect; EDAS; TOPSIS

Mediated Inner‐Sphere Electron Transfer Induces Homogeneous Reduction of CO2 via Through‐Space Electronic Conjugation**

AbstractThe electrocatalytic reduction of CO2 is an appealing method for converting renewable energy sources into value‐added chemical feedstocks. We report a co‐electrocatalytic system for the reduction of CO2 to CO comprised of a molecular Cr complex and dibenzothiophene‐5,5‐dioxide (DBTD) as a redox mediator, which achieves high activity (TOF=1.51–2.84×105 s−1) and quantitative selectivity. Under aprotic or protic conditions, DBTD produces a co‐electrocatalytic response with 1 by coordinating trans to the site of CO2 binding and mediating electron transfer from the electrode with quantitative efficiency for CO. This assembly is reliant on through‐space electronic conjugation between the π frameworks of DBTD and the bpy fragment of the catalyst ligand, with contributions from dispersive interactions and weak sulfone coordination.

Mediated Inner-Sphere Electron Transfer Induces Homogeneous Reduction of CO2 via Through-Space Electronic Conjugation.

The electrocatalytic reduction of CO2 is an appealing method for converting renewable energy sources into value-added chemical feedstocks. We report a co-electrocatalytic system for the reduction of CO2 to CO comprised of a molecular Cr complex and dibenzothiophene-5,5-dioxide (DBTD) as a redox mediator, which achieves high activity (TOF=1.51-2.84×105 s-1 ) and quantitative selectivity. Under aprotic or protic conditions, DBTD produces a co-electrocatalytic response with 1 by coordinating trans to the site of CO2 binding and mediating electron transfer from the electrode with quantitative efficiency for CO. This assembly is reliant on through-space electronic conjugation between the π frameworks of DBTD and the bpy fragment of the catalyst ligand, with contributions from dispersive interactions and weak sulfone coordination.

Preparation and Characterization of New Tetra-Dentate N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; Schiff Base with Some of Metal Ions Complexes

This study describes preparation a new series of tetra-dentate N2O2 dinuclear complexes Cr(III), Co(II)and Cu(II) of the Schiff base 2-[5-(2-hydroxy-phenyl)-1,3,4-thiadiazol-2-ylimino]-methyl-naphthalen-1-ol], (LH2) derived from 1-hydroxy-naphthalene-2-carbaldehyde with 2-amino-5-(2-hydroxy-phenyl)-1,3,4-thiadiazole. These ligands were characterized by FT-IR, UV-Vis, Mass spectra, elemental analysis, and 1H-NMR. All prepared complexes have been characterized by conductance measurement, magnetic susceptibility, electronic spectra, infrared spectrum, thermal Analysis (TGA), and metal analysis by atomic absorption. The stoichiometry of metal to ligand, magnetic susceptibility, and electronic spectra measurements show an octahedral geometry for all (Cr3+, Co2+, Cu2+) complexes. Conductivity measurement shows that the prepared (Co2+, Cu2+) complexes were nonelectrolyte except (Cr3+). Studying the extraction efficiency such as ligand concentration, temperature and incubation time, centrifuge time, amount of surfactant were evaluated and optimized. The linear range of ions Cr(III), Co(II) and Cu(II) with ligand (0.2–3, 0.2–4, 0.2–3, µg mL–1), each individually, and relative standard deviation (0.15%, 0.34%, 0.46%). The successful method was applied for the determination of trace metal ions in the wastewater.

Synthesis, characterization, potential antimicrobial, antioxidant, anticancer, DNA binding, and molecular docking activities and DFT on novel Co(II), Ni(II), VO(II), Cr(III), and La(III) Schiff base complexes

In this study, five novel complexes for Co(II), Ni(II), VO(II), Cr(III), and La(III) ions were synthesized from a tridentate NNO monobasic chelating Schiff base ligand, (Z)‐2‐((pyridin‐2‐ylimino)methyl)phenol (HL). Spectral and analytical tools were applied to elucidate the structural compositions of the new compounds. Then, geometry optimization was conducted for all the syntheses by the Gaussian 09 program via the density functional theory method to obtain optimal structures and the most essential parameters. Moreover, the biochemical behaviors of all the syntheses were explored based on the reactivity, which was tested against various cancer cell lines (HepG‐2, MCF‐7, and HCT‐116). The complexes exhibited an interestingly antiproliferative potential against human cancer cell lines, and the cytotoxicities of the new complexes were arranged to follow the order: VOL &gt; CrL &gt; NiL &gt; LaL &gt; CoL &gt; HL. The antioxidant behaviors of the complexes were studied using the DPPH assay, and VOL showed the maximum antioxidant activity, followed by LaL. The antibacterial activities of the HL ligand and its complexes were studied. Moreover, the binding nature of the complexes with calf thymus DNA (CT‐DNA) was investigated based on the spectrophotometric absorption titration, viscosity, and gel electrophoresis methods. The binding ability of the complexes with CT‐DNA was proposed to be just intercalation or replacement mode. The intrinsic binding constant Kb was calculated and arranged based on the following order: VOL (5.2 × 105) &gt; CrL (3.6 × 105) &gt; NiL (3.3 × 105) &gt; LaL (3.0 × 105) &gt; CoL (1.12 × 105) mol−1 dm−3. Docking investigations were performed using the receptors of COVID‐19's main protease viral protein (PDB ID: 6LU7) and Escherichia coli (gram [–ve] bacteria [PDB ID: 1fj4]).

Synthesis, characterization and catalytic studies of chromium(III) porphyrin complex with axial cyanate ligands

We report the synthesis and the spectroscopic, structural and electrochemical characterization of a new chromium(III) coordination compound namely the bis(cyanato-κN)[meso-tetratolylporphyrinato]chromate(III) (cryptand-222)potassium dihydrate [K(crypt-222)][CrIII(TTP)(NCO)2]·2H2O (complex I). This compound crystallizes in the orthorhombic crystal system with the non-centrosymmetric space group C2221. The chromium and the potassium atoms are located at special positions in a two-fold axis. The crystal lattice of complex I is stabilized by O__H…O, C__H…O, C__H…N and C__H…π intermolecular contacts involving the negatively charged [CrIII(TTP)(NCO)2]− species, the [K(crypt-222)]+ counterions and the two non-coordinated water molecules. Further insights on these weak intermolecular contacts are provided by the Hirshfeld surface analysis. Molecular electrostatic potential (MEP) theoretical calculation on [K(crypt-222)][CrIII(TTP)(NCO)2]·2H2O are reported. The new Cr(III) complex was efficient as a catalyst in the decomposition of the Rhodamine B (RbH) dye by hydrogen peroxide. This coordination compound was also tested as a photocatalyst of the photodecomposition of the RbH dye by molecular oxygen.