Novel Cr (III), Fe (III) and Ru (III) Vanillin Based Metallo‐Pharmaceuticals for Cancer and Inflammation Treatment: Experimental and Theoretical Studies

In this study, three novel complexes comprising trivalent Cr (III), Fe (III) and Ru (III) with imine ligand derived from 2‐amino‐3‐hydroxypyridine and o‐vanillin (H₂L) have been synthesized and characterized via wide range of spectroscopic and analytical tools such as ¹H NMR and ¹³C NMR, infrared (IR) and UV–Vis spectrophotometry, conductivity and magnetic measurements. The obtained results along with DFT data confirmed a 1:1 (metal: ligand) stoichiometry with non‐planner geometries for the three complexes. The binding action and the docking study of the prepared metal‐complexes to calf thymus DNA was also studied by absorption spectra and viscosity technique, which revealed that the three complexes interact strongly with DNA through intercalative binding mode. Significantly, these metal‐imine complexes showed strong and efficient anti‐inflammatory and antimicrobial activities against various gram‐positive (Microccus luteus), gram‐negative (Escherichia coli and Serratia marcescence) bacteria, and three strains of fungus. Moreover, all complexes exhibited more potent cytotoxicity effect on the outgrowth of different types of carcinoma cells, including human colon (HCT‐116 cell line), breast (MCF‐7 cell line), and hepatic cellular (HepG‐2), than the clinically‐proven Vinblastine standard.     

Ru(III), Cr(III), Fe(III) complexes of Schiff base ligands bearing phenoxy Groups: Application as catalysts in the synthesis of vitamin K3

Two polydentade Schiff base ligands and their Ru(III), Cr(III) and Fe(III) complexes were synthesized and characterized by elemental analysis (C, H, N), UV/Vis, FT IR, ¹H and ¹³C NMR, LC–MS/MS, molar conductivity and magnetic susceptibility techniques. The absorption bands in the electronic spectra and magnetic moment measurements verified an octahedral environment around the metal ions in the complexes. The thermal stabilities were investigated using TGA. The synthesized complexes were used in the catalytic oxidation of 2-methyl naphthalene (2MN) to 2-methyl-1,4-naphthoquinone; vitamin K₃, menadione, 2MNQ; using hydrogen peroxide, acetic acid and sulfuric acid. L₁-Fe(III) complex showed very efficient catalytic activity with 58.54% selectivity in the conversions of 79.11%.     

Synthesis,Characterization and Magnetic Studies of μ‐Oxamido Copper (II) ‐ Chromium (III) Heterodinuclear Complexes

Three new μ‐oxamido‐bridged heterodinuclear copper (II)‐chromium (III) complexes formulated [Cu(Me₂oxpn)Cr‐(L)₂](NO₃)₃, where Me₂oxpn denotes N,N'‐bis(3‐amino‐2, 2‐dimethylpropyl)oxamido dianion and L represents 5‐methyl‐1,10‐phenanthroline (Mephen), 4,7‐diphenyl‐1,10‐phenanthroline (Ph₂phen) or 2,2′‐bipyridine (bpy), have been synthesized and characterized by elemental analyses, IR and electronic spectral studies, magnetic moments of room‐temperature and molar conductivity measurements. It is proposed that these complexes have oxamido‐bridged structures consisting of planar copper (II) and octahedral chromium (III) ions. The variable temperature magnetic susceptibilities (4.2–300 K) of complexes [Cu(Me₂oxpn)Cr(Ph₂phen)₂](NO₃)₃ (1) and [Cu(Me₂oxpn)Cr(Mephen)₂] (NO₃)₃ (2) were further measured and studied, demonstrating the ferromagnetic interaction between the adjacent chromium (III) and copper (II) ions through the oxamido‐bridge in both complexes 1 and 2. Based on the spin Hamiltonian, ? = ‐ 2J?₁ · ?₂, the exchange integrals J were evaluated as + 21.5 an^?1 for 1 and + 22.8 cm^?1 for 2.     

Coordination behaviour,molecular docking,density functional theory calculations and biological activity studies of some transition metal complexes of bis‐Schiff base ligand

Coordination compounds of Mn (II), Fe (III), Co (II), Ni (II), Cu (II) and Cd (II) ions were synthesized from reaction with Schiff base ligand 4,6‐bis((E)‐(2‐(pyridin‐2‐yl)ethylidene)amino)pyrimidine‐2‐thiol (HL) derived from the condensation of 4,6‐diaminopyrimidine‐2‐thiol and 2‐(pyridin‐2‐yl)acetaldehyde. Microanalytical data, magnetic susceptibility, infrared and ¹H NMR spectroscopies, mass spectrometry, molar conductance, powder X‐ray diffraction and thermal decomposition measurements were used to determine the structure of the prepared complexes. It was found that the coordination between metal ions and bis‐Schiff base ligand was in a molar ratio of 1:1, with formula [M (HL)(H₂O)₂] X_n (M = Mn (II), Co (II), Ni (II), Cu (II) and Cd (II), n = 2; Fe (III), n = 3). Diffuse reflectance spectra and magnetic susceptibility measurements suggested an octahedral geometry for the complexes. The coordination between bis‐Schiff base ligand and metal ions was through NNNN donor sites in a tetradentate manner. After preparation of the complexes, biological studies were conducted using Gram‐positive (B. subtilis and S. aureus) and Gram‐negative (E. coli and P. aeruginosa) organisms. Metal complexes and ligand displayed acceptable microbial activity against both types of bacteria.     

Green synthesis approach for novel benzenesulfonamide nanometer complexes with elaborated spectral,theoretical and biological treatments

New series of nano‐sized bi‐homonuclear Ce (III), ZrO (II), Sn (II), Pb (II), Cr (III), Fe (III) and Cu (II) complexes with 4‐[(2,4‐dihydroxybenzylidene)amino]‐N‐(1,3‐thiazol‐2‐yl) benzenesulfonamide (H₃L) were synthesized via green solid‐state method. The structural and molecular formulae of all synthesized complexes were established based on variable spectral, analytical and theoretical implementations. FT‐IR study confirms the coordination of H₃L with metal ions through the Schiff base and sulfonamide centers in di‐basic tetra‐dentate mode. Thermal analysis, magnetic moment and electronic spectra are attributing to octahedral configuration around Ce (III), Cr (III) and Fe (III) centers, while with ZrO (II), Sn (II), Pb (II) and Cu (II) centers, acquired tetrahedral arrangement. TEM and XRD studies, represent the nanometer characters of most metal ion complexes. TGA curves are utilized to compute the activation thermo‐kinetic parameters over different decomposition stages applying Coats‐Redfern method. Theoretical implementation executed by Gaussian09 program exerted the structures for the best atomic orientation over whole molecules. QSAR data were achieved over Hyper Chem 8.1 program through molecular mechanics process. Docking complexes between free ligand and different protein receptors were obtained through AutoDock Tools 4.2. Antimicrobial, antifungal and antitumor activities of the metal complexes were studied in comparing with free ligand to assert their potential therapeutic uses. H₃L, Ce (III), Fe (III) and Cu (II) complexes displayed high antibacterial activity near that of standard Gentamycin. Moreover, Cr (III) complex displayed highest cytotoxicity against human liver Carcinoma cell line (HEPG2).     

The Synthesis and Characterization of s‐Triazine‐Cored Tripodal Structure and Its Salen/Salophen‐Bridged Fe/Cr(III) Capped Complexes

A novel Schiff base compound was synthesized, and its complexation properties with Fe(III) and Cr(III) were investigated. Tripodal ligand was synthesized by the reaction of s‐triazine and 4‐hydroxybenzaldehyde. Then a Schiff base involving 8‐hydroxyquinoline was synthesized by the reaction of 5‐aminomethyl‐8‐hydroxyquinoline ( QN ) and 2,4,6‐tris(p‐formylphenoxy)‐1,3,5‐triazine ( TRIPOD ) in methanol/chloroform media. The obtained Schiff base ( QN-TRIPOD ) was then reacted with four trinuclear Fe(III) and Cr(III) complexes including tetradentate Schiff bases N ,N ′‐bis(salicylidene)ethylenediamine (salenH₂)/bis(salicylidene)‐o‐phenylenediamine (SalophenH₂). The synthesized ligand and complexes were characterized by means of elemental analysis carrying out ¹H NMR, FTIR spectroscopy, thermal analyses, and magnetic susceptibility measurements. Finally, metal ratios of the prepared complexes were determined by using atomic adsorption spectrometry.     

Synthesis and characterization of rhodium(III), iridium(III), ruthenium(III) and osmium(III) complexes containing sterically hindered heterocyclic ligands

Summary Some thiazolidine-2-thione and thiomorpholin-3-one complexes of rhodium(lll), iridium(III), ruthenium(III) and osmium(III) have been prepared and characterized by chemical analysis, conductivity measurements, room temperature magnetic moment studies, electronic, i.r. and far i.r. spectra and n.m.r. measurements. From the magnetic properties it was concluded that the above ligands form low-spin complexes with all the metal ions. The position and multiplicity of the metal-halogen stretching modes in the far-i.r. region have been extensively investigated and discussed; the results are particularly useful in distinguishing between themer- andfac-isomers in the octahedral compounds of the ML₃ X₃ type. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of the crystal field theory and the various parameters have been calculated. On the basis of the electronic spectra a trigonal bipyramidal geometry,D _3h, has been established for the Ru(tm)₂Cl₃ complex; the Ir(rm)₂Cl₃ · H₂O complex has also been prepared. It is penta-coordinated and a trigonal bipyramidal environment is suggested for the iridium(III) ion.     

Physicochemical characterization of nanobidentate ferrocene‐based Schiff base ligand and its coordination complexes: Antimicrobial,anticancer, density functional theory,and molecular operating environment studies

A novel bidentate Schiff base ligand (HL, Nanobidentate Ferrocene based Schiff base ligand L (has one replaceable proton H)) was prepared via the condensation of 2‐amino phenol with 2‐acetyl ferrocene. The ligand was characterized using elemental analysis, mass spectrometry, infrared (IR) spectroscopy, ¹proton nuclear magnetic resonance (H‐NMR) spectroscopy, scanning electron microscopy (SEM), and thermal analysis. The corresponding 1:1 metal complexes with some transition‐metal ions were additionally characterized by their elemental analysis, molar conductance, SEM, and thermogravimetric ana1ysis (TGA). The complexes had the general formula [M(L)(Cl)(H₂O)₃]xCl·nH₂O (M = Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II)), (x = 0 for Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), x = 1 for Cr(III) and Fe(III)), (n = 1 for Cr(III), n = 3 for Mn(II) and Co(II), n = 4 for Fe(III), Ni(II), Cu(II), Zn(II), and Cd(II)). Density functional theory calculations on the HL ligand were also carried out in order to clarify molecular structures by the B31YP exchange‐correlation function. The results were subjected to molecular orbital diagram, highest occupied mo1ecu1ar orbital–lowest occupied molecular orbital, and molecular electrostatic potential calculations. The parent Schiff base and its eight metal complexes were assayed against four bacterial species (two Gram‐negative and two‐Gram positive) and four different antifungal species. The HL ligand was docked using molecular operating environment 2008 with crystal structures of oxidoreductase (1CX2), protein phosphatase of the fungus Candida albicans (5JPE), Gram(?) bacteria Escherichia coli (3T88), Gram(+) bacteria Staphylococcus aureus (3Q8U), and an androgen‐independent receptor of prostate cancer (1GS4). In order to assess cytotoxic nature of the prepared HL ligand and its complexes, the compounds were screened against the Michigan cancer foundation (MCF)‐7 breast cancer cell line, and the IC₅₀ values of compounds were calculated.     

Preparation,characterization, biological activity,density functional theory calculations and molecular docking of chelates of diazo ligand derived from m‐phenylenediamine and p‐chlorophenol

A novel azo dye ligand, 2,2′‐(1,3‐phenylenebis(diazene‐2,1‐diyl))bis(4‐chlorophenol), was synthesized from the diazotization of m ‐phenelyenediamine and coupling with p ‐chlorophenol in alkaline medium. Mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of the azo ligand (H₂L) were prepared and characterized using elemental analyses, infrared spectroscopy, electron spin resonance, magnetic susceptibility, conductance measurements and thermal analyses. The UV–visible, ¹H NMR and mass spectra of the ligand and its chelates were also recorded. The analytical data showed that the metal‐to‐ligand ratio in the mononuclear azo complexes was 1:1. Diffuse reflectance and magnetic moment measurements revealed the complexes to have octahedral geometry. The infrared spectral data showed that the chelation behaviour of the ligand towards transition metal ions was through phenolic oxygen and azo nitrogen atoms. The electronic spectral results indicated the existence of π → π* (phenyl rings) and n → π* (─N═N) and confirmed the mentioned structure. Molar conductivity revealed the non‐electrolytic nature of all chelates. The presence of water molecules in all complexes was supported by thermal studies. Molecular docking was used to predict the binding between H₂L and the receptors of breast cancer mutant 3hb5‐oxidoreductase, crystal structure of Escherichia coli (3 t88) and crystal structure of Staphylococcus aureus (3q8u). The molecular and electronic structure of H₂L was optimized theoretically and the quantum chemical parameters were calculated. In addition, the effects of the H₂L azo ligand and its complexes on the inhibition of bacterial or fungal growth were evaluated. The prepared complexes had enhanced activity against bacterial or fungal growth compared to the H₂L azo ligand.     

Synthesis,spectral, MOE and cytotoxic studies of nano Ru (III), Pr (III) and Gd (III) metal complexes with new Schiff base ligand based on dibenzoyl methane and anthranilic acid

Three metal complexes of Gd (III), Pr (III) and Ru (III) metal ions with Schiff base ligand (H₂L) (prepared through l:2 condensation of dibenzoyl methane and anthranilic acid) were prepared and characterized using various physio-chemical methods like: elemental analyses, IR, mass spectrometry, magnetic moment, ¹H NMR, SEM and TG/DTG thermal analysis. The analytical and spectroscopic tools showed that the complexes had composition of ML type with octahedral geometry. The mass spectra gave the possible molecular ion peaks of the Schiff base ligand and three metal chelates. The ¹H NMR data supported the IR finding that the ligand coordinated to the metal ions via carboxylate proton displacement. Thermal analysis (TG/DTG) was utilized to differentiate between coordinated and hydrated water molecules. The Schiff base (H₂L) and its metal complexes have been screened for their antibacterial activity against Gram (+) bacteria (Streptococcus aureus and Bacillis subtilis), Gram (−) bacteria (Salmonella typhimurium and Escherichia coli) and two fungi (Aspergillus fumigatu and Candida albicans) organisms by agar diffusion method. The anticancer activity was screened against human breast cancer cell line (MCF-7). The H₂L ligand and its metal chelates were docked using MOE 2008 software with crystal structure of Gram (+) bacteria: Staphylococcus aureus (PDB ID: 3Q8U) and Gram (−) bacteria: Salmonella typhimurium (PDB ID: lDZR) to identify the binding orientation or conformation of the complex in the active site of the protein.     

Synthesis and characterization of novel oxime-imine ligands and their heteronuclear ruthenium(III) complexes

Vicinal carbonyl oxime (HL¹) and oxime-imine (H₂L²) ligands and their mononuclear Ru(III) and Cu(II), heterodinuclear Ru(III)-Mn(II), Ru(III)-Ni(II), Ru(III)-Cu(II), and heterotrinuclear Ru(III)-Cu(II)-Ru(III) chelates were synthesized and characterized by elemental analysis, molar conductivity, IR, ESR, ICP-OES, magnetic moment measurements, and thermal analyses studies. The free ligands were also characterized by ¹H NMR spectra. The carbonyl-oxime ligand coordinates through the oxygen of =N-OH to form a six-membered chelate ring. The quadridentate tetraaza ligand (H₂L²) obtained by condensing of the bidentate ligand 1-p-diphenylmethane-2-hydroxyimino-2-(1-naphthylamino)-1-ethanone (HL¹) with 1,2-phenylenediamine coordinates with Ru(III) through its nitrogen donors in the equatorial position with the loss of one of the oxime protons and concomitant formation of an intramolecular hydrogen bond. Stoichiometric and spectral results of the metal complexes indicated that the metal: ligand ratios in the mononuclear complexes of the ligand (HL¹) were found to be 1: 2, while these ratios were 1: 1 in the mononuclear complexes of the ligand (H₂L²). The metal: ligand ratios of the dinuclear complexes were found to be 2: 1, and this ratio was 3: 2 in the trinuclear complex. The article is published in the original.     

Spectro-thermal characterization of chromium(III) and manganese(II) complexes with carboxyamide

Complexes of Cr(III) and Mn(II) with N′,N″-bis(3-carboxy-1-oxopropanyl) 2-amino-N-arylbenzamidine (H₂L¹) and N′,N″-bis(3-carboxy-1-oxophenelenyl) 2-amino-N-arylbenzamidine (H₂L²) have been synthesized and characterized by various physico-chemical techniques. The vibrational spectral data are in agreement with coordination of amide and carboxylate oxygen of the ligands with the metal ions. The electronic spectra indicate octahedral geometry around the metal ions, supported by magnetic susceptibility measurements. The thermal behavior of chromium(III) complexes shows that uncoordinated nitrate is removed in the first step, followed by two water molecules and then decomposition of the ligand; manganese(II) complexes show two waters removed in the first step, followed by removal of the ligand in subsequent steps. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The thermal stability of metal complexes has been compared. X-ray powder diffraction determines the cell parameters of the complexes.     

Bimetallic Ru(II)–Ir(III) complexes with bridging 2,2′‐bipyrimidine: Synthesis,structures and characterization

In this work, four bimetallic Ru(II)–Ir(III) complexes with the general formula [(bpy)₂Ru(bpm)Ir(C^N)₂](PF₆)₃ (bpy = 2,2‐bipyridine, bpm = 2,2′‐bipyrimidine, C^N = 2‐phenylpyridinato ( 2 ), (2‐p‐tolyl)pyridinato ( 3 ), 2‐(2,4‐difluorophenyl)pyridinato ( 4 ), and 2‐thienylpyridinato ( 5 )) were synthesized. Complexes 2 – 5 were characterized by NMR spectroscopy, high‐resolution mass spectrometry, and elemental analysis. The structures of the complexes 2 and 4 were further confirmed by single‐crystal X‐ray diffraction analysis. All the complexes display strong absorption in the high‐energy UV region assigned to intraligand (IL) transitions, and the lower energy bands are ascribed to metal‐to‐ligand charge transfer (MLCT) transitions. The reduction and oxidation behavior of the complexes 2 – 5 were examined by cyclic voltammetry. Variation of the ligands on Ir(III) center resulted in significant changes in electrochemical properties.     

Novel Schiff base ligand and its metal complexes with some transition elements. Synthesis,spectroscopic, thermal analysis,antimicrobial and in vitro anticancer activity

A novel Schiff base ligand (H₂L) was prepared through condensation of 2,6‐diaminopyridine and o‐benzoylbenzoic acid in a 1:2 ratio. This Schiff base ligand was characterized using elemental and spectroscopic analyses. A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal complexes of H₂L were prepared and characterized using elemental analysis, spectroscopy (¹H NMR, mass, UV–visible, Fourier transform infrared, electron spin resonance), magnetic susceptibility, molar conductivity, X‐ray powder diffraction and thermal analysis. The complexes are found to have trigonal bipyramidal geometry except Cr(III), Mn(II) and Fe(III) complexes which have octahedral geometry based on magnetic moment and solid reflectance measurements. The infrared spectral studies reveal that H₂L behaves as a neutral bidentate ligand and coordinates to the metal ions via the two azomethine nitrogens. ¹H NMR spectra confirm the non‐involvement of the carboxylic COOH proton in complex formation. The presence of water molecules in all reported complexes is supported by thermogravimetric studies. Kinetic and thermodynamic parameters were determined using Coats–Redfern and Horowitz–Metzger equations. The synthesized ligand and its complexes were screened for antimicrobial activities against two Gram‐positive bacteria (Bacillus subtilis and Staphylococcus aureus), two Gram‐negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and one fungus (Candida albicans). Anticancer activities of the ligand and its metal complexes against human breast cancer cell line (MCF7) were investigated. Copyright © 2016 John Wiley & Sons, Ltd.     

The synthesis and characterization of single substitute melamine cored Schiff bases and their [Fe(III) and Cr(III)] complexes

In this study, firstly, two single substitute novel ligands have been synthesized by reacting melamine with 3,4,-dihydroxybenzaldeyhde or 4-carboxybenzaldehyde. Then, eight new mono nuclear single substitute [Salen/Salophen Fe(III) and Cr(III)] complexes have been synthesized by reacting the ligands [2-(3,4-dihydroxybenzimino)-4,6-diamimo-1,3,5-triazine and 2-(4-carboxybenzimino)-4,6-diamimo-1,3,5-triazine)] with tetradentate Schiff bases N,N′-bis(salicylidene)ethylenediamine-(salenH₂) or bis(salicylidene)-o-phenylenediamine-(salophen H₂). And then, all ligands and complexes have been characterized by means of elementel analysis, FT-IR spectroscopy, ¹H NMR, LC–MS, thermal analyses and magnetic suscebtibility measurements. Finally, metal ratios of the prepared complexes were determined using AAS. The complexes have also been characterized as disorted octahedral low-spin Fe(III) and Cr(III) bridged by catechol and COO^? groups.     

Spectroscopic study of molecular structures of novel Schiff base derived from o-phthaldehyde and 2-aminophenol and its coordination compounds together with their biological activity

New Schiff base (H₂L) ligand is prepared via condensation of o-phthaldehyde and 2-aminophenol. The metal complexes of Cr(III), Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with the ligand are prepared in good yield from the reaction of the ligand with the corresponding metal salts. They are characterized based on elemental analyses, IR, solid reflectance, magnetic moment, electron spin resonance (ESR), molar conductance, ¹H NMR and thermal analysis (TGA). From the elemental analyses data, the complexes are proposed to have the general formulae [M(L)(H₂O)n]·yH₂O (where M = Mn(II) (n = 0, y = 1), Fe(II) (n = y = 0), Co(II) (n = 2, y = 0), Ni(II) (n = y = 2), Cu(II) (n = 0, y = 2) and Zn(II) (n = y = 0), and [MCl(L)(H₂O)]·yH₂O (where M = Cr(III) and Fe(III), y = 1–2). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that H₂L is coordinated to the metal ions in a bi-negatively tetradentate manner with ONNO donor sites of the azomethine N and deprotonated phenolic-OH. This is supported by the ¹H NMR and ESR data. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Fe(III), Co(II) and Ni(II) complexes), tetrahedral (Mn(II), Fe(II) and Zn(II) complexes) and square planar (Cu(II) complex). The thermal behaviour of these chelates is studied and the activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DrTGA curves using Coats-Redfern method. The parent Schiff base and its eight metal complexes are assayed against two fungal and two bacterial species. With respect to antifungal activity, the parent Schiff base and four metal complexes inhibited the growth of the tested fungi at different rates. Ni(II) complex is the most inhibitory metal complex, followed by Cr(III) complex, parent Schiff base then Co(II) complex. With regard to bacteria, only two of the tested metal complexes (Mn(II) and Fe(II)) weakly inhibit the growth of the two tested bacteria.     

Mn(III) mixed‐ligand complexes with bis‐pyrazolones and ciprofloxacin drug: synthesis,characterization and antibacterial activities

The fluoroquinolone family member ciprofloxacin is well known for its drug design and coordinating ability towards metal ions. The coordination chemistry of this drug with metal ions of biological and pharmaceutical importance is of considerable interest. Novel Mn(III) mixed‐ligand complexes of ciprofloxacin with various bis‐pyrazolone‐based dinegative bidentate ligands were synthesized and characterized on the basis of their physical properties, magnetic susceptibility measurements, (FT‐IR and electronic) spectral studies. The FAB‐mass spectrum of [Mn(A⁹)(L)(H₂O)₂]·H₂O [where H₂A⁹ = 4,4′‐(p‐tolylmethylene)bis(3‐methyl‐1‐phenyl‐4,5‐dihydro‐1H‐pyrazol‐5‐ol) and HL = 1‐cyclopropyl‐6‐fluoro‐4‐oxo‐7‐(piperazin‐1‐yl)‐1,4‐dihydroquinoline‐3‐carboxylic acid] was determined. All the synthesized compounds were screened for their bioactivity. The mixed‐ligand complexes exhibited comparable activities against two Gram‐negative (Escherichia coli and Serratia marcescens) and two Gram‐positive (Staphylococcus aureus and Bacillus subtilis) microorganisms. Copyright © 2011 John Wiley & Sons, Ltd.     

The (salophen)-bridged Fe/Cr (III) capped complexes with triphenylene core: Synthesis and characterization

This article describes synthesis of the difference carboxylic acid derivatives of triphenylene and its complexation properties with Fe/Cr (III)-salophen. For this purpose, the carboxylic acid derivatives of 2,3,6,7,10,11-hexahydroxytriphenylene were synthesized and then reacted with four new Fe(III) and Cr(III) complexes involving tetradenta Schiff bases bis(salicylidene)-o-phenylenediamine-(salophenH₂). The prepared compounds were characterized by means of elemental analysis carrying out infrared spectroscopy (IR), thermogravimetric analysis (TG), nuclear magnetic resonance (¹H NMR), elemental analysis and magnetic susceptibility measurement. The complexes can also be characterized as low-spin distorted octahedral Fe(III) and Cr (III) bridged by carboxylic acids.     

Tricoordinate Organochromium(III) Complexes Supported by a Bulky Silylamido Ligand Produce Ultra‐High‐Molecular Weight Polyethylene in the Absence of Activators

Low‐coordinate organoCr(III) complexes supported by the silylamido ligand –N(SiMe₃)DIPP (DIPP = 2,6‐diisopropylphenyl) are ethylene polymerization catalyst precursors without the need of additional cocatalyst. The reaction of CrCl₃(THF)₃ with 3 or 2 equiv. of LiN(SiMe₃)DIPP yields either a four‐membered cyclometalated Cr complex or Cr[N(SiMe₃)DIPP]₂Cl, respectively, with no trace of Cr[N(SiMe₃)DIPP]₃. Addition of 1 equiv. of LiN(SiMe₃)DIPP to Cr[N(SiMe₃)DIPP]₂Cl also leads to the four‐membered metallacycle, which upon heating transforms to a new six‐membered Cr metallacycle, likely via a σ‐bond metathesis step. Cr[N(SiMe₃)DIPP]₂Cl can be readily converted to bis(amido)Cr(III) vinyl and alkyl complexes Cr[N(SiMe₃)DIPP]₂R (R = vinyl, Bn, and Me). All of these structurally characterized low‐coordinate Cr(III) complexes with a Cr–C bond initiate the polymerization of ethylene in the absence of activators or cocatalysts, producing ultra‐high‐molecular weight polyethylene.     

Coordination modes of multidentate azodye ligand derived from 4,4′‐methylenedianiline towards some transition metal ions: Synthesis,spectral characterization,thermal investigation and biological activity

Nine new azodye metal complexes of Mn(II), Co(II), Ni(II), Cu(II), Cr(III), Fe(III), Ru(III), Hf(IV) and Zr(IV) ions have been prepared via the reaction of 5,5′‐((1E,1′E)‐(methylenebis(1,4‐phenylene))bis(diazene‐2,1‐diyl))bis(6‐hydroxy‐2‐thioxo‐2,3‐dihydropyrimidin‐4(5H)‐one) (H₄L) with the corresponding metal salts affording sandwich (1 L:1 M), mononuclear (2 L:1 M), binuclear (1 L,2 M) and tetranuclear (1 L,4 M) complexes. Elemental analyses, spectral methods, magnetic moment measurements and thermal studies were utilized to confirm the mode of bonding and geometrical structure for the ligand and its metal complexes. Infrared spectral data show that the H₄L ligand chelates with some metal ions in keto–enol–thione or keto–thione manner. It behaves in a neutral/dibasic tetradentate fashion in sandwich and binuclear complexes. Also, it acts as a neutral bidentate moiety in the Cr(III) complex. The spectra reveal that azo group participates in chelation in all complexes. Octahedral geometry was suggested for all chelates but the Cu(II) complex with square planar geometry. The thermal stability and decomposition of the compounds were studied, the data showing that the thermal decomposition ended with metal or metal oxide mixed with carbon as final product. The electron spin resonance spectrum of the Cu(II) complex demonstrates that the free electron is located in the ( ) orbital. Measurements of biological activity against human cell lines Hep‐G₂ and MCF‐7 reveal that the Cu(II) complex has a higher cytotoxicity in comparison to the free ligand and other metal complexes, with IC₅₀ values of 6.10 and 5.2 μg ml^?1, respectively, while the ligand has anti‐tumour activity relative to some of the investigated metal complexes.