A complex of ceftriaxone with Pb(II): synthesis,characterization, and antibacterial activity study

A Pb(II) complex with ceftriaxone (H₂Ceftria) antibiotic was synthesized by reaction of ceftriaxone disodium salt (hemi)heptahydrate with lead nitrate in water–ethanol medium. The complex was characterized on the basis of complexometric titration, spectrophotometric and thermogravimetric analyses, capillary electrophoresis, IR, Raman and UV–vis spectroscopies, and density functional theory calculations. Pb(II) is five-coordinate with distorted square pyramidal geometry. The coordination of Ceftria^2? to Pb(II) occurs through N and O of the triazine, lactam carbonyl, carboxylate, and amine groups. The antibacterial activity study showed that Klebsiella pneumoniae is resistant to [Pb(Ceftria)]·3H₂O. The antibacterial activity of [Pb(Ceftria)]·3H₂O against Staphylococcus aureus is reduced compared with ceftriaxone. In contrast, the antibacterial activity of [Pb(Ceftria)]·3H₂O against Escherichia coli is 28% higher than that of ceftriaxone antibiotic.     

Synthesis,spectroscopic characterization,and antibacterial assays in vitro of a new platinum(II) complex with methionine sulfoxide

A new platinum(II) complex with methionine sulfoxide was synthesized and characterized by chemical and spectroscopic techniques. Elemental analyses, mass spectrometric measurements (electrospray ionization quadrupole time-of-flight mass spectrometry), and thermal analyses of the solid compound fit the composition [(C₅H₁₀NO₃S)Pt(µ-Cl)₂Pt(C₅H₁₀NO₃S)]?·?2.5H₂O. Infrared spectroscopic data indicate coordination of the ligand to Pt(II) through the nitrogen of NH₂ and the sulfur of the S=O group. ¹H-¹⁵N nuclear magnetic resonance spectroscopic data confirm nitrogen coordination. Antibacterial activities were evaluated by antibiogram assays using the disc diffusion method. The platinum(II) complex showed antibacterial activity against Gram-negative Pseudomonas aeruginosa bacterial cells.     

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.     

Novel 3‐Hydroxy‐2‐naphthoic hydrazone and Ni(II), Co(II) and Cu(II) Complexes: Synthesis,Spectroscopic Characterization,Antimicrobial, DNA Cleavage and Computational Studies

A novel hydrazone ligand derived from condensation reaction of 3‐hydroxy‐2‐naphthoic hydrazide with dehydroacetic acid, and its Ni(II), Cu(II) and Co(II) complexes were synthesized, characterized by spectroscopic, elemental analyses, magnetic susceptibility and conductivity methods, and screened for antimicrobial, DNA binding and cleavage properties. Spectroscopic analysis and elemental analyses indicated the formula, [MLCl₂], for the complexes; square planar geometry for the nickel, and tetrahedral geometry for copper and cobalt complexes. The non‐electrolytic natures of the complexes in Dimethyl Sulphoxide (DMSO) were confirmed by their molar conductance values in the range of 6.11–14.01 Ω^?1cm²mol^?1. The copper complex had the best antibacterial activity against Staphylococcus aureus (ATCC 29213). DNA cleavage activities of the compounds, evaluated on pBR322 DNA, by agarose gel electrophoresis, in the presence and absence of oxidant (H₂O₂) and free radical scavenger (DMSO), indicated no activity for the ligand, and moderate activity for the complexes, with the copper complex cleaving pBR322 DNA more efficiently in the presence of H₂O₂. When the complexes were evaluated for antibacterial and A‐DNA activity using Molecular docking technique, the copper complex was found to be most effective against Gram‐positive (S. aureus) bacteria. [CuLCl₂] showed good hydrogen bonding interaction with the major‐groove (C₂^.G₁₃ base pair) of A‐DNA. Density functional theory (DFT) calculations of the structural and electronic properties of the complexes revealed that [CuLCl₂] had a smaller HOMO‐LUMO gap, suggesting a higher tendency to donate electrons to electron‐accepting species of biological targets.     

Synthesis,characterization and antimicrobial activity of a Zn(II) complex with 1-(1H-benzoimidazol-2-yl)-ethanone thiosemicarbazone

A new Zn(II) complex with 1-(1H-benzoimidazol-2-yl)-ethanone thiosemicarbazone [Zn(NO₃)(H₂O)(C₁₀H₁₁N₅S)]NO₃ was prepared and characterized by elemental analyses, FT-IR, ¹H NMR spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and single-crystal X-ray diffraction analysis. The coordination geometry of the pentacoordinated zinc is a distorted square pyramid. The antimicrobial activity of the complex was evaluated using a broth micro-dilution method against a panel of human pathogenic Gram positive, Gram negative bacteria and the yeast Candida albicans. The best inhibitory effect was observed against Enterobacter aerogenes (MIC = 0.031 mg mL^?1).     

Chemical, spectroscopic characterization, DFT studies and initial pharmacological assays of a silver(I) complex with N-acetyl-l-cysteine

A new silver(I) complex with N-acetyl-l-cysteine (NAC) of composition AgC₅H₈NO₃S·H₂O was synthesized and characterized by a set of chemical and spectroscopic measurements. Solid-state ¹³C nuclear magnetic resonance (SSNMR) and infrared (IR) analyses indicate the coordination of the ligand to Ag(I) through the sulfur atom. The Ag-NAC complex is slightly soluble in dimethyl sulfoxide. It is insoluble in water, methanol, ethanol, acetone and hexane. Antibacterial activity of the silver complex with N-acetyl-l-cysteine (Ag-NAC) was evaluated by antibiogram assays using the disc diffusion method. The compound showed an effective antibacterial activity against Staphylococcus aureus (Gram-positive), Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacterial cells. Biological analysis for evaluation of a potential cytotoxic effect of Ag-NAC was performed using HeLa cells derived from human cervical adenocarcinoma. The complex presented a significant cytotoxic activity, inducing 80% of cell death at a concentration of 200 μmol L⁻¹.     

New bioactive Pt(II) binary and ternary metal complexes with guaifenesin drug: Synthesis,geometrical structure,and spectroscopic and thermal characterization

Three new binary and ternary metal complexes of Pt(II) with guaifenesin (GFS) drug have been prepared by chelation to guaifenesin ligand (as primary ligand) and glycine amino acid (HGly) and 1,10‐phenanthroline (1,10‐Phen) (as secondary ligands). Characterization was conducted based on elemental analysis, molar conductance, infrared (IR) spectroscopy, thermogravimetric analysis and X‐ray diffraction. The complexes were found to have the formulae [Pt(GFS)₂]⋅3H₂O ( 1 ), [Pt(GFS)₂(Gly)]Cl⋅H₂O ( 2 ) and [Pt(GFS)₂(Phen)]Cl₂ ( 3 ). Magnetic and spectroscopic data revealed complexes 1 – 3 to have octahedral geometry. IR spectra suggested that GFS ligand coordinated in mononegative tridentate mode (OOO) for 1 but in neutral bidentate mode (OO) for 2 and 3 . In addition, HGly behaves as mononegative bidentate coordinated to Pt(II) metal via deprotonated carboxylate O and amino group. IR data also evidenced the bidentate nature of 1,10‐Phen ligand. The molecular and electronic structure of Pt(II) complex 1 was optimized theoretically and the quantum chemical parameters were calculated. Complexes 1 – 3 were screened for their antibacterial activity on Gram‐positive bacteria (Bacillus subtilis and Staphylococcus aureus ) and Gram‐negative bacteria (Escherichia coli and Neisseria gonorrhoeae ) and for their in vitro antifungal activity against Candida albicans . The three Pt(II) complexes showed remarkable biological and cytotoxic activity. The chelates were also screened for their in vitro anticancer activity against the MFC7 breast cell line. Complex 3 showed the highest activity with a low IC₅₀ value of 3.38 μg ml⁻¹.     

Experimental and Theoretical Studies of 4‐(1‐benzyl‐5‐methyl‐1H‐1,2,3‐triazol‐4‐yl)‐6‐(2,4‐dichlorophenyl)pyrimidin‐2‐amine: A Potential Antibacterial Agent

The title compound ( 1 ), 4‐(1‐benzyl‐5‐methyl‐1H‐1,2,3‐triazol‐4‐yl)‐6‐(2,4‐dichlorophenyl)pyrimidin‐2‐amine (C₂₀H₁₆Cl₂N₆), was synthesized and structurally characterized by elemental analysis, ¹H NMR and ¹³C NMR and single crystal X‐ray diffraction. The compound crystallizes as a colourless needle shaped in the triclinic system, space group P‐1 with cell constants: a = 10.7557(11) Å, b = 12.7078(17) Å, c = 15.511(2) Å, α = 68.029(4)0, β = 86.637(5)0, γ = 87.869(4)0; V = 1962.4 (4) ų, Z = 4. There are two structurally similar but crystallographically independent molecules (A and B) in the asymmetric unit of the title compound, which is linked via N‐H…Cl hydrogen bond. An intramolecular C‐H…N hydrogen also occurs in each molecule. In the crystal, each of independent molecules forms a centrosymmetric dimer with an R²₂(8) ring motifs through a pair of N‐H…N hydrogen bonds. These dimers are further connected by intermolecular N‐H…Cl and C‐H…Cl hydrogen bonds, forming an infinite two dimensional supramolecular network lying parallel to the [010] plane. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6‐311G (d, p) basis set and compared with the experimental data. Mulliken population analyses on atomic charges, HOMO‐LUMO energy levels, Molecular electrostatic potential and chemical reactivity of the title compound were investigated by theoretical calculations. The thermo dynamical properties of the title compound at different temperature have been calculated and corresponding relations between the properties and temperature have also been obtained. The in vitro antibacterial activity has been screened against Gram‐positive (Bacillus cerus and Staphylococcus epidermidis) and Gram‐Negative (Escherichia coli, Acinetobacter baumannii and Proteus vulgaris). The results revealed that the compound exhibited good to moderate antibacterial activity.     

Synthesis,characterization, density functional theory calculations,and in vitro antibacterial activity of novel transition metal complexes containing an O3-tridentate amoxicillin-based Schiff base: A silver(II) complex as alternative against Pseudomonas aeruginosa resistant to amoxicillin

Transition metal complexes containing an amoxicillin-based Schiff base (H₂L, 3 ) obtained from the condensation of amoxicillin 1 with salicylaldehyde 2 were prepared. Spectroscopic and physicochemical techniques, namely, UV–visible, Fourier-transform infrared spectroscopy, ¹H NMR, electron paramagnetic resonance, transmission electron microscopy, mass spectrometry, magnetic susceptibility, molar conductance, density functional theory (DFT) calculations, together with elemental and thermal analyses were used to characterize the synthesized complexes. Based on these studies, the general formulae [ML(H₂O)₃], where M = Mn 4 , Ni 5 , Zn 6 , and [ML(H₂O)], where M = Cu 7 , Ag 8 , were proposed for the complexes. The amoxicillin-based Schiff base ligand behaved as a dianionic O₃-tridentate chelating agent. DFT studies and magnetic and spectral data revealed octahedral geometries for Mn, Ni, and Zn atoms and distorted tetrahedral geometries for Cu(II) and Ag(II) complexes. Synthesized compounds were tested for antibacterial activity by both agar disk diffusion method and the minimum inhibitory concentration. in vitro bacterial viability revealed that complex 5 had similar antibacterial activity as 1 against Staphylococcus aureus and Staphylococcus epidermidis, whereas Pseudomonas aeruginosa, resistant to amoxicillin, was sensitive to complex 8 . The antibacterial activity of complex 8 could be attributed to its greater catalytic activity as shown by DFT calculations. Toxicity bioassay of the tested compounds showed LC₅₀ values > 1000 ppm, indicating their nontoxicity against brine shrimp nauplii (Artemia salina).     

Syntheses,characterizations, crystal structures,and biological activities of two new mixed ligand Ni(II) and Cu(II) Schiff base complexes

Two mixed-ligand complexes, [Cu(L)(2imi)] (1) and [Ni(L)(2imi)]·MeOH (2) [L = 2-(((5-chloro-2-oxyphenyl)imino)methyl)phenolato) and 2imi = 2-methyl imidazole], have been prepared by the reaction of appropriate metal salts with H₂L and 2-methyl imidazole. Their structures were characterized by microanalysis, FT-IR, UV–vis, molar conductivity, and ¹H NMR for [Ni(L)(2imi)]·MeOH. The structures were determined using single crystal X-ray diffraction. Each four-coordinate metal center, Cu(II) in 1 and Ni(II) in 2, is surrounded by donors of Schiff base (L^2?) and N of 2-methyl imidazole in square planar geometries. α-Amylase activities of these compounds have also been investigated. The experimental data showed that α-amylase was inhibited by Ni(II) complex while the Cu(II) complex causes a 1.3-fold decrease in K_m value. Antimicrobial results show that these compounds, especially the Cu(II) complex, have potential for antibacterial activity against Gram negative and Gram positive bacteria and antifungal activity against Aspergillus fumigatus.     

Synthesis,characterization, antifungal and antibacterial activities evaluation of copper (II), zinc (II) and cadmium (II) chloride and bromide complexes with new (E)-1-(3,4-dimethoxybenzylidene)-4-methylthiosemicarbazone ligand

The reactions of Cu (II), Zn (II) and Cd (II) chloride or bromide with (E)-1-(3,4-dimethoxybenzylidene)-4-methylthiosemicarbazone (MTSVT) lead to the formation of new complexes. They were characterized by spectroscopic studies: IR, ¹H and ¹³C NMR. The crystal structures of the compounds [MTSVT] ( L ), [ZnBr₂(MTSVT)₂] ( 2 ), [CdCl₂(MTSVT)₂] ( 3 ) and [CdBr₂(MTSVT)₂^.H₂O] ( 4 ) were determined by X-ray diffraction. For complexes 2 – 4 , the ion is coordinated through the sulfur atom. All compounds were tested for their antifungal activity against human pathogenic fungi Candida albicans and Aspergillus fumigatus, and for their antibacterial activity against Gram (+) Bacillus subtilis and Enterococcus faecalis as well as against Gram (−) bacteria such as Paracoccus yeei and Acinetobacter baumanii. The results indicated that the metal complexes exhibited a marked enhancement in antibacterial activity compared with the parent Schiff base.     

Antibacterial,spectral and thermal aspects of drug based‐Cu(II) mixed ligand complexes

The antibiotic agent clioquinol is well known for its drug design and coordinating ability towards metal ions. Copper(II) mixed‐ligand complexes of clioquinol with various uninegative bidentate ligands were prepared. The structure of the synthesized complexes was characterized using elemental analyses, infrared spectra, ¹H‐NMR spectra, electronic spectra, magnetic measurements, FAB mass spectrum and thermo gravimetric analyses. The kinetic parameters such as order of reaction (n) and the energy of activation (E_a) are reported using the Freeman–Carroll method. The pre‐exponential factor (A), the activation entropy (ΔS^#), the activation enthalpy (ΔH^#) and the free energy of activation (ΔG^#) were calculated. Complexes were also screened for their in vitro antibacterial activity against a range of Gram‐positive and Gram‐negative bacteria in order to set the precursors for anti‐tumourigenic agent. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,Bioactivity, and the Anion‐Binding Property of 2‐Sulfydryl‐1,3,4‐thiodiazole Derivatives

Two new compounds ( 1 and 2 ) containing 2‐sulfydryl‐1,3,4‐thiodiazole have been synthesized and optimized. They both showed wide antibacterial activity for colon bacillus, Staphylococcus aureus, S. albus, dysentery bacillus and inferior activity for Bacillus subtilis. In addition, their binding properties were evaluated for biologically important anions (F^–, Cl^–, Br^–, I^–, AcO^–, and H₂PO₄^–) by theoretical investigation, UV–vis, fluorescence, and ¹H NMR titration experiments, and they displayed strong binding ability for H₂PO₄^– without the interference of other anions tested. Especially the binding ability of compound 2 containing anthracene with H₂PO₄^– was 1000 times stronger than that of compound 1 containing nitrobenzene. Two compounds based on 2‐sulfydryl‐1,3,4‐thiodiazole have both properties of anion recognition and antibacterial activity.     

Synthesis, spectroscopic characterization, DFT studies and biological assays of a novel gold(I) complex with 2-mercaptothiazoline

A new gold(I) complex with 2-mercaptothiazoline (MTZ) with the coordination formula [AuCN(C₃H₅NS₂)] was synthesized and characterized by chemical and spectroscopic measurements, DFT studies and biological assays. Infrared (IR) and ¹H, ¹³C and ¹⁵N nuclear magnetic resonance (NMR) spectroscopic measurements indicate coordination of the ligand to gold(I) through the nitrogen atom. Studies based on DFT confirmed nitrogen coordination to gold(I) as a minimum of the potential energy surface with calculations of the hessians showing no imaginary frequencies. Thermal decomposition starts at temperatures near 160 °C, leading to the formation of Au⁰ as the final residue at 1000 °C. The gold(I) complex with 2-mercaptothiazoline (Au-MTZ) is soluble in dimethyl sulfoxide (DMSO), and is insoluble in water, methanol, ethanol, acetonitrile and hexane. The antibacterial activities of the Au-MTZ complex were evaluated by an antibiogram assay using the disc diffusion method. The compound showed an effective antibacterial activity against Staphylococcus aureus (Gram-positive) and Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacterial cells. Biological analysis for evaluation of the cytotoxic effect of the Au-MTZ complex was performed using HeLa cells derived from human cervical adenocarcinoma. The complex presented a potent cytotoxic activity, inducing 85% of cell death at a concentration of 2.0 μmol L⁻¹.     

Molecular structure,molecular docking,thermal, spectroscopic and biological activity studies of bis‐Schiff base ligand and its metal complexes

Coordination compounds of Fe(III), Zn(II), Ni(II), Co(II), Cu(II), Cd(II) and Mn(II) ions were synthesized from the ligand [4,4′‐((((ethane‐1,2‐diylbis(oxy))bis(2,1‐phenylene))bis(methanylylidene))bis(azanylylidene))diphenol]ethane (H₂L) derived from the condensation of bisaldehyde and 4‐aminophenol. Microanalysis, magnetic susceptibility, infrared, ¹H NMR and mass spectroscopies, molar conductance, X ray powder diffraction and thermal analysis were used to confirm the structure of the synthesized chelates. According to the data obtained, the composition of the 1:1 metal ion–bis‐Schiff base ligand was found to be [M(H₂L)(H₂O)₂]Cl_n (M = Zn(II), Ni(II), Co(II), Cu(II), Cd(II) and Mn(II), n = 2; Fe(III), n = 3). Magnetic susceptibility measurements and reflectance spectra suggested an octahedral geometry for the complexes. Central metals ions and bis‐Schiff base coordinated together via O2 and N2 donor sites which as evident from infrared spectra. The Gaussian09 program was applied to optimize the structural formula for the investigated Schiff base ligand. The energy gaps and other important theoretical parameters were calculated applying the DFT/B3LYP method. Molecular docking using AutoDock tools was utilized to explain the experimental behaviour of the Schiff base ligand towards proteins of Bacillus subtilis (5 h67), Escherichia coli (3 t88), Proteus vulgaris (5i39) and Staphylococcus aureus (3ty7) microorganisms through theoretical calculations. The docked protein receptors were investigated and the energies of hydrogen bonding were calculated. These complexes were then subjected to in vitro antibacterial studies against several organisms, both Gram negative (P. vulgaris and E. coli) and Gram positive (S. pyogones and B. subtilis). The ligand and metal complexes exhibited good microbial activity against the Gram‐positive and Gram‐negative bacteria.     

Synthesis,spectral, DFT calculations and antibacterial studies of Fe(III) complexes of new fluorescent Schiff bases derived from imidazo[4',5':3,4]benzo[1,2‐c]isoxazole

New fluorescent heterocyclic ligands were synthesized by the reaction of 8‐(4‐chlorophenyl)‐3‐alkyl‐3H‐imidazo[4',5':3,4]benzo [1,2‐c]isoxazol‐5‐amine with p‐hydroxybenzaldehyde and p‐chlorobenzaldehyde in good yields. The coordination ability of the ligands with Fe³⁺ ion was examined in an aqueous metanolic solution. Schiff base ligands and their metal complexes were characterized by elemental analyses, IR, UV–vis, mass, and NMR spectra. The optical properties of the compounds were investigated and the results showed that the fluorescence of all compounds is intense and their obtained emission quantum yields are around 0.15 – 0.53. Optimized geometries and assignment of the IR bands and NMR chemical shifts of the new complexes were also computed by using density functional theory (DFT) methods. The DFT‐calculated vibrational wavenumbers and NMR chemical shifts are in good agreement with the experimental values, confirming suitability of the optimized geometries for Fe(III) complexes. Also, the 3D‐distribution map for HOMO and LUMO of the compounds were obtained. The new compounds showed potent antibacterial activity and their antibacterial activity (MIC) against Gram‐positive and Gram‐negative bacterial species were also determined. Results of antibacterial test revealed that coordination of ligands to Fe(III) leads to improvement in the antibacterial activity.     

Syntheses, X-ray crystal structures, DNA binding, oxidative cleavage activities and antimicrobial studies of two Cu(II) hydrazone complexes

From a mononuclear Cu(II)-hydrazone complex [Cu(PBH)₂] (1), one μ_1,1-azido bridged dinuclear Cu(II) complex having the formula [{Cu(PBH)(μ_1,1-NNN)}₂] (2) (where HPBH = 2-pyridinecarboxaldehyde benzoyl hydrazone) has been synthesised. Both the complexes are characterised by elemental analyses, IR and UV–Vis spectroscopic studies. The tridentate hydrazone pro-ligand (HPBH) is obtained by the condensation of benzhydrazide and pyridine-2-carboxaldehyde. The structures of the complexes have conclusively been established by the X-ray single crystal diffraction method. Complex 1 and 2 both display DNA binding ability, which is ascertained by UV–Vis titration and cyclic voltammetric studies using calf thymus DNA (CT-DNA). The apparent binding constants (K_app) are of moderate values and are 2.048 × 10⁴ M⁻¹ (±0.006) and 1.644 × 10⁴ M⁻¹ (±0.005), respectively. The modes of binding of the complexes with CT-DNA has been investigated using circular dichroism, ethidium bromide displacement assay and viscosity measurements. The cleavage properties of these complexes as well as the free pro-ligand with super coiled (SC) pUC19 are studied using the gel electrophoresis method, where both the complexes displayed chemical nuclease activity in the presence of H₂O₂ via an oxidative mechanism. The antimicrobial study using the free pro-ligand, 1 and 2 against both Gram positive and Gram negative bacteria are performed, 2 showed antimicrobial activity against both Gram negative and Gram positive bacteria whereas the free ligand and 1 show no antibacterial activity.     

Syntheses,characterization, antibacterial activity and molecular modelling of phenylantimony(III) heteroleptic derivatives containing substituted oximes and piperidine dithiocarbamate

Six new heteroleptic phenylantimony(III) derivatives containing substituted oximes and dithiocarbamate moieties of the type (where R = ─C₆H₅, X = ─CH₃ ( 2a ); R = ─C₆H₄CH₃, X = ─CH₃ ( 2b ); R = ─C₆H₄Cl, X = ─CH₃ ( 2c ); R = ─C₆H₄Br, X = ─CH₃ ( 2d ); R = ─C₆H₄OH, X = ─H ( 2e ); R(X)C = ( 2f )) have been synthesized by the reactions of phenylantimony(III) dichloride with the sodium salt of substituted oximes and dithiocarbamate moiety in unimolar ratio with stirring in dichloromethane. All these newly synthesized derivatives have been characterized using physicochemical and elemental analyses. Structures have been proposed on the basis of infrared, ¹H NMR, ¹³C NMR and LC–MS spectral studies and molecular modelling. In these derivatives the oxime behaves in an unidentate manner whereas dithiocarbamate behaves in a monofunctional anisobidentate manner. Pseudo‐trigonal bipyramidal (ψ‐TBP) geometry around the antimony metal centre is proposed for these phenylantimony(III) heteroleptic derivatives. The geometry of a representative complex has been optimized through molecular modelling. These newly synthesized derivatives were screened against Bacillus subtilis (Gram‐positive) and Escherichia coli (Gram‐negative) bacteria to evaluate their antibacterial potential. The structure–activity relationship for antibacterial activity among the four derivatives 2a , 2c , 2e and 2f is discussed.     

Spectroscopic,thermal and antimicrobial properties of the copper(II) complex of Schiff base derived from 2‐(salicylidene) aminopyridine

Schiff bases and their complex combinations with metallic ions represent a class of compounds with antimicrobial activity. A ligand was prepared by condensation of the salicylaldehyde with 2‐aminopyridine obtaining 2‐(salicylidene) aminopyridine (SB) with a high capacity for complexing Cu(II) ions. The new compound has been characterized by physical constants (melting point, solubility, stability) and the chemical structure was confirmed by elemental, spectral (IR, UV–visible, ¹H NMR and ¹³C‐NMR) and thermal analyses. The elemental analysis gives a coordination ratio of 1:2 metal:Schiff base. Lethal dose 50 (DL₅₀) values of new Schiff base and their complex with metallic ions were established. The antimicrobial activity of this complex was tested in comparison with the activity of the corresponding Schiff base on strains of Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Escherichia coli, Candida albicans, and Klebsiella. These were compared with the activity of the reference drugs (chloramphenicol, tetracycline, ofloxacin and nystatin) on the above‐mentioned strains. It has been established that all compounds tested were very active against both Gram‐positive and Gram‐negative bacteria. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and antibacterial activity of novel pyrano[2,3-d]pyrimidine-4-one–3-phenylisoxazole hybrids

A series of ethyl 2,7-dimethyl-4-oxo-5-phenyl-3-[(3-phenylisoxazol-5-yl)methyl]-3,5-dihydro-4H-pyrano[2,3-d]pyrimidine-6-carboxylates was synthesized and screened for antibacterial activity against Gram positive and Gram negative bacterial species. All new compounds were characterized by ¹H, ¹³C NMR, IR, and mass spectra. The results of the antibacterial study indicated that all compounds exhibited good to excellent antibacterial activity.