Synthesis,characterization, and antimicrobial activities of two mononuclear metal(II) complexes with (Z)-3-hydroxy-4-(3-hydroxy-3-phenylacryloyl)phenyl benzoate

Two mononuclear complexes with a β-diketone ligand (Z)-3-hydroxy-4-(3-hydroxy-3-phenylacryloyl)phenyl benzoate (L), [CoL₂(CH₃CH₂OH)₂] (1), and [MnL₂(CH₃CH₂OH)₂] (2) were prepared. Both complexes were characterized by X-ray crystallography, confirming that the central metal(II) are coordinated by four oxygens from two L and two oxygens from two ethanols. Both complexes were assayed for in vitro antibacterial (Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae) activities and showed better antimicrobial activity against Gram positive strains than Gram negative strains.     

Ni(II) and Cu(II) complexes of new unsymmetrical N2O2 Schiff bases derived from 3-(2-aminobenzylimino)-1-phenylbutan-1-ol: synthesis,structure, antibacterial properties,and electrochemistry

Two new N₂O₂ unsymmetrical Schiff bases, H₂L¹ = 3-[({o-[(E)-(o-hydroxyphenyl)methylideneamino]phenyl}methyl)imino]-1-phenyl-1-buten-1-ol and H₂L² = 3-[({o-[(E)-(2-hydroxy-1-naphthyl)methylideneamino]phenyl}methyl)imino]-1-phenyl-1-buten-1-ol, and their copper(II) and nickel(II) complexes, [CuL¹] (1), [CuL²] (2), [NiL¹] (3), and [NiL²] (4), have been synthesized and characterized by elemental analyses and spectroscopic methods. The crystal structures of these complexes have been determined by X-ray diffraction. The coordination geometry around Cu(II) and Ni(II) centers is described as distorted square planar in all complexes with the CuN₂O₂ coordination more distorted than the Ni ones. The electrochemical studies of these complexes indicate a good correlation between the structural distortion and the redox potentials of the metal centers. The ligand and metal complexes were also screened for their in vitro antibacterial activity.     

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 and antimicrobial activity of zinc(II) ibuprofen complexes with nitrogen-based ligands

Metal carboxylate complexes possess different carboxylate coordination modes, e.g. monodentate, bidentate, and bridging bidentate. Five Zn(II) complexes were prepared and characterized in order to examine their coordination modes in addition to their biological activity. The syntheses were started by preparation of [Zn(ibup)₂(H₂O)₂] (1). Then, different nitrogen-donor ligands reacted with 1 to produce [Zn(ibup)₂(2-ampy)₂] (2), [Zn(ibup)(2-ammethylpy)] (3), [Zn(ibup)(2,2′-bipy)] (4), and [Zn₂(ibup)₄(2-methylampy)₂] (5) (ibup = ibuprofen, 2-ampy = 2-aminopyridine, 2-ammethylpy = 2-aminomethylpyridine, 2,2′-bipy = 2,2′-bipyridine, 2-methylampy = 2-(methylamino)pyridine). IR, ¹H NMR, ¹³C{¹H}-NMR and UV–vis spectroscopies were used for characterization. The crystal structures of 2 and 5 were determined by single-crystal X-ray diffraction. Investigation of in vitro antibacterial activities for the complexes against Gram-positive (Micrococcus luteus, Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis) bacteria were done using agar well-diffusion method. Complex 1 showed antibacterial activity against Gram-positive bacteria. Complexes 2 and 3 did not exhibit antibacterial activity. Complex 4 showed antibacterial activity and was chosen for further studies to determine the inhibition zone diameter for different concentrations and to set the minimum inhibitory concentration. The antibacterial activity against most of the bacteria was minimized as a result of the complexation of zinc ibuprofen with 2,2′-bipy in 4.     

Synthesis,physico-chemical characterization and bioevaluation of Ni(II), Pd(II), and Pt(II) complexes with 1-(o-tolyl)biguanide: Antimicrobial and antitumor studies

New complexes of type [M(tbg)₂]Cl₂ [tbg = 1-(o-tolyl)biguanide; M = Ni(II), Pd(II), and Pt(II)] were synthesized and characterized to develop new biologically active compounds. The features of the complexes were assigned from microanalytical and thermal data. The NMR, FT-IR, and UV-Vis spectra were established by comparison with HtbgCl. All complexes exhibit a square-planar geometry resulting from the chelating behavior of tbg. The HtbgCl and [Ni(tbg)₂]Cl₂ complexes were fully characterized by single-crystal X-ray diffraction. The HtbgCl species crystallize in the monoclinic C2/c spatial group, while the Ni(II) complex adopts an orthorhombic Pna2₁ spatial group. The structure is stabilized by a complex hydrogen bonds network. The in vitro antimicrobial assays revealed improved antimicrobial activity for complexes in comparison with the ligand against both planktonic and biofilm embedded microbial cells. The most efficient compound, showing the largest spectrum of antimicrobial activity, including Gram-positive and Gram-negative bacteria, as well as fungal strains, in both planktonic and biofilm growth states was the Pd(II) complex, followed by the Pt(II) complex. The Pt(II) compound exhibited the most significant antiproliferative activity on the human cervical cancer SiHa cell line, inducing a cell cycle arrest in the G2/M phase.     

Novel 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone and Zn(II), Cu(II), Ni(II) and Co(III) complexes: Synthesis,characterization, crystal structure,antioxidant, antimicrobial and antiproliferative activity

New zinc (II), copper (II), nickel (II) and cobalt (III) complexes, [Zn (HL)₂]I₂ (1) , [Cu (HL)Cl₂] (2) , [Cu (HL)Br₂] (3) , [Cu (HL)(H₂O)₂](ClO₄)₂ (4) , [Ni (HL)₂]I₂·H₂O (5) , [Co(L)₂]Cl (6) , [Co(L)₂]NO₃ (7) , [Co(L)₂]I·[Co(L)₂](I₃) (8) were obtained with 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone ( HL ). The isothiosemicarbazone ligand was characterized by NMR (¹H and ¹³C), IR spectroscopy and X-ray diffraction. All the complexes were characterized by elemental analysis, IR, UV–Vis, ESI-MS spectroscopy, molar conductivity, magnetic susceptibility measurements. X-ray diffraction analysis on the monocrystal and powder elucidated the structure of the complexes 1 , 5 , 7 and 8 . The ligand and the complexes were tested for their antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. Also, the antiproliferative properties of these compounds on human leukemia HL-60, human cervical epithelial HeLa, human epithelial pancreatic adenocarcinoma BxPC-3, human muscle rhabdomyosarcoma spindle, large multinucleated RD cells and normal MDCK cells have been investigated. The nickel complex 5 and cobalt complexes 6 , 7 showed promising antiproliferative activity and low toxicity.     

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.     

Theoretical,antimicrobial, antioxidant,in vitro cytotoxicity,and cyclin-dependent kinase 2 inhibitor studies of metal(II) complexes with bis(imidazol-1-yl)methane-based heteroscorpionate ligands

Abstract

A series of C-centered heteroscorpionate-based homoleptic manganese(II), nickel(II), and copper(II) complexes of type [M(L^1–3)₂] (1–9) have been synthesized by using the ligands (2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL¹), (4-diethylamino-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL²) and (5-bromo-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL³). The geometric parameters of the complexes were determined using UV-vis and theoretical studies suggesting distorted octahedral geometry around metal(II) ion. Frontier molecular orbital analysis supports bioefficacy of the complexes. Antimicrobial activity of the metal(II) complexes were determined against two Gram(–ve) (Escherichia coli and Klebsiella pneumoniae) and two Gram(+ve) (Bacillus cereus and Staphylococcus aureus) bacteria, and three fungal (Candida albicans, Candida glabrata, and Candida krusei) strains. Antioxidant activity of nickel(II) and copper(II) complexes were evaluated against ABTS, DPPH, and H₂O₂ free radicals. In vitro cytotoxicity activity of nickel(II) and copper(II) complexes against human breast adenocarcinoma (MCF-7), cervical (HeLa), and lung (A549) cancer cell lines along with one normal human dermal fibroblasts (NHDF) cell line were carried out by MTT assay, which shows the potent activity of copper(II) complex 8 with respect to the standard drug cisplatin. Molecular docking studies evidence the interaction of complexes with cyclin-dependent kinase 2 receptor (CDK2).     

Two new zinc(II) and mercury(II) complexes based on N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide): synthesis,crystal structures and antibacterial activities

Reaction of N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide), C₂₀H₁₈F₂N₄O₂, ( L^F ), with zinc chloride and mercury(II) chloride produced different types and shapes of neutral coordination complexes, namely, dichlorido[N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide)‐κ²N,O]zinc(II), [ZnCl₂(C₂₀H₁₈F₂N₄O₂)], ( 1 ), and dichlorido[N,N′‐(cyclohexane‐1,2‐diylidene)bis(4‐fluorobenzohydrazide)‐κ⁴O,N,N′,O′]mercury(II), [HgCl₂(C₂₀H₁₈F₂N₄O₂)], ( 2 ). The organic ligand and its metal complexes are characterized using various techniques: IR, UV–Vis and nuclear magnetic resonance (NMR) spectroscopies, in addition to powder X‐ray diffraction (PXRD), single‐crystal X‐ray crystallography and microelemental analysis. Depending upon the data from these analyses and measurements, a typical tetrahedral geometry was confirmed for zinc complex ( 1 ), in which the Zn^II atom is located outside the bis(benzhydrazone) core. The Hg^II atom in ( 2 ) is found within the core and has a common octahedral structure. The in vitro antibacterial activities of the prepared compounds were evaluated against two different bacterial strains, i.e. gram positive Bacillus subtilis and gram negative Pseudomonas aeruginosa bacteria. The prepared compounds exhibited differentiated growth‐inhibitory activities against these two bacterial strains based on the difference in their lipophilic nature and structural features.     

Synthesis,crystal structure,and antibacterial activity of mononuclear nickel(II) and cobalt(III) Schiff-base complexes

Four new mononuclear complexes, [Ni(L¹)(NCS)₂] (1), [Ni(L²)(NCS)₂] (2), [Co(L¹)(N₃)₂]ClO₄ (3), and [Co(L²)(N₃)₂]ClO₄ (4), where L¹ and L² are N,N′-bis[(pyridin-2-yl)methylidene]butane-1,4-diamine and N,N′-bis[(pyridin-2-yl)benzylidene]butane-1,4-diamine, respectively, have been prepared. The syntheses have been achieved by reaction of the respective metal perchlorate with the tetradentate Schiff bases, L¹ and L², in presence of thiocyanate (for 1 and 2) or azide (for 3 and 4). The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 are distorted octahedral geometries. The antibacterial activity of all the complexes and their constituent Schiff bases have been tested against Gram-positive and Gram-negative bacteria.     

Spectroscopic,anti-bacterial,anti-cancer and molecular docking of Pd(II) and Pt(II) complexes with (E)-4-((dimethylamino)methyl)-2-((4,5-dimethylthiazol-2-yl)diazenyl)phenol ligand

New ligand (E)-4-((dimethylamino)methyl)-2-((4,5-dimethylthiazol-2-yl)diazenyl)phenol (HDmazo) was prepared by the coupling reaction between 4,5-dimethylthiazol-2-amine and 4-((dimethylamino)methyl)phenol. Moreover, the [MCl₂(HDmazo)] and [M(HDmazo)₂] [M^II = Pd and Pt] were prepared using the direct reaction of equivalent molar of HDmazo and Na₂PdCl₄ or K₂PtCl₄. The HDmazo and its complexes were investigated by different spectroscopic techniques. In complexes (1–2) HDmazo ligand behaves as bidentate style through the nitrogen of azo group and nitrogen of thiazole ring towards Pd(II) and Pt(II). Or in a bidentate fashion via the oxygen atom of the hydroxylate group and nitrogen atom of azo group as mono-anion in complexes (3–4). Further, the study of biological activity against four pathogenic bacteria showed that compound (3) exhibited good activity compared to other compounds. Additional the anti-tumor action against A2870 cell lines was screened, and the complexes (1) and (2) displayed good activity with 7.45 ± 0.98 µM and 13.23 ± 1.43 µM, respectively. The binding mechanism of the prepared compounds with EGFR tyrosine kinase, was investigated using molecular docking experiments.     

Synthesis,spectroscopic, thermal and biological aspects of drug‐based copper(II) complexes

A series of novel complexes of the type Cu(II)(L_n)₂(H₂O)₂]^•xH₂O [where L_n = L _1–4 , these ligands being described as: L ₁ , 2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)phenol, x = 1; L ₂ , 2‐({4‐[6,7‐dihydrothieno[3,2‐c] pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)‐5‐(methoxy)phenol, x = 2; L ₃ , 5‐chloro‐2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino}methyl)phenol, x = 2; and L ₄ , 5‐bromo‐4‐chloro‐2‐({4‐[6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐ylsulfonyl]phenylimino} methyl)phenol, x = 1] was investigated. They were characterized by elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR and electronic spectra, magnetic measurements and thermal studies. The FAB‐mass spectrum of [Cu(II)( L ₁ )₂(H₂O)₂]^•H₂O was determined. A magnetic moment and reflectance spectral study revealed that an octahedral geometry could be assigned to all the prepared complexes. Ligands (L_n) and their metal complexes were screened for their in vitro antibacterial activity against Bacillus subtillis, Pseudomonas aeruginosa, Escherichia coli and Serratia marcescens bacterial strains. Kinetic parameters such as order of reaction (n), the energy of activation (E_a), the pre‐exponential factor (A), the activation entropy (ΔS^≠), the activation enthalpy (ΔH^≠) and the free energy of activation (ΔG^≠) are reported. Copyright © 2011 John Wiley & Sons, Ltd.     

Nickel versus copper: enhanced antibacterial activity in a series of new nickel(II) Schiff base complexes

Five new Ni(II) Schiff base complexes [NiL^x(Solv)₂] denoted by NiL^x, x = 1–5, were synthesized and characterized. The Schiff base ligands were synthesized from the condensation of 5-bromo-2-hydroxy-3-nitrobenzaldehyde with different aliphatic and aromatic diamines. The X-ray crystal structure of NiL³ was determined. The ligands and complexes were tested as antibacterial agents against two gram(+) and two gram(?) human pathogenic bacteria. The complexes showed moderate antibacterial activity against both gram type bacteria. The new Ni(II) complexes showed enhanced antibacterial activity compared to the previously reported Cu(II) complexes of the same ligands.     

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.     

Zinc(II) complexes of 2-pyridine-derived N (4)- p -tolyl thiosemicarbazones: study of in vitro antibacterial activity

Reaction of N(4)-p-tolyl-2-formylpyridine thiosemicarbazone (H2Fo4pT), N(4)-p-tolyl-2-acetylpyridine thiosemicarbazone (H2Ac4pT), and N(4)-p-tolyl-2-benzoylpyridine thiosemicarbazone (H2Bz4pT) with ZnCl₂ gave [Zn(H2Fo4pT)Cl₂] (1), [Zn(H2Ac4pT)Cl₂] (2), and [Zn(H2Bz4pT)Cl₂] (3). In the first two complexes a tridentate N_py–N–S thiosemicarbazone binds to the zinc while in the latter N–S coordination occurs. Upon coordination the antibacterial activity against Salmonella typhimurium increases in 1 and 3.     

Synthesis,characterization, crystal structure and toxicity evaluation of Co (II), Cu (II), Mn (II), Ni (II), Pd (II) and Pt (II) complexes with Schiff base derived from 2-chloro-5-(trifluoromethyl)aniline

A bidentate NO donor Schiff base, 2-(((2-chloro-5- (trifluoromethyl)phenyl)imino)methyl) phenol ( HL ¹ ) and its complexes [Co(L¹)₂(H₂O)₂] ( 1 ), [Cu(L¹)₂] ( 2 ), [Mn(L¹)₂(H₂O)₂] ( 3 ), [Ni(L¹)₂(H₂O)₂] ( 4 ), [Pd₂(L¹)₂(OAc)₂·1.16H₂O] ( 5 ), [Pt(L¹)₂] ( 6 ) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, IR, ¹H-NMR, ¹³C-NMR, UV–Vis, mass spectroscopies and X-ray powder diffraction (XRD). The molecular structures of ligand HL ¹ and two complexes ( 2 and 5 ) were confirmed by X-ray crystallography analysis on the monocrystal. In this complexes, the metal ions are in distorted square-planar environments. The copper (II) complex is mononuclear and crystallized in a monoclinic space group P21/c, whereas palladium (II) complex is dinuclear and crystallized in the trigonal crystal system R-3. The toxicity of the ligand and complexes was evaluated on both plant and animal cells, using the plant species Triticum aestivum L. and the crustacean Artemia franciscana Kellogg. At concentrations up to 100 μM the compounds presented very little toxicity on Artemia franciscana Kellogg. Moreover, the palladium (II) complex was devoid of any toxicity on the plant cells.     

Synthesis,structural studies and bio-activity of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with p -amino acetophenone salicyloyl hydrazone

Complexes of the type [M(pash)Cl] and [M(Hpash)(H₂O)SO₄] (M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hpash = p-amino acetophenone salicyloyl hydrazone) have been synthesized and characterized by elemental analyses, molar electrical conductance, magnetic moments, electronic, ESR and IR spectra, thermal studies and X-ray powder diffraction. All the complexes are insoluble in common organic solvents and are non-electrolytes. The magnetic moment values and electronic spectra indicate a square-planar geometry for Co(II), Ni(II) and Cu(II) chloride complexes and spin-free octahedral geometry for the sulfato complexes. The ligand coordinates through >C=N–,–NH₂ and a deprotonated enolate group in all the chloro complexes, and through >C=N–, >C=O and–NH₂ in the sulfato complexes. Thermal analyses (TGA and DTA) of [Cu(pash)Cl] show a multi-step exothermic decomposition pattern. ESR spectral parameters of Cu(II) complexes in solid state at room temperature suggest the presence of the unpaired electron in d _{x ² ? y ²} . X-ray powder diffraction parameters for [Cu(pash)Cl] and [Ni(Hpash)(H₂O)SO₄] correspond to tetragonal and orthorhombic crystal lattices, respectively. The complexes show a fair degree of antifungal activity against Aspergillus sp., Stemphylium sp. and Trichoderma sp. and moderate antibacterial activity against E. coli and Clostridium sp.     

Synthesis,characterization, and antimicrobial properties of two Cu(II) complexes derived from a benzimidazole ligand

Two copper(II) complexes, [Cu(L)₂](ClO₄)₂] and [Cu(L)(bipy)](ClO₄)₂, were prepared and characterized by the spectroscopic and analytic methods, where L is N-butylbenzimidazole and bipy is 2,2′-bipyridine. Single crystals of [Cu(L)(bipy)](ClO₄)₂ suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a DMF solution of the complex and the complex was found to crystallize as [Cu(L)(bipy)](ClO₄)₂·DMF. The asymmetric unit contains one [Cu(L)(bipy)]²⁺, two uncoordinated perchlorates, and one DMF solvate. Coordination geometry around Cu(II) is distorted square pyramidal with τ value of 0.31. Thermal properties of the complexes were examined by thermogravimetric analysis, indicating that the complexes are thermally stable to 310?°C. The metal complexes were screened for their in vitro antibacterial and antifungal activities Bacillus subtilis and Bacillus cereus (as Gram(+) bacteria), Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae (as Gram(–) bacteria), and Saccharomyces cerevisiae, Candida utilis, and Candida albicans (as yeasts). The complexes show antibacterial and antifungal activities against bacteria and yeasts.     

Synthesis,characterization, and antibacterial evaluation of copper(II) complexes supported by phenylacetic acid derivatives,and diamine ligands

Four mixed-ligand complexes, [Cu₃(cpa)₆(pda)₁] (1) (cpa = 4-chlorophenylacetic acid, pda = 1,2-diaminopropane), [Cu₃(fpa)₆(tn)₁] (2) (fpa = 4-fluorophenylacetic acid, tn = 1,3-diaminopropane), [Cu₃(cpa)₆(en)₁] (3) (cpa = 4-chlorophenylacetic acid, en = ethylenediamine), and [Cu₃(fpa)₆(pda)₁] (4) (fpa = 4-fluorophenylacetic acid, pda = 1,2-diaminopropane), were synthesized by reacting 4-chlorophenylacetic acid or 4-fluorophenylacetic acid, the diamines, and metal salts. Their structures were determined by elemental analysis and single-crystal X-ray diffraction analysis. The antimicrobial activities for the metal complexes were evaluated against Escherichia coli, Pseudomonas putida, Bacillus subtilis, and Bacillus cereus. The antimicrobial results indicated that the four synthesized complexes displayed good inhibitory activity against E. coli and B. subtilis, and could be promising antibacterial agents.     

Synthesis, characterization and antimicrobial activity of palladium(II) complexes with some alkyl derivates of thiosalicylic acids: Crystal structure of the bis(S-benzyl-thiosalicylate)-palladium(II) complex, [Pd(S-bz-thiosal)2]

S-Alkyl (R = benzyl, methyl, ethyl, propyl and butyl) derivatives of thiosalicylic acid and the corresponding palladium(II) complexes were prepared and their structures were proposed on the basis of infrared, ¹H and ¹³C NMR spectroscopy. The cis geometrical configurations of the isolated complexes were proposed on the basis of an X-ray structural study of the bis(S-benzyl-thiosalicylate)-palladium(II), [Pd(S-bz-thiosal)₂] complex.Antimicrobial activity of the tested compounds was evaluated by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) in relation to 26 species of microorganisms. The tested ligands, with a few exceptions, show low antimicrobial activity. The palladium(II) complexes, [Pd(S-R-thiosal)₂], have statistically significant higher activity than the corresponding ligands. The complexes [Pd(S-et-thiosal)₂] and [Pd(S-pro-thiosal)₂] displayed the strongest activity amongst the all tested compounds. The palladium(II) complexes show selective and moderate antibacterial activity and significant antifungal activity. The most sensitive were Aspergillus fumigatus and Aspergillus flavus.