Synthesis,characterization and biological properties of mixed ligand complexes of cobalt(II/III) valproate with 2,9‐dimethyl‐1,10‐phenanthroline and 1,10‐phenanthroline

The synthesis of mononuclear cobalt(II/III) complexes with two different ligands (complex 2: [Co(valp)₂(2,9‐dmp)] and complex 3: [Co(valp)₂(H₂O)(1,10‐phen)]) was investigated and the characterization of both complexes was achieved using IR, UV–Vis, and single crystal X‐ray diffraction. Using single crystal X‐ray diffraction, the crystal structure of each of the complexes was determined. Additionally, the biological activity of these complexes was studied in five gram‐positive and four gram‐negative bacterial strains. Whereas in all gram‐negative bacteria tested, cobalt valproate complexes did not show any anti‐bacterial activity, both complexes had effects on gram positive bacteria. Complex 2 demonstrated good anti‐bacterial activity against all gram‐positive bacteria with inhibition zone diameter (IZD) ranging between 15–28 mm. Complex 3 exhibited low inhibition activity against all gram‐positive bacteria except E. faecalis with IZD ranging between 11.3–13.7 mm. Moreover, as an indication of its uses as industrial catalyst, the rate of bis(p‐nitrophenyl) phosphate (BNPP) hydrolysis when catalyzed by these complexes was measured at different temperatures, concentrations and pH. Complex 2 proved to be a better catalyst to induce the hydrolysis of BNPP.     

New Zn(II) complexes based on biologically active substituted acetic acid and nitrogen donor ligands: synthesis,crystal structure and biological applications

The complexes [Zn(phenylacetato)₂(2-aminopyridin)₂] (3), [Zn(phenylacetato)₂(1,10-phenanthroline)]·H₂O (4), and [Zn(phenylacetato)₂(2,9-dimethyl-1,10-phenanthroline)]·0.5 H₂O (5) were prepared and characterized by IR-, UV–Visible, ¹H and ¹³C NMR spectroscopy, and single crystal X-ray diffraction. BNPP hydrolysis of the complexes and their parent nitrogen ligands showed that the hydrolysis rate of bis-(4-nitrophenyl) phosphate (BNPP) was 1.7 × 10⁵ L mol^?1 s^?1 for 3, 3.1 × 10⁵ L mol^?1 s^?1 for 4 and 4.3 × 10⁴ L mol^?1 s^?1 for 5. Antibacterial activities show the effect of complexation on activity against Gram-positive (S. epidermidis, S. aureus, E. faecalis, M. luteus and B. subtilis) and Gram-negative (K. pneumonia, E. coli, P. mirabilis and P. aeruginosa) bacteria using the agar well diffusion method. Complex 4 showed good activity against G? bacteria except P. aeruginosa, and against G+ bacteria except E. ferabis. Complex 5 showed no activity against G? bacteria, low activity against M. luteus and B. subtilis bacteria and high activity against S. epidemidis and S. aureus. Complex 3 did not show any activity against G? or G+ bacteria.     

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.     

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.     

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.     

Synthesis and Characterization of Some New Heteroaromatic Compounds Having Chirality Adjacent to a 1,3,4‐Thiadiazole Moiety and Their Antimicrobial Activities

Through a cyclization reaction of 2‐phenylbutyric acid with N‐ phenylthiosemicarbazide and POCl₃, novel 1,3,4‐thiadiazole derivatives were synthesized. Their structures were confirmed using IR, ¹H NMR, and ¹³C NMR spectroscopies and elemental analysis. The antibacterial activities of the obtained 1,3,4‐thiadiazole derivatives were tested against Gram‐negative bacteria (Salmonella enteritidis , Salmonella typhimurium , Enterobacter aerogenes , Salmonella infantis , Salmonella kentucky , and Escherichia coli ) and Gram‐positive bacteria (Staphylococcus aureus , Bacillus subtilis , and Enterococcus durans ) using a disk diffusion method. Moreover, an antifungal activity experiment was performed against Candida albicans using the disk diffusion method. It was observed that the synthesized 1,3,4‐thiadiazole derivatives exhibited effective antimicrobial activity against S. aureus , E. coli , and C. albicans . Based on these results, the 1,3,4‐thiadiazole derivatives can be considered as a source of bioactive agents for pharmacological and medicinal applications.     

A new azo‐Schiff base: Synthesis,characterization, biological activity and theoretical studies of its complexes

A new Azo‐Schiff base ligand L was prepared by reaction of m‐hydroxy benzoic acid with (Schiff base B) of 3‐[2‐(1H–indol‐3‐yl)‐ethylimino]‐1.5‐dimethyl‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐ylamine. This synthesized ligand was used for complexation with different metal ions like Ni(II), Co(II), Pd(II) and Pt(IV) by using a molar ratio of ligand: metal as 1:1. Resulted compounds were characterized by NMR (¹H and ¹³C), UV–vis spectroscopy, TGA, FT‐IR, MS, elemental analysis, magnetic moment and molar conductivity studies. The activation thermodynamic parameters, such as ΔE*, ΔH^*, ΔS^*, ΔG^*and K are calculated from the TGA curves using Coats ‐ Redfern method. Hyper Chem‐8 program has been used to predict structural geometries of compounds in gas phase. The biological activities of Schiff base and its complexes had been tested in vitro against, two Gram positive bacteria (Bacillus subtillis and Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli and Pseudomonas aeruguinosa).     

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.     

Synthesis,Characterization, Antimicrobial Screening,and Computational Studies of a Tripodal Schiff Base Containing Pyrimidine Unit

A novel tripodal Schiff base ligand, 5‐amino‐2,4,6‐tris(4‐carboxybenzimino)‐1,3‐pyrimidine (TTPS), was synthesized for the first time by the reaction of 2,4,5,6‐tetraaminopyrimidine with 4‐carboxybenzaldehyde. The ligand was characterized by means of ultraviolet–visible, Fourier transform infrared, one‐dimensional ¹H‐NMR, and one‐dimensional ¹³C‐NMR spectroscopies and elemental microanalysis. The Fourier transform infrared and NMR studies revealed that one of the NH₂ group in 2,4,5,6‐tetraaminopyrimidine is not involved in bonding. The in vitro antimicrobial activities of the ligand were investigated against Gram‐negative bacteria: Escherichia coli (ATCC 6749) and Pseudomonas aeruginosa (ATCC 9027), Gram‐positive bacteria: Staphylococcus aureus (ATCC 6538P) and Bacillus cereus (ATCC 14579), and fungi: Candida albicans and Aspergillus niger by the agar well diffusion technique. TTPS exhibits good activity against the test microorganisms. The minimum inhibitory concentrations of TTPS against S. aureus were compared with tetracycline and gentamicin, which are conventional bacterial drugs. The upper level of Lorke's method was used to determine the acute toxicity of the compound. The acute toxicity test indicates that TTPS is toxic at doses above 2154 mg/kg. The in vivo antimalarial assay was carried out on Plasmodium berghei based on the 4‐day suppressive method. The result shows a general dose‐dependent significant parasitemia inhibition compared with the negative control with TTPS having inhibition of 72.20% at 50 mg/kg and 65.81% at 25 mg/kg close to the value (87.22%) of the standard drug artesunate 5 mg/kg. Density functional theory method was used to complement this experimental investigation.     

Synthesis,Antibacterial Activity,and Docking Studies of 1,2,3‐triazole‐tagged Thieno[2,3‐d]pyrimidinone Derivatives

Novel (1‐(substituted phenyl)‐1H ‐1,2,3‐triazol‐4‐yl)methyl‐2‐(4‐oxo‐5,6,7,8‐tetrahydrobenzo[1,2]thieno[2,3‐d ]pyrimidin‐3(4H )‐yl)acetate derivatives were synthesized. All the compounds showed significant antibacterial activity against Gram‐negative (Escherichia coli and Klebsiella pneumonia ) and Gram‐positive (Bacillus subtilis and Bacillus cereus ) bacteria. Particularly, (1‐(3‐nitrophenyl)‐1H ‐1,2,3‐triazol‐4‐yl)methyl‐2‐(4‐oxo‐5,6,7,8‐tetrahydrobenzo[1, 2]thieno[2,3‐d ]pyrimidin‐3(4H )‐yl)acetate was found to be most potent against E. coli , K. pneumonia , and B. subtilis with MIC 25 μg/ml. Molecular docking was also performed on purine riboswitch of B. subtilis and thiamine pyrophosphate riboswitch of E. coli .      

Ultrasonic‐assisted synthesis and biological evaluation of a nano‐rod diorganotin phosphonic diamide: Precursor for the fabrication of SnP2O7 nano‐structure

Nanorods of a diorganotin phosphonic diamide with formula [Sn(CH₃)₂(Cl)₂(L)₂]{L = C₆H₅(O)P(NHC₆H₁₁)₂} have been synthesized by sonochemical processes at different concentrations without any surfactant or capping agent. The structure and morphology of the prepared complex were investigated by using SEM‐EDAX, XRD, DLS, UV–Vis and FT‐IR spectroscopy. Nanoparticles with well‐defined rod shapes and sizes in the range 30–40 nm have been obtained. Also bulk form of the titled complex was synthesized and characterized by ¹H, ¹³C, ³¹P, ¹¹⁹Sn NMR, UV–Vis and FT‐IR spectroscopy and compared with its nano‐size. The thermal stabilities at bulk and nano‐size scale have been studied by thermal gravimetric (TG) and differential thermal analysis (DTA). Further, SnP₂O₇ nanoparticles were synthesized by direct calcination at 730 °C under air atmosphere and characterized using XRD, SEM, and TEM. From XRD measurements, we determined the mean size of the crystallites about 27.4 nm. It is found that the size and morphology of the tin pyrophosphate nano‐structures are dependent upon the particles size of precursor compound as well. Two different forms of metal coordination compound (1a, 1b) and the corresponding ligand (L) were screened for their antibacterial activity against the selected Gram‐positive and Gram‐negative bacteria, showing bactericidal activity for complexes 1a and 1b. In vitro cytotoxicity of compounds was studied against human carcinoma cell lines, A2780 (ovarian cancer) and PC‐3 (prostate cancer). Results indicated that 1a and 1b possess relatively strong cytotoxic activity against cancer cells with IC₅₀ values ranging from 93.2 to 376.2 μM for two exposure time (24 and 48 h).     

Co(II), Ni(II), Cu(II) and Zn(II) complexes of aminothiazole‐derived Schiff base ligands: Synthesis,characterization, antibacterial and cytotoxicity evaluation,bovine serum albumin binding and density functional theory studies

Transition metal complexes of type M(L)₂(H₂O)_x were synthesized, where L is deprotonated Schiff base 2,4‐dihalo‐6‐(substituted thiazol‐2‐ylimino)methylphenol derived from the condensation of aminothiazole or its derivatives with 2‐hydroxy‐3‐halobenzaldehyde and M = Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ (x = 0 for Cu²⁺ and Zn²⁺; x = 2 for Co²⁺ and Ni²⁺). The synthesized Schiff bases and their metal complexes were thoroughly characterized using infrared, ¹H NMR, electronic and electron paramagnetic resonance spectroscopies, elemental analysis, molar conductance and magnetic susceptibility measurements, thermogravimetric analysis and scanning electron microscopy. The results reveal that the bidentate ligands form complexes having octahedral geometry around Co²⁺ and Ni²⁺ metal ions while the geometry around Cu²⁺ and Zn²⁺ metal ions is four‐coordinated. The geometries of newly synthesized Schiff bases and their metal complexes were fully optimized in Gaussian 09 using 6–31 + g(d,p) basis set. Fluorescence quenching data reveal that Zn(II) and Cu(II) complexes bind more strongly to bovine serum albumin in comparison to Co(II) and Ni(II) complexes. The ligands and their complexes were evaluated for in vitro antibacterial activity against Escherichia coli ATCC 25922 (Gram negative) and Staphylococcus aureus ATCC 29213 (Gram positive) and cytotoxicity against lever hepatocellular cell line HepG2.     

Syntheses,characterization, powder X‐ray diffraction analysis and antibacterial and antioxidant activities of triphenylantimony(V) heteroleptic derivatives containing substituted oximes and morpholine dithiocarbamate

Triphenylantimony(V) heteroleptic derivatives containing substituted oximes and morpholine dithiocarbamate of the type Ph₃Sb[R(R′)C:NO]₂[S₂CN(CH₂CH₂)₂O] (where R = ─C₆H₅, R′ = ─CH₃ (I); R = ─C₆H₄CH₃, R′ = ─CH₃ (II); R = ─C₆H₄Cl, R′ = ─CH₃ (III); R = ─C₆H₄Br, R′ = ─CH₃ (IV); R = ─C₆H₄OH, R′ = ─H (V); R(R′)C = CCH₂(CH₂)₃CH₂ (VI)) were synthesized by successive substitution reactions of triphenylantimony(V) dibromide with the sodium salt of substituted oximes and morpholine dithiocarbamate in unimolar ratio. All these newly synthesized derivatives were characterized using physicochemical and elemental analyses and tentative structures have been proposed on the basis of infrared, (¹H, ¹³C) NMR and liquid chromatography–mass spectra. Spectral data revealed that the oxime behaves in a monodentate manner whereas morpholine dithiocarbamate behaves in an anisobidentate manner and thus distorted octahedral geometry has been proposed for these derivatives. Nanometric particle size (ca 25 nm) and monoclinic crystal system have been determined using power X‐ray diffraction data of two representative derivatives. Furthermore, these newly synthesized derivatives were screened against two bacteria, Bacillus subtilis (Gram‐positive) and Escherichia coli (Gram‐negative), to evaluate their antibacterial potential. Derivative VI exhibited maximum zone of inhibition (30 mm) against E. coli. Additionally two derivatives (I and II) were tested for their antioxidant potential, with derivative II exhibiting higher antioxidant potential (233 μM g^?1). Structure–activity relationships were also investigated.     

Synthesis,antimicrobial activity and molecular docking of di‐ and triorganotin (IV) complexes with thiosemicarbazide derivatives

Six organotin (IV) complexes with two ligands derived from 2,3‐butanedione and thiosemicarbazide have been synthesized and fully characterized by several spectroscopic techniques, including ¹¹⁹Sn NMR and single crystal X‐ray diffraction. Reactions of the ligand diacetyl‐2‐(thiosemicarbazone)‐3‐(3‐hydroxy‐2‐naphthohydrazone), L¹H₂, with SnR₂Cl₂ (R = Me, Bu, Ph) lead to the obtaining of complexes 1 – 3 with general formula [SnR₂L¹] (R = Me 1 , R = Bu 2 , R = Ph 3 ), in which the ligand is doubly deprotonated and behaves as a N₂SO donor, whereas from the reactions of diacetyl‐2‐thiosemicarbazone, HATs, with the same organotin precursors any complex could be isolated. By contrast, reaction of HATs with SnR₃Cl induces the ligand cyclization to form a 1,2,4‐triazine‐3‐thione that binds to the metal as a monoanionic donor in a mono or bidentate manner to form compounds 4 – 6 with formula [SnR₃L²] (R = Me 4 , R = Bu 5 , R = Ph 6 ). The antimicrobial activity of the ligands and the six complexes was tested towards bacteria and fungi, including clinical isolated strains. The results show that the ligands are devoid of activity, except HATs that displays activity against Bacillus subtilis. Conversely, the complexes exhibit good antimicrobial properties against Gram positive and negative bacteria, yeasts and moulds. The best results are obtained for complexes [SnBu₃L²] 5 and [SnPh₃L²] 6 , indicating that their more lipophilic nature could play an important role in the ease of microbial cell penetration. In some cases, these complexes display similar or higher activity than that of ampicillin and miconazole, used as antibacterial and antifungal positive controls, respectively. Docking study with DHPS protein (S. aureus) has shown that out of six drugs, the compound 6 has the best binding affinity (?8.5 Kcal/mol).     

Silver–N‐Heterocyclic Carbene Complexes: Synthesis,Characterization, and Antimicrobial Properties

Six new silver complexes containing symmetrical N ‐heterocyclic carbene (NHC ) ligands were synthesized by the reaction of azolium salts with Ag₂O in CH₂Cl₂ . These complexes were tested against Gram‐negative bacterial strains (Escherichia coli and Pseudomonas aeruginosa ), Gram‐positive bacterial strains (Enterococcus faecalis and Staphylococcus aureus ), and fungal strains (Candida albicans and Candida tropicalis ), and all tested complexes showed good activity against the different microorganisms.     

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.     

Antimicrobial and Antimalarial Activity of Novel Synthetic Mononuclear Ruthenium(II) Compounds

The present work was aimed that the two Ruthenium compounds namely, [Ru(A)₂(B)]Cl₂, where A = 1,10‐phenanthroline; B = 2‐NO₂‐phenyl thiosemicarbazone (Compound R₁)/2‐OH‐phenyl thiosemicarbazone (Compound R₂) have been tested for antibacterial activity at the concentrations of 1 mg/mL against various Gram‐Positive organisms (Lactobacillus, Staphylococcus pyrogenes, Bacillus subtilis, Staphylococcus aureus & Bacillus megatarium) and Gram‐Negative organisms (Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Enterobacter aerogenes, Salmonella paratyphi, Klebsiella pneumonia & Proteus mirabilis). The compounds were also tested for antifungal activity against Aspergillus clavatus, Aspergillus niger, Colletotrichum & Penicillium notatum by using agar diffusion assay and antimalarial activity against Plasmodium falciparum (Strain 3D7) using MTT assay. The results concluded that the compound R₁ exhibited significant antibacterial activity than R₂ against Gram‐Negative bacteria with zones of inhibition ranging from 15‐20 mm. and mild antibacterial activity against Gram‐Positive bacteria in comparison to tetracycline, streptomycin and rifampicin. These complexes were found to have moderate antifungal activity with no activity was however observed against Aspergillus niger. The compound, R₁ exhibited antimalarial activity at 10 μg/mL, whereas R₂ did not show antimalarial activity upto 50 μg/mL. Sensitivity to the compounds was greatest in the gram‐negative bacteria, followed by the gram‐positive bacteria and fungi.     

Highly Efficient One‐Pot Three‐Component Synthesis and Antimicrobial Activity of 2‐Amino‐4H‐chromene Derivatives

A remarkably efficient three‐component reaction to synthesize 2‐amino‐4H‐chromenes derivatives from malononitrile, various aromatic aldehydes, and orcinol was described at room temperature in CH₂Cl₂ in the presence of catalytic amount of triethylamine. In a facile one‐pot procedure, excellent yields of products were achieved in less than 1 h. Some of the synthesized 2‐amino‐4H‐chromenes derivatives demonstrated potent antibacterial activities against Gram‐positive bacteria including Staphylococcus aureus and Bacillus anthracis, indicated by disk method, minimum inhibitory concentration, and minimum bactericidal concentration approaches. However, none of the tested compounds expressed any antibacterial activities against Enterococcus faecalis and Gram‐negative bacteria.     

An Efficient One‐Pot Synthesis of Highly Substituted Pyridone Derivatives and Their Antimicrobial and Antifungal Activity

A series of carboxamide and cyano functionalized pyridone derivatives 4a – q have been synthesized via one‐pot synthesis of various aldehydes 1a – q , acetoacetanilide 2 , and cyanoacetamide 3 . The reaction was simple and afforded pyridone derivatives in good yield, 89 to 93%. The novel pyridone derivatives were achieved by Hantzch one‐pot synthesis. Moreover, the synthesized compounds were screened against Gram‐positive and Gram‐negative bacteria and fungi for their activity. Among them, compound 4c shows highest inhibition at 4.25 mm against Staphylococcus aureus and 3.75 mm against Escherichia coli Gram‐positive and Gram‐negative bacteria, respectively.     

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.