Antimicrobial activity and spectral, magnetic and thermal studies of some transition metal complexes of a Schiff base hydrazone containing a quinoline moiety

A series of new copper(II), cobalt(II), nickel(II), manganese(II), iron(III), and uranyl(VI) complexes of the Schiff base hydrazone 7-chloro-4-(benzylidene-hydrazo)quinoline (HL) were prepared and characterized. The Schiff base behaves as a monobasic bidentate ligand. Mononuclear complexes with the general composition [ML2(Cl)m(H2O)2(OEt)n] x xEtOH (M = Cu(II), Co(II), Ni(II), Mn(II), Fe(III) or UO2(VI); m and n = 0-1; x = 1-3) were obtained in the presence of Li(OH) as a deprotonating agent. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes except the Cu(II) and UO2(VI) ones. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, while the UO2(VI) complex displays its favored heptacoordination. The Schiff base ligand, HL, and its complexes were tested against one strain gram +ve bacteria (Staphylococcus aureus), gram -ve bacteria (Escherichia coli), and Fungi (Candida albicans). The prepared metal complexes exhibited higher antibacterial activities than the parent ligand and their biopotency is discussed.     

Synthesis, characterization and biological activities of Cu(II), Co(II), Mn(II), Fe(II), and UO2(VI) complexes with a new Schiff Base hydrazone: O-hydroxyacetophenone-7-chloro-4-quinoline hydrazone

The Schiff base hydrazone ligand HL was prepared by the condensation reaction of 7-chloro-4-quinoline with o-hydroxyacetophenone. The ligand behaves either as monobasic bidentate or dibasic tridentate and contain ONN coordination sites. This was accounted for be the presence in the ligand of a phenolic azomethine and imine groups. It reacts with Cu(II), Ni(II), Co(II), Mn(II), UO(2) (VI) and Fe(II) to form either mono- or binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, NMR, Mass, and UV-Visible spectra. The magnetic moments and electrical conductance of the complexes were also determined. The Co(II), Ni(II) and UO(2) (VI) complexes are mononuclear and coordinated to NO sites of two ligand molecules. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, the Ni(II) complex is octahedral while the UO(2) (VI) complex has its favoured heptacoordination. The Co(II), Mn(II) complexes and also other Ni(II) and Fe(III) complexes, which were obtained in the presence of Li(OH) as deprotonating agent, are binuclear and coordinated via the NNNO sites of two ligand molecules. All the binuclear complexes have octahedral geometries and their magnetic moments are quite low compared to the calculated value for two metal ions complexes and thus antiferromagnetic interactions between the two adjacent metal ions. The ligand HL and metal complexes were tested against a strain of Gram +ve bacteria (Staphylococcus aureus), Gram -ve bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited high antibacterial activities.     

Synthesis, magnetic, spectral, and antimicrobial studies of Cu(II), Ni(II) Co(II), Fe(III), and UO2(II) complexes of a new Schiff base hydrazone derived from 7-chloro-4-hydrazinoquinoline

A new hydrazone ligand, HL, was prepared by the reaction of 7-chloro-4-hydrazinoquinoline with o-hydroxybenzaldehyde. The ligand behaves as monoprotic bidentate. This was accounted for as the ligand contains a phenolic group and its hydrogen atom is reluctant to be replaced by a metal ion. The ligand reacted with Cu(II), Ni(II), Co(II), Fe(III), and UO2(II) ions to yield mononuclear complexes. In the case of Fe(III) ion two complexes, mono- and binuclear complexes, were obtained in the absence and presence of LiOH, respectively. Also, mixed ligand complexes were obtained from the reaction of the metal cations Cu(II), Ni(II) and Fe(III) with the ligand (HL) and 8-hydroxyquinoline (8-OHqu) in the presence of LiOH, in the molar ratio 1:1:1:1. It is clear that 8-OHqu behaves as monoprotic bidentate ligand in such mixed ligand complexes. The ligand, HL, and its metal complexes were characterized by elemental analyses, IR, UV-vis, mass, and 1H NMR spectra, as well as magnetic moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an extra square-planar geometry, while Ni(II) mixed complex has also formed a tetrahedral configuration and UO2(II) complex which formed a favorable pentagonal biprymidial geometry. Magnetic moment of the binuclear Fe(III) complex is quite low compared to calculated value for two iron ions complex and thus shows antiferromagnetic interactions between the two adjacent ferric ions. The HL and metal complexes were tested against one stain Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited higher antibacterial acivities.     

噻吩甲酰基吡唑啉酮缩β-丙氨酸配合物的合成、表征及极谱行为

An ewacylpyrazolone Schiff base and its metal complexes were synthesized. The electrochemical behaviour of complexes was studied. In non-aqueous solvent, the new Schiff base 1-phenyl-3-methyl-4-(2-thenoyl)-5-pyrazolone-2-alanine (HL) was synthesized by the reaction of 2-alanine with 1-phenyl-3-methyl-4-(2-thenoyl)-5-pyrazolone and its complexes UO2(II), Cu(II), Co(II) and Fe(II) were obtained from refluxing a solution of Schiff base and metal nitrate. The polarographic wave of Cu(II) complex was determined at 1.24V(vs.SCE) in the medium of HAc-NaAc (PH=4.6). On the basis of elemental analysis and molar conductance, the general formula of the complexes, UO2L2?H2O,CuL2?2H2O,CoL2?2H2O and FeL2?2H2O, were given. They were characterized by IR, UV-visible, 1H NMR, 13CNMR, thermal analyses and magnetic moments. The results show that the metal ions except UO2 2+ exhibit six coordination in the complexes. The peak current is produced by the reduction of Cu2+ in the copper complex, and the number of electron transfer is 1 at electrode reaction.     

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 anticancer activities of Schiff base ligand and its transition metal mixed ligand complexes with heterocyclic base

A new Schiff base ligand (HL) was prepared via a condensation reaction of quinoline‐2‐carboxaldhyde with 2‐aminophenol in a molar ratio of 1:1. Its transition metal mixed ligand complexes with 1,10‐phenanthroline (1,10‐phen) as co‐ligand were also synthesized in a 1:1:1 ratio. HL and its mixed ligand complexes were characterized using elemental analysis, infrared, ¹H NMR, mass and UV–visible spectroscopies, molar conductance, magnetic measurements, solid reflectance, thermal analysis, electron spin resonance and X‐ray diffraction. Molar conductance measurements showed that all complexes have an electrolytic nature, except Cd(II) complex. From elemental and spectral data, the formulae [M(L)(1,10‐phen)(H₂O)]Cl_x?nH₂O (where M = Cr(III) (x = n = 2), Mn(II) and Ni(II) (x = 1, n = 2), Fe(III) (x = n = 2), Co(II), Cu(II) and Zn(II) (x = 1, n = 2)) and [Cd(L)(1,10‐phen)Cl]?3H₂O for the metal complexes have been proposed. The geometric structures of complexes were found to be octahedral. Powder X‐ray diffraction reflected the crystalline nature of the complexes; however, the Schiff base is amorphous. HL and its mixed ligand complexes were screened against Gram‐positive bacteria (Streptococcus pneumoniae and Bacillus subtilis) and Gram‐negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Antifungal activity was determined against Aspergillus fumigatus and Candida albicans, the data showing that most complexes had activity less than that of the Schiff base while Mn(II), Fe(III) and Ni(II) complexes showed no significant antifungal activity. The anticancer activity of HL and its metal complexes was also studied against breast and colon cell lines. The metal complexes showed IC₅₀ higher than that of HL, especially the Cu(II) complex which showed the highest IC₅₀ against breast cell line.     

Ligational behavior of a bidentate coumarin derivative towards CoII,NiII, and CuII: synthesis,characterization, electrochemistry,and antimicrobial studies

A series of new Co(II), Ni(II), and Cu(II) complexes of Schiff base derived from coumarin have been prepared and characterized by analytical and spectral methods. The Schiff base is synthesized by the condensation of 2,6-diaminopyridine and 3-acetylcoumarin in 1 : 1 stoichiometric ratio. All complexes have 1 : 1 metal : ligand ratio except the nickel complex, where it was found to be 1 : 2. UV-Vis spectra and magnetic moment studies confirm the existence of tetrahedral and octahedral geometries around cobalt(II) and nickel(II) metal ions, respectively, but copper(II) chloride/nitrate/sulfate complexes have square-planar geometry and copper(II) acetate complex is distorted octahedral. ESR spectra of copper complexes at room temperature and liquid nitrogen temperature were tetragonal. All the complexes were found to be more active against bacteria except Ni(II) complex; only CuLSO₄ and CuL(CH₃COO)₂ have shown the enhanced activity against fungi.     

Transition metal complexes of a Schiff base: synthesis,characterization, and antibacterial studies

Synthesis of a new Schiff base derived from 2-hydroxy-5-methylacetophenone and glycine and its coordination with compounds Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and UO₂(VI) are described. The ligand and complexes have been characterized on the basis of analytical, electrical conductance, infrared, ESR and electronic spectra, magnetic susceptibility measurements, and thermogravimetric analysis. The ligand is a dibasic tridentate (ONO) donor in all the complexes except Zn(II), where it is a monobasic bidentate (OO) donor. The solid state DC electrical conductivity of ligand and its complexes have been measured over 313–398 K, and the complexes were semiconducting. Antibacterial activities of ligand and its metal complexes have been determined by screening the compounds against various Gram (+) and Gram (?) bacterial strains.     

Synthesis,structural, and biological studies of some bivalent metal ion complexes with the tridentate Schiff base ligand

New complexes of a Schiff base derived from 2-hydroxy-5-chloroacetophenone and glycine with Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and UO₂(VI) have been synthesized. The ligand and the complexes have been characterized on the basis of analytical data, electrical conductance, IR, ESR, and electronic spectra, magnetic susceptibility measurements and thermogravimetric analysis. The ligand acts as a dibasic tridentate (ONO) donor molecule in all the complexes except the Zn(II) complex, where it acts as a monobasic bidentate (OO) donor. Antibacterial activities of the ligand and its metal complexes have been determined by screening the compounds against various Gram(+) and Gram(−) bacterial strains. The solid state d.c. electrical conductivity of the ligand and its complexes has been measured over 313–398 K and the complexes were found to be of semiconducting nature. The article is published in the original.     

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.     

Transition metal complexes of Schiff base ligand based on 4,6-diacetyl resorcinol

Novel Schiff base ligand based on the condensation of 4,6-diacetyl resorcinol with 2-amino-4-methylthiazole in addition to its metal complexes with Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) ions have been synthesized. The structure, electronic properties, and thermal behaviour of Schiff base and its metal complexes have been studied by elemental analysis, mass, ¹H NMR, IR spectra, thermal analysis, and theoretically by density function theory. The ligand acted as mononegative bidentate (NO) ligand and all complexes showed octahedral geometry except Cu (II) showed tetrahedral geometry as indicated from the spectral and magnetic studies. The Cu (II), Zn (II) and Cd (II) complexes were non electrolytes while the rest of the complexes were electrolytes. The antibacterial plus anticancer activities of the parent Schiff base and its metal complexes were screened. In addition, the molecular docking study was performed to explore the possible ways for binding to Crystal Structure of Human Astrovirus capsid protein (5ibv) receptor.     

Anti-hepatocellular carcinoma,antioxidant, anti-inflammation and antimicrobial investigation of some novel first and second transition metal complexes

New coordination compounds of some selected metal ions from the first and second transition metals series with a Schiff base were synthesized and characterized. The Schiff base is derived from 4-Aminoantipyrine and 3-(hydroxyimino) butan-2-one. The compounds were characterized by different analysis tools like; elemental analysis, mass spectra, Fourier transform infrared (FTIR) as well as electronic spectra, magnetic measurements, molar conductance and thermal analysis technique. All complexes were formed with 1:1 (metal: ligand) stoichiometry except Mn (II) where 1:2 (Mn: ligand) is formed. Schiff base ligand interacted as a tridentate ligand by using the nitrogen atoms of the imine and the oximato groups and the carbonyl oxygen atom as donor groups with all studied metal ions except copper (II) and manganese (II) where the carbonyl oxygen is not shared in the coordination. These complexes show various physicochemical properties. X-ray powder diffraction shows different crystal systems; Cd (II) complex: hexagonal, Cu (II) complex: orthorhombic; and [Ni (II), Mn (II), Rh (III) & Pd (II)] complexes: monoclinic. All compounds showed potent cytotoxicity against the growth of human liver cancer cell lines. The square planar Pd (II) complex was more active than those of octahedral geometries of all other synthesized complexes. Cd (II) complex has the highest microbial growth inhibition than the rest of the prepared complexes. The docking active sites interactions were evaluated using the selected proteins EGFR tyrosine kinase and protein crystal structure of GlcN-O-P synthase. in vitro antioxidant assay revealed potent free radical scavenging activity of the three synthesized Cu (II), Pd (II) and Rh (III) complexes that exceeded the standard ascorbic acid. Pd (II) complex shows the most significant inhibition denaturation percent.     

Synthesis and spectroscopic studies of homo-binuclear, alkoxo bridged homo- and hetero-tetranuclear metal complexes of a bis-N2O4 Schiff base ligand derived from ethanolamine and macroacyclic tetranaphthaldehyde

Three new homo-binuclear Ni(II), Cu(II), Zn(II) complexes (2-4), homo-tetranuclear Cu(II) complex (5), and hetero-tetranuclear Cu(II)-Ni(II) complex (6) of a macroacyclic potentially bis-hexadentate N2O4 Schiff base have been synthesized. The imino-alcohol ligand, H4L was obtained by the condensation of ethanolamine with 2,2'-[2,3-bis(1-formyl-2-naphthyloxymethyl)-but-2-ene-1,4-diyldioxy]bis(naphthalene-1-carbaldehyde). The structures of both the Schiff base and its complexes have been proposed by elemental analyses, spectroscopic data i.e. IR, 1H and 13C NMR, UV-vis, electrospray ionisation mass spectra, molar conductivities and magnetic susceptibility measurements. The ligand has two similar compartments to bind first primary two metal ions, and acts bi- or tetra-negative, bis-tetradentate forming five membered chelate ring. However, secondary two metal ions (either Cu2+ or Ni2+) are ligated with dianionic oxygen atoms of the alcohol groups and are linked to the 1,10-phenanthroline-nitrogen atoms in the tetranuclear complexes (5 and 6).     

Phosphorus Schiff base ligand and its complexes: Experimental and theoretical investigations

A phosphorus-containing Schiff base was prepared from bis{3-[2-(4-amino-1,5-dimethyl-2-phenylpyrazol-3-ylideneamino)ethyl]indol-1-ylmethyl}phosphinic acid and paraformaldehyde as a novel antibacterial compound. The reaction of the Schiff base ligand with VO(IV), Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II) and Pt(IV) led to binuclear species of metal complexes, depending on the ratio of metal ion and ligand. The ligand and its complexes were investigated using elemental analysis, Fourier transform infrared, ¹H NMR, ¹³C NMR, UV–visible and mass spectra, thermogravimetric analysis, conductivity measurements and thermal analysis. The results showed that the Schiff base behaves as a tetradentate ligand; moreover, on the basis of conductance results, of all the prepared complexes are non-electrolytes, excepting the Pt(IV) complex. The metal complexes were found to be formed with a metal-to-ligand ratio of 2:1, except for the Pt(IV) complex with a ratio of 1:1. The activation thermodynamic parameters (ΔE*, ΔH*, ΔS*, ΔG* and K) and the activation energy of thermal decomposition were determined from thermogravimetric analysis using the Coats–Redfern method. The biological activities of the metal complexes were screened against the growth of bacteria and fungi in vitro to assess the antimicrobial potential and study the toxicity of the compounds. The prepared compounds have noteworthy antimicrobial properties.     

Synthesis,Characterization, and Thermal Investigation of Some Metal Complexes Containing Polydentate ONO-Donor Heterocyclic Schiff Base Ligand

Cu(II), Co(II), Ni(II), and Zn(II) metal complexes with new heterocyclic Schiff base derived from 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2-one and 3-methoxysalicylaldehyde have been synthesized and characterized on the basis of elemental analyses, electronic, IR, and ¹H NMR spectra, and also by aid of molar conductivity measurements, magnetic moment measurements, and thermogravimetric analyses. It has been found that the Schiff base behaves as a neutral bidentate (NO) and tridentate (ONO) ligand forming chelates with 1 : 2 (metal : ligand) stoichiometry. Octahedral configuration is suggested for metal complexes. The conductivity data for the Ni(II) complexes are consistent with those expected for a 1 : 2 electrolyte.     

New metal(II) complexes with ceftazidime Schiff base

Complexes of Co(II), Ni(II) and Cu(II) with the Schiff base (LH) derived from ceftazidime and salicylaldehyde were synthesized. The proposed structures of the new metal complexes based on the results of elemental analyses, molar conductivity, IR, DRUV and ¹H NMR spectra, effective magnetic moment and thermal analysis were discussed. The surface morphology of Schiff base and metal complexes was studied by SEM. The composition of the metal complexes was ML₂, where L is the deprotonated Schiff base ligand and M = Co(II), Ni(II) and Cu(II). IR spectral data indicated the Schiff base ligand being bidentately coordinated to the metallic ions with N and O atoms from azomethine and phenolic groups. All the complexes have square-planar geometry and are nonelectrolytes. The thermal analysis recorded that TG, DTG, DTA and DSC experiments confirmed the assigned composition and gave information about the thermal stability of complexes in dynamic air atmosphere. Theoretical investigation of the molecular structure of Schiff base ligand and its complexes was studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. The newly synthesized complexes were tested for in vitro antibacterial activity against selected Gram-negative and Gram-positive bacterial strains, and they exhibited an antibacterial activity superior to that of the Schiff base ligand.     

Some divalent metal(II) complexes of novel potentially tetradentate Schiff base N,N′‐bis(2‐carboxyphenylimine)‐2,5‐thiophenedicarboxaldhyde: Synthesis,spectroscopic characterization and bioactivities

A novel tetradentate dianionic Schiff base ligand, N ,N ′‐bis(2‐carboxyphenylimine)‐2,5‐thiophenedicarboxaldhyde (H₂L) and some first row d‐transition metal chelates (Co(II), Cu(II), Ni(II) and Zn(II)) were synthesized and characterized using various physicochemical and spectroscopic methods. The spectroscopic data suggested that the parent Schiff base ligand coordinates through both deprotonated carboxylic oxygen and imine nitrogen atoms. The free Schiff base and its metal chelates were screened for their antimicrobial activities for various pathogenic bacteria and fungi using the agar well diffusion method. The antibacterial and antifungal activities of all the newly synthesized compounds are significant compared to the standard drugs ciprofloxacin and nystatin. The antioxidant activities of the compounds were determined by reduction of 1,1‐diphenyl‐2‐picrylhydrazyl and compared with that of vitamin C as a standard. DNA binding ability of the novel Schiff base and its complexes was investigated using absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and thermal denaturation. The obtained results clearly demonstrate that the binding affinity with calf thymus DNA follows the order: Cu(II) complex > Ni(II) complex > Zn(II) complex > Co(II) complex >H₂L. Furthermore, the DNA cleavage activity of the newly synthesized ligand and its metal complexes was investigated using supercoiled plasmid DNA (pUC18) gel electrophoresis.     

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.     

Coordination compounds of some transition metal ions with new Schiff base ligand derived from dibenzoyl methane. Structural characterization,thermal behavior,molecular structure,antimicrobial, anticancer activity and molecular docking studies

Series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes were prepared with tetradentate Schiff base ligand derived by condensation of 2‐aminophenol with dibenzoylmethane. The novel Schiff base H₂L (2–2′‐((1Z,1Z’)‐(1,3‐diphenyl propane‐1,3 diylidene) bis (azanylylidene) diphenol) and its binary metal complexes were characterized by physicochemical procedures i.e. elemental analysis, FT‐IR, UV–Vis, thermal analyses (TGA/DTG), mass spectrometry, magnetic susceptibility and conductometric measurements. On the basis of these studies, an octahedral geometry for all these complexes was proposed expect Ni(II) complex which had tetrahedral geometry. Molar conductivity values revealed that the complexes were electrolytes except Mn(II), Zn(II) and Cd(II) complexes were non electrolytes. The ligand bound to the metal ions via two azomethine N and two phenolic OH as indicated from the IR and ¹H NMR spectral study. The molecular and electronic structures of H₂L and its zinc complex were optimized theoretically and the quantum chemical parameters were calculated. The antimicrobial activity against a number of bacterial organisms as Streptococcus pneumonia, Bacillus Subtilis, Pseudomonas aeruginosa and Escherichia coli and fungi as Aspergillus fumigates, Syncephalastrum racemosum, Geotricum candidum and Candida albicans by disk diffusion method were screened for the Schiff base and its complexes. The Cd(II) complex has potent antimicrobial activity. Anticancer activity of the Schiff base ligand and its metal complexes were evaluated in human cancer (MCF‐7 cells viability). The Cr(III) complex exhibited higher activity than other complexes and ligand. Molecular docking was used to predict the binding between Schiff base ligand (H₂L) and its Zn(II) complex and the receptors of RNA of amikacin antibiotic (4P20) and human‐DNA‐Topo I complex (1SC7). The docking study provided useful structural information for inhibition studies.     

Co(II), Ce(III) and UO2VI) bis-salicylatothiosemicarbazide complexes: binary and ternary complexes, thermal studies and antimicrobial activity

A series of new metal complexes of Co(II), Ce(III) and UO(2)(VI), with the Schiff base ligand, H2L, bis-salicylatothiosemicarbazide have been prepared in presence of different molar ratios of LiOH.H2O as a deprotonating agent. Also, the ternary complexes were prepared by using 2-aminopyridine (2-Ampy) or oxalic acid (Ox) as a secondary ligand. All synthesized compounds were identified and confirmed by elemental analyses, molar conductivities, spectral (UV-Vis, IR, 1H NMR, mass) and magnetic moment measurements as well as TG-DSC technique. The changes in the selected vibrational absorption bands in IR and NMR spectra of the Schiff base ligand upon coordination indicate that, the ligand behaves as a neutral, monoanionic and/or dianionic tetradentate manner with ONNO donor sites. Conductance measurements suggest the non-electrolytic and 1:1 electrolytic nature of the metal complexes. Thermal studies suggest a mechanism for degradation of the metal complexes as function of temperature supporting the chelation modes, moreover, show the possibility of obtaining new complexes pyrolytically in the solid state which cannot be synthesized from solution. Antimicrobial screening of the free ligand and its binary complexes showed that, the free ligand and some metal complexes possess antimicrobial activities towards four type of bacteria and five types of fungi and these results were compared with eleven type of known antibiotics.