Antibacterial Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Schiff bases Derived from Fluorobenzaldehyde and Triazoles

Antibacterial Schiff bases derived from 1,2,4-triazoles as well as their metal complexes incorporating cobalt(II), nickel(II), copper(II) and zinc(II) have been synthesized and characterized. Physico-chemical studies suggest that an octahedral geometry for the cobalt(II), nickel(II) and zinc(II)and square-planer geometry for the copper(II) complexes. These complexes have been screened for antibacterial activity against three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Pseudomonas aeruginosa) bacterial strains, and results compared with the activity of the free ligands. The metal complexes were found to be more potent against one or more bacterial strains than the free ligands.     

Antibacterial cobalt(II), nickel(II) and zinc(II) complexes of nicotinic acid-derived Schiff-bases

Nicotinic acid derived Schiff bases and their transition metal [cobalt(II), nickel(II) and zinc(II)] complexes have been prepared and characterized by physical, spectral and analytical data. The Schiff bases act as deprotonated tridentate ligands for the complexation of the above mentioned metal ions. These complexes, possessing the general formula [M(L)2] [where M = Co(II), Ni(II) and Zn(II) and L = HL1-HL4] showed an octahedral geometry of the metal ions. For determining the effect of metal ions upon chelation, the Schiff bases and their complexes have been screened for antibacterial activity against several pathogenic strains of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The new metal derivatives reported here were more bactericidal against one or more bacterial species as compared to the uncomplexed Schiff bases.     

Synthesis, characterization and biological studies of sulfonamide Schiff's bases and some of their metal derivatives

A new series of Schiff base ligands derived from sulfonamide and their metal(II) complexes [cobalt(II), copper(II), nickel(II) and zinc(II)] have been synthesized and characterized. The nature of bonding and structure of all the synthesized compounds has been explored by physical, analytical and spectral data of the ligands and their metal(II) complexes. The authors suggest that all the prepared complexes possess an octahedral geometry. The ligands and metal(II) complexes have been screened for their in vitro antibacterial activity against bacterial strains, Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi and for antifungal activity against fungal strains, Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. These assays enabled the identification of the metal complexes as an effective antimicrobial agent with low cytotoxicity.     

Antifungal Cobalt(II), Copper(II), Nickel(II) and Zinc(II) Complexes of Furanyl-,Thiophenyl-, Pyrrolyl-, Salicylyl- and Pyridyl-derived Cephalexins

Some novel cephalexin-derived furanyl, thiophenyl, pyrrolyl, salicylyl and pyridyl Schiff's bases and their cobalt (II), copper (II), nickel (II) and zinc (II) complexes have been synthesized and studied for their antifungal properties against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The presence of metal ions in the investigated Schiff's base complexes reported here lead to significant antifungal activity, whereas the parent ligands were generally less active.     

Antifungal cobalt(II), copper(II), nickel(II) and zinc(II) complexes of furanyl-,thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-derived cephalexins

Some novel cephalexin-derived furanyl, thiophenyl, pyrrolyl, salicylyl and pyridyl Schiff's bases and their cobalt (II), copper (II), nickel (II) and zinc (II) complexes have been synthesized and studied for their antifungal properties against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The presence of metal ions in the investigated Schiff's base complexes reported here lead to significant antifungal activity, whereas the parent ligands were generally less active.     

Design,synthesis, and biological properties of triazole derived compounds and their transition metal complexes

Triazole derived Schiff bases and their metal complexes (cobalt(II), copper(II), nickel(II), and zinc(II)) have been prepared and characterized using IR, ¹H and ¹³C NMR, mass spectrometry, magnetic susceptibility and conductivity measurements, and CHN analysis data. The structure of L², N-[(5-methylthiophen-2-yl)methylidene]-1H-1,2,4-triazol-3-amine, has also been determined by the X-ray diffraction method. All the metal(II) complexes showed octahedral geometry except the copper(II) complexes, which showed distorted octahedral geometry. The triazole ligands and their metal complexes have been screened for their in vitro antibacterial, antifungal, and cytotoxic activity. All the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. It is revealed that all the synthesized complexes showed better activity than the ligands, due to coordination.     

Antibacterial and antifugal mono- and di-substituted symmetrical and unsymmetrical triazine-derived Schiff-bases and their transition metal complexes

A new series of antibacterial and antifungal triazine-derived mono- and di-substituted (symmetrical and unsymmetrical) Schiff-bases and their cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments and IR and electronic spectral measurements. IR spectra indicated the ligands to act as tridentate towards divalent metal ions via a trazine-N, the azomethine-N and, indole-NH and deprotonated-O of salicylaldehyde. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II) and Zn(II)complexes and square-pyramid for Cu(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies show the metal complexes to be more antibacterial/ antifungal against two or more species as compared to the uncomplexed Schiff-base ligands.     

Studies on biologically active complexes of cobalt(II) and nickel(II) with dithiooxamide-derived ligands.

A number of cobalt(II) and nickel(II) complexes with novel dithiooxamide ligands derived from precursors such as benzonitrile, benzosulfonamide, benzaldehyde, benzoic acid, and phenol have been synthesized and characterized on the basis of their elemental analysis molar conductance, magnetic moment, H NMR and electronic and IR spectral data. These ligands and their complexes have been screened for their antibacterial activities against bacterial species Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, and Tuberculi bacilli. The studies indicate that in comparison to the ligands their metal complexes are more potent and antibacterial.     

In-vitro antibacterial, antifungal and cytotoxic activities of some coumarins and their metal complexes

A series of new antibacterial and antifungal coumarin-derived compounds and their transition metal complexes [cobalt (II), copper (II), nickel (II) and zinc (II)] have been synthesized, characterized and screened for their in vitro antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Bacillus cereus, Corynebacterium diphtheriae, Staphylococcus aureus and Streptococcus pyogenes bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, Candida glaberata. The results of these studies show the metal complexes to be more antibacterial and antifungal as compared to the uncomplexed coumarins. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.     

Synthesis,characterization and biological studies of sulfonamide Schiff’s bases and some of their metal derivatives

A new series of Schiff base ligands derived from sulfonamide and their metal(II) complexes [cobalt(II), copper(II), nickel(II) and zinc(II)] have been synthesized and characterized. The nature of bonding and structure of all the synthesized compounds has been explored by physical, analytical and spectral data of the ligands and their metal(II) complexes. The authors suggest that all the prepared complexes possess an octahedral geometry. The ligands and metal(II) complexes have been screened for their in vitro antibacterial activity against bacterial strains, Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi and for antifungal activity against fungal strains, Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. These assays enabled the identification of the metal complexes as an effective antimicrobial agent with low cytotoxicity.     

Metal binding and antibacterial activity of ciprofloxacin complexes

Four novel cobalt(II), copper(II), nickel(II) and zinc(II) complexes of the fluoroquinolone antibiotic ciprofloxacin have been prepared. The compounds were characterized by IR, UV-Visible, molar conductivity and elemental analyses. In all of the complexes, the drug ligand, ciprofloxacin (CFL) was coordinated through two carbonyl oxygen atoms. Octahedral and square-planar geometries have been proposed for the cobalt(II), nickel(II) and zinc(II), and copper(II) complexes, respectively. In vitro tests of susceptibility to these metal complexes showed stronger activity than that of ciprofloxacin against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Bacillus dysenteriae.     

Structural elucidation and biological significance of 2-hydroxy-1-naphthaldehyde derived sulfonamides and their first row d-transition metal chelates

2-Hydroxy-1-naphthaldehyde derived sulfonamides and their first row d-transition metal chelates [cobalt (II), copper (II), nickel (II) and zinc (II)] have been synthesized and characterized. The nature of bonding and structure of all the compounds have been deduced from elemental analyses, infrared, 1H NMR, 13C NMR, mass spectrometry, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry has been suggested for all the complexes. The metal complexes were screened for their antibacterial and antifungal activities on different species of pathogenic bacteria and fungi and their biopotency has been discussed. The results of these studies revealed that all compounds showed moderate to significant antibacterial activity against all bacterial strains and good antifungal activity against various fungal strains. In-vitro cytotoxic properties of all the compounds against Artemia salina was also studies by brine shrimp bioassay.     

Synthesis, spectral characterization and in vitro biological studies of Co(II), Ni(II) and Cu(II) complexes with 1,2,4-triazole Schiff bases

A series of metal complexes of cobalt(II), nickel(II) and copper(II) have been synthesized with newly derived biologically active ligands. These ligands were synthesized by the condensation of 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and 8-formyl-7-hydroxy-4-methylcoumarin. The probable structure of the complexes has been proposed on the basis of elemental analyses and spectral (IR, Uv-Vis, magnetic, ESR, FAB-mass and thermal studies) data. Electro chemical study of the complexes is also reported. All these complexes are non-electrolytes in DMF and DMSO. All the ligands and their Co(II), Ni(II) and Cu(II) complexes were screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Staphylococcus pyogenes and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Aspergillus flavus and cladosporium) activities by MIC method. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.     

Synthesis,spectral characterization and in vitro biological studies of Co(II), Ni(II) and Cu(II) complexes with 1,2,4-triazole Schiff bases

A series of metal complexes of cobalt(II), nickel(II) and copper(II) have been synthesized with newly derived biologically active ligands. These ligands were synthesized by the condensation of 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and 8-formyl-7-hydroxy-4-methylcoumarin. The probable structure of the complexes has been proposed on the basis of elemental analyses and spectral (IR, Uv-Vis, magnetic, ESR, FAB-mass and thermal studies) data. Electro chemical study of the complexes is also reported. All these complexes are non-electrolytes in DMF and DMSO. All the ligands and their Co(II), Ni(II) and Cu(II) complexes were screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Staphylococcus pyogenes and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Aspergillus flavus and cladosporium) activities by MIC method. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.     

In vitro antibacterial, antifungal & cytotoxic activity of some isonicotinoylhydrazide Schiff's bases and their cobalt (II), copper (II), nickel (II) and zinc (II) complexes

Isonicotinoylhydrazide Schiff's bases formed by the reaction of substituted and unsubstituted furyl-2-carboxaldehyde and thiophene-2-carboxaldehyde with isoniazid and, their Co (II), Cu (II), Ni (II) and Zn (II) complexes have been synthesized, characterized and screened for their in vitro antibacterial activity against Mycobacterium tuberculosis, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Bacillus cereus, Corynebacterium diphtheriae, Staphylococcus aureus and Streptococcus pyogenes bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. The results of these studies show the metal complexes to be more antibacterial and antifungal against one or more bacterial/fungal strains as compared to the uncomplexed compounds. The brine shrimp bioassay indicated Schiff's bases, L3 and L6 and, their Cu (II) and Ni (II) metal complexes to be cytotoxic against Artemia salina, while all other compounds were inactive (LD50 > 1000).     

In-vitro antibacterial, antifungal and cytotoxic properties of sulfonamide--derived Schiff's bases and their metal complexes

A series of new antibacterial and antifungal Schiff's bases derived from sulfonamides, as well as their transition metal complexes incorporating cobalt (II), copper (II), nickel (II) and zinc (II) were synthesized, characterized and screened for their in-vitro antibacterial activity against six Gram-negative (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi and Shigella dysentriae) and four Gram-positive (Bacillus cereus, Corynebacterium diphtheriae, Staphylococcus aureous and Streptococcus pyogenes) bacterial strains and for in-vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, Candida glaberata. The results of these studies show the metal complexes to be more antibacterial and antifungal as compared to the uncomplexed Schiffs' bases. The brine shrimp bioassay was also carried out to study the in-vitro cytotoxic properties of these synthesized ligands and their complexes.     

Antibacterial and Antifugal Mono- and Di-substituted Symmetrical and Unsymmetrical Triazine-derived Schiff-bases and their Transition Metal Complexes

A new series of antibacterial and antifungal triazine-derived mono- and di-substituted (symmetrical and unsymmetrical) Schiff-bases and their cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments and IR and electronic spectral measurements. IR spectra indicated the ligands to act as tridentate towards divalent metal ions via a trazine-N, the azomethine-N and, indole-NH and deprotonated-O of salicylaldehyde. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II) and Zn(II)complexes and square-pyramid for Cu(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies show the metal complexes to be more antibacterial/antifungal against two or more species as compared to the uncomplexed Schiff-base ligands.     

Binding of transition metal ions [cobalt, copper, nickel and zinc] with furanyl-, thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-derived cephalexins as potent antibacterial agents

A method is described for the preparation of novel cephalexin-derived furanyl-, thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-containing compounds showing potent antibacterial activity. The binding of these newly synthesized antibacterial agents with metal ions such as cobalt(II), copper(II), nickel(II) and zinc(II) has been studied and their inhibitory properties against various bacterial species such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae are also reported. These results suggest that metal ions to possess an important role in the designing of metal-based antibacterials and that such complexes are more effective against infectious diseases compared to the uncomplexed drugs.     

Metal binding and antibacterial activity of ciprofloxacin complexes

Four novel cobalt(II), copper(II), nickel(II) and zinc(II) complexes of the fluoroquinolone antibiotic ciprofloxacin have been prepared. The compounds were characterized by IR, UV-Visible, molar conductivity and elemental analyses. In all of the complexes, the drug ligand, ciprofloxacin (CFL) was coordinated through two carbonyl oxygen atoms. Octahedral and square-planar geometries have been proposed for the cobalt(II), nickel(II) and zinc(II), and copper(II) complexes, respectively. In vitro tests of susceptibility to these metal complexes showed stronger activity than that of ciprofloxacin against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Bacillus dysenteriae.     

In-vitro antibacterial, antifungal and cytotoxic activity of cobalt (II), copper (II), nickel (II) and zinc (II) complexes with furanylmethyl- and thienylmethyl-dithiolenes: [1, 3-dithiole- 2-one and 1,3-dithiole-2-thione

Some antibacterial and antifungal furanylmethyl-and thienylmethyl dithiolenes and, their Co(II), Cu(II), Ni (II) and Zn (II) complexes have been synthesized, characterized and screened for their in vitro antibacterial activity against four Gram-negative; Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Shigella flexeneri, and two Gram-positive; Bacillus subtilis and Staphylococcus aureus bacterial strains, and for in-vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. All compounds showed significant antibacterial and antifungal activity. The metal complexes, however, were shown to possess better activity as compared to the simple ligands. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties.