Synthesis, Characterization and Biological Studies of Some Transition Metal Complexes with Pyrazine Schiff Base Hydra zone Ligand

2020 ◽  
Vol 15 (2) ◽  
pp. 61-72

New pyrazine carbohydra zone ligand N'-(1-(5-chloro-2-hydroxyphenyl) ethylidene) pyrazine-2-carbohydrazide (H2L), prepared by the condensation of equimolar amounts of pyrazine-2-carbohydrazide with 2-hydroxy-5-chloroacetophenone in methanol, reacts with suitable metal salt precursors to give complexes of two general formulae: [M(HL)(Cl)(H2O)2] {M = Mn(II), Co(II), Ni(II) and Cu(II)} and [M(L)(H2O)] {M = Zn(II) and Cd(II)}. Structure of ligand was confirmed by elemental analysis, IR, 1H and 13C NMR and mass spectroscopy, while synthesized complexes were additionally characterized by magnetic susceptibility measurements, molar conductivity measurements, XRD, ESR (for Cu(II)), SEM and thermogravimetric analysis. Spectroscopic studies confirmed a tridentate ONO donor behavior of the ligand towards the central metal ion. The molar conductance (12–17 W–1 cm2 mol–1) measurements in DMSO indicated non-electrolytic nature. Thermal behavior of the complexes suggests their extended stability and the thermal decomposition generally proceeds via partial loss of the organic moiety and ends with the formation of respective metal oxide as a final product. Various kinetic and thermodynamic parameters were evaluated using the Coats-Redfern method. The solid-state electrical conductivity of the complexes measured in the temperature range 303-463 K suggested their semiconducting behavior. The ligand and its metal complexes were screened in vitro for their antibacterial activity against the Gram-positive bacteria S. aureus and B. subtilis, the Gram-negative bacteria E. coli and S. typhi and the fungi C. albicans and A. niger. The obtained results indicated improved activity of the complexes compared to the free ligand against all studied bacterial and fungal species.

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
Sulekh Chandra ◽  
Smriti Raizada ◽  
Monika Tyagi ◽  
Archana Gautam

A series of metal complexes of Cu(II) and Ni(II) having the general composition[M(L)X2]with benzil bis(thiosemicarbazone) has been prepared and characterized by element chemical analysis, molar conductance, magnetic susceptibility measurements, and spectral (electronic, IR, EPR, mass) studies. The IR spectral data suggest the involvement of sulphur and azomethane nitrogen in coordination to the central metal ion. On the basis of spectral studies, an octahedral geometry has been assigned for Ni(II) complexes but a tetragonal geometry for Cu(II) complexes. The free ligand and its metal complexes have been tested in vitro against a number of microorganisms in order to assess their antimicrobial properties.


2009 ◽  
Vol 2009 ◽  
pp. 1-6 ◽  
Author(s):  
Sulekh Chandra ◽  
Shikha Parmar ◽  
Yatendra Kumar

A series of metal complexes of Zn(II) and Hg(II) having the general composition [where L = 2-formylpyridine thiosemicarbazone; M = Zn(II) and Hg(II); X = , and ] have been prepared and characterized by elemental chemical analysis, molar conductance, and spectral (IR and mass) studies. The IR spectral data suggests the involvement of sulphur and azomethane nitrogen in coordination to the central metal ion. On the basis of spectral studies, a tetrahedral geometry has been assigned for Zn(II) and Hg(II) complexes. The free ligand and its metal complexes have been tested in vitro against a number of microorganisms in order to assess their antimicrobial properties.


2009 ◽  
Vol 63 (5) ◽  
Author(s):  
Ajay Mishra ◽  
Shivani Mishra ◽  
Narender Kaushik

AbstractSynthesis, characterization and biological studies of some thiodiamine metal complexes are described. Cobalt(II) and copper(II) complexes of type [Cu(L)2Cl2] and [Co(L)2SO4], where L = (cyclohexyl-N-thio)-1,2-ethylenediamine (L1) and (cyclohexyl-N-thio)-1,3-propanediamine (L2), were synthesized. The synthesized copper and cobalt thiodiamine complexes were characterized by elemental analysis, IR, mass, UV-VIS and 1H NMR spectroscopic studies. Thiodiamines coordinate as a bidentate N-S ligand. The binding sites are azomethine nitrogen and thioamide sulfur. Molar conductance values in dimethylsulfoxide indicate non-electrolyte nature of the complexes. In vitro-antimicrobial screening shows promising results against both bacterial and fungal strains.


Author(s):  
AMAL M ALOSAIMI ◽  
INES EL MANNOUBI ◽  
SAMI A ZABIN

Objective: This work aimed at synthesizing tridentates asymmetrical Schiff base ligands containing sulfur atom and using them for preparing metal complexes with the iron triad metals. The prepared compounds were assayed in vitro for antimicrobial potential and in vivo molluscicidal activity. Methods: The unsymmetrical tridentate Schiff bases (SL1, SL2, and SL3) were prepared using 2-aminothiophenol as primary amine and condensed with 2-carboxybenzaldehyde, 2-hydroxy-1-naphthaldehyde, and 7-formyl-8-hydroxyquinoline. These ligands were used in preparing metal complexes with iron triad metals. The synthesized Schiff base ligands and their corresponding metal complexes were characterized and their proposed structures were confirmed using different physical and spectroscopic analytical techniques. All ligands and their corresponding metal complexes were assayed against different bacterial and fungal strains using the agar disk-diffusion technique. The molluscicidal activity was performed according to the standard reported methods as cited in the literature and by observing the toxicity and lethal dose according to the WHO guidelines. Results: The synthesized ligands behave as tridentate (NOS) ligands and form mononuclear complexes with the general formula [M(SL)2] with an octahedral geometry around the central metal ion. Metal complexes were non-electrolytic in nature. The in vitro antibacterial and antifungal examination results showed weak activity of the ligands, and there was enhanced activity with the complexes. The in vivo molluscicidal activity of the tested compounds showed good activity. Conclusion: The targeted compounds were prepared successfully, characterized, and showed some biological activity but lower than the standard reference drugs.


Author(s):  
VAIRALAKSHMI M ◽  
PRINCESS R ◽  
JOHNSON RAJA S

Objectives: The aim of our work was to synthesize novel mixed ligand-metal complexes and evaluation of antimicrobial, antioxidant assay, and analysis of catalytic oxidation of cyclohexane. Methods: The complexes were characterized by means of various physicochemical techniques such as elemental analysis, molar conductance, magnetic susceptibility, infrared (IR), electronic absorption, 1H NMR (proton magnetic resonance), and mass spectral studies. The antimicrobial screening study was done by disc diffusion method. The catalytic activity of the complexes was observed in the oxidation of cyclohexane using eco-friendly hydrogen peroxide as oxidant. Results: On comparing the 1H NMR and IR spectral data of free ligand and its complexes, it was found to be azomethine (CH=N) proton which is formed in the free ligand. During complexation, the azomethine proton is coordinated to the metal ion and the phenolic oxygen is coordinated to the metal ion by deprotonation. The analytical data and mass spectra of the ligand and the complexes confirm the stoichiometry of metal complexes as being of the (MLY)Cl type and the metal to ligand ratio is 1:1. The antimicrobial, antioxidant, and catalytic potential were evaluated and the result shows the better activity of the complexes than the ligand. Conclusion: It was found to be copper(II) and zinc(II) complexes which are effective against all the bacteria when compared to standard drug streptomycin. Copper(II) complex was found to be effective antibacterial agent against Aspergillus niger and Aspergillus flavus in comparison to the standard drug Nystatin. The zinc complex exhibited good catalytic activity.


2012 ◽  
Vol 77 (5) ◽  
pp. 627-637 ◽  
Author(s):  
Pal Singh ◽  
Nanda Srivastava

Mononuclear metal complexes of the type [ML1]Cl2 (where, M = = Cu(II), Co(II) or Ni(II) and L1 = ligand) were synthesized by the reaction of a new N4 coordinating ligand, derived from diacetylbisethylenediamine with benzoic acid, and the corresponding hydrated metal chloride salts. The metal complexes were characterized by elemental analysis, melting point determination, molar conductance and magnetic moment measurements, IR, UV-Vis, 1H- and 13C-NMR, and ESR spectroscopy. The ligand and all the metal complexes were stable in the solid state at room temperature. From the analytical and spectroscopic investigations, the stoichiometry of the complexes was found to be 1:1 (metal:ligand). Based on the electronic spectra and magnetic moment data, the metal complexes had a square planar geometry. The molar conductance values show the 1:2 electrolytic nature of the metal complexes. A cyclic voltammetric study of the Cu(II) metal complex has also performed, which showed one electron quasi-reversible reduction around -0.92 to -1.10 V. In vitro biological activities of the ligand and metal complexes was checked against two bacteria Bacillus subtilis and Escherichia coli and two fungi Aspirgillus niger and A. flavus which showed the antibacterial and antifungal properties of the ligand and its metal complexes.


2018 ◽  
Vol 6 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Ahmad S. Abu-Khadra ◽  
Ahmed S. Afify ◽  
Amr Mohamed ◽  
Rabie S. Farag ◽  
Hassan Y. Aboul-Enein

Aim:Metal complexes of (E)-N-(4-(thiophen-2-ylmethyleneamino) phenylsulfonyl) acetamide (S.TH) Schiff bases derived from sulfacetamide (N-[4-(amino-phenyl) sulfonil] acetamide) and 2-thiophenecarboxaldehyde were synthesized and characterized.Methods and Results:The synthesized compositions have been characterized using different physico-chemical techniques. The investigation included elemental analysis, melting point measurements, proton NMR, UV spectroscopy, FT-IR, magnetic susceptibility, conductance measurements, mass spectral analysis, and inductively coupled plasma mass spectrometry (ICP-MS) for determining the concentrations of metal ions. The measured values for molar conductance indicated that the majority of the prepared complexes were nonelectrolytes. The biological activity of the prepared compositions has been investigated.Conclusion:Spectroscopic studies suggested that most of the complexes were coordinated in a regular octahedral arrangement where S.TH ligand and the central metal atom were coordinated through two N amino azomethine groups (−HC=N−) and two sulfur atoms of S thiophene rings in 2L:1M molar ratio. Complexes have shown a promising activity upon screening for the antibacterial characteristics, and antifungal (Aspergillus fumigatesandCandida albicans)


Author(s):  
Mallikarjun S. Yadawe ◽  
Shrishila N. Unki ◽  
Sangamesh A. Patil

Some lanthanum(III) complexes have been synthesized by reacting lanthanum(III) metal salt with Schiff bases derived from 3-substituted-4-amino-5-mercapto-1,2,4-triazole and glyoxal/biacetyl/benzyl. All these complexes are not soluble in common organic solvents. However sparingly soluble in DMF and DMSO. The chemical analysis of the complexes confirmed to the stoichiometry of the type La(III)LNO3·H2O. La(III)LCl·H2O and La(III)LNCS·H2O respectively. The chelation of the complexes has been proposed in the light of analytical, spectral studies. The measured molar conductance values indicate that, the complexes are non-electrolytes. The Schiff bases and their complexes have been screened for their antibacterial and antifungal activities. The results of these studies show the metal complexes to be more antibacterial and antifungal as compared to the uncomplexed coumarins.


2020 ◽  
Vol 32 (4) ◽  
pp. 759-764
Author(s):  
K. Savitha ◽  
S. Vedanayaki

Co(II), Ni(II) and Cu(II) homo binuclear Schiff base metal complexes were synthesized from terephthalaldehyde and 2-amino-4-chlorophenol in methanol using template method. The structure of the ligand and its metal complexes were established by elemental, molar conductance, UV, magnetic moment, IR, 1H & 13C NMR, EPR, mass, thermal and PXRD. Molar conductance values showed that all complexes were non-electrolytic in nature. The IR spectral data provides the coordination of azomethine nitrogen and oxygen with central metal ion. UV, ESR and magnetic moment values suggest square planar geometry for Co(II), Ni(II) and Cu(II) complexes. TGA and DSC analysis data show the thermal stability of the ligand and its metal complexes. The crystalline nature of ligand and its metal complexes were investigated by powder-XRD. The DNA cleavage activities of all the complexes assayed on PUC18 DNA shows nuclease ability.


2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
J. Senthil Kumaran ◽  
S. Priya ◽  
N. Jayachandramani ◽  
S. Mahalakshmi

A new series of Cu (II), Ni (II), Co (II) and Zn (II) complexes have been synthesized from the Schiff base derived from 4-hydroxy-3-methoxybenzylidine-4-aminoantipyrine and 2-aminophenol. The structural features have been determined from their elemental analysis, magnetic susceptibility, molar conductance, Mass, IR, UV-Vis,1H-NMR,13C-NMR and ESR spectral studies. The redox behavior of the copper complex has been studied by cyclic voltammetry. The data confirm that the complexes have composition of ML2type. The electronic absorption spectral data of the complexes propose an octahedral geometry around the central metal ion. All the metal complexes with DNA structure were guided by the presence of inter-molecular C–HO and C–HN hydrogen bonds. The biological activity of the synthesized compounds were tested against the bacterial species such asBacillus subtilis, Staphylococcus aureus, Proteus vulgarisand fungal species such asCandida albicansby thewell-diffusionmethod.


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