scholarly journals Synthesis, spectroscopic, biological activities and DFT calculations of nickel(II) mixed-ligand complexes of tridentate Schiff bases

2020 ◽  
Vol 45 (1) ◽  
pp. 18
Author(s):  
Abidemi Iyewumi Demehin ◽  
Mary Adelaide Oladipo ◽  
Banjo Semire

Ni(II) mixed-ligand complexes of [NiLNH3] (where L= N-salicylidene-o-aminophenol (L1), N-(5-methoxysalicylidene-o-aminophenol) (L2) and N-(2-hydroxy-1-naphthalidene)-o-aminophenol) (L3) containing ONO tridentate Schiff bases and ammonia were synthesized and characterized by elemental analysis, infrared, ultraviolet-visible, proton and carbon-13 spectroscopies. Theoretical calculations were also performed on the optimized structures of the Ni(II) mixed-ligand complexes. The Infrared and ultraviolet-visible spectra of the complexes were calculated, and the results compared with the corresponding experimental spectra to augment the experimental structural identification. The elemental analysis data confirmed the formation of 1:1:1 [metal: Schiff base: ammonia] molar ratio. The NMR spectra showed that the Schiff bases coordinated to the Ni(II) ion via the two deprotonated phenolic oxygen and azomethine nitrogen atoms. The biological studies showed that the complexes exhibited higher antibacterial and antioxidant activities than the free Schiff base ligands.

2020 ◽  
Vol 12 (1) ◽  
pp. 251-258
Author(s):  
S. Isyaku ◽  
H.N. Aliyu ◽  
E.C. Ozoro ◽  
T. Abubakar

Manganese(II) complexes of Schiff bases; 2-acetylthiophene-4‑phenylthiosemi-carbazone (AT-PTSC) and 2-furylmethylketone-4-phenylthiosemi-carbazone  (AF‑PTSC) derived from condensation of 2-acetylthiophene and 2-furylmethylketone (2-acetylfuran) each with 4-phenylthiosemicarbazide in (1:1 molar ratio) ethanol, have been synthesized. The Schiff bases and the Mn(II) complexes were characterized on the basis of melting point/decomposition temperature, solubility, magnetic susceptibility, infrared spectra, molar conductance measurements,  elemental and gravimetric  analyses. The Mn(II) complexes show moderate values of decomposition temperatures. The Schiff bases and the complexes were soluble in some common organic solvents. Infrared spectral data of the Schiff bases and their complexes, indicate coordination of the Schiff bases to the metal(II) ion via azomethine nitrogen. The effective magnetic moment of the Mn(II) complexes suggested an octahedral geometry. The molar conductance values of the complexes show that the complexes are electrolytes. The results of the elemental analysis of the ligands and their complexes are in good agreement with the calculated values, suggesting a 1:2 (metal-ligand) ratio. Antimicrobial screenings of the ligands and their complexes were conducted against gram-positive (Staphylococcus aureus,) and two gram-negative (Salmonella typhi, and Escherichia coli) bacteria specie. Also three fungi mainly (Candida albicans, Mucus indicus and Aspergillus flavus) were tested. The results showed that both the ligands and the complexes are active against the bacteria and the fungi specie. Keywords: Ligand, Schiff base, 4-phenylthiosemicarbazide, 2-acetylthiophene, 2-acetylfuran molar conductivity, magnetic susceptibility, elemental analysis.


2020 ◽  
Vol 12 (1) ◽  
pp. 85-92
Author(s):  
S. Isyaku ◽  
H.N. Aliyu ◽  
E.C. Ozoro ◽  
T. Abubakar

Manganese (II) complexes of Schiff bases; 2-acetylthiophene 4‑phenylthiosemi-carbazone (AT-PTSC) and 2-furylmethylketone-4-phenylthiosemi-carbazone (AF‑PTSC) derived from condensation of 2-acetylthiophene and 2-furylmethylketone (2-acetylfuran) each with 4-phenylthiosemicarbazide in (1:1 molar ratio) ethanol, have been synthesized. The Schiff bases and the Mn(II) complexes were characterized on the basis of melting point/decomposition temperature, solubility, magnetic susceptibility, infrared spectra, molar conductance measurements,  elemental and gravimetric  analyses. The Mn(II) complexes show moderate values of decomposition temperatures. The Schiff bases and the complexes were soluble in some common organic solvents. Infrared spectral data of the Schiff bases and their complexes, indicate coordination of the Schiff bases to the metal(II) ion via azomethine nitrogen. The effective magnetic moment of the Mn(II) complexes suggested an octahedral geometry. The molar conductance values of the complexes show that the complexes are electrolytes. The results of the elemental analysis of the ligands and their complexes are in good agreement with the calculated values, suggesting a 1:2 (metal-ligand) ratio. Antimicrobial screenings of the ligands and their complexes were conducted against gram-positive (Staphylococcus aureus,) and two gram-negative (Salmonella typhii, and Escherichia coli) bacteria specie. Also three fungi mainly (Candida albicans, Mucus indicus and Aspergillus flavus) were tested. The results showed that both the ligands and the complexes are active against the bacteria and the fungi specie. Keywords: Ligand, Schiff base, 4-phenylthiosemicarbazide, 2-acetylthiophene, 2-acetylfuran molar conductivity, magnetic susceptibility, elemental analysis.


2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Temitayo Aiyelabola ◽  
Ezekiel Akinkunmi ◽  
Efere Obuotor ◽  
Idowu Olawuni ◽  
David Isabirye ◽  
...  

Coordination compounds of 4-hydroxy-3-nitro-2H-chromen-2-one and their mixed ligand complexes with aminoethanoic acid and pyrrolidine-2-carboxylic acid were synthesized by the reaction of Cu(II) and Zn(II) salts in molar ratio 1 : 2 for the coumarin complexes and 1 : 1 : 1 for the mixed ligand complexes, in basic media. The compounds formed were characterized using infrared, Uv-vis spectrophotometric analyses, mass spectrometry, magnetic susceptibility measurements, and EDX analyses. It was concluded that 4-hydroxy-3-nitro-2H-chromen-2-one coordinated as a monobasic ligand for all the complexes; it also coordinated via the carbonyl moiety in the case of the Cu(II) mixed ligand complexes. Similarly it was proposed that the amino acids also coordinated in a bidentate fashion via their amino nitrogen and carboxylate oxygen atoms. The synthesized compounds were screened for their antimicrobial and cytotoxic activities. The complexes exhibited marginal antimicrobial activity but good cytotoxic activity.


2020 ◽  
Vol 32 (12) ◽  
pp. 3157-3164
Author(s):  
Kiran Singh ◽  
Preeti Siwach ◽  
Amit Sharma

A series of metal-complexes of Co2+, Ni2+, Cu2+, Zn2+ and Pd2+ with new Schiff base named 5-methyl-4-((3-fluoro-4-methoxybenzylidiene)-amino)-3-thiol-s-triazole have been synthesized and characterized. Schiff base is formed by the condensation of 3-fluoro-4-methoxy-benzaldehyde and 4-amino-3-mercapto-5-methyl-1,2,4-triazoles (AMMT). After synthesis, Schiff base is characterized by IR and NMR techniques. Metal complexes are characterized by different techniques as IR, NMR, ESR, electronic and fluorescence. Elemental analysis and magnetic measurements of metal complexes have also been carried out. Using different techniques, tentative geometry for newly synthesized complexes have been proposed i.e. square planar for copper and palladium complexes and octahedral for rest of the metal complexes. The biological activities of all the metal complexes of this series are also examined.


2011 ◽  
Vol 8 (3) ◽  
pp. 1258-1263 ◽  
Author(s):  
A. K. Mapari ◽  
M. S. Hate ◽  
K. V. Mangaonkar

The mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with Schiff basesN-(2-hydroxy-1-naphthylidene)-4-methylaniline (L1H) andN-(2-hydroxybenzylidene)-2,3-dimethylaniline (L2H) have been synthesized and characterized. The resulting complexes were characterized by elemental analysis, thermogravimetric analysis, magnetic moment measurements, conductivity measurements,1H NMR, IR, UV-visible and ESR spectral studies. The Schiff bases acts as bidentate monobasic ligands, coordinating through deprotonated phenolic oxygen and azomethine nitrogen atoms. The complexes are non-electrolytic in DMSO. The presence of the two coordinated water molecules in these complexes was indicated by IR spectra and thermogravimetric analysis of the complexes. From the analytical and spectral data the stoichiometry of these complexes have been found to be [M(L1)(L2)(H2O)2] {where M = Co(II) , Ni(II), Cu(II) and Zn(II)}. It is found that Co(II), Ni(II), Cu(II) and Zn(II) complexes exhibited octahedral geometry. The antimicrobial activities of ligands and their mixed ligand complexes were screened by disc diffusion method. It is found that the metal complexes have higher antimicrobial activity than the free ligand.


2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Nayaz Ahmed ◽  
Mohd Riaz ◽  
Altaf Ahmed ◽  
Madhulika Bhagat

The present paper deals with the synthesis and characterization of metal complex of tridentate Schiff base ligand derived from the inserted condensation of 2-aminobenzimidazole (1H-benzimidazol-2-amine) with salicylaldehyde (2-hydroxybenzaldehyde) in a 1 : 1 molar ratio. Using this tridentate ligand, complex of Zn(II) with general formula ML has been synthesized. The synthesized complex was characterized by several techniques using molar conductance, elemental analysis, FT-IR, and mass and 1HNMR spectroscopy. The elemental analysis data suggest the stoichiometry to be 1 : 1 [M : L]. The complex is nonelectrolytic in nature as suggested by molar conductance measurements. Infrared spectral data indicate the coordination between the ligand and the central metal ion through deprotonated phenolic oxygen, imidazole nitrogen of benzimidazole ring, and azomethine nitrogen atom. Spectral studies suggest tetrahedral geometry for the complex. The pure compound, synthesized ligand, and metal complex were screened for their antimicrobial activity.


2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Suman Malik ◽  
Suparna Ghosh ◽  
Bharti Jain ◽  
Archana Singh ◽  
Mamta Bhattacharya

The present paper deals with the synthesis and characterization of metal complexes of Schiff base derived from xipamide, a diuretic drug. The bidentate ligand is derived from the inserted condensation of 5-aminosulfonyl-4-chloro-N-2,6-dimethyl phenyl-2-hydroxybenzamide (Xipamide) with salicylaldehyde in a 1 : 1 molar ratio. Using this bidentate ligand, complexes of Hg(II), Zn(II), and VO(IV) with general formula ML2 have been synthesized. The synthesized complexes were characterized by several techniques using molar conductance, elemental analysis, magnetic susceptibility, FT-IR spectroscopy, electronic spectra, mass spectra, and particle size analysis. The elemental analysis data suggest the stoichiometry to be 1 : 2 [M : L]. All the complexes are nonelectrolytic in nature as suggested by molar conductance measurements. Infrared spectral data indicate the coordination between the ligand and the central metal ion through deprotonated phenolic oxygen and azomethine nitrogen atoms. Spectral studies suggest tetrahedral geometry for Hg(II), Zn(II) complexes, and square pyramidal geometry for VO(IV) complex. The pure drug, synthesized ligand, and metal complexes were screened for their antifungal activities against Aspergillus niger and Aspergillus flavus. The ligand and its Hg(II) and VO(IV) complexes were screened for their diuretic activity too.


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