Synthesis, characterization and thermal decomposition of copper(II), nickel(II) and cobalt(II) complexes of 3-amino-5-methylpyrazole Schiff-bases

Metal Complexes of New Bioactive Pyrazolone Phenylhydrazones; Crystal Structure of 4-Acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one phenylhydrazone Ampp-Ph

The condensation reaction of phenylhydrazine and dinitrophenylhydrazine with 4-acetyl and 4-benzoyl pyrazolone precipitated air-stable acetyldinitrophenylhydrazone Ampp-Dh, benzoylphenylhydrazone Bmpp-Ph and benzoyldinitrophenylhydrazone Bmpp-Dh in their keto imine form; a study inspired by the burning interest for the development of new bioactive materials with novel properties that may become alternative therapeutic agents. Elemental analysis, FTIR, ¹H, and ¹³C NMR, and mass spectroscopy have been used to justify their proposed chemical structures, which were in agreement with the single crystal structure of Bmpp-Dh earlier reported according to X-ray crystallography. The single crystal structure of 4-acetyl-3-methyl-1-phenyl--pyrazoline-5-one phenylhydrazone Ampp-Ph, which crystallizes in a triclinic crystal system with a P-1 (No. 2) space group is presented. Octahedral Mn(II), Ni(II), Co(II), and Cu(II) complexes of these respective ligands with two molecules each of the bidentate Schiff base, coordinating to the metal ion through the azomethine nitrogen C=N and the keto oxygen C=O, which were afforded by the reaction of aqueous solutions of the corresponding metal salts with the ligands are also reported. Their identity and proposed structures were according to elemental analysis, FTIR spectroscopy, UV-VIS spectrophotometry (electronic spectra) and Bohr magnetic moments, as well as thermogravimetric analysis (TGA) results. A look at the antibacterial and antioxidant activities of synthesized compounds using the methods of the disc diffusion against some selected bacterial isolates and 1,1-diphenyl-2-picryl-hydrazil (DPPH) respectively, showed biological activities in relation to employed standard medicinal drugs.

Synthesis and Characterization of Bioactive Acylpyrazolone Sulfanilamides and Their Transition Metal Complexes: Single Crystal Structure of 4-Benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one Sulfanilamide

Two Schiff base ligands Ampp-Sn 1 and Bmpp-Sn 2, afforded by a condensation reaction between sulfanilamide and the respective acylpyrazolone carbonyl precursors, their Mn(II), Co(II), Ni(II), and Cu(II) complexes prepared by the reaction of ligands and corresponding metal salts in aqueous solutions, were synthesized and then characterized by both analytical and spectroscopic methods, in a view to developing new improved bioactive materials with novel properties. On the basis of elemental analysis, spectroscopic and TGA results, transition metal complexes, with octahedral geometry having two molecules of the bidentate keto-imine ligand each, have been proposed. The single crystal structure of Bmpp-Sn according to X-ray crystallography showed a keto-imine tautomer type of Schiff base, having three intramolecular bonds, one short N2⋯H2⋯O3 hydrogen bond of 1.90 Å and two long C13⋯H13⋯O2 and C32⋯H32⋯O3 hydrogen bonds of 2.48 Å. A moderate to low biological activities have been exhibited by synthesized compounds when compared with standard antimicrobial agents on screening the synthesized compounds against Staphylococcus aureus, Bacillus pumilus, Proteus vulgaris, and Aeromonas hydrophila for antibacterial activity and against free radical 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) for antioxidant activity.

2-Hydroxynaphthalene-1-carbaldehyde- and 2-(aminomethyl)pyridine-based Schiff base Cu(II) complexes for DNA binding and cleavage

Three mononuclear Cu(II) complexes, [CuCl(naph-pa)] (1), [Cu(bipy)(naph-pa)]Cl (2), and [Cu(naph-pa)(phen)]Cl (3) ((naph-pa)=Schiff base derived from the condensation of 2-hydroxynaphthalene-1-carbaldehyde and 2-picolylamine (=2-(aminomethyl)pyridine), bipy=2,2'-bypiridine, and phen=1,10-phenanthroline) were synthesized and characterized. Complex 1 exhibits square-planar geometry, and 2 and 3 exhibit square pyramidal geometry, where Schiff base and bipy/phen act as NNO and as NN donor ligands, respectively. CT (Calf thymus)-DNA-binding studies revealed that the complexes bind through intercalative mode and show good binding propensity (intrinsic binding constant K(b): 0.98×10(5), 2.22×10(5), and 2.67×10(5) M(-1) for 1-3, resp.). The oxidative and hydrolytic DNA-cleavage activity of these complexes has been studied by gel electrophoresis: all the complexes displayed chemical nuclease activity in the presence and absence of H(2)O(2). From the kinetic experiments, hydrolytic DNA cleavage rate constants were determined as 2.48, 3.32, and 4.10 h(-1) for 1-3, respectively. It amounts to (0.68-1.14)×10(8)-fold rate enhancement compared to non-catalyzed DNA cleavage, which is impressive. The complexes display binding and cleavage propensity to DNA in the order of 3>2>1.

Transition metal complexes of 5-bromosalicylidene-4-amino-3-mercapto-1,2,4-triazine-5-one: Synthesis, characterization, catalytic and antibacterial studies

Transition metal complexes of 5-bromosalicylidene-4-amino-3- mercapto-1,2,4-triazine-5-one with metal precursors, such as Cu(II), Ni(II), Co(II) and Pd(II), were synthesized and characterized by physicochemical and spectroscopic techniques. All the complexes are of the ML type. Based on analytical, spectral data and magnetic moments, the Co(II) and Ni(II) complexes were assigned octahedral geometries, while the Cu (II) and Pd(II) complexes square planar. A study on the catalytic oxidation of benzyl alcohol, cyclohexanol, cinnamyl alcohol, 2-propanol and 2- methyl-1-propanol was performed with N-methylmorpholine-N-oxide (NMO) and molecular oxygen as co-oxidants. All the complexes and their parent organic moiety were screened for their biological activity on several pathogenic bacteria and were found to possess appreciable bactericidal properties.

Synthesis and characterization of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with Schiff base derived from 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine

A few (1:1) and (1:2) metal complexes of cobalt(II), nickel(II), copper(II) and zinc(II) have been isolated with ligand derived from the condensation of 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine with 2-acetylpyridine (L(1)) and characterized by elemental analysis, conductivity measurements, infrared, electronic, (1)H NMR spectral data, magnetic and thermogravimetric analyses. Due to insolubility in water and most of the common organic solvents and infusibility at higher temperatures, all the complexes are thought to be polymeric in nature. A square-planar geometry was suggested for copper(II) and octahedral proposed for cobalt(II), nickel(II) and zinc(II). Some of the chemically synthesized compounds have been screened in vitro against the three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Escherichia coli) organisms. It is observed that the coordination of metal ion has pronounced effect on the microbial activities of the ligand. The metal complexes have higher antimicrobial effect than the free ligands.