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AbstractA Schiff base (imine) ligand, (E)-4-((2-hydroxy-3,5-diiodobenzylidene)amino)-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide (HL), was synthesized by condensation of 3,5-diiodosalicylaldehyde with sulfamethazine. The ligand was then complexed with Zn(II), Cu(II), Ni(II), Co(II) and Fe(II) employing a metal to ligand ratio of 1:2 to form chelates (1-5), [M(L)2(H2O)2]. Characterization was done by UV-visible, FTIR, 1H and 13C NMR spectroscopy, elemental analysis, magnetic moments, thermogravimetric analyses (TGA) and conductance studies. The Schiff base behaved as a bidentate ligand and metal chelates assumed octahedral geometry. MOE-docking was employed to assess binding of the Schiff base (HL) and its chelates (1-5) with 1T2P, 1VVQ, 2W61, 3U2D, 4H8E and 5K18 proteins. Results indicated that Zn(II) chelate (1) and Fe(II) chelate (5) are the most potent compounds. Antibacterial and antibiofilm activities were executed against Enterococcus faecalis, Staphylococcus aureus, Proteus mirabilis and Klebsiella pneumoniae. Antifungal activities were performed against Candida albicans and Aspergillus niger. The Schiff base exhibited moderate antibacterial/antifungal activities that were enhanced on chelation with metal ions. Zinc(II) chelate (1) and Fe(II) chelate (5) show excellent antibacterial/antifungal activities. Complex 2 exhibited good antibiofilm activity. [ABSTRACT FROM AUTHOR]

Four mononuclear complexes of Cu(II) and Zn(II) having a Schiff-base ligand and 1,10-phenanthroline/2,2′-bipyridine have been synthesized and characterized. From electronic spectral and magnetic susceptibility data, octahedral geometry has been proposed for the complexes. DNA-binding behaviors of these complexes are studied by absorption titration, electrochemical, and viscosity methods. The results indicate that the complexes bind to calf thymus DNA in an intercalative mode. The gel electrophoresis results reveal that 1 cleaves pBR322 DNA effectively. The ligand and its complexes have been screened for their antimicrobial activities against a few microorganisms. The data exhibit that they are better antimicrobial agents than the ligand. [ABSTRACT FROM PUBLISHER]

A dinuclear copper(II) complex with a newly synthesized tridentate Schiff-base ligand 2-[(2-hydroxy-ethylimino)-methyl]-4,6-diiodo-phenol (HL), of formula [Cu2L2Cl2 · C4H8O] (1), was prepared. Both the ligand and the complex were characterized by X-ray crystallography, confirming that the Schiff base is tridentate and its dinuclear copper(II) complex is five-coordinate from one nitrogen and two oxygens from L and two chlorides. The complex was assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae) activities by the MTT method. Complex 1 exhibited better antimicrobial activity than the ligand. [ABSTRACT FROM AUTHOR]

A new series of acyclic mononuclear copper(II) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and copper perchlorate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show a d-d transition in the range 500-800 nm, electrochemical studies of the complexes show irreversible one-electron-reduction process around -1.10 to -1.60 V. The reduction potential of the mononuclear copper(II) complexes shifts toward anodic direction upon increasing the chain length of the imine compartment. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μeff = 1.72-1.76 BM, close to the spin-only value of 1.73 BM. Electrochemical and catalytic studies of the complexes were compared on the basis of increasing the chain length of the imine compartment. All the complexes were screened for antifungal and antibacterial activities. [ABSTRACT FROM AUTHOR]

Schiff bases (L) viz, N,N',N'',N'''-tetra-3,4-dimethoxybenzalidene-3,3'-diaminobenzidine (TDBD), N,N',N'',N'''-tetra-4-hydroxy-3-methoxybenzalidene-3,3'-diaminobenzidine (THMBD), and N,N',N'',N'''-tetra-3-hydroxy-4-nitrobenzalidene-3,3'-diaminobenzidine (THNBD) afford binuclear [M2LCl4] complexes where M = Cu(II) or Zn(II). These Schiff bases and their binuclear complexes have been characterized by analytical and spectral data showing square-planar geometry on metalation with Cu2+. Intercalative binding of these complexes with DNA has been investigated by electronic absorption spectroscopy, viscosity measurements, cyclic voltammetry, and differential pulse voltammetry. Control DNA cleavage experiments using pUC19 supercoiled (SC) DNA and minor groove binder distamycin suggest that these synthesized complexes bind to the major groove. In the presence of a reducing agent like 3-mercaptopropionic acid (MPA), they show chemical nuclease activity. They also show an efficient photo-induced DNA cleavage on irradiation with a monochromatic UV light of 360 nm in the presence of inhibitors. Control experiments indicate the inhibition of cleavage in the presence of singlet oxygen quencher like sodium azide and the enhancement of cleavage in D2O show the formation of singlet oxygen as reactive species. The superoxide dismutase (SOD)-mimetic activity of the synthesized complexes has been assessed for their ability to inhibit the reduction of nitroblue tetrazolium chloride (NBT). The complexes have promising SOD-mimetic activity. The antimicrobial results indicate that the complexes inhibit the growth of bacteria and fungi more than free ligands. [ABSTRACT FROM AUTHOR]

Adduct formation between R2SnCl2 (R = methyl and phenyl) and PhSnCl3 as acceptors and Cu(II) complexes of tetradentate Schiff-base ligands [CuL], where L = [Salen, bis(salicylaldehyde)ethylenediimine], [3-MeOSalen, N,N'-bis(3-methoxysalicylaldehyde)ethylenediimine], [5-MeOSalen, N,N'-bis(5-methoxysalicylaldehyde)ethylenediimine], [5-BrSalen, N,N'-bis(5-bromosalicylaldehyde)ethylenediimine], [salpn, N,N'-bis(salicylaldehyde)1,3-propanediimine], [Salophen, bis(salicylaldehyde)phenylenediimine], [3-MeOSalophen, N,N'-bis(3-methoxysalicylaldehyde)phenylenediimine], and [5-MeOSalophen, N,N'-bis(5-methoxysalicylaldehyde)phenylenediimine], as donors have been investigated in acetonitrile by UV-Vis spectrophotometric analysis. The formation constants and thermodynamic free energies were measured using UV-Vis titration for 1 : 1 adduct formation at various temperatures (T = 293-313 K). The trend of adduct formation for copper Schiff-base complexes with a given tin acceptor decreases as follows: [image omitted] [image omitted]; [image omitted] The trend of the reaction of RnSnCl4-n acceptors toward a given copper Schiff-base complex is PhSnCl3 > Ph2SnCl2 > Me2SnCl2. The reactivity of PhSnCl3 toward Cu(Salen), Cu(Salpn), and Cu(Salophen) increases with increasing temperature. [ABSTRACT FROM AUTHOR]