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In the present investigation, a Schiff base N'(1),N'(3)-bis(Z)-(2-hydroxynapthyl)methylidene]benzene-1,3-dicarbod ihydrazide (L-1) and its Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized as novel photosensitizing agents for photodynamic therapy (PDT). The interaction of these complexes with calf thymus DNA (CT DNA) has been explored using absorption, thermal denaturation and viscometric studies. The experimental results revealed that Co(II) and Ni(II) complexes on binding to CT DNA imply a covalent mode, most possibly involving guanine N7 nitrogen of DNA, with an intrinsic binding constant K-b of 4.5 x 10(4) M-1 and 4.2 x 10(4) M-1, respectively. However, interestingly, the Cu(II) complex is involved in the surface binding to minor groove via phosphate backbone of DNA double helix with an intrinsic binding constant K-b of 5.7 x 10(4) M-1. The Co(II), Ni(II) and Cu(II) complexes are active in cleaving supercoiled (SC) pUC19 DNA on photoexposure to UV-visible light of 365 nm, through O-1(2) generation with quantum yields of 0.28, 0.25 and 0.30, respectively. Further, these complexes are cytotoxic in A549 lung cancer cells, showing an enhancement of cytotoxicity upon light irradiation. (C) 2013 Elsevier B.V. All rights reserved.

A new tetra-aza macrocyclic ligand, L (C24H16N12O2S4) and its complexes of type, [MLCl2] and [CuL]Cl2 (where M = Ni(II), Co(II); L = N,N′-(benzene-1,3-diyldi-1,3,4-thiadiazole-5,2-diyl)bis{2-[(5-benzene-1,3-diyl-1,3,4-thiadiazol-2-yl)amino]acetamide}) were synthesized and characterized by the spectral and analytical techniques. An octahedral geometry has been proposed for Ni(II) and Co(II) complexes while Cu(II) complex exhibit a square planar geometry. All the synthesized metal complexes were screened for their in vitro antimicrobial activity against selected species of pathogenic bacteria and fungi. The binding property of the complexes with CT-DNA was studied by absorption spectral analysis, followed by viscosity measurement and thermal denaturation studies. The photo induced cleavage studies revealed that the complexes possess photonuclease property against pUC19 DNA under UV–visible irradiation.

The two Fe(II) complexes of fused aromatic N and S containing ligands of the type [Fe(HMq)3] (PF6)2 [complex (1)] and [Fe(HSeq)3] (PF6)2 [complex (2)] (where HMq = 2-mercapto-4-methylquinoline and HSeq = 2-seleno-4-methylquinoline) were synthesized and structurally characterized. The DNA binding property of the complexes with calf thymus DNA has been investigated using absorption spectra, viscosity measurements, as well as thermal denaturation experiments. Intrinsic binding constant Kb has been estimated at room temperature. The absorption spectral studies indicate that the complexes intercalate between the base pairs of the CT-DNA tightly with intrinsic DNA binding constant of 1.9 × 106 M−1 for complex (1) and 2.5 × 106 M−1 for complex (2) in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2, respectively. Detailed analysis revealed that the metal complexes intercalates into the DNA base stack as intercalator. The oxidative cleavage activity of the complexes (1) and (2) were studied by using gel electrophoresis ...

The three Ni(II) complexes of fused aromatic N-containing ligands such as [Ni(bnp)(3)](PF(6))(2) (1), [Ni(phen)(2)(bnp)](PF(6))(2) (2) and [Ni(bpy)(2)(bnp)](PF(6))(2) (3) (where bnp=dibenzo(b)1,8-naphthpyridine, phen=1,10-phenanthroline and bpy=bipyridine) were synthesized and structurally characterized. Elemental analysis, magnetic and spectroscopic data suggested octahedral geometry for all the complexes. Binding of these complexes with (ds)DNA were analyzed by absorption spectra, viscosity and thermal denaturation studies. Detailed analysis revealed that the metal complexes intercalates into the DNA base stack as intercalator. The oxidative cleavage activities of the complexes were studied with supercoiled (SC)pUC19 DNA by using gel electrophoresis, and the results show that complexes have potent nuclease activity.

Mixed ligand complexes of the type [Ni(phen)2(bnp)](PF6)2 · 2H2O (1) and [Ni(bpy)2(bnp)](PF6)2 · 2H2O (2) (where phen, 1,10,Phenanathroline; bpy, 2,2 bipyridine; bnp, benzo[1.8]naphthyridinone-2-ol) have been synthesized and characterized by employing analytical and spectral methods. The DNA binding properties of the complexes with calf thymus-DNA were studied by using absorption spectra, viscosity measurements as well as thermal denaturation experiments. The absorption spectra indicated that the Ni(II) complexes intercalate tightly between the base pairs of the DNA with intrinsic DNA binding constants of 1.9 × 104 M−1 for (1) and 2.5 × 104 M−1 for (2) in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2, respectively. The large enhancement in the relative viscosity of DNA on binding to the bnp supports the proposed DNA binding modes. The oxidative cleavage and photo-cleavage activity of complexes (1) and (2) were studied. The photo-induced DNA cleavage activities of the complexes in the presence and absence of d...

With the aim of evaluating interaction between double-stranded calf thymus (ds)DNA and sulphur containing fused planar rings, the derivatives of 1,8-naphthyridine containing thiono groups were synthesized by the condensation of 2-mercapto-3-formyl[1,8]naphthyridines using 1-chloroacetone, 2-chloroacetamide, chloroaceticacid, and 2-chloro-1-phenylethanone in the presence of anhydrous potassium carbonate as s catalyst under solvent free microwave irradiation. The structures of the compounds were elucidated on the basis of elemental analysis, IR, (1)H NMR, and mass spectra. The interaction of thieno[2,3-b]-1,8-naphthyridine-2-carboxylic acid (TNC) (3a) with ct-DNA was studied by UV-Vis spectrophotometry, viscosity, thermal denaturation, as well as cyclic voltammetry experiments. On binding to DNA, the absorption spectrum underwent bathochromic and hypochromic shifts. Binding parameters, determined from spectrophotometric measurements indicated a binding constant of Kb=2.1 x 10(6) M(-1). The thieno[2,3-b]-1,8-naphthyridine-2-carboxylic acid (3a) increases the viscosity of sonicated rod-like DNA fragments. The binding of TNC to DNA increased the melting temperature by about 4 degrees C. The decrease in peak current heights and shifts of peak potential values are observed by the addition of calf thymus DNA in cyclic voltammetry studies.

The synthesis and characterisation of title complexes of the ligand Methylquinolino[3,2-b][1,5]benzodiazepine (MQBD) and Methyl-quinolino[3,2-b][1,5]benzoxazepine (MQBO) are reported. The complexes have been characterized by elemental analysis, molar conductance, magnetic studies, IR,1H NMR and UV-visible studies. They have the stoichiometry [ML2Cl2] where M=Co(II)/Ni(II), L=MQBD/MQBO and [MLCl2] where M=Zn(II)/Cd(II), L=MQBD/MQBO. The antibacterial and antifungal activity of the metal complexes has been investigated.

2-Chloro-6-methylquinoline-3-carbaldehyde was condensed witho-Phenylenediammine and 2-aminophenol in presence of potassium iodide. The resulting Methylquinolino[3,2-b][1,5]benzodiazepine (MQBD) and Methylquinolino[3,2-b][1,5]benzoxazepine(MQBO) were characterized by elemental analysis and spectral studies. The metal chelatesvizPd(II), Rh(III) and Ru(III) of ligands were prepared and characterized by metal-ligand (M:L) ratio, UV-Visible, IR,1H NMR spectroscopes and magnetic properties. The antibacterial and antifungal activity of MQBD, MQBO and its metal complexes were screened against various bacteria and fungi. The results show that all these samples are good antimicrobial agents.

A new class of Cu(II) and Co(II) complexes of azo-containing Schiff base of the type [Cu(L1)2] and [Co(L1)2], where L1 = 4-[(E)-{2-hydroxy-3-[(E)-(4-bromophenyl)diazenyl]benzylidene}amino]benzoic acid have been synthesized and characterized. Extension of conjugation and the presence of free carboxylic acid group of the ligand L1 increased the wavelength of the complexes from visible region to the near IR region (620–850 nm). The Cu(II) and Co(II) complexes interacted with CT-DNA via intercalative mode with the respective Kb value of 3.2 × 104 M−1 and 2.9 × 104 M−1 and acted as proficient photocleavers of SC pUC19 DNA in UV-A light, forming 1O2 as the reactive oxygen species with the quantum yield of 0.38 and 0.36, respectively. Furthermore, the Cu(II) and Co(II) complexes showed photocytotoxicity toward two selected tumor cell lines MCF-7 and A549 by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) method, and the Cu(II) complex exhibits higher photocytotoxicity than Co(II) complex against each of the selected cell lines, this result is identical with their DNA binding ability order.

Pure ZnS and ZnS:Y nanoparticles were synthesized by a chemical coprecipitation route using EDTA-ethylenediamine as a stabilizing agent. X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrometry (FTIR), thermogravimetric-differential scanning calorimetry (TG-DSC), and UV-visible and photoluminescence (PL) spectroscopy were employed to characterize the as-synthesized ZnS and ZnS:Y nanoparticles, respectively. XRD and TEM studies show the formation of cubic ZnS:Y particles with an average size of ~4.5 nm. The doping did not alter the phase of the zinc sulphide, as a result the sample showed cubic zincblende structure. The UV-visible spectra of ZnS and ZnS:Y nanoparticles showed a band gap energy value, 3.85 eV and 3.73 eV, which corresponds to a semiconductor material. A luminescence characteristics such as strong and stable visible-light emissions in the orange region alone with the blue emission peaks were observed for doped ZnS nanoparticles at room temperature. The PL intensity of orange emission peak was found to be increased with an increase in yttrium ions concentration by suppressing blue emission peaks. These results strongly propose that yttrium doped zinc sulphide nanoparticles form a new class of luminescent material.

Two mixed ligand complexes of the type [M(phen)(2)(qbdp)](PF(6))n.xH(2)O where M = Co(III) and Ni(II), qbdp = quinolo[3,2-b] benzodiazepine and phen = 1,10-phenanthroline, n = 3 or 2, x = 2 or 3 have been synthesized and characterized by employing analytical and spectral methods. The DNA binding property of the complexes with calf thymus-DNA has been investigated by using absorption spectra, viscosity measurements as well as thermal denaturation studies. The absorption spectral results indicate that the Co(III) and Ni(II) complexes intercalate between the base pairs of the DNA tightly with intrinsic DNA binding constant of 6.4 x 10(4) and 4.8 x 10(4) M(-1) in Tris HCl buffer containing 50 mM NaCl, respectively. The large enhancement in the relative viscosity of DNA on binding to the quinolo [3,2-b] benzodiazepine supports the proposed DNA binding modes. The complexes on reaction with super coiled (SC) DNA shows nuclease activity.

The synthesis and characterization of title complexes of the ligand Quinolino[3,2-b]benzodiazepine (QBD) and Quinolino[3,2-b]benzoxazepine (QBO) are reported. The complexes have been characterized by elemental analysis, molar conductance, magnetic studies, IR,HNMR, and UV-visible studies. They have the stoichiometry [ML2C12], where M=Co(II)/Ni(II), L=QBD/QBO, and [MLC12], where M=Zn(II)/Cd(II), L=QBD/QBO. The antibacterial and antifungal activity of the metal complexes has been investigated. The complexes were found to have higher antimicrobial activity than the parent ligand.

DNA binding and photocleavage characteristics of a series of mixed ligand complexes of the type[M(bpy)2qbdp](PF6)n⋅xH2O(whereM=Co(III) or Ni(II),bpy=2.2′-bipryidine, qbdp = Quinolino[3,2-b]benzodiazepine,n=3or 2 andx=5or 2) have been investigated. The DNA binding property of the complexes with calf thymus DNA has been investigated by using absorption spectra, viscosity measurements, as well as thermal denaturation studies. Intrinsic binding constant (Kb) has been estimated under similar set of experimental conditions. Absorption spectral studies indicate that the Co(III) and Ni(II) complexes intercalate between the base pairs of the CT-DNA tightly with intrinsic DNA binding constant of1.3×106and3.1×105M-1in Tris-HCl buffer containing 50 mM NaCl, respectively. The proposed DNA binding mode supports the large enhancement in the relative viscosity of DNA on binding to quinolo[3,2-b]benzodiazepine. The oxidative as well as photo-induced cleavage reactions were monitered by gel electrophoresis for both complexes. The photocleavage experiments showed that the cobalt(III) complex can cleave pUC19 DNA effectively in the absence of external additives as an effective inorganic nuclease.

Herein we have explored the highly efficient and environmentally benign clay mineral, Fe(III)–montmorillonite [Fe(III)–Mt], for adsorption of methylene blue (MB) dye from aqueous solution under ambient conditions. The Fe(III)–Mt was interacted with MB dye solution at different pH, temperature and solid-to-liquid ratio. The concentration of MB dye removal was estimated from its optical density at λmax = 665 nm using UV–Vis spectrophotometer. The MB dye removal was rapid at basic pH and increases with temperature up to 40 °C. A complete reduction (100%) was occurred in about 7 min at pH 7 and 10 while at pH 3 in about 10 min. The time taken for complete reduction at 0, 30 and 40 °C are 10, 7 and 5 min respectively. The removal followed by adsorption of dye molecules on the spent clay mineral was evident from FESEM/EDX analysis. More importantly, Fe(III)–Mt could be separated and retrieved easily after the reaction by centrifugation from the degraded MB dye solution. The experimental results of MB dye removal from Fe(III)–Mt follows the pseudo first order kinetics. This study reveals that Fe(III)–Mt has the potential to be used as reductant/adsorbant to remove cationic pollutants effectively and rapidly from drinking water and large scale of industrial wastewater.