Green synthesis of nickel-doped magnesium ferrite nanoparticles via combustion for facile microwave-assisted optical and photocatalytic applications.

NixMg1-xFe2O4(x = 0, 0.2, 0.4, 0.6) nanoparticles were symphonized via combustion with microwave assistance in the presence of Tamarindus indica seeds extract as fuel. Nanoparticles nature, size, morphology, oxidation state, elemental composition, and optical and luminescence properties were analysed using PXRD, FTIR, SEM, EDX, and HRTEM with SAED, XPS, UV-Visible and photoluminescence spectroscopy. PXRD analysis confirms that synthesized nanoparticles are spinel cubic and have a 17-18 nm average crystalline size. Tetrahedral and octahedral sites regarding stretching vibrations were confirmed by FTIR analysis. SEM and HRTEM data it is disclosed that the morphology of synthesized nanoparticles has nano flakes-like structure with sponge-like agglomeration. Elemental compositions of prepared nanoparticles were confirmed through EDX spectroscopy. XPS Spectroscopy confirmed and revealed transition, oxidation states, and elemental composition. The band gap and absorption phenomenon were disclosed using UV-visible spectroscopy, where the band gap declines (2.1, 2, 1.6, 1.8 eV), with increase in nickel NixMg1-xFe2O4(x = 0, 0.2, 0.4, 0.6) doping. Photoluminescence intensity reduces with an incline in nickel doping, was confirmed and disclosed using photoluminescence spectroscopy. Dyes (Methylene blue and Rhodamine B) degradation activity was performed in the presence of NDMF nanoparticles as a photocatalyst, which disclosed that 98.1% of MB dye and 97.9% of RB dye were degraded in 0-120 min. Regarding initial dye concentration and catalyst load, 5 ppm was initiated as the ideal initial concentration for both RB and MB dyes. 50 mg catalyst dosage was found to be most effective for the degradation of MB and RB dyes. In comparison, pH studies revealed that photodegradation efficiency was higher in neutral (MB-98.1%, RB-97.9%) and basic (MB-99.6%, RB-99.3%) conditions than in acidic (MB-61.8%, RB-60.4%) conditions.

Macrocyclic complexes: synthesis, characterization, antitumor and DNA binding studies.

The present paper deals with the synthesis of novel macrocyclic complexes of the type [MLX]X, where [(M = Co(II) (1), and Ni(II) (2) X = (Cl2)]. The complexes are synthesized by the reaction of ligand(L)diquinolineno[1,3,7,9]tetraazacyclododecine-7,15-ethane(14H,16H)-benzene with the corresponding metal salts. The synthesized complexes are thoroughly characterized by elemental analysis, FT-IR, 1H-NMR, Mass and electronic spectra. The complexes (1) and (2) were evaluated for in vitro cytotoxicity against human breast adenocarcinoma cell (MCF-7). MTT cytotoxicity studies shows both the complexes are most effective. The binding properties of these complexes with calf thymus-DNA were studied by absorption, emission spectra, viscosity measurements, and thermal denaturation studies. On binding to CT-DNA, the absorption spectrum undergoes bathochromic and hypochromic shifts. The absorption spectral results indicate that the intrinsic binding constant (Kb) are 4.8 × 105 M-1 for (1) and 3.9 × 105 M-1 for (2) respectively, suggesting that complex (1) binds more strongly to CT-DNA than complex (2). The viscosity measurement results revealed the viscosity of sonicated rod like DNA fragments increased when the complex was added to the solution of CT-DNA. The synthesized ligand and its metal complexes are screened for antibacterial and antifungal activities.

Tuneable luminescence properties of EDTA-assisted ZnS:Mn nanocrystals from a yellow-orange to a red emission band.

Luminescence technology has been improved with the help of semiconductor nanoparticles that possess novel optical and electrical properties compared with their bulk counterpart. The aim of this study was to design semiconductor nanocrystals in their pure (ZnS) or doped form (ZnS:Mn) with different concentrations of Mn2+ ions by a wet chemical route stabilized by ethylenediamine tetra-acetic acid (EDTA) and to evaluate their luminescence properties. The nanocrystals were characterized by physicochemical techniques such as X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SEAD), EDS, and ultraviolet (UV)-visible light and photoluminescence (PL) studies. These results showed the presence of cubic phase and spherically shaped nanocrystals. A blue shift with respect to their bulk counterpart was observed. PL emission spectra were observed with a fixed blue peak and the yellow-orange bands were red shifted towards the red region under the same excitation wavelength. The orange-red bands were attributed to the radiation transition of electrons in 3d5 unfilled shells of Mn2+ ions [4 T1 (4 G)-6 A1 (6 S)]; the ZnS matrix varied with Mn2+ concentration. Shift and increase in the intensity of the PL and absorption bands were observed with increase in Mn content. The study showed that Mn2+ -doped ZnS nanocrystal emission bands can be tuned from the yellow-orange to the red regions under a controlled synthesis process and could be used as promising luminescent emitters in the biology field upon functionalization with suitable materials. Further studies on construction with various other materials will be useful for practical applications.

DNA binding, photoactivated DNA cleavage and cytotoxic activity of Cu(II) and Co(II) based Schiff-base azo photosensitizers.

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 3.2×10(4) M(-1) and 2.9×10(4) M(-1) and acted as proficient photocleavers of SC pUC19 DNA in UV-A light, forming (1)O2 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.

Synthesis, DNA interactions and antibacterial PDT of Cu(II) complexes of phenanthroline based photosensitizers via singlet oxygen generation.

Cu(II) complexes [Cu(mqt)(B)H2O]ClO4(1-3) of 2-thiol 4-methylquinoline and phenanthroline bases (B), viz 1,10-phenanthroline (phen in 1), Dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 2) and Dipyrido[3,2-a:2',3'-c]phenazine (dppz in 3) have been prepared and characterized by elemental analysis, IR, UV-Vis, magnetic moment values, EPR spectra and conductivity measurements. The spectral data reveal that all the complexes exhibit square-pyramidal geometry. The DNA-binding behaviors of the three complexes were investigated by absorption spectra, viscosity measurements and thermal denaturation studies. The DNA binding constants for complexes (1), (2) and (3) were determined to 2.2×10(3), 1.3×10(4) and 8.6×10(4)M(-1) respectively. The experimental results suggest that these complexes interact with DNA through groove-binding mode. The photo induced cleavage studies shows that the complexes possess photonuclease property against pUC19 DNA under UV-Visible irradiation via a mechanistic pathway involving formation of singlet oxygen as the reactive species. Antimicrobial photodynamic therapy was studied using photodynamic antimicrobial chemotherapy (PACT) assay against Escherichiacoli and all complexes exhibited significant reduction in bacterial growth on photoirradiation.

Luminescence properties of blue-red emitting multilayer coated single structure ZnS/MnS/ZnS nanocomposites.

Uncoated ZnS, MnS and ZnS/MnS/ZnS nanocomposites were successfully synthesized by chemical co-precipitation method in air atmosphere by varying the thicknesses of MnS layer. Characterization techniques such as X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), UV-visible absorption and photoluminescence (PL) spectroscopy were used to characterize the novel ZnS/MnS/ZnS nanocomposites. The obtained particles were highly crystalline and monodispersed with an average particles size of 4.5-6.5 nm. The room temperature photoluminescence (PL) study of ZnS/MnS/ZnS nanocomposites showed an enhanced intensity with different concentration of manganese acetate. The presences of MnS layer in the nanocomposite have tuned the PL emission in the IR region. Addition of manganese acetate (0.1-0.4 M) in the nanocomposite showed a distinct PL emission peak centered at 740 nm i.e. in the red region with significant red shift. The PL emission of ZnS and MnS were tuned in the nonvisible IR region. It is shown that the variation in thickness of MnS layer leads to an enhanced photoluminescence intensity/efficiency of ZnS/MnS/ZnS nanocomposites.

Novel complexes of Co(III) and Ni(II) containing peptide ligands: synthesis, DNA binding and photonuclease activity.

The new cobalt(III) and nickel(II) complexes of the type [M(L)2(H2O)2](n)(+) (where M = Co(III) or Ni(II) ion, n = 3 for Co and 2 for Ni, L = peptides Fmoc. Ala-val-OH (F-AVOH), Fmoc-Phe-Leu-Ome (F-PLOMe) and Z-Ala-Phe-CONH2 (Z-APCONH2)) were synthesized and structurally characterized by FTIR, (1)H NMR, elemental analysis and electronic spectral data. An octahedral geometry has been proposed for all the synthesized Co(III) and Ni(II) metal complexes. The binding property of the complexes with CT-DNA was studied by absorption spectral analysis, followed by viscosity measurement and thermal denaturation studies. Detailed analysis revealed that the metal complexes intercalates into the DNA base stack as intercalator. The photo induced cleavage studies shows that the complexes possess photonuclease property against pUC19 DNA under UV-Visible irradiation.

Metal based photosensitizers of tetradentate Schiff base: promising role in anti-tumor activity through singlet oxygen generation mechanism.

In the present investigation, a Schiff base N'(1),N'(3)-bis[(Z)-(2-hydroxynapthyl)methylidene]benzene-1,3-dicarbodihydrazide (L1) 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 Kb of 4.5×10(4)M(-1) and 4.2×10(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 Kb of 5.7×10(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 365nm, through (1)O2 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.

Synthesis, antimicrobial, DNA-binding and photonuclease studies of cobalt(III) and nickel(II) Schiff base complexes.

New metal complexes of the type [M(nih)(L)](PF(6))(n)·xH(2)O and [M(nih)(2)](PF(6))·xH(2)O (where M=Co(III) or Ni(II), L=1,10-phenanthroline (phen)/or 2,2' bipyridine (bpy), nih=2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone, n=2 or 1 and x=3 or 2) have been synthesized and characterized by elemental analysis, magnetic, IR and (1)H NMR spectral data. The electronic and magnetic moment 2.97-3.07 B.M. data infers octahedral geometry for all the complexes. The IR data reveals that Schiff base (nih) form coordination bond with the metal ion through azomethine-nitrogen, phenolic-oxygen and carbonyl-oxygen in a tridentate fashion. In addition, DNA-binding properties of these six metal complexes were investigated using absorption spectroscopy, viscosity measurements and thermal denaturation methods. The results indicated that the nickel(II) complex strongly bind with calf-thymus DNA with intrinsic DNA binding constant K(b) value of 4.9×10(4) M(-1) for (3), 4.2×10(4) M(-1) for (4), presumably via an intercalation mechanism compared to cobalt(III) complex with K(b) value of 4.6×10(4) M(-1) (1) and 4.1×10(4) M(-1) (2). The DNA Photoclevage experiment shows that, the complexes act as effective DNA cleavage agent.

Cobalt(II), Nickel(II) and Copper(II) complexes of a tetradentate Schiff base as photosensitizers: Quantum yield of 1O2 generation and its promising role in anti-tumor activity.

In the present investigation, a Schiff base N'1,N'3-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant Kb of 2.6×10(4) M(-1), 5.7×10(4) M(-1) and 4.5×10(4) M(-1), respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.

Synthesis, DNA-binding, DNA-photonuclease profiling and antimicrobial activity of novel tetra-aza macrocyclic Ni(II), Co(II) and Cu(II) complexes constrained by thiadiazole.

A new tetra-aza macrocyclic ligand, L (C(24)H(16)N(12)O(2)S(4)) and its complexes of type, [MLCl(2)] and [CuL]Cl(2) (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.

Synthesis, characterization and antimicrobial studies of 2-(4-methoxy-phenyl)-5-methyl-4-(2-arylsulfanyl-ethyl)-2,4-dihydro-[1,2,4] triazolo-3-ones and their corresponding sulfones.

In the present investigation, a series of novel 2-(4-methoxy-phenyl)-5-methyl-4-(2-arylsulfanyl-ethyl)-2,4-dihydro-[1,2,4] triazolo-3-ones and their corresponding sulfones were prepared with the objective of developing better antimicrobial agents. The chemical structures of the newly synthesized compounds were characterized by spectral (IR, (1)H NMR, (13)C NMR and LCMS) methods. The newly synthesized compounds (4a-i) and (5a-e, 5h) were screened for their antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. The antifungal activity was tested against Rhizopus oryzae, Aspergillus niger, Aspergillus flavus, Candida albicans and Saccharomyces cerevisiae. Among all the compounds synthesized, compounds 4d and 5b exhibited significant antibacterial activity.

Synthesis and characterization of chitosan-based pH-sensitive semi-interpenetrating network microspheres for controlled release of diclofenac sodium.

pH-Sensitive semi-interpenetrating networks (IPNs) based on chitosan (Cs) and acrylamide-grafted hydroxyethylcellulose (AAm-g-HEC) were prepared in the form of microspheres (MPs) by emulsion-crosslinking technique using glutaraldehyde (GA) as a crosslinker. Diclofenac sodium (DS) drug was successfully encapsulated into IPN microspheres by varying the ratio of Cs and AAm-g-HEC, % drug loading, and amount of GA. DS encapsulation of up to 83% was obtained as measured by UV spectroscopy. MPs with average particle sizes in the range of 188-310microm were obtained. MPs were characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Differential scanning calorimetry (DSC). Diffusion coefficients (D) of water transport through the microspheres were determined using an empirical equation. In vitro release of DS from these matrices has been investigated in pH 1.2 and 7.4 media.

Synthesis and DNA binding studies of novel heterocyclic substituted quinoline schiff bases: a potent antimicrobial agent.

The present article deals with the synthesis of 2-chloroquinoline-3-carbaldehyde [(2-hydroxy-1-naphthyl) methylene] hydrazone (CQCMH) (2a-c) and 2-chloroquinoline-3-carbaldehyde [4-(dimethylamino) benzylidene] hydrazone (CQCDBH) (3a-c) from quinoline derivatives under suitable experimental conditions. The synthesized compounds were characterized by elemental analysis, FTIR, (1)HNMR, and mass spectral data. The selected compounds were studied for interaction with calf thymus-DNA (CT-DNA) by electronic spectra, viscosity measurements as well as thermal denaturation studies. On binding to DNA, the absorption spectrum underwent bathochromic and hypochromic shifts. The binding constant (K(b)) had value of 2.3 x 10(3) M(-1) for (2a) and 2.5 x 10(4) M(-1) for (3a). The viscosity measurements indicated that the viscosity of sonicated rod like DNA fragments increased. The synthesized derivatives have been screened for antibacterial and antifungal activities.