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Gopinathan H.,Thiruvalluvar University | Komathi N.,Muthurangam Government Arts College | Arumugham M.N.,Thiruvalluvar University
Inorganica Chimica Acta | Year: 2014

The cobalt (III) complexes, [Co(trien)(phen)] (ClO4) 2Cl, (1), [Co(trien)(phen)](NO3)3, (2) (where trien = triethylenetetramine, phen = 1,10-phenanthroline) has been synthesized and characterized by Infra-red, UV-Vis, ESI-MS and elemental analysis methods. Complex 1 was structurally characterized by single crystal X-ray crystallography. It was crystallized in a triclinic system with space group P1̄, a = 7.797(10) Å, b = 10.6584(2) Å, c = 14.889(3) Å, α = 96.83(10)°, β = 96.16(10)°, and γ = 98.88(10)°. The cobalt atom assumes a distorted octahedral geometry by coordinating to 6 nitrogen atoms from four triethylenetetramine and two 1,10-phenanthroline ligands. The binding of this cobalt (III) complex with calf thymus DNA (CT-DNA) was investigated by UV-Vis absorption, fluorescence spectroscopic, cyclic voltammetric and viscosity techniques. Also, the interactions of pBR322 DNA with these cobalt (III) complexes were studied using the gel electrophoresis method. The thermal denaturation and viscosity binding data advocates that the cobalt (III) complexes interact with DNA by groove binding. When compared to complex 2 complex 1 has more potential to the kill human liver cancer cell as revealed by the MTT assay. The cobalt (III) complexes screened for their activities in vitro on common bacteria and fungi and exhibit antimicrobial activities. © 2014 Elsevier B.V. All rights reserved. Source

Karpagam S.,Vellore Institute of Technology | Guhanathan S.,Muthurangam Government Arts College
International Polymer Processing | Year: 2015

Core-shell hyperbranched polyesters (HBPE) of third generation prepared from 2,2ʹ-bis (hydroxymethyl) propionic acid (Bis-MPA) as an ABx monomer and N-heterocyclic (indole, piperidine and piperazine) phosphoryl dichloride as a core molecule by melt condensation process. These polymers were characterized by FT-IR, 1H NMR, 13C NMR, 31P NMR, elemental analysis, and MALDI spectroscopy. The thermal behavior of the polymers has been investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). There is no weight loss observed until 250 ˚C under nitrogen atmosphere. DSC showed that the glass transition temperatures was about –14 and –30 ˚C for the prepared core-shell HBPE. The dielectric properties such as dielectric constant and loss factor for these polyesters were also studied with respect to change of frequency (50 Hz to 5 MHz). © 2015 Carl Hanser Verlag GmbH & Co. KG. Source

Prabukanthan P.,Muthurangam Government Arts College | Harichandran G.,University of Madras
Materials Science in Semiconductor Processing | Year: 2013

Zinc oxide (ZnO) thin films were deposited on sapphire substrates at room temperature by radio frequency (RF) magnetron sputtering. These films were irradiated with 100 MeV O7+ ions of the fluencies 5×10 13 ions/cm2 at room temperature (RT) and at liquid nitrogen temperature (LNT). Profilometer studies showed that the roughness of pristine and LNT irradiated ZnO thin films were higher than that of the RT irradiated ZnO thin film. The glancing angle X-ray diffraction analysis reveals a reduced intensity and increased full width at half maximum (FWHM) of the (002) diffraction peak in the case of LNT irradiated film indicating disorder. However, the intensity and FWHM of the (002) diffraction peak in the case of RT irradiated ZnO thin films are comparable to those of the pristine film. UV-visible transmission spectra show that the percentage of transmission and band gap energy are different for RT and LNT irradiated films. While the pristine ZnO thin film exhibits two emissions - a broad emission at 403 nm and a sharp emission at 472 nm in its photoluminescence spectrum; the emission at 472 nm was absent for the irradiated films. The atomic concentrations of zinc and oxygen during the irradiation process were obtained using auger electron spectroscopy. © 2012 Elsevier Ltd. Source

Karpagam S.,Vellore Institute of Technology | Guhanathan S.,Muthurangam Government Arts College
Journal of Applied Polymer Science | Year: 2013

The functional modification of poly (vinyl alcohol) (PVA) was conducted through phosphorus containing nitrogen heterocycles. This has been believed to have extensive thermal stability and heavy metal ion adsorption in the area of polymers. The heterocyclic modified polymers were characterized by Infra red (FTIR), Nuclear magnetic resonance spectroscopy, and elemental analysis. Thermogravimetric analysis studies displayed that phosphorus-containing five membered and fused heterocyclic based PVA were less thermally stable than six membered compounds. Differential scanning calorimetric studies reported that the glass transition and melting point temperature of the heterocyclic modified PVA was higher than the pure PVA. X-ray diffraction studies were done to analyze the structure of the modified polymer. Atomic force microscopy surface scans showed that the modified polymeric surface was found to have rough in micrometer scale. Modified PVA showed improved thermal stability, flame retardance, organosolubility, and surface roughness. The adsorption capacities of the modified PVA were determined for several heavy metal ions with the variation of pH. The adsorption capacity was found as 289 mg Pd2+/g of imidazole modified PVA and exhibited higher than other modified PVA. © 2013 Wiley Periodicals, Inc. Source

Karpagam S.,Vellore Institute of Technology | Guhanathan S.,Muthurangam Government Arts College
Progress in Organic Coatings | Year: 2014

Third generation of hyperbranched polyester (HP) synthesized via melt condensation and end-capped with bis indole and imidazole phosphoryl chloride. The modified polyesters subjected to different characterization viz., FTIR, 1H and 13C NMR, GPC and elemental analysis. NMR analysis was used for the determination of OH conversion that demonstrates linear units had a lower reactivity as compared to terminal OH groups in HP. The thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) studies indicated that the HP was stable up to 276 °C and the glass transition temperature was 79.6 °C. After modification of HP, thermal stability was increased for indole modified HP, but the glass transition temperature was decreased. The flame retardance of the hyperbranched polyester was also evaluated with the help of TGA analysis and showed higher value of limiting oxygen index (LOI) for modified polyesters. Morphology of the modified polyester showed more roughness than unmodified HP and this nature positive correlated with bacterial zone of inhibition value. Biological studies showed that the HP and modified HP are able to inhibit the reproduction of gram-positive and gram-negative bacteria. Indole modified HP is showed good activity compared to imidazole modified HP. © 2014 Elsevier B.V. Source

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