S. Dhanuskodi

Microwave-assisted synthesis of CdO–ZnO nanocomposite and its antibacterial activity against human pathogens

CdO-ZnO nanocomposite was prepared by microwave-assisted method and characterized by X-ray crystallography (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). It exhibits hexagonal cubic structure with an average crystallite size of 27 nm. From the UV-Vis spectra, the bandgap is estimated as 2.92 eV. The fluorescence spectrum shows a near band edge emission at 422 nm. In addition the antibacterial activity of CdO-ZnO nanocomposite was carried out in-vitro against two kinds of bacteria: gram negative bacteria (G -ve) i.e. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and gram positive bacteria (G +ve): Staphylococcus aureus, Proteus vulgaris and Bacillus spp. This study indicates the zone of inhibition of 40 mm has high antibacterial activity towards the gram positive bacterium S. aureus.

Spectroscopic and optical studies on pure and doped single crystals of sulphate-mixed l-arginine phosphate monohydrate—a nonlinear optical crystal

Single crystals of pure and transition metal ions (Cu(2+) and VO(2+))-doped L-arginine sulpho phosphate monohydrate (sulphate-mixed L-arginine phosphate monohydrate, abbreviated as LASP) have been grown by solvent evaporation of the saturated aqueous solution at room temperature and characterized by single-crystal XRD, FT-IR, UV-Vis-NIR and EPR (single-crystal rotation) spectral studies. Kurtz powder technique shows an enhanced second harmonic generation (SHG) efficiency for LASP and its doped analogues than pure LAP. The EPR studies on LASP:VO(2+) reveal that the in-plane sigma-bonding is moderately covalent and the out-of-plane pi-bonding is highly covalent, which could be attributed to the cause of enhanced powder efficiency.

Growth and characterization of a new nonlinear optical crystal—ammonium borodilactate

Abstract A new nonlinear optical material ammonium borodilactate [(NH 4 ) + (C 6 H 8 BO 6 ) − ](ABL) has been synthesized. The synthesized compound was subjected to elemental analysis to confirm the constituent elements present in the compound. Single crystals of ABL have been grown by slow evaporation of saturated aqueous solution at room temperature. The grown crystals have been characterized by NMR, FT-IR and mass spectroscopic studies. The three-dimensional crystal structure has been solved by single crystal X-ray diffraction technique. TGA and DTA studies reveal good thermal stability. Kurtz powder test shows that the SHG efficiency is comparable to that of KDP.

Photocatalytic and antibacterial activities of hydrothermally prepared CdO nanoparticles

CdO nanoparticles (NPs) were synthesized (hydrothermal) with cadmium acetate and ammonium hydroxide as starting materials and characterized by XRD, FE-SEM and FTIR. It exhibits face centred cubic structure with an average crystallite size of 43xa0nm and the lattice strain (W–H plot) is 0.0029. The surface morphological image appears particle like structure (150xa0nm). The vibrational stretching mode of Cd–O is 620xa0cm−1 whereas micro Raman reveals the overtone at 389xa0cm−1. The optical energy bandgap is found to be 2.47xa0eV from the UV–Vis spectra. Five emission peaks were recorded at 360, 429, 488, 527 and 640xa0nm upon excited at 290xa0nm. The SHG efficiency is 0.84 times of KDP. The photocatalytic performance has been evaluated of the CdO NPs for the degradation of methylene blue under sunlight irradiation. CdO NPs were screened for their in vitro antibacterial activity against human pathogens such as Gram negative (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris) and Gram positive (Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis) bacteria has been investigated.

Multifunctional properties of microwave assisted CdO–NiO–ZnO mixed metal oxide nanocomposite: enhanced photocatalytic and antibacterial activities

A facile approach for the preparation of CdO–NiO–ZnO mixed metal oxide nanocomposite was demonstrated by microwave assisted method and characterized by XRD, SEM with EDS and FTIR. XRD exhibits CdO (cubic), NiO (cubic), ZnO (hexagonal) structure with an average crystallite size of 37, 23 and 20xa0nm respectively. The lattice strain and the dislocation density are evaluated by W–H method. SEM and TEM images reveal the morphology as sheet like structure and FTIR indicates the characteristic stretching frequency as Cd–O (687xa0cm−1), Ni–O (865xa0cm−1) and Zn–O (472xa0cm−1). From the UV–Vis spectra, the bandgap is estimated as 2.75xa0eV. The fluorescence spectrum shows the emission of blue–violet (455xa0nm), green (524xa0nm) and red (678xa0nm). The prepared nanocomposite acts as an excellent photocatalyst for the removal of methylene blue dye under sun light irradiation. Furthermore, the antibacterial activity for concentrations (25, 50, 75 and 100xa0µg/mL) was carried out in-vitro against gram negative (G −xa0Ve) i.e. Escherichia coli, Pseudomonas aeruginosa, proteus mirablis, Aeromonas hydrophila, Salmonella typhi and Vibrio cholerae; gram positive bacteria (Gu2009+u2009Ve): Staphylococcus aureus, Rhodococcus rhodochrous and Bacillus subtilis. Confocal laser scanning microscopy confirms the rupture of the bacterial cell wall.

Andrographis paniculata extract mediated green synthesis of CdO nanoparticles and its electrochemical and antibacterial studies

CdO nanoparticles based on Andrographis paniculata plant extract were synthesizedby biological method and characterized by XRD, FESEM, HRTEM and FTIR. XRD exhibits face centred cubic structure with an average crystallite size of 22xa0nm and the lattice strain (W–H plot) is 0.0023. From the HRTEM, the particles are spherical. The vibrational stretching mode of Cd–O is 456xa0cm−1. From the UV–Vis spectra, the optical energy bandgap is estimated as 2.33xa0eV. The photoluminescence emission peaks at 360, 430, 486, 528 and 616xa0nm are observed for the excitation at 220xa0nm. The electrochemical study by cyclic voltammetry reveals the quasi reversible reduction and irreversible oxidation versus Saturated Calomel Electrode (SCE). The potential is referred to the Fc/Fc+ couple under the experimental conditions. The biosynthesized CdO nanoparticles are tested against gram positive (Rhodococcus rhodochrous and Staphylococcus aureus) and gram negative (Escherichia coli, Aeromonas hydrophila and Vibrio Cholera) bacterial strains. It is noted that the bioengineered CdO nanoparticles show a good antibacterial activity (zone of inhibition: E. coli-16xa0mm) bacteria.

Estimation of lattice strain in nanocrystalline RuO2 by Williamson-Hall and size-strain plot methods.

RuO2 nanoparticles (RuO2 NPs) have been successfully synthesized by the hydrothermal method. Structure and the particle size have been determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). UV-Vis spectra reveal that the optical band gap of RuO2 nanoparticles is red shifted from 3.95 to 3.55eV. BET measurements show a high specific surface area (SSA) of 118-133m(2)/g and pore diameter (10-25nm) has been estimated by Barret-Joyner-Halenda (BJH) method. The crystallite size and lattice strain in the samples have been investigated by Williamson-Hall (W-H) analysis assuming uniform deformation, deformation stress and deformation energy density, and the size-strain plot method. All other relevant physical parameters including stress, strain and energy density have been calculated. The average crystallite size and the lattice strain evaluated from XRD measurements are in good agreement with the results of TEM.

Dielectric and antibacterial studies of microwave assisted calcium hydroxide nanoparticles

Calcium hydroxide nanoparticles (Ca(OH)2NPs) were formulated through microwave assisted route and characterized by XRD, FTIR and FESEM. It exhibits hexagonal crystal structure with an average crystallite size of 30xa0nm. The TEM images show the agglomerated nanoparticles. From the UV–Vis spectra, the bandgap is estimated as 5.5xa0eV. A broad emission band with maximum intensity at around 430xa0nm is observed in photoluminescence (PL) spectrum of Ca(OH)2 NPs at room temperature. The dielectric constant and loss were studied as a function of frequency at room temperature (Ɛru2009=u200925.0 and Ɛ′′u2009=u20093.94 at 10xa0kHz).The relative powder second harmonic generation efficiency (SHG) of Ca(OH)2 NPs is comparable with the standard KDP. Antibacterial activity of Ca(OH)2 NPs at concentrations 15 and 30xa0µg/mL were screened against gram negative (Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Shigella flexneri, Proteus vulgaris, Klebsiella pneumoniae and Proteus mirabilis) and gram positive (Bacillus subtilis, Micrococcus luteus, and Streptococcus aureus) bacteria by measuring the inhibition zone.

l-Histidinium tetra­fluoro­succinate

In the crystal structure of the title compound, C6H11N3O22+·C4F4O42−, the anions and cations are linked to each other through hydrogen bonds.

Multifunctional properties of CdO nanostructures Synthesised through microwave assisted hydrothermal method

Abstract Rectangle shaped CdO was prepared by microwave assisted hydrothermal route and studied by XRD, FTIR, FESEM with EDS and HRTEM. XRD result shows cubic structure with an average crystallite size (42 nm) and the W-H lattice strain is 0.0012. FESEM and HRTEM image displays rectangle shape. From the FTIR spectra, the stretching vibration of Cd-O is 477 cm−1. The optical bandgap of CdO is 2.52 eV. From the I–V studies, the electrical conductivity is evaluated as 0.00707 S/cm. The photocatalytic studies of rectangle shaped CdO nanoparticles was assessed by monitoring the decolourization of Congo red under sunlight irradiation. It shows good antibacterial activity with a zone of inhibition of 24 mm (E. coli) and 22 mm (S. aureus) against gram negative and gram positive bacteria. Confocal microscopy investigation confirms that the rectangle shaped CdO were disrupting the bacterial cell wall.