Electrochemical and photocatalytic investigation of nickel oxide for energy storage and wastewater treatment

Nickel oxide (NiO) was synthesized via a one-step facile method. X-ray diffraction analysis confirmed the face-centered cubic structure of NiO. The bonding nature and surface purity were confirmed via Fourier-transform infrared spectroscopy. NiO revealed partial spherical morphology with less particle aggregation. The optical bandgap of NiO was found to be 3.75 eV. Cyclic voltammetry revealed well-defined oxidation and reduction peaks for NiO. The charge–discharge curve exhibited specific capacitance of 184.6 F/g at current density of 0.3 A/g. NiO electrode exhibited longer cyclic stability of 93 % up to 1500 cycles. In addition, NiO + H₂O₂ revealed efficient photocatalytic degradation of methylene blue (organic pollutant) under visible-light irradiation with degradation efficiency of ~88 %. These results confirm that nanosized NiO is more suitable for dual application.

     

Nucleation studies and characterization of potassium thiocyanate added KDP crystals grown by seed rotation technique

The effect of the addition of potassium thiocyanate on potassium dihydrogen phosphate (KDP) crystals, grown from aqueous solution by the temperature lowering method using a microcontroller based seed rotation technique has been studied. As part of nucleation studies, metastable zone width, induction period and crystal growth rate of additive added KDP are determined and analyzed with the pure system. Dielectric measurements were carried out on pure and doped crystals at various temperatures ranging from 313 to 423 K and compared. The crystalline perfection of the grown crystal was studied by the high resolution X-ray diffraction analysis. The crystal grown from additive added solution was subjected to structural, optical transmission, second harmonic generation and hardness studies and the effect of additive on pure system is investigated.     

Enhancement of stability of growth,structural and NLO properties of KDP crystals due to additive along with seed rotation

Potassium Acetate (CH₃COOK) and Potassium Citrate (K₃C₆H₅O₇) as new additives were added into the potassium dihydrogen phosphate (KDP) solutions in different molar ratios. The metastable zone width and induction period with and without these additives were determined and compared. Dielectric measurements on pure and doped KDP crystals at various temperatures ranging from 313 to 423 K were carried out by the conventional parallel plate capacitor method which results low dielectric constant value dielectrics in doped crystals. The high resolution XRD studies show that CH₃COOK doped KDP crystal and K₃C₆H₅O₇ doped KDP crystal do not contain any internal structural grain boundaries and indicates that the crystalline perfection is very good. Moreover, the addition of these potassium additives improves the quality of the crystal and yields highly transparent crystals with well defined features. The effect of additives on the growth, nucleation kinetics, structural, NLO and optical properties has been investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Copper(II) complexes of hydroxyflavone derivatives as potential bioactive molecule to combat antioxidants: synthesis,characterization and pharmacological activities

A variety of novel copper complexes were synthesized and characterized of the formulae [Cu(L¹)(OAc)], [CuL²(H₂O)], [CuL³(H₂O)], [CuL⁴(OAc)], [CuL⁵(H₂O)] [CuL⁶], [CuL⁷], [CuL⁸](OAc) and [CuL⁹], where L¹ L⁹ represents Schiff base ligands [derived by the condensation of 5‐hydroxyflavone with 4‐aminoantipyrine (L¹), o‐aminophenol (L²), o‐aminobenzoic acid (L³), o‐aminothiazole (L⁴), thiosemicarbazide (L⁵), 4‐aminoantipyrine‐o‐aminophenol (L⁶), 4‐aminoantipyrine‐o‐aminobenzoic acid (L⁷), 4‐aminoantipyrine‐o‐aminothiazole(L⁸) and 4‐aminoantipyrine‐thiosemicarbazide (L⁹)]. The spectral and magnetic results of the Cu(II) complexes exhibit square planar geometry. The DNA binding properties of copper complexes were studied by using electronic absorption spectra, viscosity and thermal denaturation experiments. The results show that the complexes were interacting with calf thymus (CT DNA). The in vitro antimicrobial activities of the investigated compounds were tested against the bacterial species and fungal species. Superoxide dismutase and antioxidant activities of the copper complexes have also been studied. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis,Spectral Characterization,and Antimicrobial Activities of Schiff Base Complexes Derived From 4-Aminoantipyrine

Novel cobalt (II), nickel (II), copper (II), and zinc (II) complexes were synthesized from Schiff base ligand derived from 4-aminoantipyrine, vanillin, and o-anisidine. The structural features were derived from their elemental analysis, molar conductance, magnetic measurements, and various spectroscopic techniques such as infrared, ultraviolet visible, nuclear magnetic resonance, and electron paramagnetic resonance spectroscopy. Antimicrobial screening tests were performed against bacteria and fungi. The comparative study of the minimum inhibitory concentration values of the Schiff base and its metal complexes indicate that the metal complexes exhibit greater antimicrobial activity than the free ligand.     

Synthesis and characterization of metal(II) complexes of poly(3-nitrobenzylidene-1-naphthylamine-co-succinic anhydride)

The alternating copolymer poly(3-nitrobenzylidene-1-naphthylamine-co-succinic anhydride) was synthesized from the Schiff base, 3-nitrobenzylidene-1-naphthylamine and succinic anhydride using hydroquinone monomethyl ether under nitrogen atmosphere. The molecular weight of the copolymer was determined by gel permeation chromatography. The metal-polymer complexes were synthesized by the reaction of THF solution of the alternating copolymer with aqueous solution of Cu(II) and Ni(II) acetates. The elemental analysis of the metal-polymer complexes suggests that the metal to ligand ratio is 1:2. The IR spectral data indicate that the metal ions are coordinated through the oxygen of the keto and ester groups. The UV-Visible, magnetic moments and ESR studies indicate square planar geometry for Cu(II) and distorted octahedral geometry for Ni(II) complexes. XRD studies revealed that the copolymer and its Cu(II) complex are crystalline, while the Ni(II) complex is amorphous. The intrinsic viscosity of the copolymer, thermal properties of metal-polymer complexes and their catalytic activity are discussed.     

Growth mechanism, dislocation etching and mechanical properties of L-arginine phosphate and deuterated L-arginine phosphate

Single crystals of L-arginine phosphate monohydrate (LAP) and its deuterated analog (dLAP) were grown from aqueous solutions. Effect of pH variation on growth of microbes in these solutions was studied. Efforts were undertaken to minimize microbial incorporation into these crystals. The grown crystals were characterized by recording the powder diffraction and identifying the diffracting planes. Dislocation contents of these crystals were estimated by etching the cleavage planes using a mixture of glacial acetic and ethanol. Growth features on habit faces of LAP and dLAP were studied. Growth takes place on the (100) plane predominantly by spreading of layers which manifests as a step pattern. Hillocks were observed on (0 0), (1 0 and ( 10) habits faces. Load dependence of microhardness was evaluated for LAP and dLAP.     

Growth and characterization of naphthalene single crystals grown by modified vertical Bridgman method

The large size 20 mm diameter naphthalene single crystals were grown by modified vertical Bridgman method. The optical quality of the grown crystal was analyzed by photoluminescence and ultraviolet visible absorption spectral measurements. Photoluminescence spectrum indicated violet emission at 410 nm. The UV–vis absorption spectrum shows the maximum at 219.32 nm. The microhardness measurements and differential thermal analysis performed to analyze the mechanical and thermal stability of the as grown crystals. The dielectric measurements were carried out at five frequencies, viz., 100 Hz, 1 kHz, 10 kHz, 100 kHz and 1 MHz and at various temperatures, ranging from 308 K to 348 K indicate an increase of the dielectric parameters with the increase of temperature at all the five frequencies. The conductivity of the material is understood to be more of electronic in nature. Also, the increase in the dielectric parameters with that of temperature is due to the temperature variation of electronic polarizability.     

Transition metal complexes of a novel quinoxaline‐based tridentate ONO donor ligand: synthesis,spectral characterization,thermal, in vitro pharmacological and molecular modeling studies

Co(II), Ni(II), Cu(II) and Zn(II) complexes of a novel tridentate heterocyclic ligand, 3‐{[(2‐benzoyl‐4‐chlorophenyl)imino]methyl}quinoxalin‐2(1H)‐one, have been synthesized. The ligand and the metal complexes were characterized using elemental analysis, molar conductance and magnetic susceptibility measurements, and UV–visible, Fourier transform infrared, ¹H NMR, ¹³C NMR, electron spin resonance and DART mass spectral data. The ligand behaves as a tridentate one, coordinating through two oxygen atoms from two keto groups and through the azomethine nitrogen atom. The thermal properties of the newly synthesized compounds were determined using thermogravimetric analysis. The ligand and its metal complexes were subjected to powder X‐ray diffraction analysis by which average crystallite size and unit cell parameters were calculated. The electrochemical behaviour of the compounds was studied using cyclic voltammetry. The ligand and the metal complexes were screened for their in vitro antimicrobial activities against the bacterial strains E. coli, K. pneumoniae, S. pneumoniae and S. aureus and the fungal species A. niger, A. flavus, P. chrysogenum and R. stolonifer. DNA binding, DNA cleavage and antioxidant activities of the compounds were also evaluated. The compounds bind with DNA through groove binding. The Cu(II) and Zn(II) complexes exhibit higher superoxide anion and hydrogen peroxide scavenging activities, respectively. The Cu(II) complex exhibits better anticancer activity against the MCF7 cell line. The compounds were subjected to molecular docking study against B‐DNA dodecamer d(CGCGAATTCGCG)₂ and vascular endothelial growth factor receptor kinase to justify the experimental DNA binding and MTT assay. Density functional theory studies were used to optimize the geometry of the compounds and to calculate the nonlinear optical properties. Copyright © 2016 John Wiley & Sons, Ltd.