Sadaf Khan

Synthesis and characterization of transition metal 2,6-pyridinedicarboxylic acid derivatives, interactions of Cu(II) and Ni(II) complexes with DNA in vitro

Mononuclear complexes M(L)Cl(2) where M=Mn(II), Fe(II), Co(II), Ni(II) and Cu(II) and (L=N,N-diethylpiperazinyl,2,6-pyridinedicarboxylate), have been synthesized and characterized by elemental analysis, FT-IR, (1)H NMR spectroscopy, UV-vis, magnetic moment, TGA/DSC, cyclic voltammetry and conductivity measurement data. The spectral data suggests that the dipicolinic acid acts as a bidentate ligand and is coordinated to the metal ion through the carboxylate oxygen. The cyclic voltammogram for Cu(L)Cl(2) complex was found to display two reversible Cu(II)/Cu(I) and Cu(II)/Cu(III) redox couple. The ligand exhibits a two-step thermolytic pattern while the complexes decompose in three stages respectively. An octahedral geometry has been proposed for both the complexes. The investigation of the interaction of the complexes with calf thymus DNA has been performed with absorption spectroscopy and fluorescence quenching experiments, which showed that the complexes are avid binders of calf thymus DNA. Also the interaction of the Cu(II) and Ni(II) complexes with plasmid DNA (pUC 19) was studied using agarose gel electrophoresis. The results revealed that these complexes can act as effective DNA cleaving agents resulting in the nicked form of DNA (pUC 19) under physiological conditions. The gel was run both in the absence and presence of an oxidizing agent (H(2)O(2)). The ligand and its complexes have also been screened against microbes in order to study their antibacterial action. The results revealed that the Cu(II) complex has activity comparable with the reference drugs gentamycin and flucanzole.

Inhibition of mild steel corrosion in presence of fatty acid imidazolines in hydrochloric acid

The corrosive behavior of mild steel in 1M HCl solutions containing selected imidazolines of fatty acids with C7-C17 was investigated using weight-loss method, potentiodynamic polarization technique and scanning elecron microscopy. The results obtained revealed that all the studied imidazolines are effective in reducing corrosion of mild steel in HCl media. The adsorption of the inhibitors on the mild steel surface obeys Langmuir’s adsorption isotherm. The thermodynamic parameters of adsorption deduced reveal a strong interaction and spontaneous adsorption of inhibitors on the mild steel surface. The influence of inhibitor concentration, solution temperature, immersion time and acid concentration on the corrosion of mild steel has also been investigated. Scanning electron microscopy(SEM) of mild steels samples is performed to show adsorption of inhibitors on metal surface. Potentiodynamic polarization data showed that the compounds studied are mixed type inhibitors in the acid solution.

Inhibition of carbon steel corrosion by azathione derivatives in organic acid solutions

Purpose – The purpose of this paper is to investigate the inhibitive effect of azathiones, namely cyclopentyl‐tetrahydro‐azathione, cyclohexyl‐tetrahydro‐azathione and isobutyl‐methyl‐tetrahydro‐azathione on the corrosion of carbon steel in formic and acetic acid solution. The effect of inhibitor concentration, immersion time, acid concentration, and solution temperature on the inhibition efficiencies of the selected azathiones were studied systematically.Design/methodology/approach – The synthesis of inhibitor was confirmed by methods such as Fourier transform infrared and nuclear magnetic resonance studies. All inhibition experiments were conducted on carbon steel in 20 percent formic acid and 20 percent acetic acid solution. Weight loss experiments were carried out according to the American Society for Testing and Materials standard procedure. Polarization studies were carried out in a three electrode cell assembly connected to an EG&G Princeton Applied Research potentiostat/galvanostat (model 173). Th...

An investigation of the inhibitive capability of synthesized thiosemicarbazides on the corrosion of carbon steel in acid solutions

Purpose – This paper mainly aims to study the influence of some thiosemicarbazides, namely, 1‐hydroxyphenyl‐4‐phenyl thiosemicarbazide (HPT), 1,4‐diphenyl thiosemicarbazide (DPT), 1‐aminophenyl‐4‐phenyl thiosemicarbazide (APT) and 1‐cinnamyl‐4‐phenyl thiosemicarbazide (CPT) on the corrosion inhibition of carbon steel in hydrochloric and sulphuric acid.Design/methodology/approach – All inhibition experiments were conducted on carbon steel in 1N HCl and 1N H2SO4 solution. Weight loss experiments were carried out according to the ASTM standard procedure. Polarization studies were carried out in a three‐electrode cell assembly connected to an EG&G Princeton applied research potentiostat/galvanostat (model 173).Findings – For all the compounds a consistent trend of increase in inhibition efficiency was observed as a function of inhibitor concentration. The adsorption of all the compounds on to the carbon steel surface in the acidic solution was found to obey the Tempkins adsorption isotherm. The values of act...