K. O. Ogunniran

Experimental and theoretical studies of (E)-N′-1-(4-propylbenzylidene)nicotinohydrazide as corrosion inhibitor of mild steel in 1 M HCl

The efficiency of a novel Schiff base namely (E)-N′-1-(4-propylbenzylidene)nicotinohydrazide (PBNH) was investigated as corrosion inhibitor of mild steel (MS) in 1M HCl using weight loss technique at 303 and 313 K. It was established that corrosion rate of mild steel increases with increase in temperature and concentration of HCl. Results showed that PBNH considerably inhibited the corrosion of mild steel in a 1 M HCl solution and inhibition efficiency is about 70% at 4 × 10−4 M PBNH at both temperatures. The inhibition efficiency of PBNH increased with an increase in concentration and temperature. The adsorption model obeys the Langmuir adsorption isotherm and the kinetic-thermodynamic model and the value of free energy of adsorption, ΔGads indicated that the adsorption of PBNH was a spontaneous process and was both an electrostatic-adsorption (physisorption) and adsorption on the basis of donor-acceptor interactions (chemisorption). Thermodynamic parameters calculated show the spontaneity and endothermic nature of the process and also reveal the favourable affinity of PBNH towards the mild steel surface. Quantum chemical calculations based on PM3 method was performed on PBNH and calculated parameters gave useful information to explain the interaction between the surface of metal and PBNH.

Cu(II) and Fe(III) complexes of sulphadoxine mixed with pyramethamine: Synthesis, characterization, antimicrobial and toxicology study

Two new mixed ligands metal complexes of sulphadoxine and pyramethamine were prepared by using CuCl2.6H2O and FeCl3.6H2O. The complexes were characterized by elemental analysis, melting point determination, molar conductivity, metal content analysis (AAS), IR, magnetic susceptibility measurements and UV-Visible spectroscopy. Based on the analytical and spectroscopic data, the complexes were proposed to have the formulae [M1L1L2(Cl)2] and [M2L1L2(Cl)3] (where M1 = Cu(II), M2 = Fe(III)), L1 = sulphadoxine, L2 = pyramethamine). The spectroscopic data proposed L1 to be a monodentate ligand and coordinated through N atom of the NH2 group in both complexes. Also, L2 was proposed to be tridentate ligand and coordinated through N atom of the NH2 groups and through N atom of imine group. However, [M1L1L2(Cl)2] and [M2L1L2(Cl)3] were proposed to possess distorted octahedral geometry. Conductivity measurement values supported the non-electrolytic nature of the complexes. The complexes have been tested in vitro against a number of pathogenic bacteria [g(+) Escherichia coli, g(+) Proteus species, g(+) Pseudomonas aeruginosa and g(+) Salmonella typhi] by using disc diffusion method. Obtained results indicated that the metal complexes exhibited better antibacterial activities as compared to the ligands. Toxicology tests against some tissues of albino rat (Rattus novergicuss) revealed toxicity of the complexes in the kidney as compared to the parent drugs. [M1L1L2(Cl)2] was found to be toxic to the sera, livers and kidneys of the rats used, while [M 2L1L2(Cl)3] was found to be non-toxic to the sera, livers and kidneys of the rats as their alkaline phosphatase (ALP) values showed non-significant difference to the control values.

Silica Functionalized Magnesium Ferrite Nanocomposites for Potential Biomedical Applications: Preparation, Characterization and Enhanced Colloidal Stability Studies

Magnetic nanocomposite material composed of silica coated MgFe2O4 for potential biomedical applications were synthesized by a two-step chemical method including solution combustion synthesis, followed by silica coatings of the ferrite nanoparticles. The effects of silica coatings on the structural, morphological and magnetic properties were comprehensively investigated using powder X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), energy dispersive absorption x-ray (EDAX), Fourier Transform Infrared spectroscopy (FTIR), thermogravimetric analysis and differential thermal analysis (TG–DTA) and vibrating sample magnetometer (VSM). The colloidal behaviour of coated MNPs in physiological saline medium like water or phosphate buffer saline (PBS) was also studied by zeta potential measurements. The XRD patterns indicate that the crystalline structure is single cubic spinel phase and the spinel structure is retained after silica coating. Also, after silica coating, the crystallite size (from Scherrer formula) decreases from 53 to 47 nm. The magnetic results show that MgFe2O4 MNPs (bare and silica coated) is ferrimagnetic at room temperature. Zeta potential studies revealed that there is enhanced colloidal stability of MgFe2O4 MNPs after silica coating in aqueous media which is an applicable potential in biomedical applications.

The Effect of polyol on Multiple Ligand Capped Silver Alloyed Nanobimetallic Particles in tri-n-octylphosphine oxide and oleic acid Matrices

The syntheses of Ag/M (M is Co, Ni, Pd, Pt and Ru) alloyed nanobimetallic particles in tri-noctylphosphine oxide and oleic acid matrices were successfully carried out by the successive reduction of ligand capped metal ions with polyols, which resulted in rapid precipitation of some fractal high index faceted hybrid Ag/M bimetal nanoparticles. The optical measurements revealed the existence of modified surface plasmon band and peak broadening resulting from reaction-limited growth processes of the metal sols, making it possible to monitor the changes spectrometrically. The bimetallic nanoparticles were further characterized by powder x-ray diffraction, x-ray photoelectron spectroscopy and electron microscopy techniques which confirmed the formation of novel core–shell and alloyed clusters. The Ag/M nanoparticles thus synthesized within TOPO/OA matrices indicated significant reduction potential as a result of their energy band gap 2.65–2.77 eV which points to the fact that they could serve as reducing agents for electrocatalytic reaction.