Hasan Nazir

Some new NiZn heterodinuclear complexes: square-pyramidal nickel(II) coordination

A new series of heterodinuclear nickel(II)zinc(II) complexes, [NiL·ZnCl 2 ·4-picoline] ( 1 ), [NiLDM·ZnCl 2 ·4-picoline] ( 2 ), [NiL·ZnBr 2 ·4-picoline] ( 3 ), [NiLDM·ZnBr 2 ·4-picoline] ( 4 ), [NiLDM·ZnBr 2 ·3-picoline] ( 5 ), [NiLDM·ZnBr 2 ·3,5-lutidine] ( 6 ) and [NiL·ZnI 2 ·4-picoline] ( 7 ), where L is N , N ′-bis(salicylidene)-1,3-diaminopropane dianion and LDM is N , N ′-bis(salicylidene)-2,2′-dimethyl-1,3-diaminopropane dianion, were prepared. The complexes were characterized by elemental analysis, thermogravimetric analysis and IR spectroscopy. X-ray crystallographic analysis of complexes 1 , 2 and 4 revealed that nickel(II) ion in heteronuclear complexes had a square-pyramidal coordination sphere. It is concluded that formation of square-pyramidal nickel(II) coordination depends strongly on the concentration of methyl pyridine present in the medium and occurs when methyl pyridine/Ni ratio is below 1.5.

A voltammetric Rhodotorula mucilaginosa modified microbial biosensor for Cu(II) determination.

It is the first report about the usage of Rhodotorula mucilaginosa as a biomaterial to construct a microbial biosensor based on carbon paste for determination of copper. Cu(II) was preconcentrated electrode surface at open circuit and then detected with electrochemical techniques, including Cyclic Voltammetry (CV) and Differential Pulse Stripping Voltammetry (DPSV). Some parameters such as pH of preconcentration solution, preconcentration time, scan rate and effect of interfering heavy metal ions were carried out for optimum responses. The best defined cathodic peak was obtained at pH 5 with 0.05 M NaNO(3) and a scan rate of 100 mV/s. The linear range for the developed microbial biosensor was found in the range of 1.0 x 10(-7) and 1.0 x 10(-5)M (0.0064 and 0.64 mg/L) at the response time of 15 min (R(2)=0.98). The easy fabrication, sensitivity, low cost and fast response time showed the advantages of the biosensor to conventional techniques.

An advanced investigation on a new algal sensor determining Pb(II) ions from aqueous media

It has been well documented that heavy metal accumulation in environment is harmful for living organisms at even trace levels. A new voltammetric algal sensor based on Phormidium sp. modification for Pb(II) determination from aqueous solutions was developed, and selectivity of the biomass to Pb(II) was investigated comprehensively. Many important experimental parameters were performed by using electrochemical techniques, including cyclic voltammetry and differential pulse stripping voltammetry. The preconcentrated ions at open circuit were reduced by scanning the potential from -1.5 to 1.5 V and current values obtained were related to the concentration of Pb(II) in the solutions. The best peak values belonging to Pb(II) were achieved at pH 8.0 with 0.05 M Tris-HCl solution. Preconcentration time was selected as 10 min, and the sensor was found in a linear range from 5.0×10(-8) M to 2.0×10(-5) M Pb(II) (0.01-4.0 mg L(-1)) with a detection limit of 2.5×10(-8) M. Other analytical properties of the developed microbial biosensor were also investigated. According to the Fourier transform infrared attenuated total reflectance (FTIR-ATR) analyses, the possible functional groups involved in Pb(II) accumulation in the Phormidium sp. were defined as carboxyl, sulphoxide and alcoholic groups. A simple chemical modification by formaldehyde both enhanced Pb(II) determination and content of functional groups involving Pb(II) binding. The proposed usage form of Phormidium sp. does not need complicated immobilization procedures and expensive preliminary preparations.

Using of Rhizopus arrhizus as a sensor modifying component for determination of Pb(II) in aqueous media by voltammetry

For the sensitive determination of Pb(II) from aqueous solutions, a new voltammetric biosensor based on carbon paste electrode modified with Rhizopus arrhizus was developed. The preconcentrated ions at open circuit were reduced by using differential pulse stripping voltammetry technique. The obtained current values were related to the concentration of Pb(II) in the solutions. The best results were achieved at pH 7 with 0.01 M Tris-HCl buffer solution applying a preconcentration time of 12 min. The linear range for the biosensor was found to be within 1.0 x 10(-7)-1.25 x 10(-5) M, with a detection limit of 0.5 x 10(-8) M. The selectivity of the microbial biosensor was explored by adding interfering heavy metals to accumulation medium one by one, and their matrix effects were also investigated in the model metal solutions. Energy dispersive X-ray spectra analysis were applied to show the specific effect of the fungal biomass on the Pb(II) determination.

Some DI- and Trinuclear Zinc Complexes: Anion Induced Complex Formation

Abstract Complexes of N,N′-bis(salicylidene)-1,3-diaminopropane, an ONNO type ligand, with ZnX2 (X = AcO−, NO3-, Cl−, Br−, I−) salts were prepared. Molecular structures of these complexes were identified using elemental analyses, IR spectrometry and X-ray diffraction techniques. It has been observed that the reactions between zinc ions and the said ligand tend to produce polynuclear complexes and depending on the anion present either di- or trinuclear complexes are formed. Thus, it can be deduced from the results presented in this article that trinuclear complexes form when the zinc salt used was the acetate or nitrate and dinuclear complexes form if the anion in the zinc salt is a halogen.

Synthesis, crystal structure and electrochemical behaviour of water soluble Schiff bases

Abstract Four water soluble Schiff bases were prepared from the reaction of salicylaldehyde and 2-hydroxy-1-naphtaldehyde with 2-amino-2-methyl-1,3-dihydroxy propane and 2-amino-2-methoxy-1,3-dihydroxy propane. Two of the Schiff bases were characterized using elemental analysis, IR spectroscopy and single crystal X-ray diffraction. In addition cyclic voltammetric studies were performed. The Schiff bases C11H5NO4 (II) and C15H17NO3 (III) crystalize in monoclinic space group P21/c with unit cell dimensions a = 10.499(2), b = 8.725(2), c = 12.635(10) Å, β = 101.649(11); a = 14.579(8), b = 9.834(13), c = 9.542(5) Å, β = 107.559(5) respectively.

Utilization of heat-dried Pseudomonas aeruginosa biomass for voltammetric determination of Pb(II)

In this research, thermally dried Pseudomonas aeruginosa cells were used as a biological material for the construction of a microbial biosensor. The preparation, optimization and application of the developed microbial biosensor, which analyzed Pb(II), are presented. The method was based on stripping of adsorbed metal ions from the modified electrode surface. Modified carbon paste electrodes were preconcentrated at open circuit, and then electrochemically measured by using cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) techniques. It was found that the thermally dried cells were capable of adsorbing Pb(II) ions from aqueous solutions and could determine the ions prominently at optimum experimental conditions. Many important parameters to acquire the best electrochemical response were carried out, including effect of different electrolyte solutions, pH, deposition potential, deposition time, ionic strength, preconcentration time, and effect of interference ions. Finally, a calibration graph was obtained with a linear range from 1.0×10(-6) to 2.0×10(-5) M Pb(II) (R(2)=0.9916) and detection limit was found as 6.0×10(-7) M Pb(II) by using 3×S(b)/m formula. Other analytical properties of the developed microbial biosensor were also investigated. The suggested usage format of P. aeruginosa for the determination of Pb(II) does not require complicated immobilization procedure, easy to handle, and not time consuming.

A crystallographic and spectroscopic study on the imine- amine tautomerism of 2-hydroxyaldimine compounds

Abstract The molecular structures of N-(2-hydroxy ethyl)-3,5-dinitrosalicylaldimine and N-N′-bis(acetophe-nylketimine)-1,4-diaminobuthane were determined using X-ray diffraction. It was established using the difference Fourier map that the phenolic hydrogens were situated on the iminic nitrogen. Identical observations of the molecular structure were made for similar Schiff bases in literature, and it was established that this situation was not in agreement with the IR and NMR results. The molecular structure of N-(4-hydroxylphenyl)-benzaldimine was determined using X-ray diffraction for comparison. Similar compounds were prepared and their FTIR spectra were investigated.

SIMULTANEOUS DETERMINATION OF C60 AND C70 FULLERENES BY A SPECTROPHOTOMETRIC METHOD

In all fullerene-producing systems, reaction products were black soot extracts reported to contain a 5–25% fullerene mixture. Toluene extraction of the soot results in a solution of C60, C70, and higherc fullerenes. Without separation, absolute determination of the contents is not possible, leaving the researcher to comment only on the C60/C70 ratio of the solution. High-performance liquid chromatography, nuclear magnetic resonance, and scanning tunneling microscopy imaging techniques were reported in the literature for determining the C60/C70 ratio of the mixtures. These methods require tedious experiments and produce slightly differing results as well. In this communication, a new and relatively quick method is proposed for the simultaneous determination of the yields of C60 and C70 (not the ratio) in fullerene-containing solutions by ultraviolet-visible spectrophotometric analysis.

Simultaneous Bacillus anthracis Spores Detection via Aminated-Poly(vinyl chloride) Coated Piezoelectric Crystal Immunosensor

Bacillus anthracis spores are a potential threat to countries in the context of biodefense. We have already seen the destructiveness of the anthrax attacks in the recent past. This study presents an aminated-poly(vinyl chloride) (PVC-NH2) coated quartz crystal microbalance (QCM) immunosensor for simultaneous rapid detection of B. anthracis spores. PVC-NH2, synthesized in the laboratory, was used as an adhesive layer for monoclonal antibody immobilization on gold quartz crystal. The prepared QCM sensor was tested using a pathogen field strain of B. anthracis (GenBank number: GQ375871.1) under static addition and flow through procedures with different spore concentrations. Fourier transform infrared spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM) were performed to characterize the surface of the sensor during the modification. Furthermore, a series of SEM micrographs were taken in order to investigate surface morphology and show the presence of the B. anthracis spores on the surface. It is concluded that B. anthracis spores can be accomplished by using amine functionalized polymer coated QCM sensors without requiring complicated immobilization procedures or expensive preliminary preparations.