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New route for preparation and characterization
of magnetite nanoparticles
M.A. Abdalla a, M.H. Jaafar a,*, Z.A. Al-Othman a, S.M. Alfadul b, M. Ali Khan b
Abstract

We report here the synthesis of naked magnetic nanoparticles by using a facile method. Magnetic nanoparticles were prepared by mixing and stirring two equivalents of iron(II) chloride tetrahydrate with three equivalents of iron(III) chloride hexahydrate at room temperature. The mixture was treated by adding 100ml of 28% ammonium hydroxide. Immediately, the color of the solution turned from orange to black. Magnetite nanoparticles precipitated and were washed three times with 5% NH4OH solution using the magnetic decantation method.

The nanoparticles have been underwent full characterization. Their surface show a bunch of hydroxyl groups which they can be used for further complexion and removal of many hazardous compound. 
 
1-[1-(3-Methylphenyl)-5-phenyl-4- phenylsulfonyl-1H-pyrazol-3-yl]ethanone
Mohamed Ghazzali,a Hatem A. Abdel-Aziz,b Khalid Al-Farhand and Seik Weng Ngc,a*
 
aDepartment of Chemistry, Faculty of Science, King Saud University, PO 2455
Riyadh 11451, Saudi Arabia, bDepartment of Pharmaceutical Chemistry, Faculty of
Pharmacy, King Saud University, PO Box 2457 Riyadh 11451, Saudi Arabia,
cDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia,
and dChemistry Department, Faculty of Science, King Abdulaziz University, PO Box
80203 Jeddah, Saudi Arabia
Correspondence e-mail: seikweng@um.edu.my
Received 4 October 2011; accepted 6 October 2011
Key indicators: single-crystal X-ray study; T = 293 K; mean _(C–C) = 0.003 A°
;
disorder in main residue; R factor = 0.041; wR factor = 0.131; data-to-parameter
ratio = 18.6.
 
ABSTRACT
Both the acetyl and phenyl substituents of the central pyrazole ring in the title compound, C24H20N2O3S, are twisted with respect to the pyrazole ring, with the twist involving the phenyl ring being greater [67.4 (1) and 29.6 (2)_]. The tolyl substituent is disordered over two positions in a 1:1 ratio; the mean planes of the aromatic ring are aligned at 67.7 (3) and 69.4 (3)_ with respect to the pyrazole ring.
 
Kinetic Analysis for Non-isothermal Decomposition of Unirradiated and    γ-irradiated Indium acetyl acetonate.
Refaat.Mohammed. Mahfouz*,Sharifa. Al-Ahmari, Amaal. Al-Fawaz, Zaid. Al-Othman, Ismail  Khaleel Warad  and Mohammed Rafiq Hussain Siddiqui
PO Box 2455, Department of chemistry, College of science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
Abstract:
Kinetic studies for the non-isothermal decomposition of un-irradiated and γ-irradiated indium acetyl acetonate In(acac)3with 102kGy total γ-ray dose were carried out in static air. The results showed that the decomposition proceeds in one major step in the temperature range of 150-2500Cwith the formation of In2O3as solid residue. The non-isothermal data for un-irradiated and γ-irradiated In(acac)3were analysed using linear Flynn-Wall-Ozawa (FWO) and nonlinear Vyazovkin (VYZ)iso-conversional methods. The results of application of these free models on the investigated data showed a systematic dependence of Ea on α indicating a simple decomposition process. No significant changes were observed in both decomposition behaviour and (Eα-α) dependency between unirradiated and γ-irradiated In(acac)3. Calcination of In(acac)3at 400oC for 5 hours led to the formation of In2O3monodispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesised nanoparticles. This is the first attempt to prepare In2O3nanoparticles by solid state thermal decomposition of In(acac)3.
 
Facile and Convenient Synthesis of New Thieno[2,3-b]-
Thiophene Derivatives
 
Yahia Nasser Mabkhot 1,*, Nabila abd Elshafy Kheder 2,† and Abdullah Mohammad Al-Majid 1
Abstract
 
A facile and convenient synthesis of bis(2-(1H-benzo[d]imidazol-2(3H)-
ylidene)-3-oxopropanenitrile), bis((3-amino-5-(methylthio)-1H-pyrazol-4-
 
yl)methanone)and bis(2-thioxo-1,2-dihydropyrimidine-5-carbonitrile)  
derivatives incorporating a thieno-[2,3-b]thiophene moiety via versatile,
 
readily accessible diethyl 3,4-dimethylthieno-[2,3-b]thiophene-2,5- 
dicarboxylate (1) is described.
  
Synthesis and Antitumor Activity of Some Pyrazole Derivatives
FATMA E.M. EL-BAIH1,* and HASSAN M. AL-HAZIMI2
1Women Students-Medical Studies & Sciences Sections, Department of Chemistry, College of Science, King Saud University, P.O. Box
22452, Riyadh 11495, Saudi Arabia
2Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
*Corresponding author: Tel:/Fax: +966 1 4772245; E-mail: zahraa205@yahoo.com
Asian Journal of Chemistry; Vol. 23, No. 3 (2011), 1309-1313
(Received: 12 May 2010; Accepted: 10 November 2010) AJC-9293

Vilsmeier-Haack chloroformylation of 1a-e using DMF and an excess of POCl3 yielded the corresponding pyrazole-4-carbaldehydes 2a-e. Reaction of 2a,c with o-bromophenol and KOH in DMF gave the target compound 5-phenoxypyrazole-4-carbaldehydes 3a,b which in turn gave the corresponding oximes 4a,b by oximation of 3a,b with hydroxylamine. Condensation of 2b,c with 1,2-diaminobenzene and 2-aminothiophenol was carried out to give tetrahydrobenzo[b]pyrazolo[3,4-e][1,4]diazepine derivatives 5a,b and benzo[b]pyrazolo[4,3- f][1,4]thiazepine derivatives 6a,b, respectively. Some of the prepared compounds was examined as cytotoxic agents. The compounds 3a, 4a, 5a and 6a were proved to be less or more active than the standared doxorubicin depending on the cell lines.
 
Key Words: Pyrazole carbaldeyhde, Pyrazole carbaldeyhde oxime, Benzopyrazolodiazepine, Benzopyrazolothiazepine.
 
Central European Journal of Chemistry
* E-mail: mghazzali@ksu.edu.sa
(a)Department of Chemistry, King Saud University,
P. O. Box 2455, Riyadh 11451, Saudi Arabia
(b)Strategic center for diabetic research, King Saud University,
P.O. Box 245, Riyadh 11411, Saudi Arabia
Khalid A. Al-Farhana, Ismail Warada, Saud I. Al-Resayesa,
Moustafa M. Foudab and Mohamed Ghazzalia*
Synthesis, structural chemistry and antimicrobial activity of -(-) borneol derivative
Abstract:
© Versita Sp. z o.o.
Received 03 January 2010; Accepted 12 April 2010
Antimicrobial activity Borneol is a monoterpene that is a part of traditional Chinese and Japanese medicine. (-) borneol reacted with methanesulfonyl chloride in THF/pyridine to afford the new 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methane sulfonate derivative in excellent yield. The product is characterized by H1NMR, C13NMR, mass spectroscopy as well as elemental analysis and its structure was identified by X-ray single crystal diffraction. The packing of 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methanesulfonate exhibits the non-classical C—H∙∙∙O hydrogen bonding in C(4) and R2 2(8) chain and ring motifs as structural determinants. This was also confirmed by the analysis of Hirshfeld surfaces. The 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methane sulfonate antimicrobial activity was tested and compared with its parent (-) borneol against three different pathogens. Particularly, 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methane sulfonate showed high sensitivity, compared to Chloramphenicol reference material, against Escherichia coli.
Keywords: (-)borneol • X-ray single crystal • Hirshfeld surfaces • C-H∙∙∙O weak hydrogen bonding •
 
Asian Journal of Chemistry; Vol. 23, No. 3 (2011), 1309-1313
KINTETIC STUDIES FOR NON-ISOTHERMAL DECOMPOSITION OF                      UN-IRRADIATED AND γ-IRRADIATED GALLIUM ACETYLACETONATE
Kh. M. Al-Khamis, Z. A. Al – Othman and R. M. Mahfouz*
King Saud University, Riyadh 11451, PO Box 2455, Department of chemistry, College of science, Kingdom of Saudi Arabia
 
Abstract
 
The non-isothermal decomposition of un-irradiated and γ-irradiated gallium acetylacetonate Ga(acac)3with 102kGy total γ-ray dose were carried out in static air. The results showed that the decomposition of Ga(acac)3proceeds  through multiple decomposition steps in the temperature range of 150-310 ◦C with the formation of Ga2O3as a final solid residue. Kinetic studies for the non-isothermal data for both un-irradiated and γ-irradiated Ga(acac)3were performed using both model-fitting and model-free approaches. In a model-fitting approach, the kinetic triplet, i.e.the apparent activation energy Ea, the pre-exponential factor ln A, and the reaction model f(α), were analyzed and calculated using Coats and Redfern, and Kennedy and Clark methods. In the model-free approach, the non-isothermal data for both un-irradiated and γ-irradiated Ga(acac)3 sample were analyzed using Flynn- Wall-Ozawa (FWO), Tang (T), and Vyazovkin (Vyz) isoconversional methods. The results of application of model-free and  model-fitting approaches to the non-isothermal data for both un-irradiated and γ-irradiated Ga(acac)3were compared and evaluated to deduce the most probable kinetic triplet that describe correctly the thermal behaviour of Ga(acac)3.

New Routes for Preparation and Characterization of Au2(CºN)2P(Ph)2CH2P(Ph)2] Complex
MOHAMMED H. JAAFAR * and A.A. AL-OHALY
Asian Journal of Chemistry; Vol. 25, No. 2 (2013), 642-644
 
ABSTRACT
The gold complex i.e., [Au2(CºN)2P(Ph)2CH2P(Ph)2] has been successfully produced by three reactions, the reaction of polymeric gold cyanide [Au(CN)]n with a suspension of bis(diphenylphosphino)methane (dppm), in acetone in a 2:1, pure ammonia (NH3), [Au(CºN)]n and (Ph)2PCH2P(Ph)2 in acetone in a 2:2:1 or that of [Au(CºN)(NH3)2] with (Ph)2PCH2P(Ph)2 in acetone in a 1:0.5 giving a white precipitate collected as Au2(CºN)2P(Ph)2CH2P(Ph)2. The complex was characterized by elemental analysis, FT-IR and NMR spectroscopy and found in agreement with the proposed formula C27H22N2P2Au2.
 
Synthesis and characterization of monomeric and polymeric pyridinylimine based Ni(II) complexes and their catalytic activities in ethylene oligomerization.
Tansir Ahamad, Saad M. Alshehri*
Department of Chemistry, King Saud University, Riyadh-11451, Kingdom of Saudi Arabia.
Abstract
A new polymeric ligand was synthesized through the reaction of 4-(pyridinylimine)phenol and formaldehyde in a basic medium, and its corresponding polymer–nickel complexes were formed in a 1 : 1 molar ratio. The synthesized compounds were characterized using elemental and spectral analyses. The monomeric and polymeric Ni(II) complexes (C1 and C2, respectively) were evaluated as catalyst precursors for ethylene oligomerization, using methylaluminoxane as an activator at two different ethylene pressures. C2 was found to be a more effective pre-catalyst than C1, with the co-catalyst having a similar effect in both cases. C2 exhibited an activity of 1.282 × 106 g (mol Ni)−1 h−1 bar−1, with an Al : Ni ratio of 2000 : 1 at room temperature and 1 atm ethylene pressure. Meanwhile C1 exhibited an activity of 1.126 × 106 g (mol Ni)−1 h−1 bar−1 under similar experimental conditions. At 5 atm ethylene pressure, C1 favoured the formation of high-density polyethylene, whereas C2 favored the formation of branched low-density polyethylene.
Key words: Ethylene, polymerization, polymer metal complex, catalyst. 
 
Behavior of colchicine treated and untreated diploid plants of Sismbrium irio under varying photoperiods
 
Jameel Ahmad Khader1, Naser Mohamed AbdEIslam1, Riaz Ullah2, Zahoor Ullah3
 
1College of Science Research Centre King Saud University P.O box2455, Riyadh 11451, Saudi Arabia
2Department of Chemistry Government Degree College Ara Khel FR Kohat KPK Pakistan
3Chemical Engineering Department, Universiti Teknologi Petronas Malaysia
 
ABSTRACT
Sisymbrium irio common names (Jangli sarsoon (Sin.), Khub Kalan, Khakshir (Urd.,Per.),Maktrusa, Naktrusa (Pun.), London rocket (Eng.) is a wild plant which that grows in the northernparts of Pakistan. In this investigation the seedlings of this plant were treated with the drug colchicines and further subjected to the varying photoperiods. As a result of these treatments, three plants appeared with evident characters of polyploidy in them. One of each in the lots is subjected to 6, 10 and 12 h photoperiod and 0.1, 0.2 and 0.3% dilution of colchicines, respectively. The behavior of one of these plants was quite encouraging which was in the lot subjected to 10 h photoperiod. In this case, seed yield was very high and it appeared to be a promising entity. However, further trials and cytological studies will confirm its genetic validity as a polyploid and economic utility.
 
Keywords: Sisymbrium irio, polyploidy, colchicines, photoperiods

Microstructure and Magnetic Studies ofZincFerrite Nano-Particles
N. M. Deraz*, A. Alarifi
Catalytic Chemistry Chair, Chemistry Department , College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
Received:  14 May 2012 / Accepted:  1 xxx 2012  / Published: 1 xxx 2012
 
Zinc ferrite nano-particles are synthesised by advanced combustion route. The nano-sized Zn ferrite characterized by X-ray diffraction (XRD), Scanning electron micrographs (SEM) and Energy dispersive X-ray (EDX) techniques. The magnetic properties were determined byusing vibrating sample magnetometer (VSM).The preparation method investigated brought about formation of moderate crystalline ZnFe2O4 as a single phase with irregular shape. Both the saturation magnetization (60 emu/g) and the remnant magnetization (20 emu/g) were found to be highly depending upon the size and crystallinity of the investigated ferrite. Our results indicate that this method might provide a promising option for synthesizing high-quality nano-sized ZnFe2O4.

Controlled Synthesis, Physicochemical and MagneticProperties ofNano-Crystalline Mn Ferrite System
N. M. Deraz*, A. Alarifi
Catalytic Chemistry Chair, Chemistry Department , College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia

Received:  7 May 2012 / Accepted:  1 xxx 2012  / Published: 1 xxx 2012

Manganese ferrite nano-particles are synthesised by combustion route by using a mixture of glycine and ammonium nitrate as fuels with corresponding metal nitrates. The nano-sized Mn ferrite characterized by X-ray diffraction (XRD), Scanning electron micrographs (SEM) and Energy dispersive X-ray (EDX) techniques. When the mixture of glycine and ammonium nitrate is used, moderate crystalline MnFe2O4 is obtained as a single phase with irregular shape. Both the saturation magnetization (80 emu/g) and the remnant magnetization (50 emu/g) were found to be highly depending upon the size and crystallinity of the investigated ferrite. Our results indicate that this method might provide a promising option for synthesizing high-quality nano-sized MnFe2O4 which has the same saturation magnetization value of bulk Mn ferrite.
 
Synthesis and characterization of monomeric and polymeric pyridinylimine-based Ni(II) complexes and their catalytic activities
in ethylene oligomerization
Tansir Ahamad and SaadMAlshehri∗
Abstract
A new polymeric ligand was synthesized through the reaction of 4-(pyridinylimine)phenol and formaldehyde in a basic medium, and its corresponding polymer–nickel complexes were formed in a 1 : 1 molar ratio. The synthesized compounds were characterized using elemental and spectral analyses. The monomeric and polymeric Ni(II) complexes (C1 and C2, respectively) were evaluated as catalyst precursors for ethylene oligomerization, using methylaluminoxane as an activator at two different ethylene pressures. C2 was found to be a more effective pre-catalyst than C1, with the co-catalyst having a similar effect in both cases. C2 exhibited an activity of 1.282 × 106 g (mol Ni)−1 h−1 bar−1, with an Al : Ni ratio of 2000 : 1 at room temperature and 1 atm ethylene pressure. Meanwhile C1 exhibited an activity of 1.126 × 106 g (mol Ni)−1 h−1 bar−1 under similar experimental conditions. At 5 atm ethylene pressure, C1 favoured the formation of high-density polyethylene, whereas C2 favoured the formation of branched low-density polyethylene.
_c 2012 Society of Chemical Industry
Keywords: ethylene; polymerization; polymer–metal complex; catalyst
 
Preparation of membranes based on high-density polyethylene graft copolymersfor phosphate anion removal
Journal of Industrial and Engineering Chemistry 19 (2013) 48–55
Magdy M.H. Senna a,*, Yasser K. Abdel-Moneam b, Osama A. Gamal b, Abdallah Alarifi a
a Catalytic Chemistry Chair, Chemistry Department, Faculty of Science, King Saud University, Riyadh, Saudi Arabia
b Chemistry Department, Faculty of Science, Menoufia University, Sheben Al-Kom, Egypt
 
This work was undertaken to synthesize graft copolymers that possess functional groups via the radiation-induced grafting of acrylamide onto a high-density  olyethylene (HDPE) substrate. The optimum conditions suitable for radiation graft copolymerization were determined. In this regard, the effects of the solvent, the inhibitor concentration, the monomer concentration and the irradiation dose on
the grafting yield were investigated. Selected properties of the prepared graft copolymers were investigated to elucidate the possibility of their practical use in the removal of metals and phosphate anions. The effects of different parameters that may affect the metal chelation process, such as pH, metal feed concentration and time of contact, were also studied. A chemically modified membrane loaded with Cu(II) was used for the removal of phosphate ions from aqueous solutions.
 
Expeditious and highly efficient protocol for the synthesis of novel diversely
substituted thieno[2,3-b]thiophene
Yahia Nasser Mabkhot ⇑, Assem Barakat ⇑, Saeed Alshahrani
Journal of Molecular Structure 1027 (2012) 15–19
 
A b s t r a c t
1,10-(3-Methyl-4-phenylthieno[2,3-b]thiophene-2,5-diyl)bis(4,4,4 triethoxybut-2-en-1-one)-3 has been reported by one-pot reaction of enaminone derivative 2 with triethylorthoformate in fairly high yields. The hitherto unknown bis-hydroxyl amine derivatives 4 via N-nucleophile under basic conditions is described. Additionally, the novel Compound 5 were synthesized by the cyclization of enaminone derivative 2 using AcOH with the aid of catalytic amount of AcONH4. Nevertheless, facile reaction sequences for the preparation of 6, 7, 8a-c, and 9a-c starting with 1,10-(3-methyl-4-phenylthieno[2,3-b]thiophene-2,5- diyl)diethanone 1 have been developed. Finally, several bis-heterocycles 10a-f were synthesized through a stepwise formation of hydrazone followed by a Michael 1,4-addition of the nucleophile nitrogen atom and provides a convenient access to an important class of nitrogen heterocycles.

Magnetic behavior and physicochemical propertiesof Ni and NiO nano-particles
 
N. M. Deraz*
Chemistry Department, College of Science, King Saud University, Riyadh,Saudi Arabia
 
Abstract
    A series of nano-crystalline Ni/NiO particles wassynthesized by a combustion route depending upon the glycine-nitrate process. The as prepared samples were characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron micrograph (TEM) and vibrating sample magnetometer (VSM) techniques.
    The XRD results revealed that the Ni powder crystallizes with the cubic phase when the molar ratio of glycine to nitrate is 1.5. Above or below that molar ratio, NiO phase coexists as an impurity along with the Ni phase. The SEM and TEM measurements of the as-synthesized powders showed that the particles are irregular in shapes and have porous morphology. Increasing the ratio between glycine and Ni-nitrate resulted in slightly agglomeration and grain growth of nano-particles depending upon high combustion heat. The magnetization value of Ni measured at room temperature is very close to the value observed for commercial Ni powder.
 
Effects of heat treatment on physicochemical properties of cerium based nickel system
 
N. M. Deraz*
Chemistry Department, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia
   
Abstract
    Cerium based nickel catalysts synthesized by impregnation method have been characterized by XRD and TEM techniques. These catalysts can be described as a mixture of nickel oxide and ceria modified by the insertion of a part of nickel in the ceria lattice. The surface and catalytic properties of Ni/Ce mixed oxide solids were determined by nitrogen adsorption at 77 K and catalytic conversion of isopropanol at different temperatures.
      The results revealed that the heat treatment brought about different modifications in the structural, morphological, surface and catalytic properties of the as synthesized catalysts. From the characterization of the as prepared catalysts, it was concluded that the as prepared catalysts contain highly dispersed NiO, well crystalline NiO and CeO2 and also Ni-Ce-O solid solution. This treatment led to a slightly increase in the crystallite size of ceria particles. On the other hand, the increase in the heat treatment resulted in an increase in the crystallite size, lattice constant and unit cell volume of nickel oxide. The formation of Ni-Ce-O solid solution with subsequent creation of oxygen vacancies increase as the heat treatment increases. However, the specific surface area, total pore volume and catalytic activity of the investigated system decrease as the preparation temperature increases from 500 to 700 oC. The sintering activation energy of NiO and ceria were found to be 2.8 and 12.7 kJ/mol, respectively.
 
Microwave assisted synthesis and characterization of olive oil based polyetheramide as anticorrosive polymeric coatings
Manawwer Alam1, Naser M Alandis2
1Research Centre-College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia Tel. 966-14676085, Fax. 966-14673140
2Department of Chemistry-College of Science, King Saud University, P.O. Box 2455 Riyadh 11451, Kingdom of Saudi Arabia Tel. 966-14673667, Fax. 966-14674136
Abstract
Virgin Olive oil (VOO) based polyetheramide (PEtA) was developed from N-N’ bis 2- hydroxyl ethyl olive fatty amide (HEOA) and orcinol through condensation polymerization. PEtA was further treated with toluylene 2,4-diisocynate (TDI) with different percentages (20-30wt%) via addition polymerization to obtain poly(ether amide urethane) (PEtAU). The structural elucidation of HEOA, PEtA and PEtAU were carried out by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. Physico-chemical and physico-mechanical properties of the material were investigated by standard methods. Thermal stability and curing behavior of virgin olive oil, HEOA, and PEtAU were assessed by thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The corrosion behavior was investigated by potentiodynamic polarization measurements in different corrosive environments (3.5wt%HCl, 5wt%NaCl, 3.5wt%NaOH, Tap water) at room temperature. The results showed that UPEtA coatings exhibit good physico-mechanical as well as corrosion resistance performance and can be safely used up to 200oC. The work is an attempt for alternate utilization of olive oil.
Keywords:  olive oil; orcinol; polyetheramide; urethane; coating
Acknowledgement
This project was supported by King Saud University, Deanship of Scientific Research, College of Science -Research Center.
 
ASPIRIN C EFFERVESCENT TABLETS BY HIGH PERFORMANCELIQUIDCHROMATOGRAPHY–PHOTODIODE ARRAY DETECTOR
 
Mohammad Rizwan Khan, Zeid Abdullah Alothman, Mu. Naushad,Ayman Abdul Ghfar, and Saikh Mohammad Wabaidur
 
Department of Chemistry, Advanced Materials Research Chair, College of Science,
King Saud University, Riyadh, Saudi Arabia
 
Abstract
High performance liquid chromatography–photodiode array (HPLC–PDA) method has beenemployed for the simultaneous determination of vitamin C (ascorbic acid) and aspirin (acetylsalicylicacid) in aspirin C effervescent tablets. Chromatographic separation of ascorbic acid (AA) andacetylsalicylic acid (ASA) was performed by reversed–phase using a Betasil C18 column with particlesize of 3 lm, 150mm_4.6mm I.D. Optimum separation was achieved in isocratic mode witha binary mobile phase (mixture of water and acetonitrile with 0.1% of formic acid, 75:25, v=v) ata flow rate of 1.0 mL min_1. Recovery of the target compounds was obtained more than 98% withgood quality parameters: linearity (r2>0.997), limit of detection (LOD) and limit of quantification(LOQ) values between 1.4_10_3 and 5.1_10_4 mg mL_1, and intra-day and interdayprecisions with relative standard deviation (RSD) lower than 2.1%. The content of the analyzedsamples ascorbic and acetylsalicylic acid was found 238.23 and 393.49 mg, respectively, which arevery close to the label claimed by the manufacturer in aspirin C effervescent tablets. Therefore, thismethod can be proposed for routine analysis of these compounds in aspirin C effervescent tablets.
 
Keywords:acetylsalicylic acid, ascorbic acid, aspirin C effervescent tablets, column,HPLC–PDA, mobile phase

Development of polyesteramine-butylated melamine formaldehyde based polymeric coatings
Manawwer Alam
 
International Journal of Polymer Anal. Charact., 17: 458–464, 2012
Research Centre-College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia
Correspondence: malamiitd@gmail.com
Abstract
In the present communication polyesteramine(PEA) resin was synthesized by condensation polymerization of triethanolamine and itaconic acid and further treated with butylated melamine formaldehyde (BMF) in different (35,40,45,50,55) phr (part per hundred part of resin) used as crosslinker and orthrophosphoric acid as catalyst. The structural elucidation of PEA was carried out by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. The physico-chemical characterization of these resin like acid value, hydroxyl value, refractive index, specific gravity were carried out by standard methods. The PEA-BMF systems were applied on mild steel strips of standard sizes by brush to evaluate their physico-mechanical and chemical/corrosion resistance test. Physico-mechanical properties and anticorrosive performance of PEA-BMF systems were investigated by standard methods. It was found that among all resin compositions PEA-BMF50 exhibited excellent coating properties.Morphology of coatings was investigated by scanning electron microscopy (SEM). Thermal stability of the resin was determined by Thermogravimetric analysis (TGA). Thermal analysis reveals that PEA-BMF50 can be safely used upto 200oC.
Keywords: Triethanolamine; Itaconic acid; Coatings
Acknowledgement
This project was supported by King Saud University, Deanship of Scientific Research, College of Science -Research Center.

Int. J. Mol. Sci. 2012, 13, 2263-2275; doi:10.3390/ijms13022263
Comprehensive and Facile Synthesis of Some Functionalized Bis-Heterocyclic Compounds Containing a
Thieno[2,3-b]thiophene Motif
Yahia N. Mabkhot *, Assem Barakat *, Abdullah M. Al-Majid and Saeed A. Alshahrani
Department of Chemistry, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; E-Mails: amajid@ksu.edu.sa (A.M.A.-M.); saddah096@hotmail.com(S.A.A.)
*   Authors to whom correspondence should be addressed; E-Mails: yahia@ksu.edu.sa (Y.N.M.); ambarakat@ksu.edu.sa (A.B.); Tel.: +96614675884; Fax: +96614675992.
Received: 6 January 2012; in revised form: 9 February 2012 / Accepted: 13 February 2012 /
Published: 20 February 2012

Abstract:A comprehensive and facile method for the synthesis of new functionalized
bis-heterocyclic compounds containing a thieno[2,3-b]thiophene motif is described. The hitherto unknown bis-pyrazolothieno[2,3-b]thiophene derivatives 2a–c, bis-pyridazin othieno[2,3-b]thiophene derivatives 4, bis-pyridinothieno[2,3-b]thiophene derivatives 6a,b, and to an analogousbis-pyridinothieno[2,3-b]thiophenenitrile derivatives 7 are obtained.Additionally, the novel bis-pyradazinonothieno[2,3-b]thiophenederivatives 9, and nicotinic acid derivatives 10, 11 are obtained via bis-dienamide 8. The structures of all newly synthesized compounds have been elucidated by 1H, 13C NMR, GCMS, and IR spectrometry. These compounds represent a new class of sulfur and Nitrogen containing heterocycles that should also be of interest as new materials.
Keywords:pyrazole; nicotinic acid; thieno[2,3-b]thiophene; enaminone; heterocycle
 
Int. J. Electrochem. Sci., 7 (2012) 12646 - 12655
Electrospinning Synthesis and Electrocatalytic Performance of Cobalt oxide/Carbon Nanofibers Nanocomposite Based PVA for Fuel Cell Applications
 
Abdullah M. Al-Enizi1, Ahmed A. Elzatahry1,2,3*, Abdel-Rahman I. Soliman1,2,4 and Salem S. Al-Theyab2
 
1 Department of chemistry, King Saud University, PO Box: 2455, Riyadh 11451, Riyadh, Kingdom of Saudi Arabia.
2 Petrochemical research chair, Department of chemistry, King Saud University, PO Box: 2455, Riyadh 11451, Riyadh, Kingdom of Saudi Arabia.
*E-mail: aelzatahry@ksu.edu.sa
 
This work concerns carbon nanofibers (CNF) as a material support to prepare nanocomposite electrode, and to use such electrode for fuel cell application. The nanocomposite electrode was produced by electrospinning mixtures of cobalt nitrate with aqueous solutions of polyvinyl alcohol (PVA) followed by high-temperature annealing process. As a result, Cobalt oxide nanoparticles have been formed and incorporated within carbon nanofibers. Conductivity, capacitance and the electrocatalytic activities of the produced nanocomposite have been studied using cyclic voltammetry, and chronoamperometry. Produced materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Energy-dispersive X-ray spectroscopy (EDX) and scanning-electron microscopy (SEM), which revealed that nanofibers in the range of 200–300 nm. The high conducting, and capacitance of the produced nanocomposite are related to the complete transfer of electrospun PVA fiber to active carbon nanofibers, and the presence of well dispersed Cobalt oxide nanoparticle, which lead to the enhancement of connectivity and the electrochemical utilization of pristine CNF during the charge/discharge process. On the other hand, the low electrocatalytic activity of the prepared electrodes towards methanol oxidation reaction can be attributed to the presence of nanostructure Cobalt oxide within the frame structure of carbon nanofibers, in addition to the complete absence of platinum materials. Therefore, based on the above investigations, carbon nanofibers composite electrode can be a potential candidate for a high-performance electrode supporting materials in fuel cells.
 
Keywords: Polyvinyl alcohol, Carbon nanofibers, Nanocomposite, Methanol Oxidation, Fuel Cells Electrocatalysis
 
Journal of Applied Polymer Science 2012. 2384-2393.
Effects of Electron Beam Irradiation on the Structure-Property Behavior of Blends Based on Low Density Polyethylene (LDPE) and Styrene-Ethylene -Butylene-Styrene-Block Copolymers
 
Magdy M.H. Senna1, Yasser K. Abdel-Moneam 2, Yousry A. Hussein 3,
Abdallah  Alarifi1
1-Catalytic Chemistry Chair, Chemistry Department, Faculty of science, King Saud University, Riyadh, Saudi Arabia  
2- Chemistry Department, Faculty of Science, Menoufia University, Sheben Al-Kom, Egypt
3-Alfanar Electrical Systems, Riyadh, Saudi Arabia
 
ABSTRACT
    Low density polyethylene (LDPE) blends with different additives were exposed to various doses of electron beam irradiation. The additives used were styrene-ethylene-butylene-styrene-block copolymers (SEBS), styrene-ethylene-butylene-styrene-block copolymer grafted with maleic anhydride (SEBS-g-MA) and mineral compounds. The structure-property behavior of electron beam irradiated blends was characterized in terms of mechanical, thermal and electrical resistivity properties. The results indicated that the unirradiated LDPE blends with the different compositions showed improved mechanical properties, thermal and volume resistivity properties than pure LDPE. However, the improvement in properties of unirradiated blends by using SEBS-g-MA was higher than using SEBS copolymer. Further improvement in the mechanical, thermal and electrical properties of the LDPE blends was achieved after electron beam irradiation. The limited oxygen index (LOI) data revealed that the LDPE/SEBS-g-MA/ ATH blend was changed from combustible to self-extinguishing material after electron beam irradiation to a dose of 100 kGy.
Keywords: LDPE, SEBS, SEBS-g-MA graft copolymer, electron beam irradiation, inorganic fillers
 
Carbohydrate Polymers 92 (2013) 943– 954
 
Antibacterial modification of cotton using nanotechnology
Moustafa M.G. Fouda a,b, E.S. Abdel-Halim a,b, Salem S. Al-Deyaba
a Petrochemical Research Chair, Chemistry Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia b Textile Research Division, National Research Center, P.O. Box 12622, Dokki, Cairo, Giza 12522, Egypt
 
Abstract
This review article is undertaken with a view to survey important scientific research and developmental works pertaining to antibacterial modification of textiles using nanotechnology as a new means to achieve such textiles. Inevitably, conventional antimicrobial agents and their applications to textiles are reported. This is followed by a focus on inorganic nanostructured materials that acquire good antibacterial activity and application of these materials to the textiles. Evaluation of the antibacterial efficacy is described. An outlook which envisions the importance of using nanotechnology in the antibacterial finishing of textiles is also outlined.

High Performance Polymers 24(6) 538–545
Microwave assisted preparation of urethane modified polyetheramide coatings from Jatropha seed oil
Manawwer Alam1, Naser M Alandis2
1Research Center-College of Science, King Saud University, P.O. Box 2455 Riyadh 11451, Kingdom of Saudi Arabia. Telephone No.966-14673667, Fax.966-14674136
2Department of Chemistry-College of Science, King Saud University, P.O. Box 2455 Riyadh 11451, Kingdom of Saudi Arabia.
Abstract
We have developed urethane modified polyetheramide (UPEtA) by the condensation polymerization reaction of N,N- bis (2-hydroxy ethyl)  Jatropha oil fatty amide (HEJA) and hydroquinone to form polyetheramide (PEtA). Jatropha PEtA was further treated with toluylene 2,6-diisocyanate (TDI) in different weight percentage (15, 20, 25 wt%) to produce UPEtA. The structural elucidation of PEtA and UPEtA was carried out by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. The coatings of UPEtA were prepared on mild steel strips to investigate their physico-mechanical and corrosion resistance performance. Physico-chemical and physico-mechanical tests were performed by standard methods. Corrosion resistance tests were examined in different corrosive media such as 3.5wt% HCl, 3.5wt% NaOH, 5.0wt% NaCl, water and xylene. The thermal behavior of UPEtA was studied by thermogravimetric analyses (TGA).  Our studies revealed that UPEtA may find application as eco-friendly corrosion protective coatings and may be safely used up to 200oC.
Key words: Polymericcoatings, Jatropha oil, Polyetheramide, Hydroquinone 
Acknowledgement
This project was supported by King Saud University, Deanship of Scientific Research, College of Science -Research Center.
*Correspondence
 
Mat.-wiss. u.Werkstofftech. 2012, 43, No. 3
Development of Corrosion Protective Polymeric Coatings from ANon-Edible Seed Oil
M. Alam1, M. R. Shaik,2 N. M. Alandis2
Abstract:
In this study, we have developed corrosion protective coatings material from Pongamia glabra seed oil. First, oil was converted to pongamia oil epoxy(POE). The resin was synthesized by the reaction of POE with phthalic acid to develop polyester(PE) and further treated with diethylene triamine (DTA) in different (20-35 %wt) amount. The structural elucidation of POE and PE were carried out by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. Thermal behavior of PE-30 was studied by thermogravimetric analyses(TGA) and differential scanning calorimetry (DSC). The coatings of PE-DTA resins were prepared on mild steel strips to investigate their physico-mechanical and corrosion performance. Corrosion protections of coated panels were examined in different corrosive media (3.5wt% HCl, 3.5wt% NaOH, 5.0%wt NaCl) using potentiodynamic polarization and AC impedance.Thermal analyses revealed that PE-30 may find application as eco-friendly corrosion protective coating safely used up to 175oC.
Keywords: pongamia glabra, oil epoxy, potentiodynamic, coatings
1Research Centre-College of Science, P.O.Box 2455, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
2Department of Chemistry, College of Science, P.O. Box 2455, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
*Corresponding Author: Manawwer Alam,Research Centre-College of Science, P.O. Box 2455, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
 
International Journal of Nanomedicine 2012:7 2829–2832
Nanofiber composites containing N-heterocyclic carbine complexes with antimicrobial activity
 
Ahmed A Elzatahry1,4 Abdullah M Al-Enizi1 Elsayed Ahmed Elsayed2,5Rachel R Butorac3Salem S Al-Deyab1 Mohammad AM Wadaan2 Alan H Cowley3
 
Abstract: This report concerns nanofiber composites that incorporate N-heterocyclic carbenes and the use of such composites for testing antimicrobial and antifungal activities. The nanofiber composites were produced by electrospinning mixtures of the gold chloride or gold acetate complexes of a bis(imino)acenaphthene (BIAN)-supported NHC with aqueous solutions of poly­vinyl alcohol (PVA). The products were characterized by scanning-electron microscopy, which revealed that nanofibers in the range of 250–300 nm had been produced. The biological activities of the nanofiber composites were tested against two Gram-positive bacteria, six Gram-negative bacteria, and two fungal strains. No activity was evident against the fungal strains. However, the gold chloride complex was found to be active against all the Gram-positive pathogens and one of the Gram-negative pathogens. It was also found that the activity of the produced nanofibers was localized and that no release of the bioactive compound from the nanofibers was evident. The demonstrated antimicrobial activities of these novel nanofiber composites render them potentially useful as wound dressings.
 
Keywords: nanofiber, electrospinning, N-Heterocyclic carbene, biopolymer, antimicrobial

International Journal of Physical Sciences Vol. 7(9), pp. 1403 - 1411, 23 February, 2012
Available online at http://www.academicjournals.org/IJPS
DOI: 10.5897/IJPS11.1364
ISSN 1992 - 1950 ©2012 Academic Journals
Full Length Research Paper
Electrochemical sensors for direct potentiometric determination of Voriconazole in pharmaceutical dosage forms and biological fluids
Nawal A. Alarfaj* and Maha F. El-Tohamy
Department of Chemistry, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia.
Accepted 24 January, 2012
The compositions and general performance characteristics of four polyvinyl chloride (PVC) membrane sensors respective to Voriconazole (VR) were described. Two of these sensors are based on the use of ion association complexes of VR with phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) as novel electroactive materials dispersed in o-nitrophenyloctyl ether (o-NPOE) plasticizer on glass assemblies. The third sensor is a coated wire type and based on the ion association incorporation of the VR with tetraphenylborate (TPB). The forth sensor is a graphite electrode type based on ion association with silicotungstic acid (STA). The developed sensors were used for the determination of VR in pure form in its pharmaceutical formulations and in biological fluids. The sensors displayed Nernstain response 57.56 ± 0.16, 58.45 ± 0.54, 56.17 ± 0.28 and 57.09 ± 0.74 mV at 25ºC, over linear concentration ranges from 9.0x10-7 to 1.0x10-2, 1.0x10-6 to 1.0x10-2, 1.0x10-6 to 1.0x10-2 and 5.0x10-6 to 1.0x10-2 molL-1 for the four mentioned sensors, respectively. The pH does not affect the sensor performances within the pH range of 3 to 8. Acceptable selectivity was obtained for VR against many inorganic cations, sugars and amino acids. Statistical student’s t-test and F test showed insignificant systematic error between proposed and reported methods.
Key words: Voriconazole, potentiometry, ion-selective electrode, graphite sensors, pharmaceutical formulations, biological fluids.

Int. J. Mol. Sci. 2012, 13, 6279-6291; doi:10.3390/ijms13056279
 
Synthesis and Characterization of Hybrid Materials Consisting of n-octadecyltriethoxysilane by Using n-Hexadecylamine as Surfactant and Q0 and T0 Cross-Linkers
OPEN ACCESS
Ismail Warad 1,*, Omar Abd-Elkader H 2,3, Saud Al-Resayes 1, Ahmad Husein 4, Mohammed Al-Nuri 4, Ahmed Boshaala 5, Nabil Al-Zaqri 1 and Taibi Ben Hadda 6
1 Department of Chemistry, Science College, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; E-Mails: resayes@ksu.edu.sa (S.A.-R.); nabil_alzaqri@yahoo.com (N.A.-Z.)
2 Electron Microscope Unit, Zoology Department, College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia; E-Mail: omabdelkader7@yahoo.com
3 Electron Microscope & Thin Films Department, Physics Division, National Research Center, Dokki 12622, Cairo, Egypt
4 Department of Chemistry, Science College, AN-Najah National University, P.O. Box 7, Nablus 00972, Palestine Territories; E-Mails: hamaydah2500@yahoo.com (A.H.); mabnuri@yahoo.com (M.A.-N.)
5 Chemistry Department, Faculty of Science, Benghazi University, P. O. Box 1308, Benghazi, 22385, Libya; E-Mail: ahmedboshaala@yahoo.co.uk
6 Materials Chemistry Laboratory, Faculty of Sciences, University of Mohammed Premier, Oujda-60000, Morocco; E-Mail: taibi.ben.hadda@gmail.com
* Author to whom correspondence should be addressed; E-Mail: warad@ksu.edu.sa; Tel.: +96-61-4675992; Fax: +96-61-4675992.
Received: 12 April 2012; in revised form: 3 May 2012 / Accepted: 10 May 2012 / Published: 21 May 2012
Abstract: Novel hybrid xerogel materials were synthesized by a sol-gel procedure. n-octadecyltriethoxysilane was co-condensed with and without different cross-linkers using Q0 and T0 mono-functionalized organosilanes in the presence of n-hexadecylamine with different hydroxyl silica functional groups at the surface. These polymer networks have shown new properties, for example, a high degree of cross-linking and hydrolysis. Two different synthesis steps were carried out: simple self-assembly followed by sol-gel transition and precipitation of homogenous sols. Due to the lack of solubility of thesematerials, the compositions of the new materials were determined by infrared spectroscopy, 13C and 29Si CP/MAS NMR spectroscopy and scanning electron microscopy. Keywords: sol-gel; solid state NMR; cross-linkers; stationary phases

spectral, thermal, and a crystalline structure of complexes containing [MeC(CH2PPh2)3Cu(I)]
Ismail Warad • Omar H Abd-Elkader •
Ahmed Boshaala • Nabil Al-Zaqri •
Belkheir Hammouti • Taibi Ben Hadda
Received: 22 April 2012 / Accepted: 3 May 2012
_ Springer Science+Business Media B.V. 2012
1 Abstract
The preparation of new [MeC(CH2PPh2)3CuCl] 1 and its derivatives 1 was carried out directly by mixing of CuCl and MeC(CH2PPh2)3 ligand in dry THF, the neutral precursor 1 served to prepare [MeC(CH2PPh2)3Cu(NCCH3)]BF4 2 and [MeC(CH2PPh2)3Cu(PCH2Ph)3]BF4 3. These complexes are characterized on the
basis of elemental analysis, IR, EDS, 1H, 13C and 31P{1H}NMR, FAB-MS, TG/ DTA and single-crystal X-ray diffraction studies. Complex 1 crystallizes in the Orthorhombic unit cells with the space group Pna2(1). The structural behavior of MeC(CH2PPh2)3 ligand in the formed complexes during the coordination reac- tion was monitored by 31P{1H}NMR in CDCl3 at room temperature for the first time.
Keywords Cu(I) complexes _ Tripodal phosphine ligands _ Crystal structure _ NMR
 
Pak. J. Bot., 44(3): 1153-1158, 2012.
EFFECT OF PROPOLIS ON GROWTH, AFLATOXINS PRODUCTION AND LIPID
METABOLISM IN ASPERGILLUS PARASITICUS SPEAR
ABEER HASHEM1*, E.F. ABD-ALLAH2 AND HEND A. ALWATHNANI1
1Botany and Microbiology Department, Faculty of Science, King Saud University, Riyadh, Saudi Arabia
2Plant Production Department, Faculty of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia
*Corresponding author. E-mail: habeer@ksu.edu.sa
Abstract
The mechanism of antifungal activities of propolis (Bee glue) was investigated for the growth, aflatoxins production, and lipids (total lipids, neutral lipids, phospholipids, and fatty acids) metabolism of Aspergillus parasiticus. The results of the present study indicated that propolis caused significant decrease in conidial production and conidial germination as well as mycelial growth (both radial and dry weight) of A. parasiticus. It was also found that aflatoxins production by A. parasiticus decreased significantly with 0.2 and 0.4 (g/100 ml) concentrations of propolis, however, 0.6 (g/100 ml) concentration caused complete inhibition of all aflatoxins production. The biochemical investigation of cellular total lipids, neutral lipids, and phospholipids of A. parasiticus suggested clear catabolic repression of lipids metabolism by propolis. Gas chromatographic analysis of cellular fatty acids indicated that propolis enhanced accumulation of saturated fatty acids suggesting resistance mechanism of fungal membrane via decreasing its fluidity and elasticity.
 
International Journal of Physical Sciences Vol. 7(9), pp. 1403 - 1411, 23 February, 2012
Available online at http://www.academicjournals.org/IJPS
DOI: 10.5897/IJPS11.1364
ISSN 1992 - 1950 ©2012 Academic Journals
Full Length Research Paper
Electrochemical sensors for direct potentiometric determination of Voriconazole in pharmaceutical dosage forms and biological fluids
Nawal A. Alarfaj* and Maha F. El-Tohamy
Department of Chemistry, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia.
Accepted 24 January, 2012
The compositions and general performance characteristics of four polyvinyl chloride (PVC) membrane sensors respective to Voriconazole (VR) were described. Two of these sensors are based on the use of ion association complexes of VR with phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) as novel electroactive materials dispersed in o-nitrophenyloctyl ether (o-NPOE) plasticizer on glass assemblies. The third sensor is a coated wire type and based on the ion association incorporation of the VR with tetraphenylborate (TPB). The forth sensor is a graphite electrode type based on ion association with silicotungstic acid (STA). The developed sensors were used for the determination of VR in pure form in its pharmaceutical formulations and in biological fluids. The sensors displayed Nernstain response 57.56 ± 0.16, 58.45 ± 0.54, 56.17 ± 0.28 and 57.09 ± 0.74 mV at 25ºC, over linear concentration ranges from 9.0x10-7 to 1.0x10-2, 1.0x10-6 to 1.0x10-2, 1.0x10-6 to 1.0x10-2 and 5.0x10-6 to 1.0x10-2 molL-1 for the four mentioned sensors, respectively. The pH does not affect the sensor performances within the pH range of 3 to 8. Acceptable selectivity was obtained for VR against many inorganic cations, sugars and amino acids. Statistical student’s t-test and F test showed insignificant systematic error between proposed and reported methods.
Key words: Voriconazole, potentiometry, ion-selective electrode, graphite sensors, pharmaceutical formulations, biological fluids.
 
Asian Journal of Chemistry; Vol. 24, No. 12 (2012), 5507-5510
Complexometric-Spectrophotometric Determination of Cisapride and Tiapride in Their Formulations†
NAWAL A. ALARFAJ
*, AZZA A. MOSTAFA and ZINAH A. ALGHAMDI
Department of Chemistry, College of Science, King Saud University, P.O. Box-22452, Riyadh 11495, Saudi Arabia
*Corresponding author: E-mail: nalarfaj@hotmail.com
AJC-11680
Simple and sensitive visible spectrophotometric methods were developed for the quantitative determination of cisapride and tiapride in their pharmaceutical formulations. The methods are based on the formation of ion association complexes with acidic dyes, which are extractable into chloroform. Cisapride was determined by its reaction with bromocresol green or bromophenol blue at pH 2.5 to yield yellow coloured complexes, peaking at 414 nm and 412 nm with bromocresol green and bromophenol blue respectively. Tiapride was determined by its reaction with tropaeolin OO(TOO) at pH 5 to yield a yellowish ion-pair complex measured at 412 nm. Good linearities were achieved in the range of 5-22.5 μg/mL cisapride with both bromocresol green and bromophenol blue and 4-20 μg/mL tiapride with mean recoveries of 100.0 ± 0.28, 100.4 ± 0.94 and 99.9 ± 0.72 %, respectively. The proposed methods were successfully applied to analyze both drugs in their tablets.
Key Words: Cisapride, Tiapride, Bromocresol green, Bromophenol blue, Tropaeolin OO, Ion pair complexes,

Int. J. Electrochem. Sci., 7 (2012) 7699 - 7711
Mixed-Ligand Complex Formation of Cu(II) with 1,2-
Diphenylethylenediamine as Primary Ligand and Amino Acids
as Secondary Ligands
iham A. Lahsasni1, Reda A. Ammar1,2, Mona F. Amin2and  Eman M. Shoukry2 
1 Department of Chemistry, Faculty of Science, King Saud University, Riyadh, Saudi Arabia
2 Department of Chemistry, Faculty of Science, Al Azhar University, Cairo, Egypt
*E-mail: dr_reda06@yahoo.com
Received:  19 March 2012  /  Accepted:  3 July 2012 /  Published: 1 August 2012
 
The binary and ternary systems of Cu(II) complexes with 1,2-diphenylethylenediamine (A) as primary ligand and amino acids (L) as secondary ligands are investigated. The stability constants of the complexes were determined potentiometrically in 50% (v/v) dioxane-water media at 25 ºC and I = 0.10 mol/L NaClO4. The relative stabilities of the ternary complexes are determined and compared with those of the corresponding binary complexes in terms of their _  log K values. Species distribution ofall complexes in solution was evaluated.
 
Asian Journal of Chemistry; Vol. 24, No. 12 (2012), 5511-5514
Kinetic Spectrophotometric Methods for the Determination of Imatinib Mesylate in Pure and Tablet Dosage Form
FATMA A. ALY
1,* and HAESSAH D. ALANAZY2
1Department of Chemistry, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia
2Department of Chemistry, College of Science, Hail University, Hail, Saudi Arabia
Simple and sensitive kinetic spectrophotometric methods were established for the determination of imatinib mesylate in pure and in its pharmaceutical dosage forms using alkaline potassium permanganate as an oxidizing agent. The methods involve determination of imatinib mesylate by kinetic studies of its oxidation at room temperature for a fixed time of 5 min. The absorbance of the green coloured manganate ions was measured at 610 nm. Alternatively, the decrease in the absorbance of permanganate upon addition of the studied drug was also measured at 525 nm. The absorbance-concentration plots were rectilinear over the ranges of 1-34 and 2-20 μg/mL for the two methods respectively. The different experimental parameters affecting the reaction were carefully studied and optimized. The stoichiometry of the reaction was determined adopting the limiting logarithmic method. The analytical performance of the proposed methods was fully validated and the results were satisfactory. The proposed methods have a great value in their application to the analysis of imatinib mesylate in quality control laboratories.
Key Words: Imatinib mesylate, Kinetic spectrophotometry, Fixed time method, Validation, Pharmaceutical preparations

Int. J. Electrochem. Sci., 7 (2012) 8213 - 8225
Comparative Potentiometric Study for Determination of Azithromycin Using Conventional PVC and Multi-Walled Carbon Nanotubes Sensors
Nawal A. Al-Arfaj, Maha F. El-Tohamy*
Department of Chemistry, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia
*E-mail: star2000star@gmail.com
new simple, accurate and reliable potentiometric method for determination of azithromycin was proposed and validated. Four types of sensors were fabricated. Conventional PVC plastic membrane (I), coated wire (II), carbon paste (III) and modified multi-wall carbon nanotubes carbon paste type (IV). The fabrication of all sensors based on the incorporation of azithromycin with phosphotungstic acid to form azithromycin-phosphotungstate as electroactive materials. The proposed sensors exhibit Nernstian response (55.10±0.19, 55.52±0.20, 57.09±0.14 and 58.04±0.11 mV decade-1) over concentration ranges 1.0 x10-6- 1.0 x10-2, 5.0 x10-7-1.0 x10-2, 1.0 x10-7-1.0 x10-2 and 1.0 x10-8-1.0 x10-2 mol L-1 for sensor I, II, III and IV, respectively. The influence of several parameters such as pH, selectivity of sensors, response time and soaking time, etc. was studied. The proposed method was successfully applied for the determination of azithromycin in its pure form, pharmaceutical dosage forms and biological fluids. The obtained results were statistically analyzed and compared with those obtained by the reported method.

Int. J. Electrochem. Sci., 7 (2012) 7888 - 7901
 
Sensitive Electrogenerated Chemiluminescence Assay For Determination of Melanin in Natural and Biological Samples
Nawal A. Alarfaj*, Mohamed Abu Elhassan Abdalla and Alawiya M. Al-Hamza
Department of Chemistry, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia
*E-mail: nalarfaj@hotmail.com
Received: 2 February 2012 / Accepted: 22 February 2012 / Published: 1 September 2012

 

A rapid, simple and highly sensitive flow-injection (FI) electrogenerated chemiluminescence (ECL) method was developed for the determination of melanin, a biological pigment present in the skin, eyes, hair, scales and it is responsible for color of them. The proposed method was based on the ECL reaction of Ru(bpy)32+ with melanin in an acidic medium. The different experimental parameters affecting the ECL intensity were carefully studied and incorporated into the procedure. The method permits the determination of 0.01 − 2.0 μg mL-1 and 3.0 − 35 μg mL-1 of melanin with correlation coefficients (r) > 0.9999. The lower limit of detection (LOD) is 0.0005 μg mL-1 (S/N = 3) and the lower limit of quantitation (LOQ) is 0.01 μg mL-1. The proposed method was successfully applied to the determination of melanin in Sepia Officinalis and natural samples.