http://blogs.najah.edu/author/emp_2016 An-Najah Blogs :: en-us Fri, 19 Apr 2024 23:49:45 IDT Fri, 19 Apr 2024 23:49:45 IDT [email protected] [email protected] http://blogs.najah.edu/staff/emp_2016/article/Synthesis-and-antimicrobial-activity-of-new-N-methyl-N-2-pyridyl-aromatic-and-heteroaromatic-hydrazonesPublished ArticlesAromatic and heteroaromatic N-methyl-N-2-pyridyl-hydrazones 3a-f were synthesized and characterized by elemental analyses and spectral data H-1 C-13 NMR and mass spectra supported the formation of the E-isomer N-Methyl-N-2-pyridylhydrazone carboxaldehydes can be readily characterized by mass spectrometry The new hydrazones 3a-h have been screened for antimicrobial activityhttp://blogs.najah.edu/staff/emp_2016/article/Short-Communication-Synthesis-and-Dethiation-of-5--Phenyl--3--thioxo-23-dihydro-1H-24-lrmbenzodiazepine--1--onelrmPublished Articles An-Najah University Journal for Research - Natural Sciences A ISSN: 1727-2114 Volume 20 2006 Pages: 207-212http://blogs.najah.edu/staff/emp_2016/article/Solvent-Effect-on-Nucleophilic-Cleavage-of-p-Chlorobenzyltrimethylsilane-Using-Tetrabutylammonium-Fluoride-in-ROH-DMSO-MediaPublished ArticlesThe rates of cleavage of p-chlorotrimethylsilane were measured in various ROH-DMSO meda R: Me Et i-Pr t-By CFCH-HOCHCH- and the results were reported These results have shown that the rates of cleavage decrease as the mole ratio of ROH increaseshttp://blogs.najah.edu/staff/emp_2016/article/Nucleophilic-Cleavage-of-Substituted-Benzyltrimethylsilanes-using-Tetraalkylammonium-Fluoride-in-DMSO-H20-MediaPublished ArticlesThe nucleophilic cleavage of substituted benzyltrimethyl-silanes in DMSO-Hz0 media using tetraalkylammonium fluoride TAAF has been studied The observed rate constants pseudo first order rate constants activation and thermodynamic parameters have been reported A mechanism for such cleavage has been proposed The results fit well Hammett equation The reaction constant p value of 67 has been reported The p value is consistent with a substantial negative charge developing in the transition statehttp://blogs.najah.edu/staff/emp_2016/article/Synthesis-of-Laser-Sensitive-Chromophores-and-their-Attachement-to-an-Antitumor-Drug-DoxorubicinPublished ArticlesFour highly conjugated laser-sensitive two-photon chromophores 9a; 9b; 9c; 9d have been synthesized Each chromophore has been attached to the anti-cancer drug doxorubcin to produce the labeled doxorubicins 12a; 12b; 12c; 12d for imaging the biologic cellular processes An-Najah University Journal for Research - Natural Sciences A ISSN: 1727-2114 Volume 14 2000 Pages: 061-081http://blogs.najah.edu/staff/emp_2016/article/A-chemically-labeled-cytotoxic-agent-Two-photon-fluorophore-for-optical-tracking-of-cellular-pathway-in-chemotherapyPublished ArticlesChemotherapy is commonly used in the treatment of cancers However the mechanism of action of many of these agents is not well understood We present the synthesis of a two-photon fluorophore C625 and its biological application when chemically linked to a chemotherapeutic agent AN-152 By using two-photon laser-scanning microscopy the drug:fluorophore conjugate can be observed directly as it interacts with receptor-positive cell lines The results of this project visually show the receptor-mediated entry of AN-152 into the cell cytoplasm and subsequently into the nucleus These observations will allow for better understanding of the drugs therapeutic mechanism which is a subject of ongoing research aimed at improving present methods for cancer therapy http://blogs.najah.edu/staff/emp_2016/article/Antimicrobial-activity-of-20-plants-used-in-folkloric-medicine-in-the-Palestinian-areaPublished ArticlesEthanolic and aqueous extracts of 20 Palestinian plant species used in folk medicine were investigated for their antimicrobial activities against five bacterial species Staphylococcus aureus Escherichia coli Klebsiella pneumoniae Proteus vulgaris Pseudomonas aeruginosa and one yeast Candida albicans The plants showed 90 of antimicrobial activity with significant difference in activity between the different plants The most antimicrobially active plants were Phagnalon rupestre and Micromeria nervosa whereas the least active plant was Ziziphus spina-christi Only ten of the tested plant extracts were active against C albicans with the most active from M nervosa and Inula viscosa and the least active from Ruscus aculeatus Of all extracts the ethanolic extract of M nervosa was the most active whereas the aqueous extract of Phagnalon rupestre was the most active of all aqueous extracts tested The ethanolic extracts 70 showed activity against both Gram positive and negative bacteria and 40 of these extracts showed anticandidal activity whereas 50 of the aqueous extracts showed antibacterial activity and 20 of these extracts showed anticandidal activity Journal of Ethnopharmacology Volume 60 Issue 3 April 1998 Pages 265-271 http://blogs.najah.edu/staff/emp_2016/article/Antimicrobial-activity-of-Micromeria-nervosa-from-the-Palestinian-areaPublished ArticlesOrganic and aqueous solvent extracts and fractions of Micromeria nervosa Desf Benth Labiatae were investigated for antimicrobial activities on several microorganisms including bacteria and yeast The different extracts differed significantly in their antimicrobial activities with the ethanolic extract being most active followed by ethyl acetate and petroleum ether extracts The least active extract was the aqueous No significant difference between the different test microorganisms in their susceptibility to different extracts with Candida albicans being the most susceptible to ethanolic extract giving 15 times the effect of nystatin One of the main active ingredients of M nervosa was isolated and identified as carvacrol No significant difference in antimicrobial activity was found between carvacrol and its isomer thymol The most susceptible test microorganism was Proteus vulgaris to carvacrol and P vulgaris and C albicans to thymol The least susceptible bacterium to both fractions was Pseudomonas aeruginosa Minimum inhibitory concentration MIC and minimum bactericidal or fungicidal concentrations MBC or MFC were determined for both compounds Journal of Ethnopharmacology Volume 58 Issue 3 November 1997 Pages 143-147 http://blogs.najah.edu/staff/emp_2016/article/Emodin-A-Naturally-Occuring-Anthraquinone-Its-Isolation-and-Spectrophotometric-Determination-in-Rumex-Cyprius-PlantPublished ArticlesA new method for isolation and specrophotometric determination of emodin is presented Emodin was isolated by thin layer chromatography tlc and column chromatography cc techniques as an orange long crystalline substance Emodin exhibits two absorption maxima at 420 and 520 nm Stability of the color and the effect of pH were studied Beers law is obeyed in the range 2-30 ppm The method is applied to the determination of emodin in roots stems and leaves of Rumex cyprius plant Spectroscopy Letters Volume 29 Issue 8 December 1996 pages 1539 - 1543http://blogs.najah.edu/staff/emp_2016/article/Plumbagin-a-Naturally-Occurring-Naphthoquinone-Its-Isolation-Spectrophotometric-Determination-in-Roots-Stems-and-Leaves-in-Plumbago-Europaea-LPublished ArticlesA new method for isolation and spectrophotometric determination of plumbagin is presented Plumbagin was isolated by thin layer chromatography TLC and column chromatography CC techniques as an orange tinged yellow long crystalline substances Plumbagin exhibits two absrop-tion maxima at 410 and 510 nm Stability of the color pKa value and the effect of pH were studied Beers law is obeyed over the range 09-45 ppm The method is applied to the determination of plumbagin in roots stems and leaves of Plumbago europaea L plant Spectroscopy Letters Volume 27 Issue 4 May 1994 pages 409 - 416http://blogs.najah.edu/staff/emp_2016/article/Spectrophotometric-Determination-of-Uranium-with-Di-2-pyridyl-Ketone-BenzoylhydrazonePublished ArticlesA method for the spectrophotometric determination of uranium VI by complexation with Di-2-pyridyl ketone benzoylhydrazone DPKBH in 50 vv ethanolic solution is described Uranium VI forms a 1:2 complex with DPKBH The complex has a maximum absorbance at 377 um Beers law is obeyed over the range 0 2 - 12 ugm1 1 The effect of pH excess reagent percentage of ethanol vv stability of the complex and the tolerance limit of many metal ions and common anions have been reported The method has been applied to the determination of uranium in Egyptian monazite sandhttp://blogs.najah.edu/staff/emp_2016/article/alpha-beta--Unsaturated-Lactone-Nitrone-Cycloadditions-a-Route-to-the-Synthesis-of-plusmnndashTussilaginPublished ArticlesReaction of nitrone V with a f1 -unsaturated lactone C4 resulted in the isolation of a single adduct 7 The observed high regiochemical control has encouraged further explorations of natural product synthesis A route to the synthesis of an interesting member of Pyrrolizidine- Alkaloid family; -Tussilagin 90 has been describedhttp://blogs.najah.edu/staff/emp_2016/article/Spectrophotometric-and-Polarographic-Studies-of-Di-2-Pyridyl-Ketone-2-ThienoylhydrazonePublished ArticlesThe spectral and differential pulse polarographic DPP behaviour of di-2-pyridyl ketone 2-thienoylhydrazone DPKTH has been investigated in 30 vv ethanol-buffer mixtures over a wide range of pH 20-120 The spectral bands located at 325 276 230 and 208 nm of the DPKTH in ethanol are assigned to the possible electronic transitions of the molecule The spectral data at various pH values indicates that the molecule characterized by the keto = enol tautomerization and the pKa value for the enolic form of the compound is determined in aqueous ethanol and was found to be 106 The effect of various operational parameters on the reduction current and the mechanism of the electrode reaction of DPKTH at the DME are discussed The main reduction peaks are attributed to the reduction of C=N centre of both the keto and enol forms This behaviour is compared with the DPP behaviour of the other related acid hydrazone compounds The applicability of DPP technique for the trace determination of DPKTH was tested under the optimum experimental conditions and the detection limit is found to be 009 mu mhttp://blogs.najah.edu/staff/emp_2016/article/Spectrophotometric-Determination-of-Uranium-in-Ores-Using-Di-2-Pyridyl-Ketone-Hydrazone-DerivativesPublished ArticlesTwo methods for the spectrophotometric determination of uranium VI are described The methods are based on the formation of colored complexes for uranium VI with 1di-2-pyridyl ketone nicotinoylhydrazone DPKNH and 2di-2-pyridyl ketone thiophenoylhydrazone DPKTH in 50 vv ethanolic solution The complexes formed a uranium VI: complexing reagent mole ratio of 1:2 Maximum absorbance is at 373 nm for UVIDPKNH and at 389 nm for UVI - DPKTH Ranges of linearity effect of pH effect of excess reagent stability of the complexes and the tolerance limit for many metal ions and common anions have been reported The two methods have been applied to the determination of uranium in eygeptian monazite sandhttp://blogs.najah.edu/staff/emp_2016/article/Spectrophotemetric-determination-of-cobalt-in-aqueous-solution-using-di-2-pyridyl-ketone-derivativesPublished ArticlesA method for the spectrophotometric determination of cobaltII is presented with a comparison of the binary complexes formed by cobaltII with di-2-pyridyl ketone nicotinoylhydrazone DPKNH di-2-pyridyl ketone 2-thiophenoylhydrazone DPKTH and di-2-pyridyl ketone benzoylhydrazone DPKBH in 50 vv ethanolic solution CobaltII forms 1:2 complexes with the three reagents Maximum absorbance is at 372 nm for CoII-DPKNH at 389 nm for CoII-DPKTH and at 370 nm for CoII-DPKBH Ranges of linearity effects of pH and excess reagent sensitivity stability of the complexes and tolerance limits of ions are reported It was concluded that the system with DPKTH is the best followed by DPKNH and then DPKBH The method was applied to the determination of cobalt in different alloys http://blogs.najah.edu/staff/emp_2016/article/Polarographic-Study-of-Some-Arylidene-2-PyridylhydrazonesPublished ArticlesThe polarographic behaviors of some arylidene-2-pyridyl hydrazones have been studied in aqueous Britton - Robinson buffer solution containing 40 ethanol using DC polarographic technique In the pH range 19 - 64 the observed single irreversible 4 - electron reduction wave is attributed to the splitting of the N - N bond and saturation of C = N centre All compounds studied are polarographically inactive in alkaline medium The effect of pH on the limiting current and E 112 as well as the reduction mechanism and the effect of substituents are discussed and compared with similar compounds The kinetic parameters of the electrode reaction have been calculatedhttp://blogs.najah.edu/staff/emp_2016/article/Spectrophotometric-Determination-of-Cobalt-with-Di-2-Pyridyl-Ketone-Benzoylhydrazone-Published ArticlesA method for the spectrophotometric determination of cobalt II by complexation with di-2-pyridyl ketone benzoylhydrazone DPKBH in 50 vv ethanolic solution is described Cobalt II forms a 1:2 complex with DPKBH The complex has maximum absorbance at 370 nm Beers law is obeyed over the range 01 - 28 gml-1 The effect of pH effect of excess reagent stability of the complex and the tolerance limit of many metal ions have been reported The method is applied to the determination of cobalt in different alloys containing other metals ions Spectroscopy Letters Volume 24 Issue 9 November 1991 pages 1145 - 1152http://blogs.najah.edu/staff/emp_2016/article/Simultaneous-Spectrophotometric-Determination-of-IronII-and-IronIII-in-Mixtures-Using-Di-2-pyridyl-Ketone-BenzoylhydrazonePublished ArticlesA method for simultaneous spectrophotometric determination of total iron ironII and ironIII in mixtures containing other metal ions has been described The method is based on the complexation of iron with di-2-pyridyl ketone benzoylhydrazone DPKBH in 50 vv ethanolic solution IronII complex with DPKBH exhibits two absorption maxima at 360 and 650 nm meanwhile ironII1 complex with DPKBH exhibits only one maximum at 360nm IronII and ironIII complexes with DPKBH have similar behaviour at 360nm Iron forms 1:2 complexes with the reagent Beers laws are obeyed over the ranges 01-2 gml-1 and 04-5 grn1-l for ironII complexes at 360 and 650nm respectively IronIII showed results similar to those obtained for ironII at 360nm The effect of pH effect of excess reagent the stability of complexes and the tolerance limit of many metal ions have been reported The method is applied to the determination of total iron ironI1 and ironII1 in synthetic solutions Spectroscopy Letters Volume 22 Issue 9 November 1989 pages 1203 - 1214http://blogs.najah.edu/staff/emp_2016/article/Kinetic-studies-of-the-hydrolysis-of-furfurylidene-benzoylhydrazonePublished ArticlesThe hydrolysis of furfurylidene benzoylhydrazoneFBH in hydrochloric acid medium has been found to follow specific acid catalysis whereas the hydrolysis in universal buffer medium has been found to follow general acid-base catalysis Mechanisms for the hydrolysis in different acidic media have been postulated The observed rate constants secondary rate constants activation and thermodynamic parameters for the hydrolysis of furfurylidene benzoylhydrazone have been reported The effect of change in percentage of ethanol in the ethanol-buffer mixture on the rate of hydrolysis has been discussed Monatshefte fr Chemie Chemical Monthly Volume 120 Number 4 April 1989 http://blogs.najah.edu/staff/emp_2016/article/Short-Communication-Solvent-Effects-on-rho-Values-of-the-Hammett-Equation-for-the-Hydrolysis-of-Benzylidene-BenzoylhydrazonesPublished ArticlesThe effect of solvents on values of the Hammett equation which characterizes the hydrolysis of Benzylidene Benzoylhydrazone BBH and its derivatives mNO2 mCH3 mOCH3 and mCl have been studied with four solvents MeOH Et0H 1 nBuOH and DMSO by UV spectrophotometry The effects of solvents on values one of the Hammett equation parameters have been reported and discussedhttp://blogs.najah.edu/staff/emp_2016/article/A-Highly-Stereoselective-Synthesis-of-EE-15-DienesPublished ArticlesSeveral representative 15-dienes were synthesized with a high degree of regioselectivity by a series of nitrone cycloadditions and subsequent deamination of the adductshttp://blogs.najah.edu/staff/emp_2016/article/The-Synthesis-and-Cycloaddition-Reactions-of-3-Azabicyclo310hex-2-ene-3-oxide-and-3-Azabicyclo320hept-2-ene-3-oxide-Highly-Strained-Bicyclic-NitronesPublished ArticlesThe synthesis of two strained bicyclic nitrones is described Subsequent cycloadditions demonstrated a high degree of regiochemical and stereochemical control http://blogs.najah.edu/staff/emp_2016/article/Homogeneous-catalysis-of-the-reaction-of-silanes-with-alcohols-using-decacarbonyl-dimanganese-0Published ArticlesDimanganese decacarbonyl catalyst has been evaluated in the reactions of HSiR3 R = Et OEt with ROH R = Me Et i-Pr t-Bu and benzyl under various conditions The order of reactivity of the alcohols decreases when more bulky alkyl groups are used and that of the silanes increases if a more electron-withdrawing group OEt is used Kinetic analysis indicates that the reaction is first order with respect to the silane to the alcohol and to the catalyst The effects of varying the solvent and adding a phosphine ligand have also been investigated http://blogs.najah.edu/staff/emp_2016/article/Thienamycin---Solution-of-the-Stereochemical-ProblemPublished ArticlesTETRAHEDRON LETTERS Issue: 45 Pages: 4359-4362 Published: 1979