Nashwa M. El-Metwaly

Umm Al-Qura University, Makkah, Makkah, Saudi Arabia

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Publications (11)21.53 Total impact

  • Journal of Thermal Analysis and Calorimetry 07/2015; DOI:10.1007/s10973-015-4838-z · 2.04 Impact Factor
  • Samy M El-Megharbel · Nashwa M El-Metwaly · Moamen S Refat ·
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    ABSTRACT: Three urate chelations were obtained when uric acid was reacted with UO2(CH3COO)2H2O, VOSO4·XH2O and ZrOCl2·XH2O salts with neutralized with 0.1M NaOH aqueous media. The 1:2 metal-to-ligand complexes [(UO2)2(C5H2N4O3)2](H2O), [(ZrO)2(H2O)2(C5H2N4O3)2] and [VO((C5H3N4O3)2] were characterized by elemental analyses, molar conductivity, (infrared, Raman and UV-vis) spectra, effective magnetic moment in Bohr magnetons, and thermal analysis (TG/DTG). The urate ligand coordinates as mononegative bidentate donor towards the mononuclear central vanadium atom and coordinated as binegative tetradentate mode towards the binuclear dioxouranium and zirconyl centers. The antibacterial activity of the metal complexes were tested against some kind of bacteria and fungi strains and compared with uric acid. The ligand, ZrO(II) and UO2(II) complex showed a week potential degradation on calf thymus DNA, whereas VO(II) complex slightly degraded the DNA. Copyright © 2015 Elsevier B.V. All rights reserved.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2015; 149:263-270. DOI:10.1016/j.saa.2015.04.069 · 2.35 Impact Factor
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    ABSTRACT: A series of metal complexes was synthesized using a simple thiourea derivative. The prepared complexes were characterized using different techniques (FTIR, ESR, X-ray diffraction [XRD], TG/DTA, and TEM). The FTIR spectrum of the ligand shows the presence of its tautomer forms (keto-enol). The ligand coordinates as a neutral bidentate in the Pt(IV), Pd(II), and Pt(II) complexes. In the case of Co(II) and Ni(II) complexes, the ligand is mono-negative bidentate. The proposed complexes are four to six coordinate. The geometries are proposed based on electronic spectral data and magnetic measurements and were verified using other tools. The XRD patterns reflect the nanocrystalline structures except for the Cu(II) complex, which is amorphous. The TEM images for platinum complexes show nanosize particles and homogeneous metal ion distribution on the complex surface. The EPR spectrum of Cu(II) complex verified the octahedral geometry of the complex. Molecular modeling was performed to assign the structural formula proposed for the ligand based on the characterization results.
    Journal of Coordination Chemistry 02/2015; 68(6):1-17. DOI:10.1080/00958972.2015.1004325 · 2.01 Impact Factor
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    Fawaz Saad · Khlood S. Abou-Melha · Nashwa M. El-Metwaly ·

    Asian Journal of Chemistry 01/2015; 27(7):2678-2684. DOI:10.14233/ajchem.2015.18839 · 0.45 Impact Factor
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    ABSTRACT: A series of thiouracil complexes was prepared, all the prepared compounds are investigated by all possible tools. The ligand coordinates towards two central atoms as a neutral hexadentate mode. The octahedral structure was proposed with Ni(II), Pt(IV) and UO2(II) complexes. Square-pyramidal and square planar with VO(II) and Pd(II) complexes, respectively. VO(II) complex was irradiated by using Gamma radiation to through a light on the probability of geometry changes with the effect of radiation. The parameters calculated from ESR spectra before and after γ-irradiation reflect the rigidity of the complex towards the effect. Such may discuss the unaffected biological behavior before and after irradiation. XRD patterns were carried out to emphasis on the nature of the particles and the purity of products. The ligand, Pt(IV) and Pd(II) are found in nanometer range. TEM is a sensitive tool used to justify on the microstructure and surface morphology. All the investigated compounds are in nanorange. TG curves reflect a lower thermal stability of all investigated complexes due to the presence of water of crystallization. Finally, a toxic effect was observed with all investigated complexes towards Gram positive bacterium as well as a resistant behavior was observed with Gram negative bacteria.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2014; 132C:751-761. DOI:10.1016/j.saa.2014.05.084 · 2.35 Impact Factor
  • Moamen S Refat · Nashwa M El-Metwaly ·
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    ABSTRACT: Two derivatives of thiosemicarbazide were prepared. Their complexes were prepared using Mn(II) and Cu(II) salts. All the isolated complexes are characterized using the following spectra: IR, UV-Vis, Mass, (1)H NMR and X-ray diffraction. Magnetic measurements and thermal analysis are the other additive tools for complete investigation. Mononuclear and binuclear complexes are proposed based on elemental analysis mainly. The IR spectra offer the mode of coordination of each ligand with each metal ion. The electronic spectra and magnetic measurements are proposing the structural geometry of the investigated complexes. The octahedral geometry proposed for Mn(II) complexes but the square-planar for Cu(II) complexes. The (1)H NMR spectra were done for all organic compounds used in this study and displaying the most suitable tautomer of them. X-ray diffraction of H(2)L(1) and its complexes show their amorphous nature but H(2)L(2) ligand and its complexes show their nanocrystalline nature. The TG analysis was used to prove the presence of solvent molecules attached with the complexes as covalently or physically. Finally, the biological investigation was carried out for H(2)L(2) ligand and its complexes and displaying the inhibition activity of Cu(II) complex than the Mn(II) one.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2012; 92:336-46. DOI:10.1016/j.saa.2012.02.041 · 2.35 Impact Factor
  • Moamen S Refat · Nashwa M el-Metwaly ·
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    ABSTRACT: The reactions of the two common dyes [2TMPACT and 4PENI] with Mn(II), Co(II), Ni(II) and Cu(II) ions were done. All the isolated complexes have been characterized by physicochemical and spectroscopic techniques. The IR data reflect the bidentate mode of 2TMPACT towards the mononuclear complex [Mn(II)] even its tetradentate in binuclear complexes [Co(II) and Cu(II)]. However, the bidentate mode is the only behavior of 4PENI ligand towards each metal ion in its mononuclear complexes. The UV-vis spectral analysis beside the magnetic moment measurements are proposed different geometries concerning each metal ions with the two ligands under investigation, as the Mn(II)-2TMPACT complex is an octahedral but Mn(II)-4PENI is a tetrahedral geometry. All the synthesized compounds are thermogravimetrically investigated. The proposed thermal decomposition was discussed for each compound with each step as well as, the kinetic parameters were calculated for all preferrible decomposition steps. The mass spectroscopy tool was used to emphasis on the suitable molecular formula proposed and the fragmentation patterns were displayed. The fluorescence properties of the synthesized ligands and their complexes were studied in DMSO at room temperature.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2011; 81(1):215-27. DOI:10.1016/j.saa.2011.05.108 · 2.35 Impact Factor
  • Nashwa M el-Metwaly · Moamen S Refat ·
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    ABSTRACT: A new series of heavy metal complexes are prepared. Sn(II), Sb(III), Pb(II) and Bi(III) are the metal ions used in complexation with two thiosemicarbazide ligands. The IR and (1)H NMR spectra of the free ligands display their presence in thiole-thione forms coincide with each other. The IR spectra of the complexes support the presence of 2:2 molar ratio (M:HL) with HL(1) ligand and 1:1 beside 1:2 with HL(2). The ligand coordinates as bi molecules in some complexes and displays two tautomer forms at the same complex molecule (1)H NMR spectra of Sn(II) and Sb(III) complexes were done and comes coincide with IR data. The electronic spectral analysis displays a lower shift appearance in n→π* charge transfer band in most isolated complexes. As well as, a new band is shinned in visible region with Sb(III), Bi(III) complexes and Sn(II)-HL(2). This band is pointed to its use in spectrophotometric analysis for these metal ions. The TG analysis for all isolated compounds was briefly discussed. The molecular modeling parameters support the stability of thiole form of the free ligands in comparing with their thiones by a small difference. The antibacterial and antifungal activities were studied against some organisms and reveal the priority of most investigated complexes.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2011; 81(1):519-28. DOI:10.1016/j.saa.2011.06.045 · 2.35 Impact Factor
  • Moamen S. Refat · Nashwa M. El-Metwaly ·
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    ABSTRACT: A new series of sodium barbital complexes with Alkaline earth metals (Mg2+, Ca2+, Sr2+ and Ba2+ ions) was prepared. The molecular formulas for the isolated complexes were suggested basically on the elemental analysis data. The binuclear central were proposed for all investigated complexes. The geometry suggested based on knowing the coordination sits for each complex was built on concerning with the shift observed in IR spectra surround the coordinating groups. The shifts in charge transfer bands appeared in the electronic spectra of the complexes supports the coordination process. The presence of solvent molecules coordinately attached with central metal atoms as well as the conjugated anions was supported based on thermogravimetric analysis. The kinetic parameters were calculated for each complex. The theoretical calculations for the molecular modeling structures reflect an insight about their stability in comparing with the free ligand. The XRD studies were performed and concluding the nanocrystalline feature for all complexes. The biochemical effect of all investigated compounds was performed towards Gram-negative and Gram-positive bacteria as well as their degradation effect on calf Thymus DNA. The biological performance is the major goal in this study especially with such essential metal ions.
    Journal of Molecular Structure 03/2011; 988(1-3):111-118. DOI:10.1016/j.molstruc.2010.12.039 · 1.60 Impact Factor
  • Nashwa M El-Metwaly · Moamen S Refat ·
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    ABSTRACT: This work represents the elaborated investigation for the ligational behavior of the albendazole ligand through its coordination with, Cu(II), Mn(II), Ni(II), Co(II) and Cr(III) ions. Elemental analysis, molar conductance, magnetic moment, spectral studies (IR, UV-Vis and ESR) and thermogravimetric analysis (TG and DTG) have been used to characterize the isolated complexes. A deliberate comparison for the IR spectra reveals that the ligand coordinated with all mentioned metal ions by the same manner as a neutral bidentate through carbonyl of ester moiety and NH groups. The proposed chelation form for such complexes is expected through out the preparation conditions in a relatively acidic medium. The powder XRD study reflects the amorphous nature for the investigated complexes except Mn(II). The conductivity measurements reflect the non-electrolytic feature for all complexes. In comparing with the constants for the magnetic measurements as well as the electronic spectral data, the octahedral structure was proposed strongly for Cr(III) and Ni(II), the tetrahedral for Co(II) and Mn(II) complexes but the square-pyramidal for the Cu(II) one. The thermogravimetric analysis confirms the presence or absence of water molecules by any type of attachments. Also, the kinetic parameters are estimated from DTG and TG curves. ESR spectrum data for Cu(II) solid complex confirms the square-pyramidal state is the most fitted one for the coordinated structure. The albendazole ligand and its complexes are biologically investigated against two bacteria as well as their effective effect on degradation of calf thymus DNA.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 09/2010; 78(1):196-204. DOI:10.1016/j.saa.2010.09.021 · 2.35 Impact Factor
  • Nashwa M. El-Metwaly ·
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    ABSTRACT: Mononuclear complexes of 5-hydroxyl-3-oxopyrazoline-1-carbothiohydrazide, H3HOC, with VO2+, Co(II), Ni(II), Cu(II) and Cd(II) have been isolated. The elemental analyses, magnetic, spectral [u.v.–vis., i.r., e.s.r. 1H n.m.r. and mass] with thermal analysis have been used to characterize the isolated complexes. The ligand behaves as a mononegative tridentate with Ni(II) and Co(II) ions and neutral bidentate in [Cu(H3HOC)(NO3)2]0.5 H2O, [VO(H3HOC)SO4] and [Cd(H3HOC)Cl2C2H5OH]C2H5OH complexes. The octahedral structure was suggested for all the isolated complexes except VO2+. The TG analyses recorded different decomposition steps started at a temperature, indicating thermally unstable complexes. Screening showed antimicrobial activity for Cd(II) and Ni(II) complexes against the investigated bacteria as well as a significant adverse effects on DNA but a moderate effect is displayed with the other complexes.
    Transition Metal Chemistry 01/2007; 32(1):88-94. DOI:10.1007/s11243-006-0135-9 · 1.31 Impact Factor