Search for: metal-ion
0.008 seconds
Total 136 records

    Dft study on gas-phase interaction between histidine and alkali metal ions (li+, na+, k+); and influence of these ions on histidine acidity

    , Article Journal of Theoretical and Computational Chemistry ; Volume 8, Issue 3 , 2009 , Pages 475-490 ; 02196336 (ISSN) Tavasoli, E ; Fattahi, A. R ; Sharif University of Technology
    The gas-phase metal affinities of histidine Li+, Na+ and K+ ions have been determined theoretically employing the hybrid B3LYP exchangecorrelation functional and using 6-311++G** basis sets. All computations indicate that the metal ion affinity decreases on going from Li+ to Na+ and K+ for the considered amino acid. Different types of M+ coordinations on several histidine conformers/tautomers were considered in detail. The optimized structures indicate that Li+ and Na+ prefer a tri-dentate coordination, bonding with a nitrogen atom of imidazole ring (N τ), NH2, and an oxygen atom of a carbonyl, while in the K+-histidine lowest-energy conformer, the cation appears to be bi-coordinated to both... 

    Removal of toxic heavy metal ions from waste water by functionalized magnetic core–zeolitic shell nanocomposites as adsorbents

    , Article Environmental Science and Pollution Research ; Volume 20, Issue 6 , June , 2013 , pp. 3900-3909 ; 1614-7499 Padervand, M. (Mohsen) ; Gholami, M. R. (Mohammad Reza) ; Sharif University of Technology
    Functionalized magnetic core–zeolitic shell nanocomposites were prepared via hydrothermal and precipitation methods. The products were characterized by vibrating sample magnetometer, X-ray powder diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, and transmission electron microscopy analysis. The growth of mordenite nanocrystals on the outer surface of silica-coated magnetic nanoparticles at the presence of organic templates was well approved. The removal performance and the selectivity of mixed metal ions (Pb2+ and Cd2+) in aqueous solution were investigated via the sorption process. The batch method was employed to study the sorption kinetic,... 

    Synthesis and characterization of M(II) (M = Cd, Hg and Pb) complexes with naphthodiaza-crown macrocyclic ligand and study of metal ion recognition by fluorescence, 1H NMR spectroscopy, and DFT calculation

    , Article Journal of Coordination Chemistry ; Volume 69, Issue 18 , 2016 , Pages 2793-2803 ; 00958972 (ISSN) Ghanbari, B ; Zarepour Jevinani, M ; Sharif University of Technology
    Taylor and Francis Ltd 
    To find metal ion recognition by L (L = O2N2-donor naphthodiaza-crown macrocyclic ligand), the complexes [ML]2+ (M = Cd, Hg and Pb) were synthesized and characterized by IR, 1H, 13C NMR, and mass spectrometry, as well as elemental microanalysis. Hg(II) showed perceptible enhancement of the fluorescence of L in which ultra-low limit of detection for Hg(II) by L was determined as 1 nM in ethanol and DMSO. L reserved selectivity of Hg(II) in its binary mixtures with metal cations in solution. A 1 : 1 stoichiometry was found for the interaction of Hg(II) with L while Benesi–Hildebrand method was applied to calculate its complexation binding constant (K BH) employing fluorescence... 

    Anti-aggregation of gold nanoparticles for metal ion discrimination: a promising strategy to design colorimetric sensor arrays

    , Article Sensors and Actuators, B: Chemical ; Volume 270 , 2018 , Pages 545-551 ; 09254005 (ISSN) Najafzadeh, F ; Ghasemi, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
    The first report of anti-aggregation-based sensor arrays is presented. The strategy is based on the competitive interaction of citrate-capped gold nanoparticles (AuNPs) and heavy metal ions (i.e., Hg(II), Ag(I), Fe(III), and Pb(II)) with three aggregation reagents (i.e., cysteine, melamine, and arginine). In the presence of aggregation reagent, the color and UV–vis spectra of AuNPs are changed indicating the aggregation of AuNPs. Addition of the aggregation reagents which are firstly treated with the ions, causes AuNPs turn from the aggregation to the dispersion state. The anti-aggregation capability of ions towards various aggregation reagents is different because of distinct stability... 

    Dft study of bond energies and attachment sites of sample divalent cations (mg2+, ca2+, zn2+) to histidine in the gas phase

    , Article Journal of Theoretical and Computational Chemistry ; Volume 8, Issue 3 , 2009 , Pages 347-371 ; 02196336 (ISSN) Tavasoli, E ; Fattahi, A ; Sharif University of Technology
    In view of better understanding interactions of amino acids and peptides with metallic cations in the isolated state, the model system histidineM 2+ (M2+ = Mg2+, Ca2+, Zn 2+) has been studied theoretically. The computations have been performed with the help of the density functional theory (DFT) and the B3LYP functional. The extended basis set was the standard 6-311++G**. All the molecular complexes obtained by the interaction between several energetically low-lying tautomers/conformers/zwitterions of histidine and the cations on different binding sites were considered. Our study shows that complexes of histidine with Mg2+, Ca2+, Zn2+ are rather similar. In the isolated state, the most... 

    Stabilities and isomeric equilibria in aqueous solution of monomeric metal ion complexes of adenosine 5′-diphosphate (ADP3-) in comparison with those of adenosine 5′-monophosphate (AMP2-)

    , Article Chemistry - A European Journal ; Volume 9, Issue 4 , 2003 , Pages 881-892 ; 09476539 (ISSN) Bianchi, E. M ; Sajadi, S. A. A ; Song, B ; Sigel, H ; Sharif University of Technology
    Under experimental conditions in which the self-association of the adenine phosphates (AP), that is, of adenosine 5′-monophosphate (AMP2-) and adenosine 5′-diphosphate (ADP3-), is negligible, potentiometric pH titrations were carried out to determine the stabilities of the M(H;AP) and M(AP) complexes where M2+=Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, or Cd2+ (25°C; I = 0.1m, NaNO3). It is concluded that in the M(H;AMP)+ species M2+ is bound at the adenine moiety and in the M(H;ADP) complexes at the diphosphate unit; however, the proton resides in both types of monoprotonated complexes at the phosphate residue. The stabilities of nearly all the M(AMP) and M(ADP)- complexes are... 

    Theoretical investigation on the structure and properties of alumazine⋯m complexes (M = Li+, Na+, K+, Be2+, Mg2+, and Ca2+)

    , Article Journal of Theoretical and Computational Chemistry ; Volume 12, Issue 5 , August , 2013 ; 02196336 (ISSN) Rasekh, M. F ; Sharif University of Technology
    The nature of alumazine⋯M (M = Li+, Na+, K+, Be2+, Mg2+, AND Ca2+) interactions was studied by ab initio calculations. The interaction energies were calculated at MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p) level. The calculations suggest that the size and charge of cation are two important factors that affect the interaction energy, charge transfer values and the variation in aromaticity of alumazine ring upon complexation. The theory of atoms in molecules (AIM) and natural bond orbital (NBO) analyses of complexes indicate that the variation of densities and the extent of charge shifts upon complexation correlate well with the obtained interaction energies. Finally, nucleus independent chemical... 

    Theoretical study of borazine: cation-π (Be 2+, Mg 2+, and Ca 2+) interaction

    , Article Structural Chemistry ; 2012 , Pages 1-7 ; 10400400 (ISSN) Fathi Rasekh, M ; Sharif University of Technology
    The geometries of the complexes of Be 2+, Mg 2+, and Ca 2+ metal cations with borazine ring were studied. The complexes were optimized at the B3LYP level and the 6-311++G(d,p) basis set. Then, the interaction energies corrected by basis set super position error were calculated in the same level. The results show that interaction energy is strongly dependent on the charge-to-size ratio of the cation. Therefore, Be 2+ cation has the most interaction energy value with respect to Mg 2+ and Ca 2+ metal cations. Natural bond orbital analysis was performed to calculate the charge transfer and natural population analysis of the complexes. Quantum theory of atoms in molecules was also applied to... 

    Interaction of Mg2+, Ca2+, Zn2+ and Cu+ with cytosine nucleosides: Influence of metal on sugar puckering and stability of N-Glycosidic bond, a DFT study

    , Article Journal of Molecular Structure: THEOCHEM ; Volume 913, Issue 1-3 , 2009 , Pages 117-125 ; 01661280 (ISSN) AliakbarTehrani, Z ; Fattahi, A ; Pourjavadi, A ; Sharif University of Technology
    The coordination geometries, electronic features, absolute metal ion affinities, geometrical multiplicity and binding strength for the complexes formed by Mg2+, Ca2+, Zn2+ and Cu+ with cytidine and deoxycytidine have been determined theoretically employing the hybrid B3LYP exchange-correlation functional and using 6-311++G(d,p) orbital basis sets. Our study shows that the most stable coordination modes of cytosine nucleosides with these cations are rather similar. In the isolated state, the most stable form corresponds to a tridentate complex in which the cation interacts with three oxygen atoms: one from the carbonyl oxygen of cytosine moiety and two from the sugar unit (i.e., O5′ and O4′).... 

    Not completely innocent: how argon binding perturbs cationic copper clusters

    , Article Journal of Physical Chemistry A ; Volume 124, Issue 43 , 2020 , Pages 9004-9010 Jamshidi, Z ; Lushchikova, O. V ; Bakker, J. M ; Visscher, L ; Sharif University of Technology
    American Chemical Society  2020
    Argon is often considered as an innocent probe that can be attached and detached to study the structure of a particular species without perturbing the species too much. We have investigated whether this assumption also holds for small copper cationic clusters and demonstrated that small but significant charge transfer from argon to metal changes the remaining binding positions, leading in general, to weaker binding of other argon atoms. The exception is binding to just one copper ion, where the binding of the first argon facilitates the binding of the second. © 2020 American Chemical Society  

    Water adsorption in the organic phase for the D2EHPA-kerosene/water and aqueous Zn2+, Co2+, Ni2+ sulphate systems

    , Article Hydrometallurgy ; Volume 88, Issue 1-4 , 2007 , Pages 92-97 ; 0304386X (ISSN) Darvishi, D ; Haghshenas, D. F ; Etemadi, S ; Keshavarz Alamdari, E ; Sadrnezhaad, Kh ; Sharif University of Technology
    Water adsorption by bis-2-ethylhexyl phosphoric acid (D2EHPA) during the extraction of zinc, cobalt and nickel using a D2EHPA-kerosene/H2O mixture is investigated. Based on the experimental results, about 1 mol of water is adsorbed by 2 mol of D2EHPA (which exists in the form of a dimer), irrespective of the pH. Water adsorption decreases with presence of zinc, cobalt and nickel. The stoichiometric coefficients of D2EHPA in water adsorption reactions are determined with and without zinc, cobalt and nickel by applying the slope-analysis method. It is experimentally confirmed that 1.0, 1.8 and 1.2 mol of adsorbed water will be rejected from the organic phase when zinc, cobalt and nickel are... 

    An overview on eco-friendly polymer composites for heavy metal ion remediation

    , Article Current Analytical Chemistry ; Volume 17, Issue 6 , 2021 , Pages 737-753 ; 15734110 (ISSN) Nazir, M. S ; Palvasha, B. A ; Tahir, Z ; Ul Hassan, S ; Ali, Z ; Akhtar, M. N ; Azam, K ; Abdullah, M. O ; Sharif University of Technology
    Bentham Science Publishers  2021
    Background: Water contamination by noxious heavy metals due to urbanization is a global environmental problem. Heavy metal ions pollution makes the water unsuitable for drinking and is also highly toxic to human beings and eco-system. The remediation of heavy metals is therefore very crucial. Methods: Adsorbents based on biopolymer and eco-friendly polymer composites have been developed and fabricated to remediate and remove heavy metals from the ecosystem. Results: In recent years biocomposites have been successful as cost-effective adsorbents for the remediation of various contaminants with their eco-friendly nature and sustainability. Conclusion: This review article gives an overview on... 

    Poly (vinyl alcohol)/graphene oxide nanocomposite films and hydrogels prepared by gamma ray

    , Article Plastics, Rubber and Composites ; Volume 48, Issue 2 , 2019 , Pages 42-47 ; 14658011 (ISSN) Frounchi, M ; Dadbin, S ; Tabatabaei, M ; Sharif University of Technology
    Taylor and Francis Ltd  2019
    Poly (vinyl alcohol)/graphene oxide (PVA/GO) gamma irradiated nanocomposite films and hydrogels were prepared. In composite films, GO was initially irradiated by gamma ray in order to improve interactions between GO and PVA. The film containing 1 wt-% GO was very strong where tensile modulus and tensile yield strength were 45 and 115% higher than those of pure PVA. In the second set of experiments PVA/GO hydrogels were made by irradiating PVA/GO suspensions by gamma ray at various doses. It was an interesting finding that GO increased the gel portion of hydrogels through contribution of H-bonds between PVA and GO. The hydrogels prepared at 20 kGy had remarkable water swelling ratio that... 

    DFT/B3LYP study of thermochemistry of D-glucosamine, a representative polyfunctional bioorganic compound

    , Article Scientia Iranica ; Volume 15, Issue 4 , 2008 , Pages 422-429 ; 10263098 (ISSN) Fattahi, A ; Ghorat, M ; Pourjavadi, A ; Kurdtabar, M ; Torabi, A. A ; Sharif University of Technology
    Sharif University of Technology  2008
    D-glucosamine, as a representative polyfunctional compound, is a bioactive amino sugar. In this study, the gas phase thermochemical properties of D-glucosamine, including its Metal Ion Affinity (MIA), metal binding sites, Anion Affinity (AA), acidity and proton affinity, have been explored, using the Density Functional Theory (DFT) and a 6-311++G**basis set. The summary of the MIA and AA results (in kcal/mol-1) are: Li+ = 67.6, Na+ = 51.1, K+ = 37.3, Mg2+ = 207.9, Ca2+ = 150.4, Zn2+ = 251.2, Cl- = 27.4, CN- = 28.0. The acidity values calculated at different sites, including four -OH groups and one -NH2 group, range from 344.0 to 373.0 kcal/mol-1. These results, surprisingly, indicate how... 

    Thermochemical Properties of Thymine & Deoxythymidine

    , M.Sc. Thesis Sharif University of Technology Shakorian Fard, Mehdi (Author) ; Fattahi, Alireza (Supervisor)
    Nowadays, there is no doubt about the importance of investigation of physicochemical properties of nucleosides in order to determine the structure of these biopolymers. Nucleotides have a variety of roles in cellular metabolism. They are the constituents of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the molecular repositories of genetic information. The metal ions play a significant role in several biological processes. Synthesis, replication, and cleavage of DNA and RNA as well as their structure integrity are affected by the presence of these ionized metals in the cell nucleus. To understand the role of cations in the biophysics of DNA, it is necessary first to... 

    Stability of binary and ternary copper (II) complexes of 2((4-methyl-5-nitro-6-(pyrrolidine-l-yl)pyrimidine-2-yl) amino) propionic acid in aqueous solution

    , Article Scientia Iranica ; Vol. 21, Issue. 6 , 2014 , pp. 2029-2035 ; ISSN: 10263098 Sajadi, S. A. A ; Bagherzadeh, G ; Khaleghian, M ; Kermani, M ; Sharif University of Technology
    The acidity and stability constants of M (MNPPAP) (MNPPAP: 2((4-methyl-5-nitro-6-(pyrrolidine-l-yl)pyrimidine-2-yl)amino)propionic acid) M: Cu2+, Cu (Bpy)2+ (Bpy: 2,2'-Bipyridine), or Cu(Phen) (Phen: 1,10-Phenanthroline) complexes were determined by potentiometric pH titration. It is shown that the stability of the binary Cu (MNPPAP) complex is determined by the basicity of the carboxylate group on one side and amine group on the other side. It is demonstrated that the equilibrium, Cu(Har)2+ (H ar: Heteroaromatic ligand such as Bpy or Phen) + Cu(MNPPAP) ^ Cu(Har)(MNPPAP) + Cu2+, is displacement due to the well known experience that mixed ligand complexes formed by a divalent 3d ion, a... 

    Influence of metal complexation on acidity of cytosine nucleosides: Part I, Li +, Na + and K + cation

    , Article Scientia Iranica ; Volume 19, Issue 3 , June , 2012 , Pages 535-545 ; 10263098 (ISSN) Aliakbar Tehrani, Z ; Fattahi, A ; Pourjavadi, A ; Sharif University of Technology
    Gas-phase acidities of nucleosides, combined with the knowledge of deprotonation sites, could improve our understanding of chemical reactions to biological systems. In this paper, we mainly focus our attention on the influence of cation coordination on acidities of multiple sites in cytosine nucleosides. The acidities of multiple sites in M +-L (where L represents cytosine nucleosides and M + is an alkali metal ion, including Li +, Na + and K +) complexes have been investigated theoretically, employing B3LY P6-311++G(d,p) basis sets. The geometrical characters, gas-phase acidities, sugar puckering and electronic properties of non-deprotonated and/or deprotonated complexes have been... 

    RETRACTED ARTICLE: Study of stabilities of L-cysteine and L-methionine with divalent metal ions: A comparison of thermodynamic data

    , Article 5th International Conference on Bioinformatics and Biomedical Engineering, iCBBE 2011 ; 2011 ; 9781424450893 (ISBN) Sajadi, S. A. A ; Sharif University of Technology
    The acidity and stability constants of M-Met (M: M2+; Met 1: L-methionine) complexes, determined by potentiometric pH titrations, were used to make a comparative investigation with L-cysteine (Cys). It is shown that regarding to M ion - binding properties vital differences on complex bilding were considered. It is demonstrated, that in M-Met complexes, M ion is coordinated to the carboxyl group, M ion is also able to build macrochelate over amine group. The upmentioned results demonstrate that for M-Met complex the stability constants is also largly determined by the affinity of Cu2+ for amino group but in opposite to Met, some metal ions such as Co2+, Cu2+, and Zn2+ build with Cys 2... 

    Hydrogel nanocomposite based on chitosan-g-acrylic acid and modified nanosilica with high adsorption capacity for heavy metal ion removal

    , Article Iranian Polymer Journal (English Edition) ; Volume 24, Issue 9 , September , 2015 , Pages 725-734 ; 10261265 (ISSN) Pourjavadi, A ; Mazaheri Tehrani, Z ; Salimi, H ; Banazadeh, A ; Abedini, N ; Sharif University of Technology
    Springer-Verlag London Ltd  2015
    In this study, a novel hybrid hydrogel based on chitosan, acrylic acid and amine-functionalized nanosilica was prepared and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. This hydrogel nanocomposite was used for removal of Co2+, Cu2+, Pb2+ and Zn2+ ions from aqueous solution. The metal ion adsorption was measured by inductively coupled plasma mass spectrometry. The adsorption behavior showed that the presence of modified nanosilica enhanced the porosity of the hydrogel network and affected its adsorption capacity in response to different parameters such as nanosilica content, metal ion concentration, adsorbent content,... 

    Comparison of thermochemistry of aspartame (artificial sweetener) and glucose

    , Article Carbohydrate Research ; Volume 344, Issue 1 , 2009 , Pages 127-133 ; 00086215 (ISSN) Rashidian, M ; Fattahi, A ; Sharif University of Technology
    We have compared the gas phase thermochemical properties of aspartame (artificial sweetener) and α- and β-glucose. These parameters include metal ion affinities with Li+-, Na+-, K+-, Mg+2-, Ca+2-, Fe+2-, Zn+2-ions, and chloride ion affinity by using DFT calculations. For example, for aspartame, the affinity values for the above described metal ions are, respectively, 86.5, 63.2, 44.2, 255.4, 178.4, 235.4, and 300.4, and for β-glucose are 65.2, 47.3 32.9, 212.9, 140.2, 190.1, and 250.0 kcal mol-1, respectively. The study shows differences between the intrinsic chemistry of aspartame and glucose. © 2008 Elsevier Ltd. All rights reserved