Search for: complexation
0.01 seconds
Total 1203 records

    Chrysin/β-cyclodextrin supramolecular system: a quantum mechanical investigation

    , Article Journal of the Iranian Chemical Society ; Volume 15, Issue 10 , 2018 , Pages 2401-2410 ; 1735207X (ISSN) Ghiasi, M ; Gerayeli, N ; Tafazzoli, M ; Sharif University of Technology
    Chrysin is a bioflavonoid which possesses a wide range of important biological activities. In present study, we used a quantum mechanical approach to shed light on the antioxidant ability and antioxidant mechanism of chrysin to scavenge hydroxyl radical (˙OH) in solution phase. The analysis of the theoretical bond dissociation enthalpy (BDE) values and spin density of the radicals to determine the delocalization possibilities at B3LYP/6-311++G** level clearly shows the importance of the A-ring and the 7-OH group in antioxidant reactivity. In the next step, the inclusion of chrysin with β-CD has been investigated extensively using theoretical methods. Density functional theory (M05-2X)... 

    Synthesis, characterization and catalytic study of a novel iron(III)-tridentate Schiff base complex in sulfide oxidation by UHP

    , Article Inorganic Chemistry Communications ; Volume 12, Issue 1 , 2009 , Pages 21-25 ; 13877003 (ISSN) Bagherzadeh, M ; Amini, M ; Sharif University of Technology
    An hydrazone Schiff base-iron(III) complex using salicylidene benzoyl hydrazine (L) as ligand has been synthesized and characterized by elemental analyses, IR, 1H and 13C NMR and UV-Vis spectroscopy. Oxidation of sulfides to sulfoxides in one-step was conducted by this complex catalyst using urea hydrogen peroxide (UHP) in mixture of CH2Cl2/CH3OH (1:1) under air at room temperature. The effect of the reaction conditions on the oxidation of methylphenylsulfide was studied by varying the amount of the catalyst, reaction temperature, reaction time and the amount of UHP. The results showed that using this system in the oxidation of sulfides, sulfoxides were obtained as the main products,... 

    Aluminum solvate complexes forming in acidic methanol-acetone mixtures studied by 27Al NMR spectroscopy

    , Article Journal of Solution Chemistry ; Volume 38, Issue 2 , 2009 , Pages 159-169 ; 00959782 (ISSN) Samadi Maybodi, A ; Pourali, S. M ; Tafazzoli, M ; Sharif University of Technology
    27Al NMR spectroscopy is a powerful tool for the study of coordination and solvation in both aqueous and nonaqueous solutions. In this study, the complexes coexisting upon dissolution of AlCl3 in acidic acetone + methanol solutions are shown to consist essentially of mixed hexacoordinated species of the general formula [Al(CH3OH) 6-n (CH3COCH3) n ]3+ (n=1,2 and 3), all exhibiting distinctly different 27Al shielding effects. The relative populations of the various mixed species are found to be highly dependent upon the acetone:methanol mole ratio that in the more acetone-rich mixtures with aluminum become appreciably coordinated by acetone. The results demonstrate that the key factor for the... 

    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... 

    Synthesis of chiral palladium oxazolidine and imine complexes: Investigation the oxazolidine-imine conversion by DFT method

    , Article Polyhedron ; Volume 160 , 2019 , Pages 130-138 ; 02775387 (ISSN) Molaee, H ; Moghadam, M ; Mirkhani, V ; Tangestaninejad, S ; Mohammadpoor Baltork, I ; Abbasi Kajani, A ; Kia, R ; Sharif University of Technology
    Elsevier Ltd  2019
    Reaction of 2-pyridinecarboxaldehyde with L-Alaninol (as a chiral amine) or 2-amino-2-methyl-1-propanol (AMP) in the presence of PdCl2 produced the new and attractive palladium(II) complexes which were synthesized by in situ method. The presence of an extra methyl group in AMP other than L-Alaninol induced the different chelating mode and, therefore, several structurally different palladium complexes obtained. Correspondingly, the chiral amine with PdCl2 produced the imine product, (Iminol (1)), and an oxazolidine compound (Imizol (1′)) as minor product. Also, the use of AMP in formation of palladium complexes led to the synthesis of imine (Ampynol (2)) and oxazolidine (Ampyzol (3))... 

    Reliable clustering of Bernoulli mixture models

    , Article Bernoulli ; Volume 26, Issue 2 , May , 2020 , Pages 1535-1559 Najafi, A ; Motahari, S. A ; Rabiee, H. R ; Sharif University of Technology
    International Statistical Institute  2020
    A Bernoulli Mixture Model (BMM) is a finite mixture of random binary vectors with independent dimensions. The problem of clustering BMM data arises in a variety of real-world applications, ranging from population genetics to activity analysis in social networks. In this paper, we analyze the clusterability of BMMs from a theoretical perspective, when the number of clusters is unknown. In particular, we stipulate a set of conditions on the sample complexity and dimension of the model in order to guarantee the Probably Approximately Correct (PAC)-clusterability of a dataset. To the best of our knowledge, these findings are the first non-asymptotic bounds on the sample complexity of learning or... 

    Interplay between competitive and cooperative interactions in a three-player pathogen system

    , Article Royal Society Open Science ; Volume 7, Issue 1 , 2020 Pinotti, F ; Ghanbarnejad, F ; Hövel, P ; Poletto, C ; Sharif University of Technology
    Royal Society Publishing  2020
    In ecological systems, heterogeneous interactions between pathogens take place simultaneously. This occurs, for instance, when two pathogens cooperate, while at the same time, multiple strains of these pathogens co-circulate and compete. Notable examples include the cooperation of human immunodeficiency virus with antibiotic-resistant and susceptible strains of tuberculosis or some respiratory infections with Streptococcus pneumoniae strains. Models focusing on competition or cooperation separately fail to describe how these concurrent interactions shape the epidemiology of such diseases. We studied this problem considering two cooperating pathogens, where one pathogen is further structured... 

    Targeted synthesis of NIR luminescent rhenium diimine cis,trans-[Re(NN)(CO)2(L)2]n+ complexes containing N-Donor axial ligands: photophysical, electrochemical, and theoretical studies

    , Article ChemPlusChem ; Volume 85, Issue 11 , 2020 , Pages 2518-2527 Shakirova, J. R ; Nayeri, S ; Jamali, S ; Porsev, V. V ; Gurzhiy, V. V ; Levin, O. V ; Koshevoy, I. O ; Tunik, S. P ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re((Formula presented.))(CO)3(NCMe)]OTf ((Formula presented.) =phenantroline and neocuproine) afforded cis,trans-Re((Formula presented.))(CO)2(NCMe)2]+ acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4’-bipyridine, N-methyl-4,4’-bipyridine) gave a novel family of the diimine cis,trans-[Re((Formula presented.))(CO)2(L)2]+ complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from... 

    Synthesis, characterization, electrochemical and solvatochromic investigations of novel monomeric and polymeric vanadyl schiff-base complexes

    , Article Journal of Coordination Chemistry ; Volume 60, Issue 9 , 2007 , Pages 973-983 ; 00958972 (ISSN) Boghaei, D. M ; Bezaatpour, A ; Behzad, M ; Sharif University of Technology
    This article describes the synthesis and characterization of oxovanadium(IV) complexes containing tetradentate Schiff-base ligands derived from condensation of ethylenediamine, meso-1,2-diphenyl-1,2-ethylenediamine, 1,2-orthophenylenediamine and 1,2-cyclohexanediamine with 5-bromo-3-nitro-2- hydroxybenzaldehyde. The novel VOL1:[VO(5-Br-3-NO2salen)], VOL2:[VO(5-Br-3-NO2saloph)] and VOL3:[VO(5-Br- 3-NO2salchxn)] complexes were obtained in orange polymeric form with (V=O) stretching bands at 878, 884 and 884 cm-1, respectively, but the VOL4 complex was obtained as a green monomer with (V=O) stretching band at 978 cm-1. The redox process in acetonitrile was reversible for VOL4 and E° was... 

    Biodesulfurization of dibenzothiophene by a newly isolated thermophilic bacteria strain

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 25, Issue 3 , 2006 , Pages 65-72 ; 10219986 (ISSN) Hosseini, S. A ; Yaghmaei, S ; Mousavi, S.M ; Jadidi, A.R ; Sharif University of Technology
    Microbiological analyses of soil chronically exposed to petroleum complex compounds of some oil springs in south of Iran resulted in isolation and purification of a new native thermophilic strain which is capable to desulfurize petroleum sulfur compounds by 4-S mechanism. Dibenzothiophene (DBT) was selected as a complex sulfiir compound model and many experiments were done to identify the metabolic pathway. The results of these experiments show that DBT is ultimately converted to 2-hydroxybiphenyl (2-HBP) and sulfite. This is a special metabolic pathway in that there is no effect on the carbon skeleton of organic compounds and would be ideal for desulfurization to upgrade the petroleum... 

    Modeling of network security-related behaviours using NVML

    , Article 8th International Multitopic Conference, INMIC 2004, 24 December 2004 through 26 December 2004 ; 2004 , Pages 506-511 ; 0780386809 (ISBN); 9780780386808 (ISBN) Shahriari, H. R ; Jalili, R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2004
    Nowadays, security has become an important issue for organizations especially in e-commerce applications. The spreading of networks and increasing of their complexity has complicated the task of security analysis, therefore automatic approaches have received more attention recently. This paper proposes a model-based approach to analyze the overall security of a network, based on the interaction of hosts within the network. A simple language is introduced far modeling securityrelated behaviours of networks and systems. Using the language, a case study is described and its formal model and security properties are presented. © 2004 IEEE  

    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... 

    Electrochemical characterization of the Ni-Fe alloy electrodeposition from chloride-citrate-glycolic acid solutions

    , Article Materials Chemistry and Physics ; Volume 77, Issue 2 , 2003 , Pages 352-358 ; 02540584 (ISSN) Afshar, A ; Dolati, A. G ; Ghorbani, M ; Sharif University of Technology
    Cyclic voltammetry and transient time (τ) measurements have been used to characterize the system, while potentiostatic I-t transients have been recorded to obtain the nucleation and growth mechanism. The electrodeposition of nickel, iron and nickel-iron alloys on the platinum was studied by electrochemical techniques in the presence of complexing compounds. The cyclic voltammetry results clearly show that the electrodeposition of nickel, iron and nickel-iron alloys is a diffusion-controlled process with a typical nucleation mechanism. The redox potentials of the Ni and Fe are shifted to more cathodic potentials in the complexing electrolytes. In addition, the current transients reveal that... 

    Zamin*: An artificial ecosystem

    , Article 1st EurAsian Conference on Advances in Information and Communication Technology, EurAsia-ICT 2002, Shiraz, 29 October 2002 through 31 October 2002 ; Volume 2510 LNCS , 2002 , Pages 1008-1016 ; 03029743 (ISSN); 3540000283 (ISBN); 9783540000280 (ISBN) Halavati, R ; Shouraki, S. B ; Sharif University of Technology
    Springer Verlag  2002
    One of the major goals of Artificial Life is to know 'life-as-it-could-be'. Several platforms for ALife simulations are presented but not all are suitable for every cognitive study in ALife. Platforms designed for studying the origin of life are based on a world of simple rules and simple objects, capable of producing complex organisms. But such worlds are not suitable for cognitive studies focused on complex behaviors, because they are too slow for emergence and simulation of such behaviors. A platform called Zamin is presented, which is believed to be fast, expandable, realistic, and suitable for cognitive simulations aimed to study the emergence of complex behaviors. © Springer-Verlag... 

    Synthesis, Characterization and Spectroscopic Studies of Novel Mono and bi Nuclear Zinc(II), Palladium(II) and Cobalt(II) Schiff Base Complexes: Reactivity and Interaction

    , Ph.D. Dissertation Sharif University of Technology Askarizadeh, Elham (Author) ; Mohammadi Boghaei, Davar (Supervisor)
    Due to study of reactivity and interaction of Schiff base complexes, as models of biological system such as vitamin B (B6 and B12) and enzyme (cytochtome c oxidase), some mono and binuclear Zn(II), Pd(II) and Co(II) Schiff base complexes were synthesized and characterized. As a model for vitamin B6, tridentate Schiff base ligands derived from the condensation of water soluble aldehyde with the amino acids (glycine, L-alanine, L-valine, L-leucine and L-phenylalanine) in the presence of Zn (OAc)2.2H2O give rise to the formation of five new water soluble Zn(II) complexes. The IR spectra of these complexes show that, there are prominent stretching vibration of the azomethine band (HC=N) at... 

    Synthesis and Photophysical Study of Heterobinuclear Cyclometalated Pt-Au Complexes

    , M.Sc. Thesis Sharif University of Technology Talebi Mojarad, Tahereh (Author) ; Jamali, Sirous (Supervisor)
    The cyclometalated heterobinuclear platinum-gold complexes [PtMe(bhq)(dppy)AuCl], 2, and [PtMe(bhq)(dppy)Au(NHC1)] PF6, 3, in which bhq= benzo{h}quinoline, dppy = 2-diphenylphosphinopyridine and NHC1 = 1,3-dimethylimidazol-2-ylidine have been prepared by reaction of the cyclometalated platinum complex [PtMe(bhq)(dppy)], 1, with 1 equivalent of AuCl(SMe2) or 1 equivalent of [Au(NHC1)]+ (prepared from ClAu(NHC1) and AgPF6), respectively. Complexes 2 and 3 were fully characterized using multinuclear NMR spectroscopy (1H, 31P). However complex 2was further characterized by x-ray crystallography, crystallization of complex 3 leads to form anew dimer complex 4,[Pt2(bhq)2(-dppy)2]2(PF6)2. The NMR ... 

    Using Deep Learning to Control of Complex Systems

    , M.Sc. Thesis Sharif University of Technology Aminorroaya, Saba (Author) ; Rahimi Tabar, Mohammad Reza (Supervisor)
    A complex system consists of a large number of subsystems that interact with each other and with the environment. These systems have collective behaviors that may are desired and undesired. Learning, intelligence and epilepsy are examples of desirable and undesirable collective behaviors. Control of these systems arises when they are out of the desired state or one wants to avoid approaching the system to its undesired state. For control of complex systems, we need external functions that apply to specific subsystems. These functions can be obtained from the numerical solution of Hamilton-Jacobi-Bellman equation. The Hamilton-Jacobi-Bellman equation is nonlinear and must be solved at very... 

    Direct electrochemical synthesis of copper(II) and zinc(II) complexes of the tetradentate ligand N,N′-bis(2-pyridinecarboxamide)-2-aminobenzylamine (H2bpabza). the crystal structures of the ligand and its Cu(II) complex

    , Article Polyhedron ; Volume 85 , January , 2015 , Pages 519-524 ; 02775387 (ISSN) Meghdadi, S ; Mirkhani, V ; Kia, R ; Moghadam, M ; Tangestaninejad, S ; Mohammadpoor Baltork, I ; Sharif University of Technology
    Elsevier Ltd  2015
    The direct electrosynthesis of neutral copper(II) and zinc(II) complexes of a new unsymmetrical carboxamide ligand, N,N′-bis(2-pyridinecarboxamide)-2-aminobenzylamine (H2bpabza) derived from 2-pyridinecarboxylic acid and 2-aminobenzylamine, was accomplished by electrochemical oxidation of anodic metals (copper and zinc) in an acetonitrile solution of the ligand. These compounds were characterized by elemental analyses and different spectroscopic methods. The crystal and molecular structures of the ligand, H2bpabza, and its copper complex, Cu(bpabza), were determined by X-ray diffraction. The copper atom adopts a distorted square-pyramidal (4 + 1) CuN2N′N″O coordination geometry with bpabza2-... 

    Investigation of the reaction of allyl(cyclopentadienyl)iron(II) dicarbonyl with iminium salts: Synthesis of ammonium salts of substituted five-membered-ring iron complexes

    , Article Organometallics ; Volume 26, Issue 1 , 2007 , Pages 201-203 ; 02767333 (ISSN) Ipaktschi, J ; Ziyaei Halimehjani, A ; Saidi, M. R ; Sharif University of Technology
    Series of quaternary ammonium salts of substituted five-membered-ring iron complexes were prepared by reaction of allyl(cyclopentadienyl)iron(II) dicarbonyl with iminium salts. Also, reactions of allyl-(cyclopentadienyl) iron(II) dicarbonyl with in situ prepared iminium salts afford the same products in good to excellent isolated yields. © 2007 American Chemical Society  

    Improved MPC algorithms for Edit distance and Ulam distance

    , Article IEEE Transactions on Parallel and Distributed Systems ; Volume 32, Issue 11 , 2021 , Pages 2764-2776 ; 10459219 (ISSN) Boroujeni, M ; Ghodsi, M ; Seddighin, S ; Sharif University of Technology
    IEEE Computer Society  2021
    Edit distance is one of the most fundamental problems in combinatorial optimization to measure the similarity between strings. Ulam distance is a special case of edit distance where no character is allowed to appear more than once in a string. Recent developments have been very fruitful for obtaining fast and parallel algorithms for both edit distance and Ulam distance. In this work, we present an almost optimal MPC (massively parallel computation) algorithm for Ulam distance and improve MPC algorithms for edit distance. Our algorithm for Ulam distance is almost optimal in the sense that (1) the approximation factor of our algorithm is $1+epsilon$1+ϵ, (2) the round complexity of our...