Search for: complexation
0.007 seconds
Total 1203 records

    On the computational complexity of defining sets

    , Article Discrete Applied Mathematics ; Volume 149, Issue 1-3 , 2005 , Pages 101-110 ; 0166218X (ISSN) Hatami, H ; Maserrat, H ; Sharif University of Technology
    Suppose we have a family F of sets. For every S∈F, a set D⊆S is a defining set for (F,S) if S is the only element of F that contains D as a subset. This concept has been studied in numerous cases, such as vertex colorings, perfect matchings, dominating sets, block designs, geodetics, orientations, and Latin squares. In this paper, first, we propose the concept of a defining set of a logical formula, and we prove that the computational complexity of such a problem is Σ2-complete. We also show that the computational complexity of the following problem about the defining set of vertex colorings of graphs is Σ2-complete: INSTANCE: A graph G with a vertex coloring c and an integer k.QUESTION: If... 

    Non-symmetrical tetradentate vanadyl Schiff base complexes derived from 1,2-phenylene diamine and 1,3-naphthalene diamine as catalysts for the oxidation of cyclohexene

    , Article Tetrahedron ; Volume 58, Issue 26 , 2002 , Pages 5357-5366 ; 00404020 (ISSN) Boghaei, D. M ; Mohebi, S ; Sharif University of Technology
    Two series of the novel unsymmetrical diimino tetradentate Schiff bases derived from phenylenediamine and 1,3-naphthalene diamine and their vanadyl complexes were synthesized by template and non-template methods and characterized by 1H, 13C NMR, IR, UV-Vis and elemental analysis. These complexes are used as catalysts for the selective aerobic oxidation of cyclohexene. The catalytic activity increases as the number of electron-donor groups decreases, and the catalytic selectivity is varied by changing the substituents on the ligands. The catalytic system described here is an efficient and inexpensive method for the oxidation of olefins, with the advantages of high activity, selectivity,... 

    Synthesis, characterization and study of vanadyl tetradentate Schiff base complexes as catalyst in aerobic selective oxidation of olefins

    , Article Journal of Molecular Catalysis A: Chemical ; Volume 179, Issue 1-2 , 2002 , Pages 41-51 ; 13811169 (ISSN) Boghaei, D. M ; Mohebi, S ; Sharif University of Technology
    Novel vanadyl Schiff base complexes with the general formula VOLx (x = 7-18) were synthesized and characterized by physicochemical methods. Only an orange polymeric form was obtained for VOL13, both brown polymeric and green monomeric forms were obtained for VOLx, x = 16, 17. These observations suggest that in these complexes oxovanadium(IV) exhibit a coordination number of five. Systematic substitution on the ancillary ligand have allowed V(V)/V(IV) reduction potentials to be tuned over a range of approximately 130mV. The complexes are catalysts for the aerobic oxidation of cyclohexene. Catalytic activity increases with increasing V(V)/V(IV) reduction potential and the catalytic selectivity... 

    Very well-covered graphs and local cohomology of their residue rings by the edge ideals

    , Article Journal of Algebra ; Volume 606 , 2022 , Pages 1-18 ; 00218693 (ISSN) Kimura, K ; Pournaki, M. R ; Terai, N ; Yassemi, S ; Sharif University of Technology
    Academic Press Inc  2022
    In this paper, we deal with very well-covered graphs. We first describe the structure of these kinds of graphs based on the structure of Cohen–Macaulay very well-covered graphs. As an application, we analyze the structure of local cohomology of the residue rings by the edge ideals of very well-covered graphs. Also, we give different formulas of regularity and depth of these rings from known ones and we finally treat the CMt property. © 2022 Elsevier Inc  

    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... 

    Studying Synchronization Control in Complex Systems

    , M.Sc. Thesis Sharif University of Technology Alimohammadi, Hamidreza (Author) ; Rahimi Tabar, Mohammad Reza (Supervisor)
    In this thesis, we review recent advances on controlling of complex systems. We provide in details, the concepts of synchronizability and synchronization controllability.Then we will investigate synchronization controllability under different pinning schemes, and propose a new pinning strategy to increase controllability and consequently decrease the number of required pinned nodes (known as driver nodes) to assure a stable synchronized state. We also study the network characteristics of resulted sequence of driver nodes. Finally, we will employ our proposed schemes to study the controllability of complex networks of chaotic Rossler oscillators  

    Synthesis of Homo and Hetero Bi and Multinuclear Complexes Containing Gold and Closed-Shell Metals Using Bridging Phosphine and Pyridine Ligands and Study of Their Emission Properties

    , Ph.D. Dissertation Sharif University of Technology Nayeri, Sara (Author) ; Jamali, Sirous (Supervisor)
    In this project, multi-nucleated clusters of copper (I)-gold (I) and silver (I)-gold (I) were synthesized. Initially, two tetranuclear Au2Cu2 cluster complexes [Au2Cu2(μ-(PPh2)2py)2(μ-OH)](PF6)3, and [Au2Cu2Cl2(μ-(PPh2)2 py)2](OTf)2, have been prepared by the reactions of precursor complexes [Au2(μ-(PPh2)2py)2](OTf)2, and [Cu2(μ-(PPh2)2py)2(μ-SMe2)(OTf)2], with [Cu(NCCH3)4]PF6 and AuCl(SMe2), respectively. The crystal structures of two clusters were determined by X-ray crystallography, indicating a butterfly-shaped Au2Cu2 metal core for the first and a planar-shaped Au2Cu2 metal core for second cluster. In the first cluster, the Cu atoms occupy the edge-sharing bond, while in the second... 

    Synthesis, structure and photophysical properties of binuclear methylplatinum complexes containing cyclometalating 2-phenylpyridine or benzo{h}quinoline ligands: A comparison of intramolecular Pt-Pt and π-π Interactions

    , Article Dalton Transactions ; Volume 40, Issue 36 , 2011 , Pages 9123-9130 ; 14779226 (ISSN) Jamali, S ; Czerwieniec, R ; Kia, R ; Jamshidi, Z ; Zabel, M ; Sharif University of Technology
    The binuclear cyclometalated complexes [Pt2Me 2(ppy)2(μ-dppm)], 1a, and [Pt2Me 2(bhq)2(μ-dppm)], 1b, in which ppy = 2-phenylpyridyl, bhq = benzo{h}quinoline and dppm = bis(diphenylphosphino)methane, were synthesized by the reaction of [PtMe(SMe2)(ppy)] or [PtMe(SMe 2)(bhq)] with 1/2 equiv of dppm at room temperature, respectively. Complexes 1a and 1b were fully characterized by multinuclear (1H, 31P, 13C, and 195Pt) NMR spectroscopy and were further identified by single crystal X-ray structure determination. A comparison of the intramolecular Pt-Pt and π-π interactions in complexes 1a and 1b has been made on the basis of data on crystal structures and wave functions analysis. The binuclear... 

    Cooperative abnormality detection via diffusive molecular communications

    , Article IEEE Transactions on Nanobioscience ; Volume 16, Issue 8 , 2017 , Pages 828-842 ; 15361241 (ISSN) Mosayebi, R ; Jamali, V ; Ghoroghchian, N ; Schober, R ; Nasiri-Kenari, M ; Mehrabi, M ; Sharif University of Technology
    In this paper, we consider abnormality detection via diffusive molecular communications (MCs) for a network consisting of several sensors and a fusion center (FC). If a sensor detects an abnormality, it injects a number of molecules into the medium which is proportional to its sensing output. Two transmission schemes for releasing molecules into the medium are considered. In the first scheme, each sensor releases a different type of molecule (DTM), whereas in the second scheme, all sensors release the same type of molecule (STM). The molecules released by the sensors propagate through the MC channel and some may reach the FC where the final decision regarding whether or not an abnormality... 

    Observational equivalence in system estimation: contractions in complex networks

    , Article IEEE Transactions on Network Science and Engineering ; 2017 ; 23274697 (ISSN) Doostmohammadian, M ; Rabiee, H. R ; Zarrabi, H ; Khan, U ; Sharif University of Technology
    Observability of complex systems/networks is the focus of this paper, which is shown to be closely related to the concept of contraction. Indeed, for observable network tracking it is necessary/sufficient to have one node in each contraction measured. Therefore, nodes in a contraction are equivalent to recover for loss of observability, implying that contraction size is a key factor for observability recovery. Here, developing a polynomial order contraction detection algorithm, we analyze the distribution of contractions, studying its relation with key network properties. Our results show that contraction size is related to network clustering coefficient and degree heterogeneity.... 

    A genetic approach in relay-jammer selection and power allocation for physical layer security

    , Article 8th International Symposium on Telecommunications, IST 2016, 27 September 2016 through 29 September 2016 ; 2017 , Pages 374-379 ; 9781509034345 (ISBN) Okati, N ; Mosavi, M. R ; Behroozi, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Node cooperation approaches improve physical layer security in wireless networks without applying data encryption. Selecting the appropriate nodes to cooperate as relays or friendly jammers, to degrade eavesdropper's link, is a challenging problem which has attracted a lot of attention in recent years. Various approaches, based on conventional exhaustive search, have been suggested for optimal relay-jammer selection and power allocation in the literature. The complexity of these methods is proportional to the number of intermediate nodes. As the number of intermediate nodes exceeds a specific bound, conventional exhaustive search appears infeasible due to high computational complexity. In... 

    Heterogeneous water oxidation by bidentate schiff base manganese complexes in the presence of cerium(IV) ammonium nitrate

    , Article Transition Metal Chemistry ; Volume 34, Issue 4 , 2009 , Pages 367-372 ; 03404285 (ISSN) Najafpour, M. M ; Boghaei, D. M ; Sharif University of Technology
    Oxygen evolution was observed upon mixing solid manganese(III) bidentate Schiff base complexes with aqueous solutions of cerium(IV) ammonium nitrate. However, oxygen evolution was not observed upon mixing solutions of the complexes (in acetonitrile) with Ce(IV). Electron-withdrawing substituents on the Schiff base ligands (NO2, Br) enhanced the reactivity of the manganese complexes toward oxygen evolution. Oxygen evolution was also affected by R groups on the ligands, in the order Me > Et Bz. © 2009 Springer Science+Business Media B.V  

    Synthesis of Lanthanide (III) Macrocyclic Schiff Base Complexes Containing Pyridine and their Decomposition in Aqueous Solution

    , M.Sc. Thesis Sharif University of Technology Azizi, Zahra (Author) ; Mohammadi Boghaei, Davar (Supervisor)
    This study involved the synthesis, structural characterization and studies of gadolinium (III) hexaaza macrocyclic Schiff base complexes containing pyridine head and their decomposition in aqueous solution.There are many applications of lanthanide(III) macrocyclic complexes as medicine and in the biological systems, as magnetic resonance imaging (MRI) agents, and etc.These applications require that the Gd(III) complexes be resistant to gadolinium ion release under physiological conditions.
    We considered planer macrocyclic ligands as a means to obtain highly stable complexes of Gd(III). Symmetric [2+2] Schiff base macrocyclic derived from 2,6-diacetylpyridine with amines would exhibit... 

    Model Systems for Oxygen – Evolving Complex in Photosystem II: Manganese Oxides and Manganese Complexes with O and N Donor Ligands

    , Ph.D. Dissertation Sharif University of Technology Najafpour, Mohammad Mahdi (Author) ; Mohammadi Boghaei, Davar (Supervisor)
    The aim of this study is to mimic water oxidizing complex to find new materials and also to understand their rules in this matter. To achieve this, manganese complexes containing 2,4,6-tris (2-pyridyl)-1,3,5-Triazine, 1,10-phenanthroline, 1,10-bipyridine, Schiff base, amino acids, 2,6-pyridinedicarboxylic acid, 2-pyridinecarboxylic acid have been synthesized and characterized by elemental analysis, IR, EPR, ESI-MS, electronic absorption spectroscopy, electrochemistry, X-ray diffraction and oxygen evolution in presence of oxone and Ce(IV). It is shown that the reaction between Mn(II) complexes containing 2,4,6-tris¬(2-pyridyl)-1,3,5-Triazine, 1,10-phenanthroline, 1,10-bipyridine,... 

    Discrete Morse Theory

    , M.Sc. Thesis Sharif University of Technology Kashkouie, Fatemeh (Author) ; Fanai, Hamid Reza (Supervisor)
    A number of questions from a variety of areas of mathematics lead one to the problem of analyzing the topology of a simplicial complex. However, there are few general techniques available to aid us in this study. On the other hand, some very general theories have been developed for the study of smooth manifolds. One of the most powerful, and useful, of these theories is Morse Theory. We present a combinatorial adaptation of Morse Theory, which we call discrete Morse theory that may be applied to any simplicial complex (or more general cell complex). Our goal is to present an overview of the subject of discrete Morse Theory that is sufficient both to understand the major applications of the... 

    The thermodynamic study of interaction between folic acid and
    Cu(L) 2 (L=gly, ala, val )

    , M.Sc. Thesis Sharif University of Technology khadir, Narjes (Author) ; Mohammadi Boghaei, Davar (Supervisor)
    The complexation between folic acid and the complexes of Cu(L)2 (L = Glycine, Alanine, Valine) were investigated using UV.Vis spectroscopy. The values of the equilibrium constant K and molar absorption coefficient Ɛ of the complexes were estimated in the aquation environment at various temperatures. The temperature dependence of the K can be used for the determination of the thermodynamic reaction quantities (∆G, ∆H, ∆S) for linear regression fits to the Van’t Hoff equation. The kinetic studies reveals that the stoichiometry of reaction were 1:1 for these systems. All reaction were endothermic and the values of the ∆H are positive. In all cases entropy increased and the values of the ∆S... 

    Immobilized Manganese-porphyrin and Molybdenum-Schiff Base Complexes on Functionalized Magnetic Nanoparticles as Efficient Recyclable Nanocatalysts in Hydrocarbon and Sulfide Oxidation Reactions

    , Ph.D. Dissertation Sharif University of Technology Mortazavi Manesh, Anahita (Author) ; Bagherzadeh, Mojtaba (Supervisor)
    In this thesis, functionalized Fe3O4 nanoparticles have been utilized as a support for immobilization of homogeneous catalysts. The catalytic activity of the supported heterogeneous nanocatalysts was investigated in hydrocarbon and sulfide oxidation reactions. In the first part of this research, imidazole functionalized Fe3O4 nanoparticles (Fe3O4@SiO2-Im) were used as a support to anchor manganese porphyrin complex, [MnT(4-OMeP)P]OAc; via axial ligation. Catalytic application of the immobilized manganese porphyrin was studied in oxidation of alkenes and sulfides. To find suitable reaction conditions, the effect of different parameters such as solvent and temperature on immobilization process... 

    Synthesis, Characterization, Structural and Theoretical Studies of Some New Homoleptic and Heteroleptic Diiminic and Diphosphine Copper(I) Complexes

    , M.Sc. Thesis Sharif University of Technology Heshmatnia, Faranak (Author) ; Kia, Reza (Supervisor)
    In this study first some new diimine ligands were synthesized, then mononuclear and binuclear Cu(I) complexes with starting matrials, [Cu(NCCH3)4]X (X= PF6, ClO4) or CuI, and the synthesized diimine ligands and phosphinic (POP) ligand were prepared. These complexes were characterized using 1HNMR, 31P{1H}NMR, and FT-IR spectroscopic methods and their solid state structure were determined by single crystal X-ray diffraction. Inspection of the solid-state structurs, showed variety of the stabilizing interactions shuch as NO2•••NO2, π•••π, C─H•••π, and NO2•••π. Density functional theory (DFT) was used for geometry optimization of the singlet states in gas phase and the electronic structure... 

    Analysis and Improvement of Private Set Intersection Schemes

    , M.Sc. Thesis Sharif University of Technology Kavousi, Alireza (Author) ; Mohajeri, Javad (Supervisor) ; Salmasizadeh, Mahmoud (Co-Supervisor)
    Secure multi-party computation (MPC) enables a group of mutually distrustful parties to compute a joint and agreed upon function of their private inputs without disclosing anything but the corresponding output. One of the most important secure computation protocols is private set intersection (PSI). In PSI, often two or several parties wish to find the intersection of their sets without revealing other non-common elements. There exist some other variants of PSI protocol like PSI cardinality or threshold PSI which in the former only the cardinality of the intersection set is revealed and in the latter the intersection set is revealed if its cardinality is greater (less) than a certain value.... 

    Synthesis and Characterization of a New Metallomacrocycle Complex of Au(I) Containing 4,4ˊ-Azopyridine Ligand

    , M.Sc. Thesis Sharif University of Technology Abdolrahimi, Amin (Author) ; Jamali, Sirous (Supervisor)
    Gold(I) complex of [Au2(μ-PAnP)Cl_2] (1) (PAnP = 9,10-bis(diphenylphosphino)anthracene) has been prepared from the reaction of AuCl(SMe2) with PAnP in a 2:1 molar ratio. The structure of 1 was determined using 1H NMR and 31P{1H} NMR spectroscopy in solution. The tetranuclear metallomacrocycle [Au4(μ-PAnP)2 (μ-4,4 AzoPy)2]OTf4 (2) (4,4 AzoPy = 4,4-Azopyridine) has been prepared from the reaction of complex 1 with AgOTf and 4,4-Azopyridine in a 1:2:1 molar ratio. The structure of 2 was characterized using X-ray crystallography in solid state, 1H NMR and 31P{1H} NMR spectroscopy, UV-Vis spectroscopy and photoluminescence spectroscopy in solution state. The 1 has bright green emission in solid...