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    Diastereoselective synthesis and catalytic activity of two chiral cis-dioxidomolybdenum(VI) complexes

    , Article European Journal of Inorganic Chemistry ; Volume 2018, Issue 22 , 15 June , 2018 , Pages 2549-2556 ; 14341948 (ISSN) Haghdoost, M. M ; Zwettler, N ; Golbaghi, G ; Belaj, F ; Bagherzadeh, M ; Schachner, J. A ; Mosch Zanetti, N. C ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Two enantiomerically pure chiral dioxidomolybdenum(VI) complexes (1 and 2) of the type [MoO2L] (L = dianionic, tetradentate ONNO-ligand) were synthesized and investigated in enantioselective oxidation reactions. The solid-state structures of complex 1 and 2, determined via single-crystal X-ray diffraction analysis revealed two fundamentally different coordination geometries: a C1-symmetric cis-β isomer (Λ-1), and a C2-symmetric cis-α isomer (Δ-2). In both cases, only one of the two possible helical enantiomers (Λ- or Δ-helix) was formed. The complexes were examined as precatalysts in the epoxidation of the challenging prochiral substrate trans-stilbene, using either tert-butyl hydroperoxide... 

    Stability of chiral states, role of intermolecular interactions and molecular parity violation

    , Article Computational and Theoretical Chemistry ; Volume 978, Issue 1-3 , 2011 , Pages 84-87 ; 2210271X (ISSN) Bahrami, M ; Shafiee, A ; Sharif University of Technology
    We study the problem of stability of chiral states, also known as problem of chirality, within the framework of a two-dimensional approximation of a symmetric double-well potential. We show how the symmetry breaking of the potential due to the molecular parity violation can stop the tunneling in a coherent way, accordingly stabilize the chiral states. Then, we use the quantum Brownian motion within a linear Lindblad-type equation to model how the intermolecular interactions make the tunneling incoherent, thus inducing a racemization by dephasing. Finally, we investigate the normal physical conditions where the dephasing racemization does not suppress the effects of the molecular parity... 

    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))... 

    Anomaly and nonplanar diagrams in noncommutative gauge theories

    , Article International Journal of Modern Physics A ; Volume 17, Issue 1 , 2002 , Pages 123-144 ; 0217751X (ISSN) Ardalan, F ; Sadooghi, N ; Sharif University of Technology
    Anomalies arising from nonplanar triangle diagrams of noncommutative gauge theory are studied. Local chiral gauge anomalies for both noncommutative U(1) and U(N) gauge theories with adjoint matter fields are shown to vanish. For noncommutative QED with fundamental matters, due to UV/IR mixing a finite anomaly emerges from the nonplanar contributions. It involves a generalized *-product of gauge fields  

    Visual recognition of tryptophan enantiomers using chiral self assemblies of quantum dots

    , Article ACS Applied Nano Materials ; 2021 ; 25740970 (ISSN) Fahimi Kashani, N ; Jafar Nezhad Ivrigh, Z ; Bigdeli, A ; Hormozi Nezhad, M.R ; Sharif University of Technology
    American Chemical Society  2021
    Discrimination of chiral targets is generally achieved with chiral nanomaterials. However, the limited number of intrinsic chiral nanostructures as well as their complex synthesis procedure has led to the production of chirality-induced nanomaterials as alternatives. Chirality can be induced in nanomaterials by either chirality transfer or the formation of chiral assemblies. Using the latter approach, in this work, we have provided chiral supramolecular assemblies of CdTe quantum dots (QDs) from achiral starting materials. CTAB-QD assemblies showed chiroptical activities, and their orange emission in combination with the blue emission of carbon dots was utilized as a ratiometric chiral... 

    Study ofthe NJL-Model Phase Diagram at Finite Temperature and Chemical Potential

    , M.Sc. Thesis Sharif University of Technology Hajizadeh, Ouraman (Author) ; Rouhani, Shahin (Supervisor) ; Sadooghi, Neda (Supervisor)
    We calculate NJL-Model free energy throughthe finite- temperature methods.Then according to the energy-gap equation, we determine symmetric and anti-symmetric phases under Chiral Transformation, in different regions of the phase diagram,with chemical potential() and temperature(T)as control parameter. We conclude with comparing the result of the finite temperature expansion to nonzero chemical potential to the result of,T=0 and finite ,andT=μregime.

    Geometrical influence of a deposited particle on the performance of bridged carbon nanotube-based mass detectors

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 94 , 2017 , Pages 31-46 ; 13869477 (ISSN) Ali Akbari, H. R ; Ceballes, S ; Abdelkefi, A ; Sharif University of Technology
    A nonlocal continuum-based model is derived to simulate the dynamic behavior of bridged carbon nanotube-based nano-scale mass detectors. The carbon nanotube (CNT) is modeled as an elastic Euler-Bernoulli beam considering von-Kármán type geometric nonlinearity. In order to achieve better accuracy in characterization of the CNTs, the geometrical properties of an attached nano-scale particle are introduced into the model by its moment of inertia with respect to the central axis of the beam. The inter-atomic long-range interactions within the structure of the CNT are incorporated into the model using Eringen's nonlocal elastic field theory. In this model, the mass can be deposited along an... 

    Quantum Aspects of The Origin of Life

    , M.Sc. Thesis Sharif University of Technology Khezr Seddigh Mazinani, Shobeir (Author) ; Shafie, Afshin (Supervisor)
    Many have claimed that quantum mechanics is playing a non-trivial, i.e. further from merely governing atomic and molecular realm, in living. If so, clearly quantum mechanics should have played a key role in the origin of life especially in the transition from chemical evolution to biological (Darwinian) evolution. Long before quantum aspects of living systems came to focus, It was known that all the amino acids are right handed and all the sugars are left handed in living systems. Bio-molecules having the same sense of chirality, i.e. optical activity, are called biohomochirality. Detailed studies on the structure and functioning of biomolecules buttressed the idea that the selection of... 

    Fundamental Study of Entanglement and its Application in Chirality Problem

    , Ph.D. Dissertation Sharif University of Technology Taher Ghahramani, Farhad (Author) ; Shafiee, Afshin (Supervisor)
    The origin of life is one of the fundamental problems of the science, which is not yet answered appositely. The building blocks of life’s molecules, including nucleic acids (DNA and RNA) and proteins, are composed of carbohydrates and amino acids. At the chemical level, these building blocks have definite chirality. This phenomenon is known as biological homochirality. Due to the fact that this phenomenon has taken place in the early stages of life, it is believed that the life’s origin is to a great extent connected to the origin of biological homochirality. Like every other system, at the microscopic level, life’s molecules are composed of atoms which are governed by the lows of quantum... 

    Instability in Relativistic Chiral Magnetohydrodynamics

    , M.Sc. Thesis Sharif University of Technology Rahbardar Mojaver, Mehrnoosh (Author) ; Sadooghi, Neda (Supervisor) ; Shokri, Masoud (Co-Supervisor)
    Magnetohydrodynamic is used to study many phenomena. In non-relativistic terms, it can be used to express dynamo theory and to study the evolution of a magnetic field in a conductive fluid medium. In the case of fluid particles having chiral imbalance, the instability associated with this property is observed in the system response to the small perturbation from the equilibrium state. In a relativistic framework, these equations can describe the quark-gluon plasma in the heavy ions collision in a decentralized manner and the nucleus of neutron stars. In many studies, chirality has been considered for such environments. Obtaining the dispersion relation and investigating the response of the... 

    Emergence of molecular chirality by vibrational Raman scattering

    , Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 88, Issue 3 , 2013 ; 10502947 (ISSN) Taher Ghahramani, F ; Shafiee, A ; Sharif University of Technology
    In this study, we apply the monitoring master equation describing decoherence of internal states to an optically active molecule prepared in a coherent superposition of nondegenerate internal states interacting with thermal photons at low temperatures. We use vibrational Raman scattering theory up to the first chiral-sensitive contribution, i.e., the mixed electric-magnetic interaction, to obtain scattering amplitudes in terms of molecular polarizability tensors. The resulting density matrix is used to obtain elastic decoherence rates  

    Efficient diastereo- and enantioselective synthesis of α,β-disubstituted γ-phosphono sulfonates

    , Article Tetrahedron Asymmetry ; Volume 20, Issue 21 , 2009 , Pages 2429-2431 ; 09574166 (ISSN) Enders, D ; Mirjafary, Z ; Saeidian, H
    The first asymmetric synthesis of α,β-disubstituted γ-phosphono sulfonates is reported. The key step is the Michael addition of a lithiated enantiopure sulfonate bearing an inexpensive chiral sugar auxiliary to α,β-unsaturated phosphonates in good diastereoselectivities. After chromatographic purification, the cleavage of the chiral sugar auxiliary proceeds without any epimerization or racemization to form the corresponding isopropyl sulfonate in very good overall yield (75%) and excellent diastereomeric and enantiomeric excess (de, ee ≥ 95%). © 2009 Elsevier Ltd. All rights reserved  

    Induced superconductivity in Fermi arcs

    , Article Physical Review B ; Volume 100, Issue 3 , 2019 ; 24699950 (ISSN) Faraei, Z ; Jafari, S. A ; Sharif University of Technology
    American Physical Society  2019
    When the interface of a superconductor (SC) with a Weyl semimetal (WSM) supports Fermi arcs, the chirality blockade eliminates the induction of superconductivity into the bulk of time-reversal symmetry (TRS) breaking WSM. This leaves the Fermi arc states as the only low-energy degrees of freedom in the proximity problem. Therefore the SC|WSM system will be a platform to probe transport properties which involve only the Fermi arcs. With a boundary condition that flips the spin at the boundary, we find a Z2 protected Bogoliubov Fermi contour (BFC) around which the Bogoliubov quasiparticles disperse linearly. The resulting BFC and excitations around it leave a distinct T2 temperature dependence... 

    Tunable circular conversion dichroism and asymmetric transmission of terahertz graphene metasurface composed of split rings

    , Article Optics Communications ; Volume 456 , 2020 Asgari, S ; Rahmanzadeh, M ; Sharif University of Technology
    Elsevier B.V  2020
    The asymmetric transmission (AT) has attracted wide attention due to its novel applications. In this paper, we propose and investigate a tunable polarization-dependent intrinsically chiral graphene metasurface composed of split ring arrays in terahertz (THz) region. The resonance frequency of the structure is sensitive to the graphene chemical potential. Circular conversion dichroism (CCD) of the proposed structure is tunable and is reached to 0.36. Our work paths a new approach to propose some other compact and on-chip polarization-dependent structures in THz region. Furthermore, our proposed structure could be a useful segment in polarization-dependent systems. © 2019 Elsevier B.V  

    Optical nanoprobes for chiral discrimination

    , Article Analyst ; Volume 145, Issue 20 , 2020 , Pages 6416-6434 Bigdeli, A ; Ghasemi, F ; Fahimi Kashani, N ; Abbasi Moayed, S ; Orouji, A ; Jafar Nezhad Ivrigh, Z ; Shahdost Fard, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Chiral discrimination has always been a hot topic in chemical, food and pharmaceutical industries, especially when dealing with chiral drugs. Enantiomeric recognition not only leads to better understanding of the mechanism of molecular recognition in biological systems, but may further assist in developing useful molecular devices in biochemical and pharmaceutical studies. By emerging nanotechnology and exploiting nanomaterials in sensing applications, a great deal of attention has been given to the design of optical nanoprobes that are able to discriminate enantiomers of chiral analytes. This review explains how engineering nanoparticles (NPs) with desired physicochemical properties allows... 

    Synthesis of tetrahydrofuran from maleic anhydride on Cu-ZnO-ZrO2/H-Y bifunctional catalysts

    , Article Catalysis Communications ; Volume 9, Issue 13 , 2008 , Pages 2195-2200 ; 15667367 (ISSN) Aghaziarati, M ; Soltanieh, M ; Kazemeini, M ; Khandan, N ; Sharif University of Technology
    A series of bifunctional Cu-ZnO-ZrO2/H-Y catalysts of different compositions were prepared by coprecipitating sedimentation method and were characterized by surface area and XRD analyses. The catalytic performance in synthesis of tetrahydrofuran was evaluated and optimized in a three-phase slurry batch reactor. The experimental results showed that the appropriate ratio of Cu/ZnO in the hydrogenation catalyst was 50/45, for which the conversion of maleic anhydride (MA) and selectivity of tetrahydrofuran (THF) reached 100% and 46%, respectively, at 50 bar and 493 K after 6 h of operation. Also, according to these results, it was demonstrated that the incorporation of zirconium oxide in the... 

    Organocatalytic synthesis of chiral benzopyrans

    , Article Tetrahedron Asymmetry ; Volume 17, Issue 12 , 2006 , Pages 1763-1767 ; 09574166 (ISSN) Govender, T ; Hojabri, L ; Matloubi Moghaddam, F ; Arvidsson, P. I ; Sharif University of Technology
    Benzopyrans, or chromenes, are widespread in nature and are considered to be a privileged scaffold in medicinal chemistry. Herein, we report the first organocatalyzed asymmetric synthesis of chiral benzopyrans. The benzopyran unit is constructed through a domino reaction involving an oxa-Michael attack of salicylic aldehyde derivatives onto α,β-unsaturated aldehydes, activated through iminium-ion formation with the organocatalyst, followed by an intramolecular aldol reaction and subsequent elimination of water. This overall reaction sequence provides benzopyrans with aromatic C-2 substituents in up to 60% yield and 60% enantioselectivity, while C-2 aliphatic analogues can be obtained in 90%... 

    On the Effects of Background Electromagnetic elds and Chiral Chemical Potential on the Phase Diagram of Quantum Chromodynamics

    , M.Sc. Thesis Sharif University of Technology Jamshidi, Abdollah (Author) ; Sadooghi, Neda (Supervisor)
    In particle physics, spontaneous chiral symmetry breaking generates new phases of quark matter, and leads to significant changes od quark masses. The Nambu-Jona–Lasinio (NJL) model is a useful fermionic model which describes the spontaneous chiral symmetry breaking through the creation of a condensate. This model can be for instance used to determine various phases of Quantum Chromodynamics (QCD) in finite electromagnetic fields. This work consists of several parts. First, we describe the spontaneous chiral symmetry breaking in detail. Second, we extract the NJL model from the Lagrangian density of QCD. Third, we derive a covariant form of the partition function of a fermionic system.... 

    Emergence of molecular chirality due to chiral interactions in a biological environment

    , Article Journal of Biological Physics ; Vol. 40, issue. 4 , Jul , 2014 , p. 369-386 Tirandaz, A ; Ghahramani, F. T ; Shafiee, A ; Sharif University of Technology
    We explore the interplay between tunneling process and chiral interactions in the discrimination of chiral states for an ensemble of molecules in a biological environment. Each molecule is described by an asymmetric double-well potential and the environment is modeled as a bath of harmonic oscillators. We carefully analyze different time-scales appearing in the resulting master equation at both weak- and strong-coupling limits. The corresponding results are accompanied by a set of coupled differential equations characterizing optical activity of the molecules. We show that, at the weak-coupling limit, chiral interactions prohibit the coherent racemization induced by decoherence effects and... 

    Critical Investigation of Decoherecne Theory in Different Physical Contexts

    , Ph.D. Dissertation Sharif University of Technology Tirandaz, Arash (Author) ; Shafiee, Afshin (Supervisor)
    Considering the consistency between the predictions of a theory with what is observed in experience, Quantum Mechanics is the most accurate theory in the history of physics. However, is does not present us an unmbigiuos and realistic description about the nature of the microscopic phenomena. At the heart of these issues is the so-called measurement problem. The formalism of the quantum mechanics is unitary and deterministic. Nevertheles, when one does measurements, the unitary process of the evolution of wave-function breaks due to a stochastic abruption. The results of the measurements are in correspondence with the everyday experience of the observer. Yet, the theory itself does not...