scholarly journals Hg2+-Promoted Spirolactam Hydrolysis Reaction: A Design Strategy for the Highly Selective Sensing of Hg2+ over other Metal Ions in Aqueous Media

Sensors ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 128 ◽  
Author(s):  
Mai Bay ◽  
Nguyen Hien ◽  
Subin Son ◽  
Nguyen Trinh ◽  
Nguyen Trung ◽  
...  
Keyword(s):  
Metal Ions ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Aqueous Media ◽  
Colorimetric Method ◽  
Hydrolysis Reaction ◽  
Experimental Investigations ◽  
Reaction Products ◽  
Before And After ◽  
Excitation Processes

A mercury sensor (N-(rhodamine-6G)lactam-ethylenediamine-4-dimethylamino-cinnamaldehyde—RLED) based on the Hg2+-promoted hydrolysis reaction has been designed and developed with a combination of theoretical calculations and experimental investigations. The interaction between RLED and Hg2+ goes through a fast-initial stage with formation of a 1:1 complex, followed by a slow hydrolysis process. The formation of durable intermediate complexes is due to quite a long hydrolysis reaction time. As a result, RLED can selectively detect Hg2+ in the presence of other metal ions, with a detection limit of 0.08 μM for the colorimetric method, and of 0.008 μM with the fluorescent method. In addition, the RLED sensor can work in a solution with a small amount of organic solvent, with a wide pH range from 5 to 10. The time-dependent density functional theory has been used for investigations of the excitation and de-excitation processes in RLED, intermediate complexes, and reaction products, thereby clarifying the changes in the fluorescence intensity before and after the RLED interacts with Hg2+ ions.

scholarly journals Synthesis, Structural Features and Physical Properties of a Family of Triply Bridged Dinuclear 3d-4f Complexes

2021 ◽  
Vol 7 (2) ◽  
pp. 22
Author(s):  
Itziar Oyarzabal ◽  
Estitxu Echenique-Errandonea ◽  
Eider San Sebastián ◽  
Antonio Rodríguez-Diéguez ◽  
José Manuel Seco ◽  
...  
Keyword(s):  
Metal Ions ◽  
Density Functional ◽  
Magnetic Measurements ◽  
Theoretical Calculations ◽  
Exchange Interactions ◽  
Transition Metal Ions ◽  
Structural Features ◽  
Coupling Constants ◽  
Metallic Ions ◽  
Magnetic Exchange

New dinuclear MII-LnIII complexes of general formulas [Cu(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN·H2O (LnIII = Gd (1), Tb (2), Dy (3) and Er (4)), [Ni(CH3CN)(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN (LnIII = Nd (5), Gd (6), Tb (7), Dy (8), Er (9) and Y (10)) and [Co(CH3CN)(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN (LnIII = Gd (11), Tb (12), Dy (13), Er (14) and Y (15)) were prepared from the compartmental ligand N,N′-dimethyl-N,N′-bis(2-hydroxy-3-formyl-5-bromo-benzyl)ethylenediamine (H2L). In all these complexes, the transition metal ions occupy the internal N2O2 coordination site of the ligand, whereas the LnIII ions lie in the O4 external site. Both metallic ions are connected by an acetate bridge, giving rise to triple mixed diphenoxido/acetate bridged MIILnIII compounds. Direct current (dc) magnetic measurements allow the study of the magnetic exchange interactions between the 3d and 4f metal ions, which is supported by density functional theory (DFT) theoretical calculations for the GdIII-based counterparts. Due to the weak ferromagnetic exchange coupling constants obtained both experimentally and theoretically, the magneto-thermal properties of the less anisotropic systems (compounds 1 and 6) are also studied. Alternating current (ac)magnetic measurements reveal the occurrence of slight frequency dependency of the out-of-phase signal for complexes 8, 9 and 13, while complex 15 displays well-defined maximums below ~6 K.

Revealing the Inhibition Efficiencies of Artesunate and Rutin for Corrosion of Steel: A Theoretical Study

2018 ◽  
Vol 762 ◽  
pp. 325-329 ◽  
Author(s):  
Gökhan Gece
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Theoretical Calculations ◽  
Aqueous Media ◽  
Basis Set ◽  
Orbital Energy ◽  
Molecular Orbital Energy ◽  
Experimental Findings ◽  
Corrosion Of Steel

Corrosion inhibition characteristics of artesunate and rutin on carbon steel in water has been studied using density functional theory (DFT). Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), and global reactivity properties have been calculated at the B3LYP/6-311G(d,p) basis set. The results of theoretical calculations confirm the experimental findings on the superiority of rutin to protect the corrosion of steel in aqueous media compared to artesunate.

scholarly journals Theoretical and experimental investigations into the structural, electronic, and molecular properties of 1,5-dihydropyrano[2,3-c]chromene derivatives

2019 ◽  
Vol 10 (3) ◽  
pp. 5586-5591
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Theoretical Calculations ◽  
Chemical Properties ◽  
Theoretical Data ◽  
Aromatic Aldehydes ◽  
Polarizable Continuum Model ◽  
Basis Set ◽  
Experimental Investigations ◽  
Three Component Reaction

In this study, a simple and efficient method for the synthesis of 1,5-dihydropyrano[2,3-c]chromene derivatives is reported by three component reaction of aromatic aldehydes, malononitrile, and 3-hydroxycoumarin in the presence of piperidine as base in ethanol, under reflux conditions. Also, the experimental results involving new and already synthesized compounds are compared with the theoretical calculations. The energy, molecular electrostatic potential (MEP), HOMO–LUMO energy gap, chemical properties and NMR analyses of 1,5-dihydropyrano[2,3-c]chromene derivatives in DMSO solution were estimated using density functional theory and 6-311++G (d,p) basis set. The solvent effect was explored using the polarizable continuum model (PCM) method. Increasing polarity and having no much difference in energies show the more effects of newly synthesized compounds (R2-DHPC) towards already synthesized compounds (R4-DHPC) in human body. Also, the results display that there is a good agreement between experimental and theoretical data.

scholarly journals Reactions of Rh2(CH3COO)4with thiols and thiolates: a structural study

2019 ◽  
Vol 26 (2) ◽  
pp. 450-461 ◽  
Author(s):  
Alejandra Enriquez Garcia ◽  
Farideh Jalilehvand ◽  
Pantea Niksirat
Keyword(s):  
Density Functional ◽  
Aqueous Media ◽  
Colour Change ◽  
Reaction Products ◽  
Functional Theory ◽  
Dihydrolipoic Acid ◽  
Td Dft ◽  
X Ray Absorption ◽  
Aerobic Reaction ◽  
Proteins And Peptides

The structural differences between the aerobic reaction products of Rh2(AcO)4(1; AcO−= CH3COO−) with thiols and thiolates in non-aqueous media are probed by X-ray absorption spectroscopy. For this study, ethanethiol, dihydrolipoic acid (DHLA; a dithiol) and their sodium thiolate salts were used. Coordination of simple thiols to the axial positions of Rh2(AcO)4with Rh—SH bonds of 2.5–2.6 Å keeps the RhII—RhIIbond intact (2.41 ± 0.02 Å) but leads to a colour change from emerald green to burgundy. Time-dependent density functional theory (TD-DFT) calculations were performed to explain the observed shifts in the electronic (UV–vis) absorption spectra. The corresponding sodium thiolates, however, break up the Rh2(AcO)4framework in the presence of O2to form an oligomeric chain of triply S-bridged Rh(III) ions, each with six Rh—S (2.36 ± 0.02 Å) bonds. The RhIII...RhIIIdistance, 3.18 ± 0.02 Å, in the chain is similar to that previously found for the aerobic reaction product from aqueous solutions of Rh2(AcO)4and glutathione (H3A), {Na2[Rh2III(HA)4]·7H2O}n, in which each Rh(III) ion is surrounded by about four Rh—S (2.33 ± 0.02 Å) and about two Rh—O (2.08 ± 0.02 Å). The reaction products obtained in this study can be used to predict how dirhodium(II) tetracarboxylates would react with cysteine-rich proteins and peptides, such as metallothioneins.

scholarly journals Mechanism, kinetics and selectivity of selenocyclization of 5-alkenylhydantoins: an experimental and computational study

2015 ◽  
Vol 11 ◽  
pp. 1865-1875 ◽  
Author(s):  
Biljana M Šmit ◽  
Radoslav Z Pavlović ◽  
Dejan A Milenković ◽  
Zoran S Marković
Keyword(s):  
Density Functional Theory ◽  
Double Bond ◽  
Density Functional ◽  
Computational Study ◽  
Theoretical Calculations ◽  
Reaction Products ◽  
Dft Methods ◽  
Functional Theory ◽  
H Nmr ◽  
Good Agreement

The mechanism and selectivity of a bicyclic hydantoin formation by selenium-induced cyclization are investigated. The proposed mechanism involves the intermediates formed by an electrophilic addition of the selenium reagent on a double bond of the starting 5-alkenylhydantoin prior the cyclization. These intermediates are readily converted into the more stable cyclic seleniranium cations. A key step of the mechanism is an intramolecular cyclization which is realized through an anti-attack of the internal nucleophile, the amidic nitrogen, to the seleniranium cation yielding the intermediate imidazolinium cations. Their deprotonation is followed by the formation of the fused bicyclic reaction products. Important intermediates and key transition states are studied by using density functional theory (DFT) methods. The pathways of the reaction are investigated in detail. There are two regioselective pathways related to 5-exo and 6-endo products. Theoretical calculations and the monitoring of the cyclization reaction using 1H NMR spectroscopy are in a good agreement with the proposed mechanism and are consistent with our experimental results. The preferred pathway for formation of 5-exo products is confirmed.

Novel repaglinide complexes with manganese(II), iron(III), copper(II) and zinc(II): Spectroscopic, DFT characterization and electrochemical behavior

2016 ◽  
Vol 57 (8) ◽  
pp. 1613
Author(s):  
S. Sadaoui-Kacel ◽  
S. Zaater ◽  
N. Bensouilah ◽  
S. Djebbar
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Electronic Spectra ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Structural Parameters ◽  
Theoretical Data ◽  
Molar Conductance ◽  
Basis Set ◽  
Deprotonated Form

Novel transition metal complexes with the repaglinide ligand [2-ethoxy-4-[N-[1-(2piperi­dinophenyl)-3-methyl-1-1butyl] aminocarbonylmethyl]benzoic acid] (HL) are prepared from chloride salts of manganese(II), iron(III), copper(II), and zinc(II) ions in water-alcoholic media. The mononuclear and non-electrolyte [M(L)2(H2O)2]×nH2O (M = Mn2+, n = 2, M = Cu2+, n = 5 and M = Zn2+, n = 1) and [M(L)2(H2O)(OH)]×H2O (M = Fe3+) complexes are obtained with the metal:ligand ratio of 1:2 and the L-deprotonated form of repaglinide. They are characterized using the elemental and molar conductance. The infrared, 1H and 13C NMR spectra show the coordination mode of the metal ions to the repaglinide ligand. Magnetic susceptibility measurements and electronic spectra confirm the octahedral geometry around the metal center. The experimental values of FT-IR, 1H, NMR, and electronic spectra are compared with theoretical data obtained by the density functional theory (DFT) using the B3LYP method with the LANL2DZ basis set. Analytical and spectral results suggest that the HL ligand is coordinated to the metal ions via two oxygen atoms of the ethoxy and carboxyl groups. The structural parameters of the optimized geometries of the ligand and the studied complexes are evaluated by theoretical calculations. The order of complexation energies for the obtained structures is as follows: Fe(III) complex < Cu(II) complex < Zn(II) complex < Mn(II) complex. The redox behavior of repaglinide and metal complexes are studied by cyclic voltammetry revealing irreversible redox processes. The presence of repaglinide in the complexes shifts the reduction potentials of the metal ions towards more negative values.

A study of shell structure in normal to exotic nuclides within relativistic Hartree–Bogoliubov approximation

2019 ◽  
Vol 34 (02) ◽  
pp. 1950014 ◽  
Author(s):  
Smriti Thakur ◽  
Shashi K. Dhiman
Keyword(s):  
Shell Structure ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Mean Field ◽  
Neutron Number ◽  
Meson Exchange ◽  
Experimental Investigations ◽  
Neutron Separation Energy ◽  
Shell Closure ◽  
Bogoliubov Approximation

The purpose of this work is to study theoretically the shell structure of even–even isotopes in Si, S, Ar and Ca and isotones at neutron number N = 0, 28, 50 and 82. We employed Covariant Relativistic self-consistent mean field models analogous to Kohn–Sham density functional theory to construct the Nuclear Density Functionals from Lagrangian densities based on meson exchange and point coupling models. The pairing correlations of nucleons are considered by the relativistic Hartree–Bogoliubov functional based on quasi-particle operators of Bogoliubov transformations. The theoretical calculations of shell closure parameter [Formula: see text](N) and the differential variation of the two-neutron separation energy [Formula: see text](Z, N) provide recognizable signature of shell closure at N = 14 and 20 in case of Si, N = 14, 20 and 28 in S, Ar and Ca isotopes and are consistent with recent experimental investigations of new sub-shell gaps.

scholarly journals DFT calculation, biological activity, anion sensing studies and crystal structure of (E)-4-chloro-2-((pyridin-2-ylimino)-methyl)phenol

2018 ◽  
Vol 83 (6) ◽  
pp. 707-721 ◽  
Author(s):  
Nuray Yildirim ◽  
Neslihan Demir ◽  
Gökhan Alpaslan ◽  
Bahadir Boyacioğlu ◽  
Mustafa Yildiz ◽  
...  
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Anion Recognition ◽  
X Ray ◽  
Yeast Cultures ◽  
Colorimetric Response ◽  
Vis Spectroscopy ◽  
Before And After ◽  
Spectroscopy Studies ◽  
Ct Dna

(E)-4-Chloro-2-[(pyridin-2-ylimino)methyl]phenol was synthesized in the reaction of 2-aminopyridine with 5-chlorosalicylaldehyde. The structure of compound was investigated by FTIR, UV?Vis, 1H-NMR, 13C-NMR and X-ray data. In addition, characterization of the compound was realized using theoretical quantum mechanical calculations and experimental spectroscopic methods. The molecular structure of the compound was confirmed using X-ray single-crystal data, NMR, FTIR and UV?Vis, which were in good agreement with the structure predicted by the theoretical calculations using the density functional theory (DFT). Moreover, the antimicrobial activity of the compound was investigated against some bacteria and yeast cultures by the broth microdilution test. UV?Vis spectroscopy studies of the interactions between the Schiff base and calf thymus DNA (CT-DNA) showed that the compound interacts with CT-DNA via electrostatic binding. The colorimetric response of the compound receptors was investigated before and after the addition of an equivalent amount of each anion to evaluate anion recognition properties.

scholarly journals Detection and identification of Criegee intermediates from the ozonolysis of biogenic and anthropogenic VOCs: comparison between experimental measurements and theoretical calculations

2017 ◽  
Vol 200 ◽  
pp. 559-578 ◽  
Author(s):  
Chiara Giorio ◽  
Steven J. Campbell ◽  
Maurizio Bruschi ◽  
Alexander T. Archibald ◽  
Markus Kalberer
Keyword(s):  
Density Functional ◽  
Spin Trap ◽  
Theoretical Calculations ◽  
Reaction System ◽  
Molecular Structures ◽  
Chemical Mechanism ◽  
Experimental Measurements ◽  
Reaction Products ◽  
Criegee Intermediates ◽  
Wide Range

Ozonolysis of alkenes is a key reaction in the atmosphere, playing an important role in determining the oxidising capacity of the atmosphere and acting as a source of compounds that can contribute to local photochemical “smog”. The reaction products of the initial step of alkene-ozonolysis are Criegee intermediates (CIs), which have for many decades eluded direct experimental detection because of their very short lifetime. We use an innovative experimental technique, stabilisation of CIs with spin traps and analysis with proton transfer reaction mass spectrometry, to measure the gas phase concentration of a series of CIs formed from the ozonolysis of a range of both biogenic and anthropogenic alkenes in flow tube experiments. Density functional theory (DFT) calculations were used to assess the stability of the CI-spin trap adducts and show that the reaction of the investigated CIs with the spin trap occurs very rapidly except for the large β-pinene CI. Our measurement method was used successfully to measure all the expected CIs, emphasising that this new technique is applicable to a wide range of CIs with different molecular structures that were previously unidentified experimentally. In addition, for the first time it was possible to study CIs simultaneously in an even more complex reaction system consisting of more than one olefinic precursor. Comparison between our new experimental measurements, calculations of stability of the CI-spin trap adducts and results from numerical modelling, using the master chemical mechanism (MCM), shows that our new method can be used for the quantification of CIs produced in situ in laboratory experiments.

Theoretical and Experimental Evaluation of the Effect of Fluorinated Substituent on the Topological Landscape and Thermodynamic Stability of Zeolitic Imidazolate Framework Polymorphs

2018 ◽  
Author(s):  
Mihails Arhangelskis ◽  
Athanassis Katsenis ◽  
Novendra Novendra ◽  
Zamirbek Akimbekov ◽  
Dayaker Gandrath ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Mechanochemical Synthesis ◽  
Thermodynamic Stability ◽  
Experimental Evaluation ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Zeolitic Imidazolate Framework ◽  
Functional Theory ◽  
Calorimetric Measurements ◽  
And Calorimetry

By combining mechanochemical synthesis and calorimetry with theoretical calculations, we demonstrate that dispersion-corrected periodic density functional theory (DFT) can accurately survey the topological landscape and predict relative energies of polymorphs for a previously inaccessible fluorine-substituted zeolitic imidazolate framework (ZIF). Experimental screening confirmed two out of three theoretically anticipated polymorphs, and the calorimetric measurements provided an excellent match to theoretically calculated energetic difference between them.<br>

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