Theoretical Study on the Antioxidant Activity of Alkannin and its Derivatives

2011 ◽  
Vol 138-139 ◽  
pp. 1056-1062
Author(s):  
Rui Fa Jin
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Bond Formation ◽  
Hydrogen Atom Abstraction ◽  
Hydrogen Bond Formation ◽  
Electron Transfer Mechanism ◽  
Electronic Delocalization ◽  
Structural And Electronic Properties ◽  
The One ◽  
Electron Donating Groups

The structural and electronic properties of alkannin and its derivatives and their radicals were investigated at density functional level. It turned out that the presence of the dihydroxy functionality increases the radical stability through hydrogen bond formation and favors hydrogen atom abstraction. The introduction of electron-donating groups for the molecules increases the activities of antioxidants. Moreover, alkannin and its derivatives appear to be good candidates for the one-electron-transfer mechanism. Their extended electronic delocalization between adjacent rings determines low ionization potential (IP) values, and it can be further improved by the introduction of the electron-donating groups for the molecules.

Density Functional Theory Calculations of the Radical Scavenging Activity of Alkannin Derivatives

2012 ◽  
Vol 189 ◽  
pp. 225-231
Author(s):  
Xiang Peng Guo ◽  
Rui Fa Jin
Keyword(s):  
Density Functional ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Density Functional Theory Calculations ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Structural And Electronic Properties ◽  
The One

The structural and electronic properties of alkannin and its derivatives and their radicals were investigated at density functional level. It turned out that the presence of the dihydroxy functionality increases the radical stability through hydrogen bond formation. The hydrogen atom transfer for alkannin derivatives is difficult to occur compared with zero compound phenol. However, alkannin derivatives appear to be good candidates for the one-electron-transfer, particularly for alkannin derivatives with –OCOCH=CH(CH3)2 and –OCOCH2CH(CH3)2 groups. It suggests that 1–7 are expected to be the promising candidates for radical scavenging activity compounds because The ionization potential (IP) values of 1–7 are lower than that of the zero compound phenol.

THEORETICAL STUDY OF THE BAND GAP OF SrSe AND SrTe IN GW APPROXIMATION

2011 ◽  
Vol 25 (23) ◽  
pp. 1905-1914
Author(s):  
XIAO LING ZHU ◽  
HONG ZHANG ◽  
XIN LU CHENG
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Theoretical Study ◽  
Generalized Gradient ◽  
Gw Approximation ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties ◽  
Experimental Values ◽  
Interaction Approximation

Using the first-principles pseudopotential method within a generalized gradient approximation of the density functional theory, the structural and electronic properties of SrSe and SrTe have been studied. The calculated lattice parameters are in excellent agreement with experimental values, whereas the error in the minimum gap value is as high as 43.25% in SrSe . To get reliable band gap values of SrSe and SrTe , we employ the GW (G is the Green's function and W is the screened Coulomb interaction) approximation method. The result in GW approximation improves the band gap value of the SrSe greatly and agrees with the value of experimental measurement.

scholarly journals [3 + 2] versus [2 + 2] Addition: A Density Functional Theory Study on the Mechanistic Aspects of Transition Metal-Assisted Formation of 1,2-Dinitrosoalkanes

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Ernest Opoku ◽  
Richard Tia ◽  
Evans Adei
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Basis Set ◽  
Functional Theory ◽  
Activation Barriers ◽  
One Step ◽  
The One ◽  
Electron Donating Groups ◽  
Very High ◽  
Addition Pathway

The pathways for the transition metal-assisted formation of 1,2-dinitrosoalkane complexes of cobalt and its congeners, have been studied using DFT/M06 with theLACVP*basis set. The activation barriers for the one-step [3 + 2] addition pathway for the formation of 1,2-dinitrosoalkanes, proposed by Bergman and Becker, are generally low compared to the activation barriers for the [2 + 2] addition to form an intermediate, which is the first of the two-step pathway proposed by Rappé and Upton, which are very high. The barriers of the rearrangement of the Rappé intermediates to the final products by reductive elimination involving the second metal-nitrogenπ-bond are also very high. The reactions of the Co complexes have lower activation barriers than Rh and Ir complexes. The barriers of the reactions involving olefins with electron-donating groups are generally lower compared to the reactions of the parent (unsubstituted) ethylene while the activation barriers for reactions of olefins with electron-withdrawing groups are generally higher compared to the parent (unsubstituted) ethylene. The one-step [3 + 2] pathway remains the most favoured irrespective of the metal centre or the nature of the olefin. The mechanism of the reaction is therefore settled in favour of the [3 + 2] addition pathway.

scholarly journals Hydrogen transfer reaction: Bond formation and bond cleavage through the eyes of interacting quantum atoms

2019 ◽  
Vol 84 (8) ◽  
pp. 891-900
Author(s):  
Branislav Milovanovic ◽  
Mihajlo Etinski ◽  
Milena Petkovic
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Bond Cleavage ◽  
Bond Formation ◽  
Minimum Energy ◽  
Fragment Analysis ◽  
Interacting Quantum Atoms ◽  
Methoxy Radical ◽  
The One

Hydrogen transfer from hydroquinone to the methoxy radical was studied using the density functional theory. The energy decomposition technique, interacting quantum atoms, was employed for a detailed investigation of the changes that the bonds of interest go through along the minimum energy path in the vicinity of the transition state. The whole system was divided either into two or three fragments. The two-fragment analysis enabled investigation of the bond that is formed or the one that is cleaved by defining the fragments as reactants and as products, respectively. The three-fragment analysis (the fragments being semiquinone, hydrogen atom and methoxy radical) was used for the simultaneous analysis of the two phenomena, bond cleavage and bond formation. Additionally, it enabled the interaction between the particle that donates the hydrogen atom and the one that accepts it to be investigated. This interaction is characterized by attractive non-classical and repulsive classical interactions. It was demonstrated that the transferring hydrogen atom undergoes the most pronounced energy changes and gives the largest contribution to the deformation energy.

Theoretical Study on Structural and Electronic Properties of EDOT:SS Oligomers Complex

2015 ◽  
Vol 1131 ◽  
pp. 123-127
Author(s):  
Ampaiwan Marutaphan ◽  
Panida Lorwongtragool ◽  
Chatchawal Wongchoosuk
Keyword(s):  
Electronic Properties ◽  
Polymer Chain ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Gap ◽  
Average Distance ◽  
Geometry Optimization ◽  
Am1 Method ◽  
Structural And Electronic Properties ◽  
Binding Distance

In this paper, we have reported a theoretical study of the geometric and electronic structures of EDOT:SS oligomers based on semi-empirical Austin model1 (AM1) method and density functional theory at B3LYP/3-21G* level. The effects of polymer chain length of both EDOT and SS on structural and electronic properties including bond length, bond angle, binding distance, charge, the highest occupied orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and energy gap have been studied from the optimized oligomers which were built by varying repeating unit of monomer as n = 1, 2, 3 and 4. The results show that AM1 is not appropriate for geometry optimization of EDOT:SS system comparing to B3LYP/3-21G* level. The binding distance between H atom on EDOT and O atom on SS tends to close together with the average distance of 2.21 Å. The most positive charges locate at sulfur atoms on EDOT and EDOT:SS. The electrical conductivity of EDOT, SS and EDOT:SS increases when polymer chain is extended.

scholarly journals Theoretical Study of Hydrogen Bond Formation in Trimethylene Glycol-Water Complex

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Snehanshu Pal ◽  
T. K. Kundu
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Density Functional ◽  
Bond Formation ◽  
Proton Donor ◽  
Basis Set ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Water Complex ◽  
Trimethylene Glycol

A detailed quantum chemical calculation based study of hydrogen bond formation in trimethylene glycol- (TMG-) water complex has been performed by Hatree-Fock (HF) method, second-order Møller-Plesset perturbation theory (MP2), density functional theory (DFT), and density functional theory with dispersion function (DFT-D) using 6-31++G(d,p) basis set. B3LYP DFT-D, WB97XD, M06, and M06-2X functionals are used to capture highly dispersive hydrogen bond formation. Geometrical parameters, interaction energy, deviation of potential energy curve of hydrogen-bonded O–H from that of free O–H, natural bond orbital (NBO), atom in molecule (AIM), charge transfer, and red shift are investigated. It is observed that hydrogen bond between TMG and water molecule is stronger in case of TMG acting as proton donor compared to that of water acting as proton donor, and dilute TMG solution would inhibit water cluster formation.

Hetero-Diels–Alder reactions involving Fe(CO)3-coordinated dienal and formyltrimethylenemethane catalyzed by Lewis acids — A theoretical study

2009 ◽  
Vol 87 (7) ◽  
pp. 1074-1080 ◽  
Author(s):  
Carles Acosta-Silva ◽  
Òscar González-Blanco ◽  
Vicenç Branchadell
Keyword(s):  
Lewis Acids ◽  
Density Functional ◽  
Theoretical Study ◽  
Decomposition Analysis ◽  
Diels Alder ◽  
The Other ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Trans Conformer ◽  
The One

The hetero-Diels–Alder reactions of butadiene with Fe(CO)3-coordinated formylbutadiene and formyltrimethylenemethane catalyzed by Lewis acids have been theoretically studied through density functional calculations. The results obtained show that, for the reaction with (formylbutadiene)Fe(CO)3, the kinetically most favourable product is the one corresponding to the attack of butadiene on the s-cis conformer of the formylbutadiene fragment when the reaction is catalyzed by BF3, and the one corresponding to the attack on the s-trans conformer when the catalyst is TiCl4. On the other hand, for the reaction with (formyltrimethylenemethane)Fe(CO)3 catalyzed by BF3, the product corresponding to the attack on the s-trans conformer is predicted to be favoured. These results have been interpreted through an energy decomposition analysis of the potential-energy barriers.

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