Mechanisms of generation of the rotational strengths in TEM-1 β-lactamase. Part II: theoretical study of the effects of the electrostatic interactions in the near-UV

2004 ◽  
Vol 400 (4-6) ◽  
pp. 524-530 ◽  
Author(s):  
Christo Christov ◽  
Alexander Kantardjiev ◽  
Tatyana Karabencheva ◽  
Frederik Tielens
Keyword(s):  
Electrostatic Interactions ◽  
Theoretical Study ◽  
Rotational Strengths

Ab initio and DFT studies on the structures, binding energies and nature of bonds in X2Y3 metal clusters (X+ = Li+, Na+ and K+; ${\rm Y}_{3}^{2-} = {\rm Zn}_{3}^{2-}, {\rm Cd}_{3}^{2-}$ and ${\rm Hg}_{3}^{2-}$)

2015 ◽  
Vol 14 (06) ◽  
pp. 1550043 ◽  
Author(s):  
Masoud Hatami ◽  
Mehdi Bayat ◽  
Hassan Keypour ◽  
Sadegh Salehzadeh
Keyword(s):  
Ab Initio ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Theoretical Study ◽  
Population Analysis ◽  
Binding Energies ◽  
Energy Decomposition ◽  
Zinc Cadmium ◽  
Covalent Contribution ◽  
Wiberg Bond Indices

A comprehensive theoretical study on the structure and stability of linear and triangular isomers of anionic clusters of zinc, cadmium and mercury [Formula: see text] and their binding with one and two alkali metal cations ( X + = Li +, Na +, K +) has been investigated at the density functional (BP86 and B3LYP) and ab initio (MP2, MP4 and coupled cluster single and double (CCSD)) methods. The results showed that in all cases, the triangular geometry with D3h symmetry is more stable than linear one. The calculated values of interaction energies (IE) between [Formula: see text] anions and two X+ cations, Wiberg bond indices (WBI) and the electron densities at bond critical points (BCP), ρ(BCP), for Y–X bonds show that among all complexes investigated here at all levels of theory Zn 3 Li 2 and Hg 3 K 2 have the largest and the smallest values of IE, WBI and ρ(BCP), respectively. The natural charges of the atoms and WBI involved in the bonding as well as the global value of the charge transfer ΔQ from [Formula: see text] to X+ cation in X2Y3 clusters, evaluated through natural population analysis, confirmed that covalent contribution in Y–X bond formation increases from K + to Li +. Also the energy decomposition analyses (EDA) were used to detect the nature of interaction in the complexes. The results confirmed that the contribution of electrostatic interactions in present complexes is almost more than 70%.

Tuning the optoelectronic properties of oligothiophenes for solar cell applications by varying the number of cyano and fluoro substituents for solar cell applications: A theoretical study

2019 ◽  
Vol 44 (3-4) ◽  
pp. 235-242 ◽  
Author(s):  
Francisco C. Franco
Keyword(s):  
Solar Cell ◽  
Molecular Orbital ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Theoretical Study ◽  
Optoelectronic Properties ◽  
Functional Theory ◽  
Orbital Energies ◽  
Lowest Unoccupied Molecular Orbital ◽  
Improved Characteristics

Chemical modifications through substitution are observed to be effective in controlling the optoelectronic properties of various polymers for different applications. In this study, density functional theory–based calculations are employed to investigate the optoelectronic properties of several oligothiophenes based on poly(3-hexylthiophene-2,5-diyl) by varying the number of fluoro and cyano substituents attached. The resulting structures of the polymer derivatives are affected by the electrostatic interactions between the cyano or fluoro groups and the adjacent thiophene unit. Of the two, cyano substitution results in much lower frontier orbital energies for the same number of substituents. It was observed that a decrease in the highest occupied molecule orbital and lowest unoccupied molecular orbital energies correlates very strongly with the number of cyano and fluoro substituents. The effect of the cyano and fluoro groups on the frontier orbitals is also demonstrated and observed to correlate strongly with a lowering of the highest occupied molecule orbital and lowest unoccupied molecular orbital energies as the number of substituents is varied. The predicted solar cell characteristics reveal that most cyano and fluoro derivatives will have improved characteristics compared to unsubstituted poly(3-hexylthiophene-2,5-diyl). This theoretical study shows that by varying the number of electron-withdrawing substituents, the optoelectronic properties may be tuned for solar cell applications.

Experimental and theoretical study of nanoparticle deposition using electrostatic interactions

2000 ◽  
Vol 31 ◽  
pp. 1009-1010
Author(s):  
T. Krinke ◽  
H. Fissan ◽  
K. Deppert ◽  
M.H. Magnusson ◽  
L. Samuelson
Keyword(s):  
Electrostatic Interactions ◽  
Theoretical Study ◽  
Nanoparticle Deposition

scholarly journals Experimental and Theoretical Insights on Methylene Blue Removal from Wastewater Using an Adsorbent Obtained from the Residues of the Orange Industry

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4555
Author(s):  
Stephanie Giraldo ◽  
Irma Robles ◽  
Luis A. Godínez ◽  
Nancy Acelas ◽  
Elizabeth Flórez
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Theoretical Study ◽  
Orange Peel ◽  
Good Alternative ◽  
Functional Theory ◽  
Adsorption Mechanisms ◽  
Mb Adsorption

Chemical and thermochemical transformations were performed on orange peel to obtain materials that were characterized and further tested to explore their potential as adsorbents for the removal of methylene blue (MB) from aqueous solutions. The results show the high potential of some of these materials for MB adsorption not only due to the surface area of the resulting substrate but also to the chemistry of the corresponding surface functional groups. Fitting of the kinetic as well as the equilibrium experimental data to different models suggests that a variety of interactions are involved in MB adsorption. The overall capacities for these substrates (larger than 192.31 mg g−1) were found to compare well with those reported for activated carbon and other adsorbents of agro-industrial origin. According to these results and complementary with theoretical study using Density Functional Theory (DFT) approximations, it was found that the most important adsorption mechanisms of MB correspond to: (i) electrostatic interactions, (ii) H-bonding, and (iii) π (MB)–π (biochar) interactions. In view of these findings, it can be concluded that adsorbent materials obtained from orange peel, constitute a good alternative for the removal of MB dye from aqueous solutions.

Template mediated crystal engineering

1994 ◽  
Vol 52 ◽  
pp. 480-481
Author(s):  
Brigid R. Heywood ◽  
S. Champ
Keyword(s):  
Crystal Engineering ◽  
Electrostatic Interactions ◽  
Alkyl Chain ◽  
Crystallographic Axis ◽  
Two Dimensional ◽  
Engineering Process ◽  
Solution Interface ◽  
Extensive Program ◽  
Geometric Homology ◽  
Long Alkyl Chain

Recent work on the crystallisation of inorganic crystals under compressed monomolecular surfactant films has shown that two dimensional templates can be used to promote the oriented nucleation of solids. When a suitable long alkyl chain surfactant is cast on the crystallisation media a monodispersied population of crystals forms exclusively at the monolayer/solution interface. Each crystal is aligned with a specific crystallographic axis perpendicular to the plane of the monolayer suggesting that nucleation is facilitated by recognition events between the nascent inorganic solid and the organic template.For example, monolayers of the long alkyl chain surfactant, stearic acid will promote the oriented nucleation of the calcium carbonate polymorph, calcite, on the (100) face, whereas compressed monolayers of n-eicosyl sulphate will induce calcite nucleation on the (001) face, (Figure 1 & 2). An extensive program of research has confirmed the general principle that molecular recognition events at the interface (including electrostatic interactions, geometric homology, stereochemical complementarity) can be used to promote the crystal engineering process.

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