Symmetry-adapted perturbation theory study for some magnesium complexes

2012 ◽  
Vol 90 (10) ◽  
pp. 819-827
Author(s):  
Mehdi D. Esrafili ◽  
Sirous Yourdkhani
Keyword(s):  
Perturbation Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Water Molecules ◽  
Interaction Energies ◽  
Unique Role ◽  
Functional Methods ◽  
Ligand Interactions ◽  
Good Agreement

A systematic theoretical study on Mg–ligand interactions has been carried out employing both ab initio correlated wave function and density functional methods. The interactions of the Mg(CH3N2)2 moiety with BF, CO, N2, NH3, and H2O ligands have been investigated by performing calculations at the B3LYP, MP2, MP4, and CCSD(T)/6–311++G(3df,3pd) levels of theory. Results indicate that the interaction energies of the Mg(CH3N2)2–L complexes increase in the order NH3 > H2O > BF > CO > N2. Symmetry-adapted perturbation theory (SAPT) analysis has been carried out to understand the nature of the forces involved in the bonding. The SAPT results indicate that the stabilities of the Mg–L interactions are attributed mainly to electrostatic effects, while induction and dispersion forces also play a significant role. The evaluated SAPT interaction energies for the Mg(CH3N2)2–L complexes are generally in good agreement with those obtained using the supermolecule CCSD(T) methods, suggesting that SAPT is a proper method to study the intermolecular interactions in these complexes. The results also suggest an explanation for the unique role of Mg2+ as a carrier of water molecules that mediate enzymatic hydrolysis reactions.

scholarly journals Theoretical Study of the Microhydration of 1-Chloro and 2-Chloro Ethanol as a Clue for Their Relative Propensity Toward Dehalogenation

2018 ◽  
Author(s):  
George Petsis ◽  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Oscar Ventura
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Initial Step ◽  
Water Molecules ◽  
Water Solvent ◽  
Functional Methods ◽  
Electronic Distribution ◽  
Standard Reaction ◽  
Hydrogen Bonded

<p>This work reports a computational analysis of hydrogen bonded clusters of mono-, di-, tri- and tetra hydrates of the chlorohydrins CH<sub>3</sub>CHClOH (1ClEtOH) and CH<sub>2</sub>ClCH<sub>2</sub>OH (2ClEtOH). The goal of the study is to assess the role of the water solvent into the facilitation of the initial step for dehalogenation of these compounds, a process of interest in several contexts. Molecular orbital methods (MP2), density functional methods (B3LYP, M06 and wB97X-D) and composite model chemistries (CBS-QB3, G4) were employed to investigate the structure, electronic distribution and hydrogen-bonded structure of 7 monohydrates, 6 dihydrates, 5 trihydrates and 5 tetrahydrates of both species. Standard reaction enthalpy and standard Gibbs free reaction energy were computed for all aggregates with respect to <b><i>n</i></b> independent water molecules and with respect to the dimer, trimer and tetramer of water, respectively, in order to evaluate stability and hydrogen bonding network. The influence of the water chains on the length and vibrational frequencies, especially of the C-Cl and O-H bonds, was evaluated.</p>

scholarly journals Theoretical Study of the Microhydration of 1-Chloro and 2-Chloro Ethanol as a Clue for Their Relative Propensity Toward Dehalogenation

2018 ◽  
Author(s):  
George Petsis ◽  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Oscar Ventura
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Initial Step ◽  
Water Molecules ◽  
Water Solvent ◽  
Functional Methods ◽  
Electronic Distribution ◽  
Standard Reaction ◽  
Hydrogen Bonded

<p>This work reports a computational analysis of hydrogen bonded clusters of mono-, di-, tri- and tetra hydrates of the chlorohydrins CH<sub>3</sub>CHClOH (1ClEtOH) and CH<sub>2</sub>ClCH<sub>2</sub>OH (2ClEtOH). The goal of the study is to assess the role of the water solvent into the facilitation of the initial step for dehalogenation of these compounds, a process of interest in several contexts. Molecular orbital methods (MP2), density functional methods (B3LYP, M06 and wB97X-D) and composite model chemistries (CBS-QB3, G4) were employed to investigate the structure, electronic distribution and hydrogen-bonded structure of 7 monohydrates, 6 dihydrates, 5 trihydrates and 5 tetrahydrates of both species. Standard reaction enthalpy and standard Gibbs free reaction energy were computed for all aggregates with respect to <b><i>n</i></b> independent water molecules and with respect to the dimer, trimer and tetramer of water, respectively, in order to evaluate stability and hydrogen bonding network. The influence of the water chains on the length and vibrational frequencies, especially of the C-Cl and O-H bonds, was evaluated.</p>

Substituent effect on N–H bond dissociation enthalpies of carbamates: a theoretical study

2015 ◽  
Vol 93 (3) ◽  
pp. 279-288 ◽  
Author(s):  
Rupinder preet Kaur ◽  
Damanjit Kaur ◽  
Ritika Sharma
Keyword(s):  
Substituent Effect ◽  
Density Functional ◽  
Theoretical Study ◽  
Natural Bond Orbital ◽  
Stabilization Energy ◽  
Isodesmic Reactions ◽  
Bond Dissociation ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Orbital Analysis

The present investigation deals with the study of the N–H bond dissociation enthalpies (BDEs) of the Y-substituted (NH2-C(=X)Y-R) and N-substituted ((R)(H)NC(=X)YH) carbamates (X, Y = O, S, Se; R = H, CH3, F, Cl, NH2), which have been evaluated using ab initio and density functional methods. The variations in N−H BDEs of these Y-substituted and N-substituted carbamates as the effect of substituent have been understood in terms of molecule stabilization energy (ME) and radical stabilization energy (RE), which have been calculated using the isodesmic reactions. The natural bond orbital analysis indicated that the electrodelocalization of the lone pairs of heteroatoms in the molecules and radicals affect the ME and RE values depending upon the type and site of substitution (whether N- or Y-). The variations in N−H BDEs depend upon the combined effect of molecule stabilization and radical stabilization by the various substituents.

Microscopic description of the fusion excitation function of 32,36S+90,94,96Zr

2020 ◽  
Vol 29 (07) ◽  
pp. 2050046
Author(s):  
M. Rashdan ◽  
T. A. Abdel-Karim
Keyword(s):  
Excitation Function ◽  
Excited States ◽  
Density Functional ◽  
Neutron Density ◽  
Energy Density Functional ◽  
Hartree Fock ◽  
Density Distributions ◽  
Text Interaction ◽  
Good Agreement

The fusion excitation function for the systems [Formula: see text]S+[Formula: see text]Zr is investigated using a microscopic internuclear potential derived from Skyrme energy density functional. The inputs in this approach are the proton and neutron density distributions of the interacting nuclei, which are derived from Skyrme–Hartree–Fock calculations. The SkM[Formula: see text] interaction is used in the calculation of the nuclear densities as well as the internuclear potential. The coupling to low lying inelastic excited states of target and projectile is considered. The role of the neutron transfer is discussed, where it is considered through the CCFULL model calculation. A good agreement with the experimental data is obtained without adjustable parameters.

A long lasting sunscreen controversy of 4-aminobenzoic acid and 4-dimethylaminobenzaldehyde derivatives resolved by ultrafast spectroscopy combined with density functional theoretical study

2020 ◽  
Vol 22 (15) ◽  
pp. 8006-8020
Author(s):  
Chris Tsz-Leung Chan ◽  
Chensheng Ma ◽  
Ruth Chau-Ting Chan ◽  
Hui-Min Ou ◽  
Han-Xin Xie ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Density Functional ◽  
Ultrafast Spectroscopy ◽  
Theoretical Study ◽  
Pivotal Role ◽  
Aminobenzoic Acid ◽  
Sunscreen Agents

Photoprotection or photodamage: a pivotal role of water in regulating dynamics and molecular mechanism for efficacy of DMABA, DMAAP and PABA sunscreen agents.

First-Principles Study of Structural and Vibrational Properties of α-SiO2 under Pressure

2015 ◽  
Vol 775 ◽  
pp. 191-196
Author(s):  
Xiao Wei Lei ◽  
Yong Song ◽  
Kuo Yang ◽  
Hui Zhao
Keyword(s):  
High Pressure ◽  
Perturbation Theory ◽  
Infrared Spectra ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Vibrational Properties ◽  
Vibrational Modes ◽  
Density Functional Perturbation Theory ◽  
Good Agreement

Using first principles approach, we present the structural, vibrational and dielectric properties of α-SiO2. The calculations have been carried out within the density functional perturbation theory and linear response formalism using the norm-concerving pseudopotentials and a plane wave basis. All the vibrational modes identified are in good agreement with experiment. The calculated infrared spectra are also in good agreement with available experimental results both for the positions and the intensities of the main peaks. We find that the modes Eu7 and A2u4 splits in two respectively at high hydrostaticpressures. Then we calculate the infrared spectra under high pressure of different orientations. The vibrational modes in different phase transitions are reported and discussed respectively.

A theoretical study of weak interactions in phenylenediamine homodimer clusters

2016 ◽  
Vol 18 (42) ◽  
pp. 29249-29257 ◽  
Author(s):  
Chengqian Yuan ◽  
Haiming Wu ◽  
Meiye Jia ◽  
Peifeng Su ◽  
Zhixun Luo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Intermolecular Interactions ◽  
Density Functional ◽  
Theoretical Study ◽  
Natural Bond Orbital ◽  
Weak Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Weak Intermolecular Interactions

Utilizing dispersion-corrected density functional theory (DFT) calculations, we demonstrate the weak intermolecular interactions of phenylenediamine dimer (pdd) clusters, emphasizing the local lowest energy structures and decomposition of interaction energies by natural bond orbital (NBO) and atoms in molecule (AIM) analyses.

THEORETICAL STUDY ON POTENCY AND SELECTIVITY OF NOVEL NONPEPTIDE INHIBITORS OF MATRIX METALLOPROTEINASES MMP-2 AND MMP-9

2009 ◽  
Vol 08 (03) ◽  
pp. 491-506 ◽  
Author(s):  
DAI-LIN LI ◽  
QING-CHUAN ZHENG ◽  
XUE-XUN FANG ◽  
HAI-TAO JI ◽  
JIN-GANG YANG ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Density Functional ◽  
Theoretical Study ◽  
Zinc Binding ◽  
Hydroxyl Group ◽  
Interaction Energies ◽  
Binding Modes ◽  
Functional Theory ◽  
Total Interaction ◽  
Binding Affinity Calculations

Two novel matrix metalloproteinase (MMP) inhibitors, myricetin (m) and kaempferol (k), were found and the inhibitory activity is both in decreased order towards MMP-2 and MMP-9. To understand the mechanism during the processes when inhibitors bind to MMP-2 and MMP-9, molecular modeling, docking, and density functional theory (DFT) calculations were performed. The calculated results indicated that the hydroxyls on benzene ring of the inhibitors control the binding modes between inhibitors and MMPs, thus play an important role on the potency and selectivity. Besides coordinating with the N atoms of three His residues, Zn also interacts with a hydroxyl group of inhibitors by O – Zn distances of 2.66–2.78 Å in all of the docked complexes, so that the hydroxyl acts as a weak zinc binding group (ZBG). The DFT calculated results support the above analysis. The binding affinity calculations between inhibitors and MMPs present the total interaction energies in the m-MMP < k-MMP order and the solvation energy of myricetin is less than that of kaempferol, which reflect the experimental inhibitory activity.

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