scholarly journals Theoretical insight to intermolecular hydrogen bond interactions between methyl N-(2-pyridyl) carbamate and acetic acid: substituent effects, cooperativity and energy decomposition analysis

2019 ◽  
Vol 51 (2) ◽  
pp. 224-233
Author(s):  
S. M. Chalanchi ◽  
A. Ebrahimi ◽  
A. Nowroozi
Keyword(s):  
Hydrogen Bond ◽  
Acetic Acid ◽  
Active Sites ◽  
Intermolecular Hydrogen Bond ◽  
Substituent Effects ◽  
Proton Acceptor ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Energy Decomposition

In the present work, the hydrogen bond (HB) interactions between substituted syn and anti rotamers of methyl N-(2-pyridyl) carbamate and acetic acid were investigated using quantum mechanical (QM) calculations. The rotamers have two typical active sites to form hydrogen bonds with acetic acid, such that four stable complexes are found on the potential energy surface. The complexes in which the oxygen atom of carbamate acts as proton acceptor are stabilized by EWSs and are destabilized by EDSs. The trend in the effects of substituents is reversed in the other two complexes, in which the nitrogen atom of ring is involved in the interaction. According to energy data, the substituent effects on the interaction energy can be expressed by Hammett constants. The natural resonance theory (NRT) model was used to investigate the charge distribution on the carbamate group and to discuss the interaction energies. The individual HB energies were estimated to evaluate their cooperative contributions on the interaction energies of the complexes. In addition, the localized molecular orbital energy decomposition analyses (LMO-EDA) demonstrate that the electrostatic interactions are the most important stabilizing components of interactions.

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

scholarly journals A comparative study of energetics of ferrocenium and ferrocene

2018 ◽  
Author(s):  
Shawkat Islam ◽  
Feng Wang
Keyword(s):  
Decomposition Analysis ◽  
Open Shell ◽  
Electrostatic Energy ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Quantum Mechanical ◽  
High Symmetry ◽  
Energy Decomposition ◽  
Molecular Electronic ◽  
Repulsive Energy

Ferrocenium (Fc+) inherits a number of molecular/electronic properties from the neutral counterparts’ ferrocene (Fc) including the high symmetry. Both Fc+ and Fc prefer the eclipsed structure (D5h) over the staggered structure (D5d) by an energy of 0.36 kcal·mol-1. The present study using the recently developed excess orbital energy spectrum (EOES) shows that the open shell Fc+ cation exhibits similar conformer dependent configurational changes to the neutral Fc conformer pair. A further energy decomposition analysis (EDA) discloses that the reasons for the preferred structures are different between Fc+ and Fc. The dominant differentiating energy between the Fc+ conformers is the electrostatic energy (EEstat), whereas in neutral Fc, it is the quantum mechanical Pauli repulsive energy (EPauli). Within the D5h conformer of Fc+, the EOES reveals that the -electrons of Fc+ experience more substantial conformer dependent energy changes than the -electrons (assumed the hole is in a β orbital).

scholarly journals Substituent Effects on the σ···π Interactions Between Au6 Cluster and Substituted Benzene

2021 ◽  
Author(s):  
Qiang Zhao
Keyword(s):  
Quantum Chemical ◽  
Decomposition Analysis ◽  
Substituent Effects ◽  
Interaction Region ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Chemical Methods ◽  
Π Interactions ◽  
Quantum Chemical Methods ◽  
Indicator Analysis

Abstract The σ···π interactions in the Au6···PhX (X=H, CH3, OH, OCH3, NH2, F, Cl, Br, CN, NO2) complexes are studied using quantum chemical methods. The present study focuses on the different effects of electron-donating and -withdrawing substituent. The structure and binding strength of the complexes are examined. The interactions between Au6 cluster and various substituted benzene become strengthened relative to the Au6···benzene complex. The interaction region indicator analysis was performed, and the interaction region and interaction between the substituent and Au6 cluster are discussed. It is found that the substituent effects on the σ···π interactions between Au6 cluster and substituted benzene are different from π···π interactions of benzene dimer. Energy decomposition analysis was carried out to study the nature of σ···π interactions, and the substituent effects are mainly reflected on the electrostatic interaction and dispersion.

scholarly journals Consistent Inclusion of Continuum Solvation in Energy Decomposition Analysis: Theory and Application to Molecular CO2 Reduction Catalysts

2020 ◽  
Author(s):  
Yuezhi Mao ◽  
Matthias Loipersberger ◽  
Kareesa Kron ◽  
Jeffrey Derrick ◽  
Christopher Chang ◽  
...  
Keyword(s):  
Intermolecular Interactions ◽  
Chemical Reactivity ◽  
Decomposition Analysis ◽  
Substituent Effects ◽  
Co2 Reduction ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Coulombic Interaction ◽  
Model Complexes ◽  
Localized Molecular Orbitals

<p>To facilitate computational investigation of intermolecular interactions in the solution phase, we report the development of ALMO-EDA(solv), a scheme that allows the application of continuum solvent models within the framework of energy decomposition analysis (EDA) based on absolutely localized molecular orbitals (ALMOs). In this scheme, all the quantum mechanical states involved in the variational EDA procedure are computed with the presence of solvent environment so that solvation effects are incorporated in the evaluation of all its energy components. After validation on several model complexes, we employ ALMO-EDA(solv) to investigate substituent effects on two classes of complexes that are related to electrochemical CO<sub>2</sub> reduction catalysis. For [FeTPP(CO<sub>2</sub>−κC)]<sup>2−</sup> (TPP = tetraphenylporphyrin), we reveal that two ortho substituents which yield most favorable CO2 binding, −N(CH<sub>3</sub>)<sub>3</sub><sup>+</sup> (TMA) and −OH, stabilize the complex via through-structure and through-space mechanisms, respectively. The Coulombic interaction between the positively charged TMA group and activated CO<sub>2</sub> is found to be largely attenuated by the polar solvent. Furthermore, we also provide computational support for the design strategy of utilizing bulky, flexible ligands to stabilize activated CO<sub>2</sub> via long-range Coulomb interactions, which creates biomimetic solvent-inaccessible “pockets” in that electrostatics is unscreened. For the reactant and product complexes associated with the electron transfer from the <i>p</i>-terphenyl radical anion to CO<sub>2</sub> , we demonstrate that the double terminal substitution of <i>p</i>-terphenyl by electron-withdrawing groups considerably strengthens the binding in the product state while moderately weakens that in the reactant state, which are both dominated by the substituent tuning of the electrostatics component. These applications illustrate that this new extension of ALMO-EDA provides a valuable means to unravel the nature of intermolecular interactions and quantify their impacts on chemical reactivity in solution.<br></p>

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