Computational Strategies to Probe CH Activation in Dioxo-Dicopper Complexes

2018 ◽  
Author(s):  
Zhenzhuo Lan ◽  
Shaama Mallikarjun Sharada
Keyword(s):  
Transition State ◽  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Decomposition Analysis ◽  
Energy Decomposition Analysis ◽  
Ch Activation ◽  
Transition State Stabilization ◽  
Highly Sensitive ◽  
One Step ◽  
The One

Our work addresses the long-standing question of the preferred mechanism of CH activation in dioxodicopper complexes, with implications for [Cu2O2]2+ -containing enzymes as well as homogeneous and heterogeneous catalysts, which are capable of performing selective oxidation. Using density functional theory (DFT), we show that the two proposed mechanisms, one-step oxo-insertion and two-step radical recombination, have very distinct and measurable responses to changes in the electrophilicity of N-donors in the catalyst. Using energy decomposition analysis, we calculate the electronic interactions that contribute to transition state stabilization, and the effect of N-donors on these interactions. The analysis shows that oxo-insertion, by virtue of possessing a late and charged transition state, is highly sensitive to N-donor electrophilicity and barriers decrease with more electron-withdrawing N-donors. On the other hand, the radical pathway possesses an early transition state and is therefore relatively insensitive to N-donor variations. One possible strategy, going forward, is the design and execution of complementary experiments to deduce the mechanism based on the presence or absence of N-donor dependence. We adopt an alternative approach where DFT results are contrasted with prior experiments via Hammett relationships. The remarkable agreement between experimental and calculated trends for oxo-insertion with imidazole N-donor catalysts presents compelling evidence in favor of the one-step pathway for CH activation.

Computational Strategies to Probe CH Activation in Dioxo-Dicopper Complexes

2018 ◽  
Author(s):  
Zhenzhuo Lan ◽  
Shaama Mallikarjun Sharada
Keyword(s):  
Transition State ◽  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Decomposition Analysis ◽  
Energy Decomposition Analysis ◽  
Ch Activation ◽  
Transition State Stabilization ◽  
Highly Sensitive ◽  
One Step ◽  
The One

Our work addresses the long-standing question of the preferred mechanism of CH activation in dioxodicopper complexes, with implications for [Cu2O2]2+ -containing enzymes as well as homogeneous and heterogeneous catalysts, which are capable of performing selective oxidation. Using density functional theory (DFT), we show that the two proposed mechanisms, one-step oxo-insertion and two-step radical recombination, have very distinct and measurable responses to changes in the electrophilicity of N-donors in the catalyst. Using energy decomposition analysis, we calculate the electronic interactions that contribute to transition state stabilization, and the effect of N-donors on these interactions. The analysis shows that oxo-insertion, by virtue of possessing a late and charged transition state, is highly sensitive to N-donor electrophilicity and barriers decrease with more electron-withdrawing N-donors. On the other hand, the radical pathway possesses an early transition state and is therefore relatively insensitive to N-donor variations. One possible strategy, going forward, is the design and execution of complementary experiments to deduce the mechanism based on the presence or absence of N-donor dependence. We adopt an alternative approach where DFT results are contrasted with prior experiments via Hammett relationships. The remarkable agreement between experimental and calculated trends for oxo-insertion with imidazole N-donor catalysts presents compelling evidence in favor of the one-step pathway for CH activation.

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.

Vapour Pressure Isotope Effect on Evaporation from Pure Organic Phases - a PIMD Approach

2020 ◽  
Author(s):  
Luis Vasquez ◽  
Agnieszka Dybala-Defratyka
Keyword(s):  
Path Integral ◽  
Vapour Pressure ◽  
Density Functional ◽  
Isotope Effects ◽  
Tight Binding ◽  
Decomposition Analysis ◽  
Energy Decomposition Analysis ◽  
Special Importance ◽  
Non Covalent Interactions ◽  
Covalent Interactions

<p></p><p>Very often in order to understand physical and chemical processes taking place among several phases fractionation of naturally abundant isotopes is monitored. Its measurement can be accompanied by theoretical determination to provide a more insightful interpretation of observed phenomena. Predictions are challenging due to the complexity of the effects involved in fractionation such as solvent effects and non-covalent interactions governing the behavior of the system which results in the necessity of using large models of those systems. This is sometimes a bottleneck and limits the theoretical description to only a few methods.<br> In this work vapour pressure isotope effects on evaporation from various organic solvents (ethanol, bromobenzene, dibromomethane, and trichloromethane) in the pure phase are estimated by combining force field or self-consistent charge density-functional tight-binding (SCC-DFTB) atomistic simulations with path integral principle. Furthermore, the recently developed Suzuki-Chin path integral is tested. In general, isotope effects are predicted qualitatively for most of the cases, however, the distinction between position-specific isotope effects observed for ethanol was only reproduced by SCC-DFTB, which indicates the importance of using non-harmonic bond approximations.<br> Energy decomposition analysis performed using the symmetry-adapted perturbation theory (SAPT) revealed sometimes quite substantial differences in interaction energy depending on whether the studied system was treated classically or quantum mechanically. Those observed differences might be the source of different magnitudes of isotope effects predicted using these two different levels of theory which is of special importance for the systems governed by non-covalent interactions.</p><br><p></p>

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 Nanotechnology-based approaches for targeting and delivery of drugs via Hexakis (m-PE) macrocycles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Samaneh Pasban ◽  
Heidar Raissi
Keyword(s):  
Drug Delivery ◽  
Density Functional ◽  
Water Solution ◽  
Decomposition Analysis ◽  
Binding Energies ◽  
Energy Decomposition Analysis ◽  
Partial Density ◽  
High Propensity ◽  
The Stability ◽  
Novel Applications

AbstractHexakis (m-phenylene ethynylene) (m-PE) macrocycles, with aromatic backbones and multiple hydrogen-bonding side chains, had a very high propensity to self-assemble via H-bond and π–π stacking interactions to form nanotubular structures with defined inner pores. Such stacking of rigid macrocycles is leading to novel applications that enable the researchers to explored mass transport in the sub-nanometer scale. Herein, we performed density functional theory (DFT) calculations to examine the drug delivery performance of the hexakis dimer as a novel carrier for doxorubicin (DOX) agent in the chloroform and water solvents. Based on the DFT results, it is found that the adsorption of DOX on the carrier surface is typically physisorption with the adsorption strength values of − 115.14 and − 83.37 kJ/mol in outside and inside complexes, respectively, and so that the essence of the drug remains intact. The negative values of the binding energies for all complexes indicate the stability of the drug molecule inside and outside the carrier's cavities. The energy decomposition analysis (EDA) has also been performed and shown that the dispersion interaction has an essential role in stabilizing the drug-hexakis dimer complexes. To further explore the electronic properties of dox, the partial density of states (PDOS and TDOS) are calculated. The atom in molecules (AIM) and Becke surface (BS) methods are also analyzed to provide an inside view of the nature and strength of the H-bonding interactions in complexes. The obtained results indicate that in all studied complexes, H-bond formation is the driving force in the stabilization of these structures, and also chloroform solvent is more favorable than the water solution. Overall, our findings offer insightful information on the efficient utilization of hexakis dimer as drug delivery systems to deliver anti-cancer drugs.

scholarly journals Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

2015 ◽  
Vol 11 ◽  
pp. 2727-2736 ◽  
Author(s):  
Diego M Andrada ◽  
Nicole Holzmann ◽  
Thomas Hamadi ◽  
Gernot Frenking
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Heterocyclic Carbenes ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Direct Estimate ◽  
Functional Theory ◽  
Bonding Analysis

Fifteen cyclic and acylic carbenes have been calculated with density functional theory at the BP86/def2-TZVPP level. The strength of the internal X→p(π) π-donation of heteroatoms and carbon which are bonded to the C(II) atom is estimated with the help of NBO calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alkyl(amino)carbene (cAAC), mesoionic carbenes and ylide-stabilized carbenes. The bonding analysis suggests that the carbene centre in cAAC and in diamidocarbene have the weakest X→p(π) π-donation while mesoionic carbenes possess the strongest π-donation.

scholarly journals Correction: New light on an old debate: does the RCN–PtCl2 bond include any back-donation? RCN ← PtCl2 backbonding vs. the IR νCN blue-shift dichotomy in organonitriles–platinum(ii) complexes. A thorough density functional theory – energy decomposition analysis study

2019 ◽  
Vol 48 (35) ◽  
pp. 13491-13492 ◽  
Author(s):  
Girolamo Casella ◽  
Célia Fonseca Guerra ◽  
Silvia Carlotto ◽  
Paolo Sgarbossa ◽  
Roberta Bertani ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Blue Shift ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Functional Theory ◽  
Dalton Trans ◽  
Analysis Study ◽  
Back Donation

Correction for ‘New light on an old debate: does the RCN–PtCl2 bond include any back-donation? RCN ← PtCl2 backbonding vs. the IR νCN blue-shift dichotomy in organonitriles–platinum(ii) complexes. A thorough density functional theory – energy decomposition analysis study’ by Girolamo Casella et al., Dalton Trans., 2019, DOI: 10.1039/c9dt02440a.

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