scholarly journals Chemical reactivity of quinclorac employing the HSAB local principle - Fukui function

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Luis H. Mendoza Huizar ◽  
Clara H. Rios-Reyes ◽  
Nubia J. Olvera-Maturano ◽  
Juvencio Robles ◽  
Jose A. Rodriguez
Keyword(s):  
Free Radical ◽  
Chemical Reactivity ◽  
Fukui Function ◽  
Nucleophilic Attack ◽  
Electrophilic Attack ◽  
Deprotonated Form ◽  
Reactivity Descriptors ◽  
Local Principle ◽  
Total Energies ◽  
Hydrogen Substitution

AbstractIn the present work we have calculated several DFT reactivity descriptors for quinclorac at the B3LYP/6- 311++G(2d,2p) and MP2/6-311++G(2d,2p) levels of theory in order to analyze its reactivity. Reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, condensed Fukui function and total energies were determined to predict the reactivity of quinclorac. The influence of the solvent was taken into account employing the PCM model. The results indicate that the solvation modifies the values of quinclorac reactivity descriptors. The Fukui function values predict that an electrophilic attack on quinclorac might cause a dechlorination, while a nucleophilic attack might lead to a decarboxylation and a free radical attack would cause a hydrogen substitution on the quinoline ring. Quinclorac in deprotonated form would be susceptible to decarboxylation through an electrophilic attack while nucleophilic and free radical attacks would cause an attack on the hydrogens of the ring.

scholarly journals Analysis of chemical reactivity of aminocyclopyrachlor herbicide through the Fukui function

2015 ◽  
Vol 80 (6) ◽  
pp. 767-777 ◽  
Author(s):  
Luis Mendoza-Huizar
Keyword(s):  
Free Radical ◽  
Ionization Energy ◽  
Chemical Reactivity ◽  
Fukui Function ◽  
Similar Process ◽  
Neutral Form ◽  
Reactivity Descriptors ◽  
Total Energies ◽  
Global And Local ◽  
Global Reactivity Descriptors

We have calculated global and local DFT reactivity descriptors for aminocyclopyrachlor herbicide at the MP2/6-311++G (2d,2p) level of theory in the aqueous phase. Global reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, and total energies were calculated to evaluate the aminocyclopyrachlor reactivity. Local reactivity was evaluated through the Fukui function. Our results suggest that the cationic and dipolar forms of aminocyclopyrachlor exhibit similar global reactivity and they are susceptible to deamination and decarboxylation. Also, the opening of the ring might become factible through free radical attacks to the neutral form, while a similar process is caused by nucleophilic attacks on the anionic form.

scholarly journals A Theoretical Study of Chemical Reactivity of Tartrazine Through DFT Reactivity Descriptors

2017 ◽  
Vol 58 (4) ◽  
Author(s):  
Luis Humberto Mendoza Huizar
Keyword(s):  
Free Radicals ◽  
Theoretical Study ◽  
Chemical Reactivity ◽  
Nucleophilic Attack ◽  
Initial Attack ◽  
Reactivity Descriptors ◽  
Pcm Model ◽  
Total Energies ◽  
Global And Local ◽  
Global Reactivity Descriptors

<p>In this work we have calculated global and local DFT reactivity descriptors for tartrazine at B3LYP/6-311++G (2d,2p) level. Global reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, and total energies were calculated to evaluate the tartrazine reactivity in aqueous and gas conditions. Local reactivity was evaluated through the Fukui function. The influence of the solvent was taken into account with the PCM model. The results indicate that the solvation process modifies the reactivity descriptors values. From our results, it was found that an electrophilic attack allows a direct cleavage of the N=N bond. If a nucleophilic attack is considered as initial attack, it is necessary a second attack by free radicals or electrophiles to cleave the N=N bond. In the case of an initial attack by free radicals, tartrazine requires a subsequent nucleophilic attack to cleave the N=N bond.</p>

scholarly journals A DFT study of the chemical reactivity of cimetidine A, C and D in the gas, H2O, MeOH and EtOH solvents

2017 ◽  
Vol 82 (1) ◽  
pp. 25-37
Author(s):  
Huizar Mendoza ◽  
Guillermo Salgado-Morán ◽  
Wilson Cardona-Villada ◽  
Alison Pacheco ◽  
Daniel Glossman-Mitnik
Keyword(s):  
Free Radical ◽  
Gas Phase ◽  
Aqueous Phase ◽  
Chemical Reactivity ◽  
Fukui Function ◽  
Dft Study ◽  
Reactivity Descriptors ◽  
Global And Local

% Fukui % DFT s KR nema In the present work, we have analyzed the chemical reactivity of cimetidine A, C and D in different solvents; through the evaluation of global and local DFT reactivity descriptors. In the gas, MeOH and EtOH phases, cimetidine A, C and D exhibit energy differences of 3-11 kcal mol-1. But, in the aqueous phase, cimetidine A and D are approximately isoenergetic. The values of the hardness indicate that cimetidine A, C and D are more reactive in the presence of a solvent than in the gas phase. Also, our results suggest that CimC and CimD are better nucleophiles that CimA. The Fukui Function values suggest that the more reactive sites of CimA are not modified in the different solvents. In the case of CimC, the more reactive sites to electrophilic and free radical attacks are located on the thioether sulfur. For CimD, the number and place of the electrophilic and free radical sites are independent of the solvent.

Atom Condensed Fukui Function for Condensed Phases and Biological Systems and Its Application to Enzymatic Fixation of Carbon Dioxide

2019 ◽  
Author(s):  
Javier Oller ◽  
David A. Sáez ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Molecular System ◽  
Chemical Reactivity ◽  
Nucleophilic Attack ◽  
Stable Conformation ◽  
Fukui Functions ◽  
Reactivity Descriptors ◽  
Dynamics Simulations ◽  
Fixation Of Carbon Dioxide

<div><div><div><p>Local reactivity descriptors such as atom condensed Fukui functions are promising computational tools to study chemical reactivity at specific sites within a molecule. Their applications have been mainly focused on isolated molecules in their most stable conformation without considering the effects of the surroundings. Here, we propose to combine QM/MM Born-Oppenheimer molecular dynamics simulations to obtain the microstates (configurations) of a molecular system using different representations of the molecular environment and calculate Boltzmann weighted atom condensed local reac- tivity descriptors based on conceptual DFT. Our approach takes the conformational fluctuations of the molecular system and the polarization of its electron density by the environment into account allowing us to analyze the effect of changes in the molecular environment on reactivity. In this contribution, we apply the method mentioned above to the catalytic fixation of carbon dioxide by crotonyl-CoA carboxylase/reductase and study if the enzyme alters the reactivity of its substrate compared to an aqueous solution. Our main result is that the protein en- vironment activates the substrate by the elimination of solute-solvent hydrogen bonds from aqueous solution in the two elementary steps of the reaction mechanism: the nucleophilic attack of a hydride anion from NADPH on the α, β unsaturated thioester and the electrophilic attack of carbon dioxide on the formed enolate species.</p></div></div></div>

scholarly journals Computational Nutraceutics: Chemical Reactivity Properties of the Flavonoid Naringin by Means of Conceptual DFT

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Jorge Ignacio Martínez-Araya ◽  
Guillermo Salgado-Morán ◽  
Daniel Glossman-Mitnik
Keyword(s):  
Active Sites ◽  
Chemical Reactivity ◽  
Fukui Function ◽  
Conceptual Dft ◽  
Density Functionals ◽  
Structure And Properties ◽  
Dual Descriptor ◽  
Reactivity Descriptors ◽  
Koopmans Theorem ◽  
Chemical Reactivity Descriptors

The M06 family of density functionals has been assessed for the calculation of the molecular structure and properties of the Naringin molecule. The chemical reactivity descriptors have been calculated through Conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices and the dual descriptorf(2)(r). A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans' theorem approximation has been performed in order to check for the validity of the last procedure.

Global and Local Reactivity Descriptors Based on Quadratic and Linear Energy Models for α,β-Unsaturated Organic Compounds

2018 ◽  
Author(s):  
Javier Oller ◽  
Patricia Perez ◽  
Paul W. Ayers ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Fukui Function ◽  
Nucleophilic Attack ◽  
Quadratic Model ◽  
Molecular Response ◽  
Local Descriptors ◽  
Unsaturated Ketones ◽  
Global And Local

<div>Global and local descriptors of chemical reactivity can be derived from conceptual density functional theory. Their explicit form, however, depends on how the energy is defined as a function of the number of electrons. Within the existing interpolation models, here, the quadratic and the linear energy model were used to derive global descriptors as the electrophilicity and nucleophilicity (defined as the negative of the ionization potential) and local descriptors employing either the corresponding condensed fukui function in the linear model or the local response of the global descriptor in the quadratic model. The ability of these descriptors to predict the reactivity of molecules with more than one reactive site was first studied on a set of α ,β -unsaturated ketones, where experimental rate constants for the nucleophilic attack is known. With the validated descriptors the reactivity of α ,β -unsaturated carboxylic compounds with different heteroatoms as α ,β -unsaturated thioesters, esters and amides as alternative substrates for the enzymatic CO<sub>2</sub> fixation studied experimentally by Erb <i>et al.</i> was addressed. The carbon dioxide fixation involves the reduction of the neutral α ,β -unsaturated carboxylic compounds by a nucleophilic attack of a hydride anion from NADPH and the following electrophilic attack by carbon dioxide. It was found that condensed values of the linear fukui function within the fragment of molecular response approximation describe best the reactivity of α ,β -unsaturated ketones. For the two relevant processes involved in CO<sub>2</sub> fixation the amides present the largest reactivity in vacuum and in aqueous solution compared to the esters and thioesters and may, therefore, serve as alternative sustrates of carboxylases.</div>

Global and Local Reactivity Descriptors Based on Quadratic and Linear Energy Models for α,β-Unsaturated Organic Compounds

2018 ◽  
Author(s):  
Javier Oller ◽  
Patricia Perez ◽  
Paul W. Ayers ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Fukui Function ◽  
Nucleophilic Attack ◽  
Quadratic Model ◽  
Molecular Response ◽  
Local Descriptors ◽  
Unsaturated Ketones ◽  
Global And Local

<div>Global and local descriptors of chemical reactivity can be derived from conceptual density functional theory. Their explicit form, however, depends on how the energy is defined as a function of the number of electrons. Within the existing interpolation models, here, the quadratic and the linear energy model were used to derive global descriptors as the electrophilicity and nucleophilicity (defined as the negative of the ionization potential) and local descriptors employing either the corresponding condensed fukui function in the linear model or the local response of the global descriptor in the quadratic model. The ability of these descriptors to predict the reactivity of molecules with more than one reactive site was first studied on a set of α ,β -unsaturated ketones, where experimental rate constants for the nucleophilic attack is known. With the validated descriptors the reactivity of α ,β -unsaturated carboxylic compounds with different heteroatoms as α ,β -unsaturated thioesters, esters and amides as alternative substrates for the enzymatic CO<sub>2</sub> fixation studied experimentally by Erb <i>et al.</i> was addressed. The carbon dioxide fixation involves the reduction of the neutral α ,β -unsaturated carboxylic compounds by a nucleophilic attack of a hydride anion from NADPH and the following electrophilic attack by carbon dioxide. It was found that condensed values of the linear fukui function within the fragment of molecular response approximation describe best the reactivity of α ,β -unsaturated ketones. For the two relevant processes involved in CO<sub>2</sub> fixation the amides present the largest reactivity in vacuum and in aqueous solution compared to the esters and thioesters and may, therefore, serve as alternative sustrates of carboxylases.</div>

Atom Condensed Fukui Function for Condensed Phases and Biological Systems and Its Application to Enzymatic Fixation of Carbon Dioxide

2019 ◽  
Author(s):  
Javier Oller ◽  
David A. Sáez ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Molecular System ◽  
Chemical Reactivity ◽  
Nucleophilic Attack ◽  
Stable Conformation ◽  
Fukui Functions ◽  
Reactivity Descriptors ◽  
Dynamics Simulations ◽  
Fixation Of Carbon Dioxide

<div><div><div><p>Local reactivity descriptors such as atom condensed Fukui functions are promising computational tools to study chemical reactivity at specific sites within a molecule. Their applications have been mainly focused on isolated molecules in their most stable conformation without considering the effects of the surroundings. Here, we propose to combine QM/MM Born-Oppenheimer molecular dynamics simulations to obtain the microstates (configurations) of a molecular system using different representations of the molecular environment and calculate Boltzmann weighted atom condensed local reac- tivity descriptors based on conceptual DFT. Our approach takes the conformational fluctuations of the molecular system and the polarization of its electron density by the environment into account allowing us to analyze the effect of macroscopic variables like temperature or changes in the molecular environment on reactivity. In this contribu- tion, we apply the method mentioned above to the catalytic fixation of carbon dioxide by crotonyl-CoA carboxylase/reductase and study if the enzyme alters the reactivity of its substrate compared to an aqueous solution. Our main result is that the protein en- vironment activates the substrate by the elimination of solute-solvent hydrogen bonds from aqueous solution in the two elementary steps of the reaction mechanism: the nucleophilic attack of a hydride anion from NADPH on the α, β unsaturated thioester and the electrophilic attack of carbon dioxide on the formed enolate species.</p></div></div></div>

scholarly journals Chemical Reactivity of Isoproturon, Diuron, Linuron, and Chlorotoluron Herbicides in Aqueous Phase: A Theoretical Quantum Study Employing Global and Local Reactivity Descriptors

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Luis Humberto Mendoza-Huizar
Keyword(s):  
Free Radical ◽  
Aqueous Phase ◽  
Chemical Reactivity ◽  
The Other ◽  
Reactivity Descriptors ◽  
Local Reactivity ◽  
Other Hand ◽  
Aqueous Conditions ◽  
Global And Local ◽  
Local Reactivity Descriptors

We have calculated global and local DFT reactivity descriptors for isoproturon, diuron, linuron, and chlorotoluron herbicides at the MP2/6-311++G(2d,2p) level of theory. The results suggest that, in aqueous conditions, chlorotoluron, linuron, and diuron herbicides may be degraded by elimination of urea moiety through electrophilic attacks. On the other hand, electrophilic, nucleophilic, and free radical attacks on isoproturon may cause the elimination of isopropyl fragment.

scholarly journals Atom Condensed Fukui Function for Condensed Phases and Biological Systems and Its Application to Enzymatic Fixation of Carbon Dioxide

2019 ◽  
Author(s):  
Javier Oller ◽  
David A. Sáez ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Molecular System ◽  
Chemical Reactivity ◽  
Nucleophilic Attack ◽  
Stable Conformation ◽  
Fukui Functions ◽  
Reactivity Descriptors ◽  
Dynamics Simulations ◽  
Fixation Of Carbon Dioxide

<div><div><div><p>Local reactivity descriptors such as atom condensed Fukui functions are promising computational tools to study chemical reactivity at specific sites within a molecule. Their applications have been mainly focused on isolated molecules in their most stable conformation without considering the effects of the surroundings. Here, we propose to combine QM/MM Born-Oppenheimer molecular dynamics simulations to obtain the microstates (configurations) of a molecular system using different representations of the molecular environment and calculate Boltzmann weighted atom condensed local reac- tivity descriptors based on conceptual DFT. Our approach takes the conformational fluctuations of the molecular system and the polarization of its electron density by the environment into account allowing us to analyze the effect of changes in the molecular environment on reactivity. In this contribution, we apply the method mentioned above to the catalytic fixation of carbon dioxide by crotonyl-CoA carboxylase/reductase and study if the enzyme alters the reactivity of its substrate compared to an aqueous solution. Our main result is that the protein en- vironment activates the substrate by the elimination of solute-solvent hydrogen bonds from aqueous solution in the two elementary steps of the reaction mechanism: the nucleophilic attack of a hydride anion from NADPH on the α, β unsaturated thioester and the electrophilic attack of carbon dioxide on the formed enolate species.</p></div></div></div>

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