Eduardo Chamorro | Universidad Andrés Bello (original) (raw)
Papers by Eduardo Chamorro
ChemPhotoChem, Jan 20, 2023
Theoretical evidence concerning the multiradicaloid character in benzene photochemistry is report... more Theoretical evidence concerning the multiradicaloid character in benzene photochemistry is reported based on a topological analysis of the correlated electron localization function. The bonding implications of triradicaloid conditions in both ground and excited states of S1 benzene are discussed within the bonding evolution theory. Our results suggest that triradicaloid/biradicaloid structures form due to the non‐bonding density concentration over C atoms, causing the distorted geometry near the S1/S0 crossing. Biradicaloid centers formed in the excited state trigger new CC bonds, leading to a variety of photoproducts.
Toxicology in Vitro, 2022
A 3D-QSAR study based on DFT descriptors and machine learning calculations is presented in this w... more A 3D-QSAR study based on DFT descriptors and machine learning calculations is presented in this work. Our goal has been to build predictive models for classifying the carcinogenic activity of a set of aromatic amines (AA) and nitroaromatic (NA) compounds. As the main result, we stress that calculations must consider both the activated metabolites (derived from AA and NA species) and the water solvent to obtain reliable predictive classification models. We have obtained eight decision tree models that presented an accuracy of over 90% by using either Gázquez-Vela chemical potential (μ+) or the chemical hardness (η).
RSC Advances, 2020
A new series of heteroaryl nitrones were synthesized and evaluated as free radical traps due to t... more A new series of heteroaryl nitrones were synthesized and evaluated as free radical traps due to the results showed in our previous report.
Carbon, Jul 1, 2017
Understanding the kinetics of carbon-hydrogen reaction: Insights from reaction mechanisms on zigz... more Understanding the kinetics of carbon-hydrogen reaction: Insights from reaction mechanisms on zigzag edges for homogeneous and heterogeneous formation of methane, Carbon (2017),
Carbon, 2016
Methane is the main product in the reaction between molecular hydrogen and carbonaceous materials... more Methane is the main product in the reaction between molecular hydrogen and carbonaceous materials such as char, graphene and graphite. Although, pathways for the formation of methane in the carbonhydrogen reaction have been proposed attending to experimental and molecular modeling results, there is not compelling evidence of the elementary character of the steps in such pathways. In this work we propose possible mechanisms with details at molecular level that account for the formation of methane at the zigzag edge through elementary steps using molecular modeling within the framework of the density functional theory. These mechanisms involve saturation of reactive sites, hydrogenation of the edge, ring opening and desorption of methyl groups or direct desorption of methane. Thermodynamic and kinetic details for all steps were explored over temperature and pressure ranges going from 298 K to 1500 K (at 0.1 MPa) and 0.1 MPae10 MPa (at 1100 K), respectively. The proposed mechanisms show a remarkable qualitative agreement between predicted behavior of overall state functions (DH tot , DS tot , and DG tot) and the equilibrium constant for the formation of methane and the observed experimental behavior of these thermodynamic quantities for standard formation of methane from 298 K to 1500 K.
The Journal of Physical Chemistry A, 2021
1,3-Cyclohexadiene ring opening has been studied within the bonding evolution theory (BET) framew... more 1,3-Cyclohexadiene ring opening has been studied within the bonding evolution theory (BET) framework. We have focused on describing for the first time the electron pair rearrangements leading to the cis-1,3,5-hexatriene (HT) product from CHD. The nature of bonding in this process begins with the weakening of the double bonds in the Franck-Condon region. Along the 11B surface, the C-C sigma bond weakens. Meanwhile, its density redistributes toward the whole CHD ring, mainly over double bonds. Breaking of this bond occurs on the 21A surface due to the symmetrical splitting of pair density from this region. This density redistributes toward the reaction center once the pericyclic minimum is reached. The formation of the double bonds that characterize HT occurs gradually in the ground state. However, near the 21A/11A intersection, these bonds are partially established.
Theoretical Chemistry Accounts, 2016
The [3+2] Cycloaddition (32CA) reaction of nitrile ylide (NY) 10 with electron-deficient ethylene... more The [3+2] Cycloaddition (32CA) reaction of nitrile ylide (NY) 10 with electron-deficient ethylene 11 has been studied within the molecular electron density theory through DFT calculations at the MPWB1K/6-31G(d) computational level. A structural analysis of NY 10 indicates that this three-atom component has a carbenoid structure, allowing its participation in carbenoid-type (cb-type) 32CA reactions. This 32CA reaction takes place through a one-step mechanism with very low activation energy, 2.3 kcal mol−1. In gas phase, this 32CA reaction is not stereoselective and has low regioselectivity. Inclusion of solvent effects does not modify the activation energy, but increases the meta regioselectivity in clear agreement with the experimental outcomes. Electron localisation function topological analysis for the formation of the two C–C single bonds along the four competitive channels associated with this 32CA reaction makes it possible to characterise two dissimilar mechanisms. Along the more favourable meta regioisomeric channels, the 32CA reaction takes place through a two-stage one-step mechanism, while along the ortho regioisomeric channels it takes place via a synchronous C–C bond formation process.
Physical Chemistry Chemical Physics
A fundamental correlation exists between the barrier of reactive processes and the structural sta... more A fundamental correlation exists between the barrier of reactive processes and the structural stability concept, which can be cast into a model for predicting energy threshold in reactions involving organic and organometallic compounds.
Theoretical Chemistry Accounts, 2020
This paper results from a round table discussion at the CCTC2018 Conference in Changsha City, Hun... more This paper results from a round table discussion at the CCTC2018 Conference in Changsha City, Hunan, China, in December 2018. It presents a report on the status, prospects, and issues of conceptual density functional theory (CDFT). After a short exposition on the history of CDFT, its fundamentals, philosophy, and successes are highlighted. Then ten issues for reflection on the future of conceptual DFT are formulated and discussed, ending with one or more summarizing statements on the present status of various concepts/principles/practices and proposed directions for future research. The issues include the further analysis of the energy functional, E [ N , v ], extended to include effects of temperature, solvent, and mechanical forces, basic requirements for physically acceptable response functions as reactivity descriptors, the use of the grand canonical ensemble, the relevance of CDFT for chemical kinetics and thermodynamics, the domain of validity of CDFT-based principles, the combination of CDFT with reaction path calculations, information-theoretic descriptors, and the treatment of excited states and time dependence. The final issue advocates the transition of CDFT from an interpretative to a predictive mode; we believe this is of utmost importance for promoting CDFT as a viable alternative to wave function-based methods for the practicing chemist, a separate issue treated in the final section.
The Journal of organic chemistry, Jan 27, 2018
The reaction electronic flux (REF) offers a powerful tool in the analysis of reaction mechanisms.... more The reaction electronic flux (REF) offers a powerful tool in the analysis of reaction mechanisms. Noteworthy, the relation between aromaticity and REF can eventually reveal subtle electronic events associated to reactivity in aromatic systems. In this work, this relation was studied for the Triplet Zimmerman Di-π-Methane rearrangement. The aromaticity loss and gain taking place during the reaction is well acquainted by the REF, thus shedding light on the electronic nature of reactions involving dibenzobarrelenes.
RSC Adv., 2015
The gas-phase thermal decomposition of 1-chlorohexane is rationalized in terms of a two stage one... more The gas-phase thermal decomposition of 1-chlorohexane is rationalized in terms of a two stage one step reaction mechanism.
New Journal of Chemistry
There is an underlying intimate relationship between Thom's catastrophe theory and the electr... more There is an underlying intimate relationship between Thom's catastrophe theory and the electron-pair density evidenced along a reaction pathway.
RSC Advances, 2021
In celebration of the excellence and breadth of Latin American research achievements across the c... more In celebration of the excellence and breadth of Latin American research achievements across the chemical sciences, we are delighted to present an introduction to the themed collection, Celebrating Latin American talent in chemistry.
The Journal of Physical Chemistry A, 2002
The Claisen rearrangement of allyl phenyl ether, allyl phenylamine, and allyl phenyl thioether, t... more The Claisen rearrangement of allyl phenyl ether, allyl phenylamine, and allyl phenyl thioether, together with the family of H, CH 3 , OCH 3 , Cl, F, and CN, meta-substituted molecules, is studied within a density functional framework with B3LYP exchange-correlation energy functionals and 6-311G** basis set. Reactants, intermediates, and products have equilibrium configurations (with no imaginary frequency), and the two transition states possess one imaginary frequency each corroborating the proposed mechanism of a [3,3]sigmatropic rearrangement. The energy profile for the systems containing oxygen and nitrogen atoms mirrors the hardness profile along the reaction path in agreement with the maximum hardness principle. However, the molecules with sulfur atom do not follow the maximum hardness principle. This is explained in terms of the participation of the highest occupied molecular orbital (HOMO) in the reaction. The minimum polarizability principle is obeyed in all cases.
The Journal of Physical Chemistry A, 2013
The formulation of the second-order perturbation approach to the stabilization energy of the A−B ... more The formulation of the second-order perturbation approach to the stabilization energy of the A−B interacting species due to charge transfer is revisited. Intrinsic (i.e., electronic) theoretical indices for both relative electrophilicity and nucleophilicity are proposed for any electrophile (A)−nucleophile (B) pairs of combining species. By using the new descriptors, an electronic analogue to the Mayr−Patz linear free relationship has been successfully tested in the context of available experimental evidence reported for reactions of primary and secondary amines with benzhydrylium ions.
The Journal of Organic Chemistry, 2007
Theoretical Chemistry Accounts, 2016
The range of applicability of intrinsic (i.e., electronic) relative indices for quantifying elect... more The range of applicability of intrinsic (i.e., electronic) relative indices for quantifying electrophilicity and nucleophilicity responses (Chamorro et al. in J Phys Chem A 117(12):2636-2643, 2013) is extended to the characterization of coupling reactions of indoles with benzhydrylium ions and with the strongly electron-deficient heteroarene 4,6-dinitrobenzofuroxan. The reactivity categorization based on experimental kinetic evidence for such a electrophile/nucleophile coupling (Lakhdar et al. in J Org Chem 71(24):9088-9095, 2006) is rationalized in terms of purely electronic descriptors, revealing the polar nucleophilic activation of indole as a key factor associated with the initial rate-determining CC coupling process.
ChemPhotoChem, Jan 20, 2023
Theoretical evidence concerning the multiradicaloid character in benzene photochemistry is report... more Theoretical evidence concerning the multiradicaloid character in benzene photochemistry is reported based on a topological analysis of the correlated electron localization function. The bonding implications of triradicaloid conditions in both ground and excited states of S1 benzene are discussed within the bonding evolution theory. Our results suggest that triradicaloid/biradicaloid structures form due to the non‐bonding density concentration over C atoms, causing the distorted geometry near the S1/S0 crossing. Biradicaloid centers formed in the excited state trigger new CC bonds, leading to a variety of photoproducts.
Toxicology in Vitro, 2022
A 3D-QSAR study based on DFT descriptors and machine learning calculations is presented in this w... more A 3D-QSAR study based on DFT descriptors and machine learning calculations is presented in this work. Our goal has been to build predictive models for classifying the carcinogenic activity of a set of aromatic amines (AA) and nitroaromatic (NA) compounds. As the main result, we stress that calculations must consider both the activated metabolites (derived from AA and NA species) and the water solvent to obtain reliable predictive classification models. We have obtained eight decision tree models that presented an accuracy of over 90% by using either Gázquez-Vela chemical potential (μ+) or the chemical hardness (η).
RSC Advances, 2020
A new series of heteroaryl nitrones were synthesized and evaluated as free radical traps due to t... more A new series of heteroaryl nitrones were synthesized and evaluated as free radical traps due to the results showed in our previous report.
Carbon, Jul 1, 2017
Understanding the kinetics of carbon-hydrogen reaction: Insights from reaction mechanisms on zigz... more Understanding the kinetics of carbon-hydrogen reaction: Insights from reaction mechanisms on zigzag edges for homogeneous and heterogeneous formation of methane, Carbon (2017),
Carbon, 2016
Methane is the main product in the reaction between molecular hydrogen and carbonaceous materials... more Methane is the main product in the reaction between molecular hydrogen and carbonaceous materials such as char, graphene and graphite. Although, pathways for the formation of methane in the carbonhydrogen reaction have been proposed attending to experimental and molecular modeling results, there is not compelling evidence of the elementary character of the steps in such pathways. In this work we propose possible mechanisms with details at molecular level that account for the formation of methane at the zigzag edge through elementary steps using molecular modeling within the framework of the density functional theory. These mechanisms involve saturation of reactive sites, hydrogenation of the edge, ring opening and desorption of methyl groups or direct desorption of methane. Thermodynamic and kinetic details for all steps were explored over temperature and pressure ranges going from 298 K to 1500 K (at 0.1 MPa) and 0.1 MPae10 MPa (at 1100 K), respectively. The proposed mechanisms show a remarkable qualitative agreement between predicted behavior of overall state functions (DH tot , DS tot , and DG tot) and the equilibrium constant for the formation of methane and the observed experimental behavior of these thermodynamic quantities for standard formation of methane from 298 K to 1500 K.
The Journal of Physical Chemistry A, 2021
1,3-Cyclohexadiene ring opening has been studied within the bonding evolution theory (BET) framew... more 1,3-Cyclohexadiene ring opening has been studied within the bonding evolution theory (BET) framework. We have focused on describing for the first time the electron pair rearrangements leading to the cis-1,3,5-hexatriene (HT) product from CHD. The nature of bonding in this process begins with the weakening of the double bonds in the Franck-Condon region. Along the 11B surface, the C-C sigma bond weakens. Meanwhile, its density redistributes toward the whole CHD ring, mainly over double bonds. Breaking of this bond occurs on the 21A surface due to the symmetrical splitting of pair density from this region. This density redistributes toward the reaction center once the pericyclic minimum is reached. The formation of the double bonds that characterize HT occurs gradually in the ground state. However, near the 21A/11A intersection, these bonds are partially established.
Theoretical Chemistry Accounts, 2016
The [3+2] Cycloaddition (32CA) reaction of nitrile ylide (NY) 10 with electron-deficient ethylene... more The [3+2] Cycloaddition (32CA) reaction of nitrile ylide (NY) 10 with electron-deficient ethylene 11 has been studied within the molecular electron density theory through DFT calculations at the MPWB1K/6-31G(d) computational level. A structural analysis of NY 10 indicates that this three-atom component has a carbenoid structure, allowing its participation in carbenoid-type (cb-type) 32CA reactions. This 32CA reaction takes place through a one-step mechanism with very low activation energy, 2.3 kcal mol−1. In gas phase, this 32CA reaction is not stereoselective and has low regioselectivity. Inclusion of solvent effects does not modify the activation energy, but increases the meta regioselectivity in clear agreement with the experimental outcomes. Electron localisation function topological analysis for the formation of the two C–C single bonds along the four competitive channels associated with this 32CA reaction makes it possible to characterise two dissimilar mechanisms. Along the more favourable meta regioisomeric channels, the 32CA reaction takes place through a two-stage one-step mechanism, while along the ortho regioisomeric channels it takes place via a synchronous C–C bond formation process.
Physical Chemistry Chemical Physics
A fundamental correlation exists between the barrier of reactive processes and the structural sta... more A fundamental correlation exists between the barrier of reactive processes and the structural stability concept, which can be cast into a model for predicting energy threshold in reactions involving organic and organometallic compounds.
Theoretical Chemistry Accounts, 2020
This paper results from a round table discussion at the CCTC2018 Conference in Changsha City, Hun... more This paper results from a round table discussion at the CCTC2018 Conference in Changsha City, Hunan, China, in December 2018. It presents a report on the status, prospects, and issues of conceptual density functional theory (CDFT). After a short exposition on the history of CDFT, its fundamentals, philosophy, and successes are highlighted. Then ten issues for reflection on the future of conceptual DFT are formulated and discussed, ending with one or more summarizing statements on the present status of various concepts/principles/practices and proposed directions for future research. The issues include the further analysis of the energy functional, E [ N , v ], extended to include effects of temperature, solvent, and mechanical forces, basic requirements for physically acceptable response functions as reactivity descriptors, the use of the grand canonical ensemble, the relevance of CDFT for chemical kinetics and thermodynamics, the domain of validity of CDFT-based principles, the combination of CDFT with reaction path calculations, information-theoretic descriptors, and the treatment of excited states and time dependence. The final issue advocates the transition of CDFT from an interpretative to a predictive mode; we believe this is of utmost importance for promoting CDFT as a viable alternative to wave function-based methods for the practicing chemist, a separate issue treated in the final section.
The Journal of organic chemistry, Jan 27, 2018
The reaction electronic flux (REF) offers a powerful tool in the analysis of reaction mechanisms.... more The reaction electronic flux (REF) offers a powerful tool in the analysis of reaction mechanisms. Noteworthy, the relation between aromaticity and REF can eventually reveal subtle electronic events associated to reactivity in aromatic systems. In this work, this relation was studied for the Triplet Zimmerman Di-π-Methane rearrangement. The aromaticity loss and gain taking place during the reaction is well acquainted by the REF, thus shedding light on the electronic nature of reactions involving dibenzobarrelenes.
RSC Adv., 2015
The gas-phase thermal decomposition of 1-chlorohexane is rationalized in terms of a two stage one... more The gas-phase thermal decomposition of 1-chlorohexane is rationalized in terms of a two stage one step reaction mechanism.
New Journal of Chemistry
There is an underlying intimate relationship between Thom's catastrophe theory and the electr... more There is an underlying intimate relationship between Thom's catastrophe theory and the electron-pair density evidenced along a reaction pathway.
RSC Advances, 2021
In celebration of the excellence and breadth of Latin American research achievements across the c... more In celebration of the excellence and breadth of Latin American research achievements across the chemical sciences, we are delighted to present an introduction to the themed collection, Celebrating Latin American talent in chemistry.
The Journal of Physical Chemistry A, 2002
The Claisen rearrangement of allyl phenyl ether, allyl phenylamine, and allyl phenyl thioether, t... more The Claisen rearrangement of allyl phenyl ether, allyl phenylamine, and allyl phenyl thioether, together with the family of H, CH 3 , OCH 3 , Cl, F, and CN, meta-substituted molecules, is studied within a density functional framework with B3LYP exchange-correlation energy functionals and 6-311G** basis set. Reactants, intermediates, and products have equilibrium configurations (with no imaginary frequency), and the two transition states possess one imaginary frequency each corroborating the proposed mechanism of a [3,3]sigmatropic rearrangement. The energy profile for the systems containing oxygen and nitrogen atoms mirrors the hardness profile along the reaction path in agreement with the maximum hardness principle. However, the molecules with sulfur atom do not follow the maximum hardness principle. This is explained in terms of the participation of the highest occupied molecular orbital (HOMO) in the reaction. The minimum polarizability principle is obeyed in all cases.
The Journal of Physical Chemistry A, 2013
The formulation of the second-order perturbation approach to the stabilization energy of the A−B ... more The formulation of the second-order perturbation approach to the stabilization energy of the A−B interacting species due to charge transfer is revisited. Intrinsic (i.e., electronic) theoretical indices for both relative electrophilicity and nucleophilicity are proposed for any electrophile (A)−nucleophile (B) pairs of combining species. By using the new descriptors, an electronic analogue to the Mayr−Patz linear free relationship has been successfully tested in the context of available experimental evidence reported for reactions of primary and secondary amines with benzhydrylium ions.
The Journal of Organic Chemistry, 2007
Theoretical Chemistry Accounts, 2016
The range of applicability of intrinsic (i.e., electronic) relative indices for quantifying elect... more The range of applicability of intrinsic (i.e., electronic) relative indices for quantifying electrophilicity and nucleophilicity responses (Chamorro et al. in J Phys Chem A 117(12):2636-2643, 2013) is extended to the characterization of coupling reactions of indoles with benzhydrylium ions and with the strongly electron-deficient heteroarene 4,6-dinitrobenzofuroxan. The reactivity categorization based on experimental kinetic evidence for such a electrophile/nucleophile coupling (Lakhdar et al. in J Org Chem 71(24):9088-9095, 2006) is rationalized in terms of purely electronic descriptors, revealing the polar nucleophilic activation of indole as a key factor associated with the initial rate-determining CC coupling process.
Charge transfer and spin polarization are central aspects of any description of chemical reactivi... more Charge transfer and spin polarization are central aspects of any description of chemical reactivity. In this context reactivity is simply understood as the intrinsic response of a given chemical system against perturbations.
In this talk we review and discuss recent developments and applications of theoretical approximations focused on rationalize and predict the magnitude and intensity of both charge transfer and spin polarization phenomena. These advances are based on the so-called spin-polarized version of density functional theory, contributing to extend the building of a more complete picture of reactivity based on global, local and non-local electronic and nuclear reactivity descriptors.