Nivedita Acharjee - Academia.edu (original) (raw)
Papers by Nivedita Acharjee
Theoretical Chemistry Accounts, Nov 14, 2023
Theoretical Chemistry Accounts
![Research paper thumbnail of [3+2] cycloaddition reaction of N-methyl-C-(2-furyl) nitrone with maleimide derivatives: mechanistic study and selectivity, solvent and temperature effects](https://attachments.academia-assets.com/114556375/thumbnails/1.jpg)
](The [3+2] cycloaddition (32CA) reactions of N-methyl-C-(2-furyl) nitrone with maleimide derivativ... more The [3+2] cycloaddition (32CA) reactions of N-methyl-C-(2-furyl) nitrone with maleimide derivatives have been studied in gas phase, ethanol and acetonitrile solvents within the Molecular Electron Density Theory (MEDT) framework at the B3LYP-D3/6-31G(d) level. Topological analysis classifies the nitrone as a zwitter-ionic (zw-) three atom component (TAC) associated with high energy barrier, while the high global electron density transfer (GEDT) decreases the requested energy cost for the rupture of the olefinic double bond of the maleimide derivatives and consequently decreases the activation barrier. Computations show that these 32CA reactions follow a one-step mechanism with highly asynchronous bond formation, while no new covalent bonds are formed at the transition states (TSs). Moreover, strongly repulsive non-covalent interactions at the endo TSs are found, presumably leading to their energetic destabilization relative to the exo ones. The predicted exo-selectivity agrees well w...
New Journal of Chemistry
The zwitterionic type intramolecular [3 + 2] cycloaddition reactions of nitrones show remarkable ... more The zwitterionic type intramolecular [3 + 2] cycloaddition reactions of nitrones show remarkable substituent effects and varying reactivities in the cases of cyclic and acyclic alkenes.
Chemical Physics Letters, 2022
• Spectral purity increases with the increase of injection intensity. • Spectral purity increases... more • Spectral purity increases with the increase of injection intensity. • Spectral purity increases with the decrease of detuning frequency. • Frequency locking range increases for both high injection intensity and high gain.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
![Research paper thumbnail of Unveiling the Synthesis of Spirocyclic, Tricyclic and Bicyclic Triazolooxazines From Intramolecular [3+2] Azide-alkyne Cycloadditions With a Molecular Electron Density Theory Perspective](https://attachments.academia-assets.com/86783479/thumbnails/1.jpg)
](The intramolecular [3+2] cycloaddition (32CA) reactions of azido alkynes leading to spirocyclic, ... more The intramolecular [3+2] cycloaddition (32CA) reactions of azido alkynes leading to spirocyclic, tricyclic and bicyclic triazolooxazines has been studied within the molecular electron density theory (MEDT) at the MPWB1K/6-311G(d,p) level. The Electron localization function (ELF) characterizes the azido alkynes as zwitterionic species. Analysis of the Conceptual DFT indices allows classifying the azide moiety as the electrophilic counterpart and the alkyne as the nucleophilic one. These 32CA reactions are under kinetic control with the activation free energies of 23.4 - 26.7 kcal mol-1. Along the reaction path, the pseudoradical center is created initially at C4, consistent with the Parr function analysis, however the sequence of bond formation is controlled by the energetically feasible formation of the six membered oxazine ring. The intermolecular interactions at the TSs were characterized from the Quantum Theory of Atoms in Molecules (QTAIM) study and the Non covalent interaction ...
Department of Chemistry, Durgapur Government College, J. N. Avenue, Durgapur-713 214, West Bengal... more Department of Chemistry, Durgapur Government College, J. N. Avenue, Durgapur-713 214, West Bengal, India <em>E-mail</em>: nivchem@gmail.com Central Ayurveda Research Institute for Drug Development, CN Block, Sector V, Kolkata-700 091, India <em>Manuscript received online 09 December 2019, revised and accepted 09 January 2020</em> The term three atom components (TACs) is used in molecular electron density theory to denote three centre four electron π systems, which react with multiple bonded compounds to generate stereo- and regiochemically defined five membered heterocycles by [3+2] cycloaddition reactions. TACs can be allyl type or allenyl type, and the electronic distribution of TACs is a crucial factor to dictate their selectivity and reactivity in [3+2] cycloaddition reactions. Electron localization function (ELF) topological analysis of the TACs have been compared and analyzed at DFT/B3LYP/6-311G(d,p) level of theory to get a precise idea of the proposed...
ChemInform, Sep 8, 2011
The normal electron demand reaction of C-chlorophenyl-N-phenyl nitrone with benzylidene acetophen... more The normal electron demand reaction of C-chlorophenyl-N-phenyl nitrone with benzylidene acetophenone and the effects of mild Lewis acid catalysts like metal triflates and magnesium bromide on the reaction rate are reported. Frontier molecular orbital energies are calculated to rationalise the regioselectivity of the cycloaddition.
Computational and Theoretical Chemistry
Journal of the Indian Chemical Society, 2009
Several C-aryl-N-methylnitrones have been synthesised during the course of our work on 1,3-dipola... more Several C-aryl-N-methylnitrones have been synthesised during the course of our work on 1,3-dipolar cycloadditions. Detailed systematic spectroscopic investigations of all these nitrones have been undertaken. These are reported along with some generalisations made regarding their spectroscopic properties.
DFT analysis for radical capture by a series of biologically active amphiphilic α-phenyl-N-t-buty... more DFT analysis for radical capture by a series of biologically active amphiphilic α-phenyl-N-t-butyl nitrone derivatives has been reported in the present study. A detailed analysis of global and local reactivity descriptors has been presented from both natural and electrostatic based charges. Reactivities of the investigated nitrones for radical capture have been compared by interaction energy calculations derived from a perturbative orbital independent theoretical model. The transition states for radical attacks have been located and the activation barriers for radical capture are calculated. The cis attack is found to be energetically favored in each case. Finally, the hyperfine splitting constants have been computed and compared with the reported experimental findings.
Theoretical Chemistry Accounts
A molecular electron density theory (MEDT) study is performed for the [3 + 2] cycloaddition (32CA... more A molecular electron density theory (MEDT) study is performed for the [3 + 2] cycloaddition (32CA) reactions of benzonitrile oxide (BNO) and diphenyldiazomethane (DPDM) to cyclopentene (CP) and norbornene (NBN) with the objective to analyse the experimentally observed acceleration in NBN reactions relative to the CP ones. The activation enthalpy of the 32CA reaction of NBN with BNO is lowered than that of CP by 2.1–2.9 kcal mol−1 in gas phase, DMSO, acetonitrile and THF, while the corresponding differences are 1.3–1.8 kcal mol−1 with DPDM. The 32CA reactions of DPDM show lower activation parameters compared to that of BNO consistent with the respective pseudo(mono)radical and zwitterionic type characters of DPDM and BNO. The syn diastereofacial approach of NBN is energetically feasible compared to the anti one. The global electron density transfer (GEDT) is identified to anticipate the minimal electron density flux at the TS entity, which is otherwise not accounted by the global electrophilicities of the separated regents. This MEDT study allows comprehending that for these non-polar reactions, the acceleration in NBN cycloadditions compared to the CP ones is due to the relatively lower energy cost demanded for the depopulation and subsequent rupture of C–C double bond of NBN followed by sequential bonding changes along the reaction paths, rather than the “predistorted geometry towards the TSs” as previously proposed in the 32CA reactions of norbornene derivatives.
Sutapa Mandal, Kaustabh K Maiti, Avijit Banerji, Thierry Prangé, Alain Neuman & Nivedita Acharjee... more Sutapa Mandal, Kaustabh K Maiti, Avijit Banerji, Thierry Prangé, Alain Neuman & Nivedita Acharjee* a Department of Chemistry, Durgapur Government College, Durgapur 713 214, India b CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate PO, Pappanamcode, Thiruvananthapuram 695 019, India c Retired Professor, Centre of Advanced Studies on Natural Products Including Organic Synthesis, Department of Chemistry, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700 009, India d Laboratoire de Cristallographie et RMN, Biologiques, Faculté de pharmacie, 4, Av de-l’ Observatoire, 75006 Paris, France e UFR SMBH Université Paris 13, 74, rue Marcel Cachin 93000 Bobigny, France E-mail: nivchem@gmail.com; nivedita_acharjee@gmail.com
Journal of the Indian Chemical Society, 2009
Molecular orbital calculations have been performed by DFT calculations using B3LYP theory and 6-3... more Molecular orbital calculations have been performed by DFT calculations using B3LYP theory and 6-31 G (d) level of approximation for C-(4-chlorophenyl)-N-methyl nitrone on the basis of its optimised geometry. The effect of substitutions on orbital energies have been deduced by comparison to other nitrones and 1,3-dipoles.
The preferred configurations and conformations of C-aryl-N-phenyl nitrones have been predicted th... more The preferred configurations and conformations of C-aryl-N-phenyl nitrones have been predicted theoretically by detailed comparison of DFT/B3LYP/6-311+G(2d,p) calculated gauge invariant atomic orbital nuclear magnetic shielding tensors and experimentally recorded chemical shift values. The frontier molecular orbital energies, electronic chemical potentials, chemical hardness, chemical softness and global electrophilicity indices of C-aryl-N-phenyl nitrones have been calculated at DFT/B3LYP/ 6-31+G(d,p) level of theory. Condensed Fukui functions and local electrophilicity indices have been computed to characterize the reactive sites and predict the preferred interactions of C-aryl-N-phenyl nitrones to methyl and ethyl crotonates. The softness matching indices have been evaluated to determine the regioselectivity of the cycloaddition reactions. The theoretical predictions were found to be in complete agreement with the experimental results implying that the DFT based reactivity indice...
Theoretical Chemistry Accounts, Nov 14, 2023
Theoretical Chemistry Accounts
The [3+2] cycloaddition (32CA) reactions of N-methyl-C-(2-furyl) nitrone with maleimide derivativ... more The [3+2] cycloaddition (32CA) reactions of N-methyl-C-(2-furyl) nitrone with maleimide derivatives have been studied in gas phase, ethanol and acetonitrile solvents within the Molecular Electron Density Theory (MEDT) framework at the B3LYP-D3/6-31G(d) level. Topological analysis classifies the nitrone as a zwitter-ionic (zw-) three atom component (TAC) associated with high energy barrier, while the high global electron density transfer (GEDT) decreases the requested energy cost for the rupture of the olefinic double bond of the maleimide derivatives and consequently decreases the activation barrier. Computations show that these 32CA reactions follow a one-step mechanism with highly asynchronous bond formation, while no new covalent bonds are formed at the transition states (TSs). Moreover, strongly repulsive non-covalent interactions at the endo TSs are found, presumably leading to their energetic destabilization relative to the exo ones. The predicted exo-selectivity agrees well w...
New Journal of Chemistry
The zwitterionic type intramolecular [3 + 2] cycloaddition reactions of nitrones show remarkable ... more The zwitterionic type intramolecular [3 + 2] cycloaddition reactions of nitrones show remarkable substituent effects and varying reactivities in the cases of cyclic and acyclic alkenes.
Chemical Physics Letters, 2022
• Spectral purity increases with the increase of injection intensity. • Spectral purity increases... more • Spectral purity increases with the increase of injection intensity. • Spectral purity increases with the decrease of detuning frequency. • Frequency locking range increases for both high injection intensity and high gain.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The intramolecular [3+2] cycloaddition (32CA) reactions of azido alkynes leading to spirocyclic, ... more The intramolecular [3+2] cycloaddition (32CA) reactions of azido alkynes leading to spirocyclic, tricyclic and bicyclic triazolooxazines has been studied within the molecular electron density theory (MEDT) at the MPWB1K/6-311G(d,p) level. The Electron localization function (ELF) characterizes the azido alkynes as zwitterionic species. Analysis of the Conceptual DFT indices allows classifying the azide moiety as the electrophilic counterpart and the alkyne as the nucleophilic one. These 32CA reactions are under kinetic control with the activation free energies of 23.4 - 26.7 kcal mol-1. Along the reaction path, the pseudoradical center is created initially at C4, consistent with the Parr function analysis, however the sequence of bond formation is controlled by the energetically feasible formation of the six membered oxazine ring. The intermolecular interactions at the TSs were characterized from the Quantum Theory of Atoms in Molecules (QTAIM) study and the Non covalent interaction ...
Department of Chemistry, Durgapur Government College, J. N. Avenue, Durgapur-713 214, West Bengal... more Department of Chemistry, Durgapur Government College, J. N. Avenue, Durgapur-713 214, West Bengal, India <em>E-mail</em>: nivchem@gmail.com Central Ayurveda Research Institute for Drug Development, CN Block, Sector V, Kolkata-700 091, India <em>Manuscript received online 09 December 2019, revised and accepted 09 January 2020</em> The term three atom components (TACs) is used in molecular electron density theory to denote three centre four electron π systems, which react with multiple bonded compounds to generate stereo- and regiochemically defined five membered heterocycles by [3+2] cycloaddition reactions. TACs can be allyl type or allenyl type, and the electronic distribution of TACs is a crucial factor to dictate their selectivity and reactivity in [3+2] cycloaddition reactions. Electron localization function (ELF) topological analysis of the TACs have been compared and analyzed at DFT/B3LYP/6-311G(d,p) level of theory to get a precise idea of the proposed...
ChemInform, Sep 8, 2011
The normal electron demand reaction of C-chlorophenyl-N-phenyl nitrone with benzylidene acetophen... more The normal electron demand reaction of C-chlorophenyl-N-phenyl nitrone with benzylidene acetophenone and the effects of mild Lewis acid catalysts like metal triflates and magnesium bromide on the reaction rate are reported. Frontier molecular orbital energies are calculated to rationalise the regioselectivity of the cycloaddition.
Computational and Theoretical Chemistry
Journal of the Indian Chemical Society, 2009
Several C-aryl-N-methylnitrones have been synthesised during the course of our work on 1,3-dipola... more Several C-aryl-N-methylnitrones have been synthesised during the course of our work on 1,3-dipolar cycloadditions. Detailed systematic spectroscopic investigations of all these nitrones have been undertaken. These are reported along with some generalisations made regarding their spectroscopic properties.
DFT analysis for radical capture by a series of biologically active amphiphilic α-phenyl-N-t-buty... more DFT analysis for radical capture by a series of biologically active amphiphilic α-phenyl-N-t-butyl nitrone derivatives has been reported in the present study. A detailed analysis of global and local reactivity descriptors has been presented from both natural and electrostatic based charges. Reactivities of the investigated nitrones for radical capture have been compared by interaction energy calculations derived from a perturbative orbital independent theoretical model. The transition states for radical attacks have been located and the activation barriers for radical capture are calculated. The cis attack is found to be energetically favored in each case. Finally, the hyperfine splitting constants have been computed and compared with the reported experimental findings.
Theoretical Chemistry Accounts
A molecular electron density theory (MEDT) study is performed for the [3 + 2] cycloaddition (32CA... more A molecular electron density theory (MEDT) study is performed for the [3 + 2] cycloaddition (32CA) reactions of benzonitrile oxide (BNO) and diphenyldiazomethane (DPDM) to cyclopentene (CP) and norbornene (NBN) with the objective to analyse the experimentally observed acceleration in NBN reactions relative to the CP ones. The activation enthalpy of the 32CA reaction of NBN with BNO is lowered than that of CP by 2.1–2.9 kcal mol−1 in gas phase, DMSO, acetonitrile and THF, while the corresponding differences are 1.3–1.8 kcal mol−1 with DPDM. The 32CA reactions of DPDM show lower activation parameters compared to that of BNO consistent with the respective pseudo(mono)radical and zwitterionic type characters of DPDM and BNO. The syn diastereofacial approach of NBN is energetically feasible compared to the anti one. The global electron density transfer (GEDT) is identified to anticipate the minimal electron density flux at the TS entity, which is otherwise not accounted by the global electrophilicities of the separated regents. This MEDT study allows comprehending that for these non-polar reactions, the acceleration in NBN cycloadditions compared to the CP ones is due to the relatively lower energy cost demanded for the depopulation and subsequent rupture of C–C double bond of NBN followed by sequential bonding changes along the reaction paths, rather than the “predistorted geometry towards the TSs” as previously proposed in the 32CA reactions of norbornene derivatives.
Sutapa Mandal, Kaustabh K Maiti, Avijit Banerji, Thierry Prangé, Alain Neuman & Nivedita Acharjee... more Sutapa Mandal, Kaustabh K Maiti, Avijit Banerji, Thierry Prangé, Alain Neuman & Nivedita Acharjee* a Department of Chemistry, Durgapur Government College, Durgapur 713 214, India b CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate PO, Pappanamcode, Thiruvananthapuram 695 019, India c Retired Professor, Centre of Advanced Studies on Natural Products Including Organic Synthesis, Department of Chemistry, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700 009, India d Laboratoire de Cristallographie et RMN, Biologiques, Faculté de pharmacie, 4, Av de-l’ Observatoire, 75006 Paris, France e UFR SMBH Université Paris 13, 74, rue Marcel Cachin 93000 Bobigny, France E-mail: nivchem@gmail.com; nivedita_acharjee@gmail.com
Journal of the Indian Chemical Society, 2009
Molecular orbital calculations have been performed by DFT calculations using B3LYP theory and 6-3... more Molecular orbital calculations have been performed by DFT calculations using B3LYP theory and 6-31 G (d) level of approximation for C-(4-chlorophenyl)-N-methyl nitrone on the basis of its optimised geometry. The effect of substitutions on orbital energies have been deduced by comparison to other nitrones and 1,3-dipoles.
The preferred configurations and conformations of C-aryl-N-phenyl nitrones have been predicted th... more The preferred configurations and conformations of C-aryl-N-phenyl nitrones have been predicted theoretically by detailed comparison of DFT/B3LYP/6-311+G(2d,p) calculated gauge invariant atomic orbital nuclear magnetic shielding tensors and experimentally recorded chemical shift values. The frontier molecular orbital energies, electronic chemical potentials, chemical hardness, chemical softness and global electrophilicity indices of C-aryl-N-phenyl nitrones have been calculated at DFT/B3LYP/ 6-31+G(d,p) level of theory. Condensed Fukui functions and local electrophilicity indices have been computed to characterize the reactive sites and predict the preferred interactions of C-aryl-N-phenyl nitrones to methyl and ethyl crotonates. The softness matching indices have been evaluated to determine the regioselectivity of the cycloaddition reactions. The theoretical predictions were found to be in complete agreement with the experimental results implying that the DFT based reactivity indice...