1
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Medhi B, Nath U, Sarma M. Revisiting fulgide photochromism: Mechanistic decoding and electron transport from computational exploration. J Chem Phys 2024; 160:154308. [PMID: 38634497 DOI: 10.1063/5.0203307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 04/01/2024] [Indexed: 04/19/2024] Open
Abstract
The photochromic behavior of the fulgide molecule relies on ring-closure and ring-opening processes involving conical intersections during excited state transformation between isomers. The precise location and topography of these conical intersections significantly shape the decay process and fluorescence phenomena inherent to the molecule. This work combines electronic structure theory calculations using the density functional theory and wavefunction methods, as well as surface hopping simulation to analyze the photochemical behavior of an experimentally synthesized fulgide molecule, (E)-p-methylacetophenylisopropylidenesuccinic anhydride (1E). Our study reveals the conical intersection between the first excited state (S1) and the ground electronic state (S0), which emerges beyond the S1 minimum of 1E to the ring-closing side. The distinctive topography of this conical intersection appears to be sloped. These findings suggest a reduced quantum yield for the formation of the closed isomer, indicating a higher likelihood of reformation of the open isomer(s). The surface hopping simulation further supports this observation, revealing a mere ∼8% quantum yield for the formation of the closed isomer. In addition, the photoisomerization of the fulgide molecule initiates a cascade of conduction switching and holds great potential for applications in molecular electronics. Delving into the realm of molecular electronics, we have further examined the electron transport properties, disclosing the higher conductivity of the closed isomer.
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Affiliation(s)
- Biman Medhi
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India
| | - Upasana Nath
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India
| | - Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India
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2
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Medhi B, Sarma M. Deciphering the Internal Conversion Processes Involved in the Photochemical Ring-Opening of 1,3-Cyclohexadiene by Symmetric sp 2-Carbon Substitutions. J Phys Chem A 2024; 128:2025-2037. [PMID: 38426433 DOI: 10.1021/acs.jpca.4c00406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Chemical substituents hold the potential to markedly influence the photochemical behavior in molecular systems and assist in gaining a comprehensive understanding of nonadiabatic phenomena. In this study, we have conducted a comparative analysis of the influence of chemical substituents on the photochemical ring-opening of 1,3-cyclohexadiene (CHD), considering four systems: CHD, 2,3-dimethylcyclohexadiene (CHD-Me2-1), 1,4-dimethylcyclohexadiene (CHD-Me2-2), and 1,2,3,4-tetramethylcyclohexadiene (CHD-Me4), using electronic structure theory calculations and nonadiabatic molecular dynamics simulations. Employing extended multistate complete active space second-order perturbation (XMS-CASPT2) theory, we optimized reactants, S1 states, conical intersections (CIns), and products, revealing structural and energetic variations consistent with prior research. Nonadiabatic molecular dynamics simulation was used to gain insights into photochemical dynamics at state-averaged complete active space self-consistent field (SA-CASSCF) theory. CHD-Me4 exhibited reduced carbon-carbon single bond rupture rates, responsible for ring-opening, due to substituent proximity. Further, CHD-Me2-2 and CHD-Me4 displayed prolonged excited-state relaxation times, highlighting notable substituents' impact. Analysis of kinetic energy profiles of specific carbon atoms also revealed restrained atomic displacements, particularly in CHD-Me2-2 and CHD-Me4. These findings advance our understanding of how substituents modulate photochemical reactions in cyclohexadiene derivatives, guiding new molecular design and future research.
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Affiliation(s)
- Biman Medhi
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
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3
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Abiola TT, Toldo JM, do Casal MT, Flourat AL, Rioux B, Woolley JM, Murdock D, Allais F, Barbatti M, Stavros VG. Direct structural observation of ultrafast photoisomerization dynamics in sinapate esters. Commun Chem 2022; 5:141. [PMID: 36697608 PMCID: PMC9814104 DOI: 10.1038/s42004-022-00757-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/13/2022] [Indexed: 01/27/2023] Open
Abstract
Sinapate esters have been extensively studied for their potential application in 'nature-inspired' photoprotection. There is general consensus that the relaxation mechanism of sinapate esters following photoexcitation with ultraviolet radiation is mediated by geometric isomerization. This has been largely inferred through indirect studies involving transient electronic absorption spectroscopy in conjunction with steady-state spectroscopies. However, to-date, there is no direct experimental evidence tracking the formation of the photoisomer in real-time. Using transient vibrational absorption spectroscopy, we report on the direct structural changes that occur upon photoexcitation, resulting in the photoisomer formation. Our mechanistic analysis predicts that, from the photoprepared ππ* state, internal conversion takes place through a conical intersection (CI) near the geometry of the initial isomer. Our calculations suggest that different CI topographies at relevant points on the seam of intersection may influence the isomerization yield. Altogether, we provide compelling evidence suggesting that a sinapate ester's geometric isomerization can be a more complex dynamical process than originally thought.
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Affiliation(s)
- Temitope T. Abiola
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Josene M. Toldo
- grid.462456.70000 0004 4902 8637Aix Marseille Université, CNRS, ICR, Marseille, France
| | - Mariana T. do Casal
- grid.462456.70000 0004 4902 8637Aix Marseille Université, CNRS, ICR, Marseille, France
| | - Amandine L. Flourat
- grid.417885.70000 0001 2185 8223URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Benjamin Rioux
- grid.417885.70000 0001 2185 8223URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Jack M. Woolley
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Daniel Murdock
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Florent Allais
- grid.417885.70000 0001 2185 8223URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Mario Barbatti
- grid.462456.70000 0004 4902 8637Aix Marseille Université, CNRS, ICR, Marseille, France ,grid.440891.00000 0001 1931 4817Institut Universitaire de France, 75231 Paris, France
| | - Vasilios G. Stavros
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
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4
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Ghosh P, Nandy T, Singh PC, Ghosh D. Substitution enables significant new decay channels for a non-canonical amino acid. Phys Chem Chem Phys 2022; 24:17695-17702. [PMID: 35838114 DOI: 10.1039/d2cp00465h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
UV-Vis absorption spectra and emission peaks of indole and 7-fluoroindole are measured and it is observed that 7-fluoroindole quenches the fluorescence signals significantly compared to indole. This observation is elucidated via reconstruction of the potential energy surfaces, determination of the conical intersections, and dynamical studies. It is observed that a single fluorine substitution on indole leads to the appearance of several accessible low-energy conical intersections that cause fast nonradiative decay. In this paper, we have investigated the nonradiative processes of Ind and 7F-Ind theoretically using high-level methods, such as EOM-EE-CCSD, SA-CASSCF, MS-CASPT2/6-311++G(d,p) levels of theory, to study these pathways and their feasibility.
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Affiliation(s)
- Paulami Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India.
| | - Tonima Nandy
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India.
| | - Prashant C Singh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India.
| | - Debashree Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India.
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5
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Ghosh P, Ghosh A, Ghosh D. Radiationless Decay Processes of an Unnatural DNA Base: Pyrrole 2-Carbaldehyde. J Phys Chem A 2021; 125:5556-5561. [PMID: 34133168 DOI: 10.1021/acs.jpca.1c03875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pyrrole-2-carbaldehyde (Pa) forms one of the unnatural nucleic acid bases, and as a base pair with 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds), it has been known to be stable in DNA. The Ds-Pa pair is stabilized in DNA via van der Waals' interaction and shape fitting. There are some studies on the origin of its stability and reactivity in the ground state. However, for a successful unnatural base pair, it needs to be stable not only in the ground state but also upon irradiation with UV-visible light. To understand the photoinduced reactivity, we investigate the excited-state properties of the Pa base and understand the energetically feasible photoprocesses that can occur upon excitation in the UV region. Two distinct pathways are obtained. One of the pathways involves an out-of-plane mode and has some similarities with the deactivation channels in the natural pyrimidine bases. On the other hand, the second pathway involves an excited-state proton transfer.
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Affiliation(s)
- Paulami Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Arpita Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Debashree Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
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6
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Ghosh P, Ghosh D. Effect of Dimerization on the Nonradiative Processes of Eumelanin Monomer. J Phys Chem B 2021; 125:547-556. [PMID: 33410319 DOI: 10.1021/acs.jpcb.0c10555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Eumelanin is a polymeric structure made of dihydroxyindole (DHI) as the basic motif. Since the oxidative polymerization of DHI forms the core of eumelanin, understanding the effect of polymerization on its optical and photoprotective properties is crucial to elucidate the structure-function relationship of eumelanin. In this work, we investigate the effect of dimerization of DHI on the photoprocesses of eumelanin. We observe that there are several low-energy conical intersections and energetically favorable pathways for deactivation of photoexcited dimeric DHI species. While the original deactivation modes of the monomers are still important, in dimers the intermonomer dihedral angles seem to play a central role.
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Affiliation(s)
- Paulami Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Debashree Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
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7
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Ghosh P, Ghosh D. Non-radiative decay of an eumelanin monomer: to be or not to be planar. Phys Chem Chem Phys 2019; 21:6635-6642. [DOI: 10.1039/c9cp00246d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The planar and nonplanar non-radiative decay channels of eumelanin monomer.
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Affiliation(s)
- Paulami Ghosh
- School of Mathematical and Computational Sciences
- Indian Association for the Cultivation of Science
- Kolkata 700032
- India
| | - Debashree Ghosh
- School of Mathematical and Computational Sciences
- Indian Association for the Cultivation of Science
- Kolkata 700032
- India
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8
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Gómez S, Ibele LM, González L. The 3s Rydberg state as a doorway state in the ultrafast dynamics of 1,1-difluoroethylene. Phys Chem Chem Phys 2019; 21:4871-4878. [DOI: 10.1039/c8cp07766e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The deactivation dynamics of 1,1-difluoroethylene after light excitation is studied within the surface hopping formalism in the presence of 3s and 3p Rydberg states using multi-state second order perturbation theory (MS-CASPT2).
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Affiliation(s)
- Sandra Gómez
- Institute for Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- 1090 Vienna
- Austria
| | - Lea M. Ibele
- Institute for Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- 1090 Vienna
- Austria
| | - Leticia González
- Institute for Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- 1090 Vienna
- Austria
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9
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Ghosh P, Ghosh D. Effect of microsolvation on the non-radiative decay of the eumelanin monomer. Phys Chem Chem Phys 2019; 21:26123-26132. [DOI: 10.1039/c9cp05166j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A plethora of various low energy accessible deactivation modes of DHI were explored.
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Affiliation(s)
- Paulami Ghosh
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata 700032
- India
| | - Debashree Ghosh
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata 700032
- India
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10
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Ghosh P, Ghosh D. Elucidating the Photoprotection Mechanism of Eumelanin Monomers. J Phys Chem B 2017; 121:5988-5994. [DOI: 10.1021/acs.jpcb.7b05123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Paulami Ghosh
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Debashree Ghosh
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
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11
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Estrada LA, Francés-Monerris A, Schapiro I, Olivucci M, Roca-Sanjuán D. Mechanism of excited state deactivation of indan-1-ylidene and fluoren-9-ylidene malononitriles. Phys Chem Chem Phys 2016; 18:32786-32795. [DOI: 10.1039/c6cp05231b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A joint experimental and computational study on the non-radiative double bond isomerisation decay channel of indan-1-ylidene malononitrile and fluoren-9-ylidene malononitrile is presented in this work.
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Affiliation(s)
- Leandro A. Estrada
- Center for Photochemical Sciences
- Bowling Green State University
- Bowling Green
- USA
| | | | - Igor Schapiro
- Center for Photochemical Sciences
- Bowling Green State University
- Bowling Green
- USA
| | - Massimo Olivucci
- Center for Photochemical Sciences
- Bowling Green State University
- Bowling Green
- USA
- Dipartimento di Biotecnologie
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12
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Pérez-Soto R, Vázquez SA, Martínez-Núñez E. Photodissociation of acryloyl chloride at 193 nm: interpretation of the product energy distributions, and new elimination pathways. Phys Chem Chem Phys 2016; 18:5019-26. [DOI: 10.1039/c5cp07759a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of an automated TS search method leads to the finding of novel HCl elimination pathways.
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Affiliation(s)
- Raúl Pérez-Soto
- Departamento de Química Física and Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS)
- Campus Vida
- Universidade de Santiago de Compostela
- Santiago de Compostela
- Spain
| | - Saulo A. Vázquez
- Departamento de Química Física and Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS)
- Campus Vida
- Universidade de Santiago de Compostela
- Santiago de Compostela
- Spain
| | - Emilio Martínez-Núñez
- Departamento de Química Física and Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS)
- Campus Vida
- Universidade de Santiago de Compostela
- Santiago de Compostela
- Spain
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13
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Vázquez SA, Martínez-Núñez E. HCN elimination from vinyl cyanide: product energy partitioning, the role of hydrogen–deuterium exchange reactions and a new pathway. Phys Chem Chem Phys 2015; 17:6948-55. [DOI: 10.1039/c4cp05626d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A schematic diagram of HCN elimination channels from vinyl cyanide including a new CCdiss pathway.
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Affiliation(s)
- Saulo A. Vázquez
- Departamento de Química Física and Centro Singular de Investigación en Química Biológica y Materiales Moleculares
- Campus Vida
- Universidade de Santiago de Compostela
- Santiago de Compostela
- Spain
| | - Emilio Martínez-Núñez
- Departamento de Química Física and Centro Singular de Investigación en Química Biológica y Materiales Moleculares
- Campus Vida
- Universidade de Santiago de Compostela
- Santiago de Compostela
- Spain
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14
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Borges I, Aquino AJA, Lischka H. A multireference configuration interaction study of the photodynamics of nitroethylene. J Phys Chem A 2014; 118:12011-20. [PMID: 25158277 PMCID: PMC4279882 DOI: 10.1021/jp507396e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
![]()
Extended multireference configuration
interaction with singles
and doubles (MR-CISD) calculations of nitroethylene (H2C=CHNO2) were carried out to investigate the photodynamical
deactivation paths to the ground state. The ground (S0)
and the first five valence excited electronic states (S1–S5) were investigated. In the first step, vertical
excitations and potential energy curves for CH2 and NO2 torsions and CH2 out-of-plane bending starting
from the ground state geometry were computed. Afterward, five conical
intersections, one between each pair of adjacent states, were located.
The vertical calculations mostly confirm the previous assignment of
experimental spectrum and theoretical results using lower-level calculations.
The conical intersections have as main features the torsion of the
CH2 moiety, different distortions of the NO2 group and CC, CN, and NO bond stretchings. In these conical intersections,
the NO2 group plays an important role, also seen in excited
state investigations of other nitro molecules. Based on the conical
intersections found, a photochemical nonradiative deactivation process
after a π–π* excitation to the bright S5 state is proposed. In particular, the possibility of NO2 release in the ground state, an important property in nitro explosives,
was found to be possible.
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Affiliation(s)
- Itamar Borges
- Departamento de Química, Instituto Militar de Engenharia Praça General Tibúrcio , 80, 22290-270 Rio de Janeiro, Brazil
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15
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Kinzel D, González-Vázquez J, González L. H-abstraction is more efficient than cis–trans isomerization in (4-methylcyclohexylidene) fluoromethane. An ab initio molecular dynamics study. Phys Chem Chem Phys 2012; 14:6241-9. [DOI: 10.1039/c1cp22646k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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16
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Szalay PG, Müller T, Gidofalvi G, Lischka H, Shepard R. Multiconfiguration Self-Consistent Field and Multireference Configuration Interaction Methods and Applications. Chem Rev 2011; 112:108-81. [DOI: 10.1021/cr200137a] [Citation(s) in RCA: 470] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Péter G. Szalay
- Laboratory for Theoretical Chemistry, Institute of Chemistry, Eötvös Loránd University, P. O. Box 32, H-1518 Budapest, Hungary
| | - Thomas Müller
- Jülich Supercomputer Centre, Institute of Advanced Simulation, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Gergely Gidofalvi
- Department of Chemistry and Biochemistry, Gonzaga University, 502 East Boone Avenue, Spokane, Washington 99258-0102, United States
| | - Hans Lischka
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
- Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria
| | - Ron Shepard
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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Homayoon Z, Vázquez SA, Rodríguez-Fernández R, Martínez-Núñez E. Ab Initio and RRKM Study of the HCN/HNC Elimination Channels from Vinyl Cyanide. J Phys Chem A 2011; 115:979-85. [DOI: 10.1021/jp109843a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zahra Homayoon
- Departamento de Química Física y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Campus Vida, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
- Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran
| | - Saulo A. Vázquez
- Departamento de Química Física y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Campus Vida, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Roberto Rodríguez-Fernández
- Departamento de Química Física y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Campus Vida, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Emilio Martínez-Núñez
- Departamento de Química Física y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Campus Vida, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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18
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Nenov A, Cordes T, Herzog TT, Zinth W, de Vivie-Riedle R. Molecular Driving Forces for Z/E Isomerization Mediated by Heteroatoms: The Example Hemithioindigo. J Phys Chem A 2010; 114:13016-30. [DOI: 10.1021/jp107899g] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Artur Nenov
- Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, D-81377 München, Germany, and BioMolecular Optics and Munich Center for Integrated Protein Science CIPSM, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstrasse 67, D-80538 München, Germany
| | - Thorben Cordes
- Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, D-81377 München, Germany, and BioMolecular Optics and Munich Center for Integrated Protein Science CIPSM, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstrasse 67, D-80538 München, Germany
| | - Teja T. Herzog
- Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, D-81377 München, Germany, and BioMolecular Optics and Munich Center for Integrated Protein Science CIPSM, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstrasse 67, D-80538 München, Germany
| | - Wolfgang Zinth
- Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, D-81377 München, Germany, and BioMolecular Optics and Munich Center for Integrated Protein Science CIPSM, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstrasse 67, D-80538 München, Germany
| | - Regina de Vivie-Riedle
- Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, D-81377 München, Germany, and BioMolecular Optics and Munich Center for Integrated Protein Science CIPSM, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstrasse 67, D-80538 München, Germany
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19
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Alfalah S, Kinzel D, González-Vázquez J, González L. Non-adiabatic photoisomerization versus photodissociation dynamics of the chiral fluoroethylene derivative (4-methylcyclohexylidene) fluoromethane. Chem Phys 2010. [DOI: 10.1016/j.chemphys.2010.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Zou P, Strecker KE, Ramirez-Serrano J, Jusinski LE, Taatjes CA, Osborn DL. Ultraviolet photodissociation of vinyl iodide: understanding the halogen dependence of photodissociation mechanisms in vinyl halides. Phys Chem Chem Phys 2009; 10:713-28. [PMID: 19791455 DOI: 10.1039/b712117b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photodissociation of vinyl iodide has been investigated at several wavelengths between 193 and 266 nm using three techniques: time-resolved Fourier transform emission spectroscopy, multiple pass laser absorption spectroscopy, and velocity-mapped ion imaging. The only dissociation channel observed is C-I bond cleavage to produce C2H3 (nu, N) + I (2P(J)) at all wavelengths investigated. Unlike photodissociation of other vinyl halides (C2H3X, X = F, Cl, Br), in which the HX product channel is significant, no HI elimination is observed. The angular and translational energy distributions of I atoms indicate that atomic products arise solely from dissociation on excited states with negligible contribution from internal conversion to the ground state. We derive an upper limit on the C-I bond strength of D0(C2H3-I) < or = 65 kcal mol(-1). The ground-state potential-energy surface of vinyl iodide is explored by ab initio calculations. We present a model in which the highest occupied molecular orbital in vinyl halides has increasing X(np) non-bonding character with increasing halogen mass. This change leads to reduced torsional force around the C-C bond in the excited state. Because the ground-state energy is highest when the CH2 plane is perpendicular to the CHX plane, a reduced torsional force in the excited state correlates with a lower rate for internal conversion compared to excited-state C-X bond fission. This model explains the gradual change in photodissociation mechanisms of vinyl halides from the dominance of internal conversion in vinyl fluoride to the dominance of excited-state dissociation in vinyl iodide.
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Affiliation(s)
- Peng Zou
- Combustion Research Facility, Sandia National Laboratories, PO Box 969, Livermore, CA 94551-0969, USA
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Locht R, Leyh B, Dehareng D, Jochims H, Baumgärtel H. The vacuum UV photoabsorption spectroscopy of vinyl fluoride (C2H3F): The vibrational fine structure and its analysis. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2009.06.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Chang CM, Huang YH, Liu SY, Lee YP, Pombar-Pérez M, Martínez-Núñez E, Vázquez SA. Internal energy of HCl upon photolysis of 2-chloropropene at 193 nm investigated with time-resolved Fourier-transform spectroscopy and quasiclassical trajectories. J Chem Phys 2009; 129:224301. [PMID: 19071910 DOI: 10.1063/1.3023149] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Following photodissociation of 2-chloropropene (H(2)CCClCH(3)) at 193 nm, vibration-rotationally resolved emission spectra of HCl (upsilon < or = 6) in the spectral region of 1900-2900 cm(-1) were recorded with a step-scan time-resolved Fourier-transform spectrometer. All vibrational levels show a small low-J component corresponding to approximately 400 K and a major high-J component corresponding to 7100-18,700 K with average rotational energy of 39+/-(3)(11) kJ mol(-1). The vibrational population of HCl is inverted at upsilon = 2, and the average vibrational energy is 86+/-5 kJ mol(-1). Two possible channels of molecular elimination producing HCl + propyne or HCl + allene cannot be distinguished positively based on the observed internal energy distribution of HCl. The observed rotational distributions fit qualitatively with the distributions of both channels obtained with quasiclassical trajectories (QCTs), but the QCT calculations predict negligible populations for states at small J. The observed vibrational distribution agrees satisfactorily with the total QCT distribution obtained as a weighted sum of contributions from both four-center elimination channels. Internal energy distributions of HCl from 2-chloropropene and vinyl chloride are compared.
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Affiliation(s)
- Chih-Min Chang
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
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González-Vázquez J, González L. A CASSCF and CASPT2 study of the photochemistry of 1,1- and 1,2-difluoroethylenes. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2008.01.043] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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25
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Nonadiabatic Excited-State Dynamics of Aromatic Heterocycles: Toward the Time-Resolved Simulation of Nucleobases. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/978-1-4020-8184-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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26
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Zilberg S, Cogan S, Haas Y, Deeb O, González L. Conical intersections in the photoisomerization and photodissociation of a chiral fluoroethylene derivative ((4-methylcyclohexylidene) fluoromethane). Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.06.072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Blancafort L. Energetics of Cytosine Singlet Excited-State Decay Paths-A Difficult Case for CASSCF and CASPT2†. Photochem Photobiol 2007; 83:603-10. [PMID: 17017844 DOI: 10.1562/2006-05-29-ra-903] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Three deactivation paths for singlet excited cytosine are calculated at the CASPT2//CASSCF (complete active space second-order perturbation//complete active space self-consistent field) level of theory, using extended active spaces that allow for a reliable characterization of the paths and their energies. The lowest energy path, with a barrier of approximately 0.1 eV, corresponds to torsion of the C5-C6 bond, and the decay takes place at a conical intersection analogous to the one found for ethylene and its derivatives. There is a further path with a low energy barrier of approximately 0.2 eV associated with the (n(N),pi*) state which could also be populated with a low energy excitation. The path associated with a conical intersection between the ground and (n(O),pi*) states is significantly higher in energy (> 1 eV). The presence of minima on the potential energy surface for the (n,pi*) states that could contribute to the biexponential decay found in the gas phase was investigated, but could not be established unequivocally.
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Affiliation(s)
- Lluís Blancafort
- Departament de Química, Institut de Química Computacional, Universitat de Girona, Campus de Montilivi, Girona, Spain.
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Barbatti M, Lischka H. Can the Nonadiabatic Photodynamics of Aminopyrimidine Be a Model for the Ultrafast Deactivation of Adenine? J Phys Chem A 2007; 111:2852-8. [PMID: 17388405 DOI: 10.1021/jp070089w] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction path for the ultrafast deactivation of 6-aminopyrimidine (6AP) has been investigated by means of ab initio surface-hopping dynamics. The electronic vertical excitation spectrum, excited-state S1 minima, and minima on the crossing seam of 6AP resemble well those found for adenine. The deactivation from the S1 to the S0 state takes place at the ultrafast time scale of 400 fs and involves the out-of-plane ring deformation of the C4 atom, a position that is sterically restricted in adenine by the imidazole ring. Mechanical restrictions have been used to simulate in a simple way the role of the imidazole group in adenine. As a result, deactivation via out-of-plane ring deformation of the C2 and N3 atoms are observed in good agreement with predictions for adenine. These dynamics results show that the previously suggested ring puckering deactivation paths really exist at a time scale, which is compatible with experimentally observed life times. The electronic structure of the crossing seam has been shown to have the same nature as those of simple biradicaloid systems, a feature which seems to be valid for any cyclic system.
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Affiliation(s)
- Mario Barbatti
- Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090, Vienna, Austria.
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Barbatti M, Aquino AJA, Lischka H. Ultrafast two-step process in the non-adiabatic relaxation of the CH2 molecule. Mol Phys 2007. [DOI: 10.1080/00268970500417945] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Mario Barbatti
- a Institute for Theoretical Chemistry , University of Vienna , Whringerstrasse 17, A-1090 Vienna, Austria
| | - Adélia J. A. Aquino
- a Institute for Theoretical Chemistry , University of Vienna , Whringerstrasse 17, A-1090 Vienna, Austria
| | - Hans Lischka
- a Institute for Theoretical Chemistry , University of Vienna , Whringerstrasse 17, A-1090 Vienna, Austria
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Tarrazo-Antelo T, Martínez-Núñez E, Vázquez SA. Ab initio and RRKM study of the elimination of HF and HCl from chlorofluoroethylene. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2006.12.075] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
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Arulmozhiraja S, Ehara M, Nakatsuji H. Electronic excitations of fluoroethylenes. J Chem Phys 2007; 126:044306. [PMID: 17286469 DOI: 10.1063/1.2428296] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Several lowest-lying singlet electronic states of vinyl fluoride, trans-, cis-, and 1,1-difluoroethylene, trifluoroethylene, and tetrafluoroethylene were investigated by using symmetry-adapted cluster configuration interaction theory. Basis sets up to Dunning's aug-cc-pVTZ augmented with appropriate Rydberg functions were utilized for the calculations. Calculated excitation energies show a good agreement with the available experimental values. Even in the troublesome pi-->pi(*) transitions, the excitation energies obtained in the present study agree well with the experimental values except in one or two fluoroethylenes. Strong mixing between different states was noticed in a few fluoroethylenes; especially the mixing is very strong between pi-pi(*) and pi-3ppi states in trifluoroethylene. No pure pi-sigma(*) excited state was found in almost all the fluoroethylenes. Several assignments and reassignments of features in the experimental spectra were suggested. The present study does not support the existing argument that the interaction between the pi-pi(*) and sigma-sigma(*) states is the reason behind the blueshift of around 1.25 eV in the pi-pi(*) excitation energy of tetrafluoroethylene. Possible reasons, including structural changes, for this shift are discussed in detail. Several low-lying triplet excited states were also studied.
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Affiliation(s)
- Sundaram Arulmozhiraja
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyou-ku, Kyoto 615-8510, Japan
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Schreiber M, Barbatti M, Zilberg S, Lischka H, Gonzalez L. An Ab Initio Study of the Excited States, Isomerization Energy Profiles and Conical Intersections of a Chiral Cyclohexylidene Derivative. J Phys Chem A 2006; 111:238-43. [PMID: 17214459 DOI: 10.1021/jp066090x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The excited valence and Rydberg states of the chiral (4-methylcyclohexylidene) fluoromethane (4MCF) have been investigated using multiconfigurational CASSCF and CASPT2, and coupled-cluster methods (RI-CC2). A 3s Rydberg state is predicted below the valence (1)pipi* state. To gain insight into the photophysics of the cis-trans isomerization of this olefin, potential energy profiles for the valence (10pipi* state along the twisting and pyramidalization reaction coordinates have been computed using variational methods (CASSCF and multireference configuration interaction with singles and doubles (MR-CISD)). Starting from geometries with energies close to degeneracy in the valence and ground-state curves, three minima on the crossing seam that can be correlated with the conical intersections known for fluoroethylene, have been found. On the basis of these features, the photochemistry of 4MCF is discussed.
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Affiliation(s)
- Marko Schreiber
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
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Martínez-Núñez E, Vázquez S. Rotational distributions of HBr in the photodissociation of vinyl bromide at 193nm: An investigation by direct quasiclassical trajectory calculations. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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