Singlet oxygen generation versus O–O homolysis in phenyl-substituted anthracene endoperoxides investigated by RASPT2, CASPT2, CC2, and TD-DFT methods

Kupfer, Stephan; Pérez‐Hernández, Guillermo; González, Leticia

doi:10.1007/s00214-012-1295-7

Cited by 5 publications

(4 citation statements)

References 54 publications

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“…Almost no formation of • OOH radical (Scheme 2; d → e) is probably because the superoxo radical is rapidly reduced (d → f) due to the stabilization of endoperoxide species on the C1 and N4 positions of the triazine ring, as often observed for related anthracene systems. 47,48 This thus suppresses one-electron reduction of O 2 , thus promoting selective two-electron reduction.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C₃N₄) Photocatalyst Activated by Visible Light

et al. 2014

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Photocatalytic production of hydrogen peroxide (H 2 O 2 ) on semiconductor catalysts with alcohol as a hydrogen source and molecular oxygen (O 2 ) as an oxygen source is a potential method for safe H 2 O 2 synthesis because the reaction can be carried out without the use of explosive H 2 /O 2 mixed gases. Early reported photocatalytic systems, however, produce H 2 O 2 with significantly low selectivity (∼1%). We found that visible light irradiation (λ > 420 nm) of graphitic carbon nitride (g-C 3 N 4 ), a polymeric semiconductor, in an alcohol/water mixture with O 2 efficiently produces H 2 O 2 with very high selectivity (∼90%). Raman spectroscopy and electron spin resonance analysis revealed that the high H 2 O 2 selectivity is due to the efficient formation of 1,4-endoperoxide species on the g-C 3 N 4 surface. This suppresses one-electron reduction of O 2 (superoxide radical formation), resulting in selective promotion of two-electron reduction of O 2 (H 2 O 2 formation).

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Section: ■ Results and Discussionmentioning

confidence: 99%

Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C₃N₄) Photocatalyst Activated by Visible Light

et al. 2014

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“…The amount of exact Hartree–Fock exchange included in hybrid functionals given by the parameters n E appears decisive in order to match the ab initio reference value. It has been recently suggested that a percentage of exact exchange of 32% is ideal, after comparison to CASPT2/CASSCF reference although this determination holds specifically for phenyl-substituted anthracene . This calibration is likely to be highly system dependent, all the more since guanine propensity to stabilize cationic charges is related to the presence of aromatic nitrogens.…”

Section: Resultsmentioning

confidence: 99%

Stability of the Guanine Endoperoxide Intermediate: A Computational Challenge for Density Functional Theory

2014

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The addition of singlet molecular oxygen (1)O2 onto guanine is a most important and deleterious reaction in biological damage. We assess the efficiency of density functional theory for evaluating the respective stabilities of two intermediates that can form upon (1)O2 addition: a charge-separated adduct with a peroxide anion at the C8 position of guanine, and the corresponding cyclic endoperoxide across the 4,8-bond, of the imidazole ring. The reference post Hartree-Fock SCS-MP3/aug-cc-pVTZ//MP2/DZP++ level of theory provides an unambiguous assignment in favor of the endoperoxide intermediate, based on implicitly solvated structures, by -8.0 kcal·mol(-1). This value is taken as the reference for a systematic and extended benchmarck performed on 58 exchange--correlation functionals. While B3LYP remains commonly used for studying oxidative DNA lesions, we prove that the stability of the peroxide anion is overestimated by this functional, but also by other commonly used exchange-correlation functionals. The significant error (ca. +3 kcal·mol(-1) over a representative set of 58 functionals) arises from overdelocalization but also from the description of the dynamic correlation by the density functional. The significantly improved performance of several recently proposed functionals, including range-separated hybrids such as LC-BLYP, is outlined. We believe that our results will be of great help to further studies on the versatile chemistry of singlet oxygen-induced DNA damage, where complex reaction mechanisms are required to be depicted at a quantum level.

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“…Alternatively, for the same computational effort as in a CASSCF calculation, RASSCF allows for extending the number of active orbitals by restricting the excitation level and therefore can be used in larger systems or those demanding larger active spaces. Recently, the performance of RASPT2/RASSCF has been benchmarked in a number of organic molecules 11,17,18 and was shown to provide accurate results.…”

Section: Introductionmentioning

confidence: 99%

“…30−33 Excited state gradients are fundamental to exploring potential energy surfaces, e.g., in light-induced processes, but also are the main ingredients for optical quantity in emission and resonance Raman (RR) spectroscopy, which is extremely useful in providing relationships between the geometrical structures and the electronic character of the states. 18,29,34 In particular, the RR intensities of the vibrational modes are directly correlated to the excited state gradients in the Franck−Condon (FC) region. Thus, the comparison of simulated and experimental RR spectra provides a unique scenario to evaluate the accuracy of calculated excited state gradients.…”

Section: Introductionmentioning

confidence: 99%

An Assessment of RASSCF and TDDFT Energies and Gradients on an Organic Donor–Acceptor Dye Assisted by Resonance Raman Spectroscopy

Kupfer

Guthmuller

González

2012

J. Chem. Theory Comput.

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The excitation energies and gradients in the ground and the first excited state of a novel donor-(π-bridge)-acceptor 4-methoxy-1,3-thiazole-based chromophore were investigated by means of MS-RASPT2/RASSCF and TDDFT in solution. Within both methods, the excitation energies strongly depend on the employed equilibrium structures, whose differences can be rationalized in terms of bond length alternation indexes. It is shown that functionals with an increased amount of exact exchange provide the best estimation of the ground and excited state properties. While B3LYP fails to predict the excitation energies due to its intrinsic problems in describing charge transfer (CT) states, the long-range corrected CAM-B3LYP and M06-2X functionals deliver good agreement with the experimental UV/vis absorption spectrum. The calculation of resonance Raman intensity patterns is used to discern which ground and excited state gradients are best. The results clearly evidence that both CAM-B3LYP and RASSCF excited state gradients and energies in combination with CAM-B3LYP ground state gradients are appropriate to describe the CT state of this push-pull chromophore.

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Singlet oxygen generation versus O–O homolysis in phenyl-substituted anthracene endoperoxides investigated by RASPT2, CASPT2, CC2, and TD-DFT methods

Cited by 5 publications

References 54 publications

Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C₃N₄) Photocatalyst Activated by Visible Light

Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C₃N₄) Photocatalyst Activated by Visible Light

Stability of the Guanine Endoperoxide Intermediate: A Computational Challenge for Density Functional Theory

An Assessment of RASSCF and TDDFT Energies and Gradients on an Organic Donor–Acceptor Dye Assisted by Resonance Raman Spectroscopy

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Singlet oxygen generation versus O–O homolysis in phenyl-substituted anthracene endoperoxides investigated by RASPT2, CASPT2, CC2, and TD-DFT methods

Cited by 5 publications

References 54 publications

Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C3N4) Photocatalyst Activated by Visible Light

Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C3N4) Photocatalyst Activated by Visible Light

Stability of the Guanine Endoperoxide Intermediate: A Computational Challenge for Density Functional Theory

An Assessment of RASSCF and TDDFT Energies and Gradients on an Organic Donor–Acceptor Dye Assisted by Resonance Raman Spectroscopy

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Product

Resources

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Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C₃N₄) Photocatalyst Activated by Visible Light

Highly Selective Production of Hydrogen Peroxide on Graphitic Carbon Nitride (g-C₃N₄) Photocatalyst Activated by Visible Light