Revisiting the Nonadiabatic Process in 1,2-Dioxetane

Farahani, Pooria; Roca‐Sanjuán, Daniel; Zapata, Felipe; Lindh, Roland

doi:10.1021/ct4007844

Cited by 39 publications

(112 citation statements)

References 32 publications

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“…On the basis of the findings obtained in previous works on 1,2-dioxetane, 21,41 the target molecule of the present work is expected to have three decomposition channels, thermal and excited-state singlet and triplet dissociations. Regarding the photochemistry of 1,3-butadiene, experiments have reported a complete absence of fluorescence after UV irradiation, which indicates a fast radiationless decay to the ground state.…”

Section: Introductionmentioning

confidence: 78%

“…In comparison to 1,2-dioxetane, 21 the CASPT2 activation energies for the singlet and triplet chemiluminescence mechanisms are closer. The TS S 0 shows the same amount of energy as 1,2-dioxetane, 25 kcal/mol (see Table 2 of the Ref.…”

Section: Stationary Pointsmentioning

confidence: 87%

“…The TS S 0 shows the same amount of energy as 1,2-dioxetane, 25 kcal/mol (see Table 2 of the Ref. 21 ). The TS T 1 is lower in energy as compared to the TS S 1 , with a difference of 3 kcal/mol; this difference was more than 5 kcal/mol in 1,2-dioxetane.…”

Section: Stationary Pointsmentioning

confidence: 94%

“…21 The very same features apply for the decomposition of Dewar dioxetane. Several relevant structures characterize the mechanism between the reactant and products (see Figure 4): the TS related to the O 1 -O' 1 cleavage on the singlet ground state manifold (TS S 0 ,O 1 −O 1 ) in which the four singlet and four triplet excited states become degenerate with S 0 , the singlet and triplet biradical minima (Min S 1 and Min T 1 ), the triplet TS related to the C 2 -C' 2 bond rupture (TS T 1 ), and the corresponding TS of C 2 -C' 2 cleavage on the singlet excited state (TS S 1 ).…”

Section: Stationary Pointsmentioning

confidence: 98%

“…51 As it was proved in the 1,2-dioxetane study, 21 increasing the size of the basis set to even larger basis sets does not change the qualitative and quantitative aspects of the chemical process, therefore we confined our calculations by using the ANO-RCC triple-ζ quality basis set. For some sets of structures, the use of an imaginary level shift of 0.2 a.u in the CASPT2 computations was necessary in order to remove some intruder-states problems.…”

Section: Computational Detailsmentioning

confidence: 99%

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Theoretical study of the dark photochemistry of 1,3-butadiene via the chemiexcitation of Dewar dioxetane

Farahani

Lundberg

Lindh

et al. 2015

Phys. Chem. Chem. Phys.

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Excited-state chemistry is usually ascribed to photo-induced processes, such as fluorescence, phosphorescence, and photochemistry, or to bio-and chemiluminescence, in which light emission is originated by a chemical reaction. A third class of excited-state chemistry, however, is possible that promotes photochemical phenomena by chemienergizing certain chemical groups without light -chemiexcitation. By studying Dewar dioxetane, which can be viewed as the combination of 1,2-dioxetane and 1,3-butadiene, we show here how the isomerization * To whom correspondence should be addressed † Uppsala ‡ València ¶ UC 3 1 channel that characterizes the photo-induced chemistry of 1,3-butadiene can be reached at a later stage after the thermal decomposition of the dioxetane moiety. Multi-reference multiconfigurational quantum chemistry methods and accurate reaction-path computational strategies were used to determine the reaction coordinate that first decomposes the dioxetane, next transfers non-adiabatically the state from the ground to the excited state, and finally brings the system into the photochemical channel of the 1,3-butadiene group. With the present study, we open a new area of research within computational photochemistry to study chemically-induced excited-state chemistry that is difficult to tackle experimentally due to the short-lived character of the species involved in the process. The findings shall be of relevance to unveil "dark" photochemistry mechanisms which might operate in biological systems in conditions of lack of light to allow reactions that are typical of photo-induced phenomena.

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Section: Introductionmentioning

confidence: 78%

Section: Stationary Pointsmentioning

confidence: 87%

Section: Stationary Pointsmentioning

confidence: 94%

Section: Stationary Pointsmentioning

confidence: 98%

Section: Computational Detailsmentioning

confidence: 99%

See 3 more Smart Citations

Theoretical study of the dark photochemistry of 1,3-butadiene via the chemiexcitation of Dewar dioxetane

Farahani

Lundberg

Lindh

et al. 2015

Phys. Chem. Chem. Phys.

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Molecular Basis of the Chemiluminescence Mechanism of Luminol

Giussani

Farahani

Martínez‐Muñoz

et al. 2019

Chemistry A European J

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Light emission from luminol is probably one of the most popular chemiluminescence reactions due to its use in forensic science, and has recently displayed promising applications for the treatment of cancer in deep tissues. The mechanism is, however, very complex and distinct possibilities have been proposed. By efficiently combining DFT and CASPT2 methodologies, the chemiluminescence mechanism has been studied in three steps: 1) luminol oxygenation to generate the chemiluminophore, 2) a chemiexcitation step, and 3) generation of the light emitter. The findings demonstrate that the luminol double‐deprotonated dianion activates molecular oxygen, diazaquinone is not formed, and the chemiluminophore is formed through the concerted addition of oxygen and concerted elimination of nitrogen. The peroxide bond, in comparison to other isoelectronic chemical functionalities (−NH−NH−, −N−−N−−, and −S−S−), is found to have the best chemiexcitation efficiency, which allows the oxygenation requirement to be rationalized and establishes general design principles for the chemiluminescence efficiency. Electron transfer from the aniline ring to the OO bond promotes the excitation process to create an excited state that is not the chemiluminescent species. To produce the light emitter, proton transfer between the amino and carbonyl groups must occur; this requires highly localized vibrational energy during chemiexcitation.

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Dioxetane Scission Products Unchanged by Mechanical Force

Clough

Sijbesma

2014

ChemPhysChem

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Dioxetane-based force-induced light emission from polymers, or mechanoluminescence, is a powerful new way of characterizing the behavior of polymeric materials under stress. Here, we reveal that breaking the dioxetane mechanically gives strikingly similar products to those formed on thermal activation, with a singlet/triplet ratio of 1:9.9 and a total quantum yield of 9.8%. A sensitized relay scheme ensured high reproducibility in the detection of the short-lived triplet products. In addition to guiding the design of more sensitive mechanoluminescent probes, the similarity in the scission products indicates that once mechanical force releases the steric lock between the adamantyl groups, the dioxetane undergoes scission in a pathway that resembles the thermal process. Excited states are formed only after the main transition state in a region in which the excited- and ground-state surfaces are nearly degenerate, which, thus, accounts for the remarkable similarity in the scission products.

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Revisiting the Nonadiabatic Process in 1,2-Dioxetane

Cited by 39 publications

References 32 publications

Theoretical study of the dark photochemistry of 1,3-butadiene via the chemiexcitation of Dewar dioxetane

Theoretical study of the dark photochemistry of 1,3-butadiene via the chemiexcitation of Dewar dioxetane

Molecular Basis of the Chemiluminescence Mechanism of Luminol

Dioxetane Scission Products Unchanged by Mechanical Force

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