Characterization of Excited States of Quinones and Identification of Their Deactivation Pathways

Barbafina, Arianna; Latterini, Loredana; Carlotti, Benedetta; Elisei, Fausto

doi:10.1021/jp911734x

Cited by 28 publications

(33 citation statements)

References 26 publications

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“…23,24 The present system, however, is significantly perturbed, electronically by the sulfur substituent and geometrically by the bulky trimethyl lock system. The long lifetime of the transient from the flash photolysis studies, and the fact that it is quenched efficiently by oxygen, suggest that the transient is a triplet.…”

Section: Triplet Sensitization/quenching Studiesmentioning

confidence: 76%

“…3 permits calculation of the efficiency for intersystem crossing by the quinone ( ߶ ௦ , Table 1). Although quinones typically form triplets with high yields, 23 the efficiencies observed in this system do not exceed 10%, likely due to the electronic and steric effects of the sulfide and trimethyl-lock substituents, respectively.…”

Section: Triplet Sensitization/quenching Studiesmentioning

confidence: 86%

“…29 The dominant fate of 1 9 is nonemissive return to the ground state (> 90% efficiency), again in contrast to simpler benzoquinones, which typically undergo intersystem crossing to the triplet with near unit efficiency. 23 The triplet state does form with low efficiency, and again it is not like the triplet of a typical benzoquinone. Shown in Figure 9 are spin-density plots for relevant species computed using DFT M06/6-311++G**, where the trimethyl lock side chain is not displayed for clarity but is included in the calculation.…”

Section: Mechanistic Interpretationmentioning

confidence: 98%

“…We have been unable to observe luminescence from 1a, either in fluid media at room temperature or at 77K in a frozen matrix, as is typical of quinones. [23][24][25][26][27][28][29][30] Figure 3. Absorbance spectrum of 1a in methanol.…”

Section: Introduction and Synthesismentioning

confidence: 99%

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Mechanistic Studies of the Photoinduced Quinone Trimethyl Lock Decaging Process

et al. 2017

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Mechanistic studies of a general reaction that decages a wide range of substrates on exposure to visible light are described. The reaction involves a photochemically initiated reduction of a quinone mediated by an appended thioether. After reduction, a trimethyl lock system incorporated into the quinone leads to thermal decaging. The reaction could be viewed as an electron-transfer initiated reduction of the quinone or as a hydrogen abstraction -Norrish Type II -reaction. Product analysis, kinetic isotope effects, stereochemical labeling, radical clock, and transient absorption studies support the electron transfer mechanism. The differing reactivities of the singlet and triplet states are determined, and the ways in which this process deviates from typical quinone photochemistry are discussed. The mechanism suggests strategies for extending the reaction to longer wavelengths that would be of interest for applications in chemical biology and in a therapeutic setting.

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Section: Triplet Sensitization/quenching Studiesmentioning

confidence: 76%

Section: Triplet Sensitization/quenching Studiesmentioning

confidence: 86%

Section: Mechanistic Interpretationmentioning

confidence: 98%

Section: Introduction and Synthesismentioning

confidence: 99%

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Mechanistic Studies of the Photoinduced Quinone Trimethyl Lock Decaging Process

et al. 2017

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“…[49,50] The 400 nm excitation pulses of about 60 fs were generated by an amplified Ti :Sapphire laser system (Spectra Physics, Mountain View,C A). [49,50] The 400 nm excitation pulses of about 60 fs were generated by an amplified Ti :Sapphire laser system (Spectra Physics, Mountain View,C A).…”

Section: Photophysical Measurementsmentioning

confidence: 99%

Efficient Excited‐State Symmetry Breaking in a Cationic Quadrupolar System Bearing Diphenylamino Donors

et al. 2015

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We report a joint experimental and theoretical investigation of a quadrupolar D-π-A(+) -π-D system, the electron donors being diphenylamino groups and the electron acceptor being a methylpyridinium, in comparison with the dipolar D-π-A(+) system. The emission spectra of the two compounds overlap in all the investigated solvents. This finding could be rationalized by TD-DFT calculations: the LUMO-HOMO molecular orbitals involved in the emission transition are localized on the same branch of the quadrupolar structure that becomes the fluorescent portion, corresponding to that of the single-arm compound. Excited-state symmetry breaking has been rarely observed for quadrupolar systems showing negative solvatochromism and is here surprisingly revealed, even in low polarity solvents. Femtosecond transient absorption measurements revealed that an efficient photoinduced intramolecular charge transfer takes place in the quadrupolar chromophore, more efficient than in its dipolar analogue. This result is promising in view of the application of these compounds as novel two-photon absorbing materials.

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Blue Electrofluorescence Resulting from Exergonic Harvesting of Triplet Excitons

Ihn

Sim

et al. 2019

Advanced Optical Materials

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Advances in electroluminescence demand the development of emissive molecules capable of utilizing all of the electrogenerated excitons. Here, a molecular strategy to harvest the excitons without relying on late transition metals or thermal activation is designed and evaluated. The key process deployed is an exergonic, El-Sayed rule-allowed reverse intersystem crossing (ES-rISC) from the triplet n-π * transition state to the singlet π-π * transition state, followed by fluorescent decay of the latter. To demonstrate the strategy, a series of fluorescent molecules consisting of a 9,10-diphenylanthracene core and different carbonyl n-π * units (SY compounds) is created. The compounds display a strong blue fluorescence emission with high photoluminescence quantum yields of up to 0.93. Multilayer organic electroluminescence devices containing the SY compounds exhibit maximum external quantum efficiencies greater than that obtained from a singlet-exciton-only control device. This improvement is due to their capacity to utilize triplet excitons for fluorescence emission. The studies demonstrate that exergonic ES-rISC can serve as a promising pathway for creating inexpensive and tractable organic dopants for high-efficiency electroluminescence.

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Characterization of Excited States of Quinones and Identification of Their Deactivation Pathways

Cited by 28 publications

References 26 publications

Mechanistic Studies of the Photoinduced Quinone Trimethyl Lock Decaging Process

Mechanistic Studies of the Photoinduced Quinone Trimethyl Lock Decaging Process

Efficient Excited‐State Symmetry Breaking in a Cationic Quadrupolar System Bearing Diphenylamino Donors

Blue Electrofluorescence Resulting from Exergonic Harvesting of Triplet Excitons

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