Radiationless decay of the second excited singlet states of aromatic thiones: Experimental verification of the energy gap law

Maciejewski, Andrzej; Safarzadeh–Amiri, Ali; Verrall, R. E.; Steer, Ronald P.

doi:10.1016/0301-0104(84)85054-5

Cited by 62 publications

(30 citation statements)

References 49 publications

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“…This value is about 15 times higher than for S 2 ‐XT in CCl 4 , for which τ

_{S_{2}}

= 38 ps (26). Such a large difference reflects the fact that the energy of S 2 ‐DMTU is much greater than that of XT (24). The obtained value of k s testifies to a high reactivity of the thiocarbonyl group of S 2 ‐DMTU.…”

mentioning

confidence: 99%

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Taras-Goślińska

Wenska

Skalski

et al. 2007

Photochemistry and Photobiology

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Intramolecular processes of deactivation of 1,3‐dimethyl‐4‐thiouracil (DMTU) from the second excited singlet (S2) (π, π*) and the lowest excited triplet (T1) (π, π*) states have been studied using perfluoro‐1,3‐dimethylcyclohexane (PFDMCH) as a solvent. The spectral and photophysical (PP) properties of DMTU in CCl4, hexane and water have also been described. For the first time, the fluorescence from S2 state DMTU has been observed. The picosecond lifetime of DMTU in the S2 state (τ S 2) in PFDMCH has been proposed to be determined by a very fast intramolecular reversible process of hydrogen abstraction from the ortho methyl group by the thiocarbonyl group. The shortening of τ S 2 in CCl4 is interpreted to be caused by the intermolecular interactions between DMTU (S2) and the solvent. Results of the phosphorescence decay as a function of DMTU concentration were analyzed using the Stern–Volmer formalism, which enabled determination of the intrinsic lifetime of the T1 state (τ0 T 1) and rate constants of self‐quenching (ksq). The lifetimes, τ0 T 1, of DMTU in PFDMCH and CCl4 are much longer than the values hitherto obtained in more reactive solvents. The PP properties of DMTU both in the S2 and T1 states have been shown to be determined by the thiocarbonyl group.

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“…This value is about 15 times higher than for S 2 ‐XT in CCl 4 , for which τ

_{S_{2}}

mentioning

confidence: 99%

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Taras-Goślińska

Wenska

Skalski

et al. 2007

Photochemistry and Photobiology

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“…As solvents we used: perfluoro1,3-dimethylcyclohexane, PFDMCH, 3-methylpentane, 3MΡ, and benzene, C6H6. As we have shown many times [2][3][4][5][6][7][8][9][10]29], only the use of perfluoroalkanes as solvents ensures the possibility of investigating intramolecular properties of thiones in the S2-and Τ1-states. The use of 3MΡ, a typical aliphatic hydrocarbone, ensures that the interactions with thioketones in the S2 and T1 -state are limited to the reaction of hydrogen abstraction only [5, 7-10, 15, 16] as the universal (physical) interactions are in it negligibly weak [5, 8-10, 29, 30].…”

Section: Resultsmentioning

confidence: 99%

“…A characteristic feature distinguishing the whole group of thioketones is strong fluorescence from the S2-state occurring with violation of the (527) classical Kasha rule [1]. For certain aromatic thioketones in perfluoroalkanes the quantum yield of this fluorescence reaches φ F 10 -1 which is the highest value ever measured in solution for fluorescence from higher energy states [2].…”

Section: Introductionmentioning

confidence: 97%

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Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S₂- and T₁-States

et al. 1996

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Spectral and photophysical properties of a few aromatic thioketones in their S2-and T1-state, in particular those determined by their interactions with solvents, are discussed. The reasons for a drastically different behaviour of thioketones in interactions with benzene as well as saturated hydrocarbons and perfluoroalkanes are analysed in more detaił. Results of the time-resolved transient absorption measurements in the pico-and nanosecond time scale are given. An analysis of these results proves that a product of the decay of the S2-state of xanthione in benzene is a new transient (τile > 60 ps) individuum which, regarding the system properties and the conditions of the experiment, has been identified as an exciplex in S 2 -state formed as a result of an efficient interaction with benzene molecule. Also in xanthione/alkane systems the involvement of a transient individuum was proved. Most probably, this individuum was a thioketyl radical which could be formed by hydrogen abstraction from a hydrocarbon molecule by xanthione in the S2 -state. Such individua act as intermediates in passing excitation to the triplet states of thioketones and are effective channels of the S2-state decay. The changes observed in the transient absorption spectra of xanthione in C 6 Η6 in the time range of 10 -7 -10 -6 s can be attributed to the formation of an excimer in the T1-state as a result of the T1-state selfquenching.

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“…(i) Apart from the phosphorescence excitation spectrum of jet-cooled PT (6), the triplet manifold of PT has so far only been studied in the condensed phase (7)(8)(9)(10)(11) and recently in a novel theoretical approach concerning spin-forbidden transitions (12). None of the T 1 ← S 0 absorption spectra presented here has been recorded before.…”

Section: Introductionmentioning

confidence: 95%

The T1←S0 Absorption Spectrum of Gaseous 4H-Pyran-4-thione

Ruth

Fernholz

Brint

et al. 2002

Journal of Molecular Spectroscopy

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Radiationless decay of the second excited singlet states of aromatic thiones: Experimental verification of the energy gap law

Cited by 62 publications

References 49 publications

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S₂- and T₁-States

The T1←S0 Absorption Spectrum of Gaseous 4H-Pyran-4-thione

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Radiationless decay of the second excited singlet states of aromatic thiones: Experimental verification of the energy gap law

Cited by 62 publications

References 49 publications

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Intra- and Intermolecular Electronic Relaxation of the Second Excited Singlet and the Lowest Excited Triplet States of 1,3-Dimethyl-4-thiouracil in Solution¶

Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S2- and T1-States

The T1←S0 Absorption Spectrum of Gaseous 4H-Pyran-4-thione

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Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S₂- and T₁-States