Deuterium isotope effects on the 1T .far. 0S radiationless decay rate in stilbene

Saltiel, Jack; D'Agostino, Joan T.; Herkstroeter, William G.; Saint-Ruf, G.; Buu‐Hoï, Ng. Ph.

doi:10.1021/ja00789a022

Cited by 39 publications

(21 citation statements)

References 6 publications

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“…In glassy media at 77 K torsional excursions to twisted geometries are inhibited and decay is primarily from nearly planar triplets in which transoid geometries about S 0 double bonds are maintained. 7, 8 As expected, decay rate constants in diethyl ether-isopentane-ethanol (5 : 5 : 2, EPA) increase with decreasing T 1 -S 0 energy gap, Table 1. 7 The opposite lifetime trend is observed in fluid hydrocarbon solution at ambient T.…”

Section: Introductionsupporting

confidence: 69%

Triplet and ground state potential energy surfaces of 1,4-diphenyl-1,3-butadiene: theory and experiment

Saltiel

Dmitrenko

Pillai

et al. 2008

Photochem Photobiol Sci

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Relative energies of the ground state isomers of 1,4-diphenyl-1,3-butadiene (DPB) are determined from the temperature dependence of equilibrium isomer compositions obtained with the use of diphenyl diselenide as catalyst. Temperature and concentration effects on photostationary states and isomerization quantum yields with biacetyl or fluorenone as triplet sensitizers with or without the presence of O(2), lead to significant modification of the proposed DPB triplet potential energy surface. Quantum yields for ct-DPB formation from tt-DPB increase with [tt-DPB] revealing a quantum chain process in the tt --> ct direction, as had been observed for the ct --> tt direction, and suggesting an energy minimum at the (3)ct* geometry. They confirm the presence of planar and twisted isomeric triplets in equilibrium (K), with energy transfer from planar or quasi-planar geometries (quantum chain events from tt and ct triplets) and unimolecular decay (k(d)) from twisted geometries. Starting from cc-DPB, varphi(cc-->tt) increases with increasing [cc-DPB] whereas varphi(cc-->ct) is relatively insensitive to concentration changes. The concentration and temperature dependencies of the decay rate constants of DPB triplets in cyclohexane are consistent with the mechanism deduced from the photoisomerization quantum yields. The experimental DeltaH between (3)tt-DPB* and (3)tp-DPB*, 2.7 kcal mol(-1), is compared with the calculated energy difference [DFT with B3LYP/6-31+G(d,p) basis set]. Use of the calculated DeltaS = 4.04 eu between the two triplets gives k(d) = (2.4-6.4) x 10(7) s(-1), close to 1.70 x 10(7) s(-1), the value for twisted stilbene triplet decay. Experimental and calculated relative energies of DPB isomers on the ground and triplet state surfaces agree and theory is relied upon to deduce structural characteristics of the equilibrated conformers in the DPB triplet state.

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Section: Introductionsupporting

confidence: 69%

Triplet and ground state potential energy surfaces of 1,4-diphenyl-1,3-butadiene: theory and experiment

Saltiel

Dmitrenko

Pillai

et al. 2008

Photochem Photobiol Sci

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“…With respect to the latter, the involvement of vinylic out-of-plane C-H vibrations as inducing modes in enhancing intersystem crossing probably accounts for the positional specificity of the effect of deuterium substitution on the lifetime of perpendicular stilbene triplets, 3 p*. 6,81 The much longer lifetime of 1 p* of 1,1′-biindanylidene relative to 1 p* of stilbene 80 was an early indication that vinylic Hs also play an important role in facilitating 1 p* decay. Recent transient absorption observations on the α,α′dimethyl-and α,α′-diethylstilbenes provide convincing confirmation of this proposition.…”

Section: Photochemical and Photobiological Sciences Papermentioning

confidence: 99%

Competing adiabatic and nonadiabatic pathways in the cis–trans photoisomerization of cis-1,2-di(1-methyl-2-naphthyl)ethene. A zwitterionic twisted intermediate

Saltiel

Kumar

Redwood

et al. 2014

Photochem Photobiol Sci

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Identical fluorescence lifetimes and spectra of cis- and trans-1,2-di(1-methyl-2-naphthyl)ethene reveal an adiabatic cis → trans photoisomerization pathway that accounts for a significant fraction of observed cis → trans photoisomerization quantum yields. The fluorescence quantum yields of both isomers decrease as the solvent is changed from methylcyclohexane to the more polarizable toluene or to the more polar acetonitrile and there is a corresponding increase in the photoisomerization quantum yield in the trans → cis direction. The pronounced solvent dependence of the contribution of the adiabatic pathway to cis → trans photoisomerization--methylcyclohexane (70%), toluene (45%), acetonitrile (31%)--is consistent with the participation of a zwitterionic twisted intermediate, (1)p*, on the singlet excited state surface which is stabilized as the polarizability and/or polarity of the solvent is increased. Solvent stabilization of (1)p* favours the nonadiabatic photoisomerization pathways of both isomers and diminishes the cis → trans adiabatic pathway.

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“…From the apparent correspondence between the growth of the HNS photoproduct at 500 nm and the decay of the HNS and deuterated HNS transient absorptions at 440 nm (Figure 7), it is considered likely that the growth of the photoproduct is related to the decay of the short-lived species at 440 nm. It has been reported that deuteration of the ethylenic positions on transstilbene increases the triplet-state lifetime by 30% 41 The absence of an observable increase in the transient lifetime for fully deuterated HNS suggests that the short-lived 440-nm absorbing transient species is not an excited triplet state. No effect of oxygen was observed on the 440-nm transient decay.…”

Section: Resultsmentioning

confidence: 98%

Influence of steric effects on the excited triplet-state lifetime of 2,2'-dinitrostilbene and 2,2',4,4',6,6'-hexanitrostilbene in acetonitrile solution

Smit¹

1992

J. Phys. Chem.

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Deuterium isotope effects on the 1T .far. 0S radiationless decay rate in stilbene

Cited by 39 publications

References 6 publications

Triplet and ground state potential energy surfaces of 1,4-diphenyl-1,3-butadiene: theory and experiment

Triplet and ground state potential energy surfaces of 1,4-diphenyl-1,3-butadiene: theory and experiment

Competing adiabatic and nonadiabatic pathways in the cis–trans photoisomerization of cis-1,2-di(1-methyl-2-naphthyl)ethene. A zwitterionic twisted intermediate

Influence of steric effects on the excited triplet-state lifetime of 2,2'-dinitrostilbene and 2,2',4,4',6,6'-hexanitrostilbene in acetonitrile solution

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