Influence of triplet—triplet excitation transfer on the decay function of donor luminescence

Kobashi, Harumichi; Morita, Tomoaki; Mataga, Noboru

doi:10.1016/0009-2614(73)80070-3

Cited by 35 publications

(12 citation statements)

References 11 publications

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“…The L value found here is smaller than that found for triplet-triplet energy transfer between the ir-electron orbitals of some aromatic chromophores (Kobashi et al, 1973;Strambini and Galley, 1975) or for one-electron transfers (Alexandrov et al, 1978, and the references therein). Following Marcus' nomenclature (Marcus and Sutin, 1984) for one-electron transfers and writing the exponential distance dependence in Eq.…”

Section: -2contrasting

confidence: 73%

Distance dependence of the tryptophan-disulfide interaction at the triplet level from pulsed phosphorescence studies on a model system

Lee

Galley

1989

Biophysical Journal

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In the present study the distance dependence of tryptophan-disulfide interaction is examined with a view to both utilizing the interaction as a more quantitative indicator of subtle conformational changes in proteins as well as elucidating the interaction mechanism. To examine perturbations specifically at the indole triplet level 2-(3-indolyl)-ethyl phenyl ketone (IEPK) in which excitation is transferred with high efficiency to the triplet state of the indole moiety was employed. Phosphorescence decays of IEPK excited by a laser pulse in 70/30 (vol/vol) ethanolether at 77 K were measured in the presence of various concentrations of simple disulfides. The nonexponential phosphorescence decays arising from a distribution of fixed chromophoreperturber separations and the steady-state quenching of IEPK were accounted for with an exponential dependence of the quenching rate constant with distance. The small effective Bohr radius (0.8 A) that appears in the exponent emphasizes the localized nature of the interaction. Comparison of the triplet quenching rate constant obtained at quencher contact with IEPK to that estimated in proteins suggests a dependence on the triplet energy of the indole moiety and an endothermic nature for the quenching process. The study predicts that in proteins tryptophan-disulfide interactions are very localized in nature and should give rise to detectable anomalous decays only out to 2 A beyond van der Waals contact between the interacting partners.

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Section: -2contrasting

confidence: 73%

Distance dependence of the tryptophan-disulfide interaction at the triplet level from pulsed phosphorescence studies on a model system

Lee

Galley

1989

Biophysical Journal

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“…L has been estimated to be 1 &12, 48 For approach to the ?r face of the azoalkane we can calculate the difference in R when the alkyl group is n-butyl or tert-butyl. Using van der Waals radii of 2.23 A for meth lene and 3.15 A for a tertk,, difference of 6.3, or a k q difference of about 4.5, applying eq 1 .45, 50 The steric factors for the three aromatic triplet sensitizers bracket the predicted value, and the steric factors for the ketone triplets all fall very close to that value (see Table 111).…”

Section: Discussionmentioning

confidence: 99%

Steric effects in singlet and triplet electronic energy transfer to azo compounds

Wamser¹,

Medary²,

Kochevar³

et al. 1975

J. Am. Chem. Soc.

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Rate constants have been determined for the solution-phase quenching of singlet and triplet excited states of a variety of sensitizers (aromatic hydrocarbons, aryl and alkyl ketones, a-diketones) by a series of azo compounds with varying steric properties. Both singlet and triplet quenching are attributed to electronic energy transfer by the collisional, electronexchange mechanism. Steric hindrance to exothermic triplet energy transfer is significant, with azo-n-butane a better acceptor than azo-tert-butane by a factor of 3.6-10.7. Steric hindrance to singlet energy transfer is less pronounced (comparable steric factors are 1.7-2.9), apparently because diffusion rather than energy transfer is rate limiting in solution. For a given donor-acceptor pair, singlet energy transfer is two to three times faster than triplet energy transfer. The triplet energy level of the azobutanes is estimated to be 53 f 1 kcal/mol. Bimolecular electronic energy transfer reactions may D * + A -D + A *proceed by at least three different r n e~h a n i s m s :~.~ (1) longrange resonance energy transfer, which acts over distances up to about 50 8, by dipole-dipole interactions; (2) shortrange collisional energy transfer, which requires electronexchange interactions between the donor and acceptor molecular orbitals; (3) radiative energy transfer, involving donor emission and reabsorption of the photon by the acceptor. For triplet electronic energy transfer, the individual transitions of both the donor and the acceptor are spin-forbidden, and only the collisional electron-exchange mechanism is operative. Singlet electronic energy transfers have been demonstrated to proceed by all of the mechanisms above.Given the necessity of a collision for electron-exchange energy transfer, steric hindrance might be expected whenever the donor and/or acceptor chromophores are surrounded by bulky groups. In fact, steric hindrance to energy transfer has only infrequently been Studies which have specifically sought steric hindrance to energy transfer have produced both positive2-" and results. We have undertaken a systematic study of rates of electronic energy transfer from a variety of sensitizers to a series of azo compounds with varying steric properties. Azo compounds were chosen as the main substrates for this study because (1) they have low triplet and singlet energy levels and therefore can efficiently quench a large number of sensitizer^;'^-'^ (2) the azo chromophore is small and highly localized, and thus can be effectively blocked by steric interactions; (3) azo compounds are readily synthesized with various alkyl groups located on either side of the chromophore; (4) the photochemical behavior of azo compounds has been rather thoroughly s t~d i e d ; '~,~~ and (5) singlet energy transfer to azo compounds has been shown t o proceed by the electron-exchange mechanism.16 Experimental SectionMaterials. All the azo compounds were prepared by the method of Stowell," distilled, and determined to be >95% pure by gas chromatographic analysis. Azo-...

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“…for the concentration of benzophenone triplet, [3BP*], at B = Ct"V2/(2[Q]) = 4R2(irD)xl2N (10) Thus the curve fitting for experimental phosphorescence decay exemplified in Figure 1 with eq 7 by the leastsquares method will determine the values of and C for every curve. This provides the basis for an estimation of kinetic parameters such as rate constant for spontaneous deactivation of benzophenone triplet (fe0), quenching radius (B), and the diffusion coefficient for the benzophenone carbonyl and an ester carbonyl group (D).…”

Section: Methodsmentioning

confidence: 99%

Photochemistry in polymer solids. 3. Kinetics for nonexponential decay of benzophenone phosphorescence in acrylic and methacrylic polymers

Horie¹,

Morishita²,

Mita³

1984

Macromolecules

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The laser-pulse-excited phosphorescence of benzophenone molecularly dispersed in poly(methyl methacrylate) (PMMA), poly(isopropyl methacrylate) (PIPMÁ), and poly(methyl acrylate) (PMA) decays nonexponentially for the temperature range ß< T < Tg, while it decays single-exponentially for both T < ß and T > Tg of each polymer. The kinetics for the nonexponential decay of benzophenone triplet in these polymer matrices at 80-433 K are given by using the diffusion-controlled rate coefficient with a time-dependent transition term for the dynamic quenching process of benzophenone triplet by side-chain ester groups of the matrix polymers. The resulting kinetic parameters, namely the reciprocal lifetime (l/ ), a factor characteristic of the deviation from single-exponential decay (C), and the diffusion coefficient of interacting groups (D), reflect molecular motion at the glass transition (Tg) and other secondary transitions (Ta. and ß) of the matrix polymers.

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Influence of triplet—triplet excitation transfer on the decay function of donor luminescence

Cited by 35 publications

References 11 publications

Distance dependence of the tryptophan-disulfide interaction at the triplet level from pulsed phosphorescence studies on a model system

Distance dependence of the tryptophan-disulfide interaction at the triplet level from pulsed phosphorescence studies on a model system

Steric effects in singlet and triplet electronic energy transfer to azo compounds

Photochemistry in polymer solids. 3. Kinetics for nonexponential decay of benzophenone phosphorescence in acrylic and methacrylic polymers

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