Abstract
Data is presented on the quenching of 9,10-dicyanoanthracene by benzene derivatives in acetonitrile. The quenching occurs via a charge transfer mechanism with the quenching rate constants exhibiting a Rehm–Weller dependence on the free energy change of the electron transfer reaction. The quenching of the prompt fluorescence brings about an increase in the delayed fluorescence of DCA as a result of intersystem crossing in the exciplex, and a modified Wilkinson’s plot has been used to determine the efficiency of triplet formation during the quenching of DCA fluorescence by benzene derivatives. We suggest that intersystem crossing yields in the exciplex are unity, and variations in triplet state yields as a result of singlet state quenching reflect partitioning between exciplex formation and solvent-separated radical ion pair (SSRIP) formation. The data clearly show competition between exciplex formation and SSRIP formation, with the latter becoming dominant when the free energy for electron transfer exceeds the solvent reorganisation energy.
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G. J. Kavarnos, N. J. Turro, Photosensitization by reversible electron transfer: Theories, experimental evidence, and examples, Chem. Rev., 1986, 86, 401.
M. A. Fox, and M. A. Channon, Photoinduced Electron Transfer, Elsevier: Amsterdam, 1988.
D. Rehm and A. Weller, Kinetics of fluorescence quenching by electron and H-atom transfer, Isr. J. Chem., 1970, 8, 259.
A. Weller, Photoinduced electron-transfer in solution—exciplex and radical ion-pair formation free enthalpies and their solvent dependence, Z. Phys. Chem. Wiesbaden, 1982, 133, 93.
A. Weller, Exciplex and radical pairs in photochemical electron-transfer, Pure Appl. Chem., 1982, 54, 1885.
H. Masuhara and N. Mataga, Ionic photo-dissociation of electron-donor—acceptor systems in solution, Acc. Chem. Res., 1981, 14, 312.
N. Mataga, Photochemical charge-transfer phenomena—picosecond laser photolysis studies, Pure Appl. Chem., 1984, 56, 1255.
K. Kikuchi, A new aspect of photoinduced electron-transfer in acetonitrile, J. Photochem. Photobiol., A, 1992, 65, 149.
K. Kikuchi, T. Niwa, Y. Takahashi, H. Ikeda, T. Miyashi and M. Hoshi, Evidence of exciplex formation in acetonitrile, Chem. Phys. Lett., 1990, 173, 421.
K. Kikuchi, Y. Takahashi, M. Hoshi, T. Niwa, T. Katagiri and T. Miyashi, Free enthalpy dependence of free-radical yield of photoinduced electron-transfer in acetonitrile, J. Phys. Chem., 1991, 95, 2378.
I. R. Gould, R. H. Young and S. Farid, Dynamics of photoinduced electron transfer in solution in Honda, K. Photochemical processes in organized molecular systems, Amsterdam, Elsevier Science Publ., 1991, pp. 19–40.
I. R. Gould, R. H. Young, L. J. Mueller and S. Farid, Mechanisms of exciplex formation—roles of superexchange, solvent polarity, and driving-force for electron-transfer, J. Am. Chem. Soc., 1994, 116, 8176.
I. R. Gould, D. Ege, J. E. Moser and S. Farid, Efficiencies of photoinduced electron-transfer reactions—role of the marcus inverted region in return electron-transfer within geminate radical-ion pairs, J. Am. Chem. Soc., 1990, 112, 4290.
I. R. Gould, R. H. Young, R. E. Moody and S. Farid, Contact and solvent-separated geminate radical ions pairs in electron-transfer photochemistry, J. Phys. Chem., 1991, 95, 2068.
W. S. Chung, N. J. Turro, I. R. Gould and S. Farid, Effect of external-pressure on photoinduced electron-transfer reactions in the marcus inverted region, J. Phys. Chem., 1991, 95, 7752.
E. Vauthey, Effect of steric hindrance on the dynamics of charge recombination within geminate ion pairs, J. Phys. Chem. A, 2000, 104, 1804.
E. Vauthey, Investigation of the photoinduced electron transfer reaction between 9,10-dicyanoanthracene and 1-methylnaphthalene in acetonitrile using picosecond transient grating spectroscopy, J. Phys. Chem. A, 1997, 101, 1635.
T. Niwa, K. Kikuchi, N. Matsusita, M. Hayashi, T. Katagiri, Y. Takahashi and T. Miyashi, Solvent effects on photoinduced electron-transfer reactions, J. Phys. Chem., 1993, 97, 11960.
S. Iwai, S. Murata, R. Katoh, M. Tachiya, K. Kikuchi and Y. Takahashi, Ultrafast charge separation and exciplex formation induced by strong interaction between electron donor and acceptor at short distances, J. Chem. Phys., 2000, 112, 7111.
P. Jacques and D. Burget, On the necessity of distinguishing “n” from “π” quenchers in electron transfer studies, J. Photochem. Photob., A, 1992, 68, 165.
P. Jacques, E. Haselbach, A. Henseler, D. Pilloud and P. Suppan, Multiple Rehm-Weller plots in the electron-transfer quenching of singlet excited 9,10-dicyanoanthracene, J. Chem.Soc., Faraday Trans., 1991, 87, 3811.
D. Burget, P. Jacques, E. Vauthey, P. Suppan and E. Haselbach, Marcus inverted region—nature of donor–acceptor pairs and free-ion yields, J. Chem. Soc., Faraday Trans., 1994, 90, 2481.
E. Vauthey, D. Pilloud, E. Haselbach, P. Suppan and P. Jacques, The reliability of free-ion yield in photoinduced electron-transfer reactions—the model system 9,10-dicyanoanthracene biphenyl in acetonitrile, Chem. Phys. Lett., 1993, 215, 264.
E. A. Chandros and J. Ferguson, Absorption and fluorescence of sandwich dimers. Theory of the excimer state, J. Chem. Phys., 1966, 45, 397.
S. E. Mylon, S. N. Smirnov and C. L. Braun, Exciplex dipole moments: Cyanoanthracene acceptors and methyl-substituted benzene donors, J. Phys. Chem. A, 1998, 102, 6558.
A. F. Olea, D. Worrall, F. Wilkinson, S. L. Williams and A. A. Abdel-Shafi, Solvent effects on the photophysical properties of 9,10-dicyanoanthracene, Phys. Chem. Chem. Phys., 2002, 4, 1615.
A. R. Horrocks, A. Kearvell, K. Tickle and F. Wilkinson, Mechanism of fluorescence quenching in solution. Part 2. Quenching by xenon and intersystem crossing efficiencies, Trans. Faraday Soc., 1966, 528, 3393.
C. A. Parker, Delayed Fluorescence and Phosphorescence, ed. A. B. Zahlan, The Triplet State, 1st edn., Cambridge, Cambridge University Press, Cambridge, 1967, pp. 353–390.
Progress in Reaction Kinetics 5, ed. J. B. Birks and G. Porter, Pergamon Press, Oxford, 1970, p. 181.
J. B. Birks, Photophysics of Aromatic Molecules, John Wiley, New York, 1970.
K. Kikuchi, M. Hoshi, T. Niwa, Y. Takahashi and T. Miyashi, Heavy-atom effects on the excited singlet-state electron- transfer reaction, J. Phys. Chem., 1991, 95, 38.
I. R. Gould, R. H. Young, L. J. Mueller, A. C. Albrecht and S. Farid, Electronic-structures of exciplexes and excited charge-transfer complexes, J. Am. Chem. Soc., 1994, 116, 8188.
P. Jacques, X. Allonas, P. Suppan and M. Von Raumer, The interplay between steric hindrance and exergonicity in the rates of excited state quenching, J. Photochem. Photobiol., A, 1996, 101, 183–184.
J. O. Howell, J. M. Goncalves, C. Amatore, L. Klasinc, R. M. Wightman and J. K. Kochi, Electron transfer from aromatic hydrocarbons and their p-complexes with metals. Comparison of the standard oxidation potentials and vertical ionization potentials, J. Am. Chem. Soc., 1984, 106, 3968–3976.
T. N. Inada, C. S. Miyazawa, K. Kikuchi, M. Yamauchi, T. Nagata, Y. Takahashi, H. Ikeda and T. Miyashi, Effects of molecular charge on photoinduced electron transfer, J. Am. Chem. Soc., 1999, 121, 7211–7219.
C. K. Mann and K. K. Barnes, Electrochemical Reactions in Nonaqueous Systems, Marcel Dekker, New York, 1970.
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Dedicated to Professor Jean Kossanyi on the occasion of his 70th birthday.
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Olea, A.F., Worrall, D.R. & Wilkinson, F. Variations in efficiencies of triplet state and exciplex formation following fluorescence quenching of 9,10-dicyanoanthracene due to charge transfer interactions. Photochem Photobiol Sci 2, 212–217 (2003). https://doi.org/10.1039/b207748e
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DOI: https://doi.org/10.1039/b207748e