Abstract
Pathways of electron transfer reaction between p-nitroacetophenone (p-NAP) and ascorbic acid (AA) photosensitized by dimers of 3,3′-disulfopropyl-5,5′-dichlorothiacyanine triethylammonium (TC) and 3,3′-disulfopropyl-5,5′-dichloro-9,11-[ββ-dimethyltrimethylene]thiadicarbocyanine triethylammonium (TDC) are considered. In aqueous solution the dyes are present as an equilibrated mixture of monomers (M−) and dimers (M22−). In contrast to monomers, the dimers of TC are characterized by a noticeable yield of intersystem crossing, whereas for TDC the triplet-triplet absorption of both monomers and dimers is easily observed upon ns-laser pulse. In the presence of p-NAP and AA the triplet state of the dimers of both dyes is mostly quenched by p-NAP yielding the radical pair [M2−˙p-NAP−˙] with subsequent dissociation of M2−˙ into M− and M˙ followed by one-electron reduction of M˙ by AA. These steps constitute a pathway of photosensitization by the dimers. For TDC an additional pathway of photosensitization was found to occur. The primary step consists of electron transfer in the excited singlet state of the dimer resulting in the formation of the radicals M˙ and M2−˙. The next steps involve one-electron reduction of M˙ by AA and one-electron oxidation of M2−˙ by p-NAP which results in the formation of M− followed by dimerization.
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A. K. Chibisov, Electron transfer in photochemical reactions Usp. Khim. 1981 50 1169–1196.
A. K. Chibisov, Electron transfer in photochemical reactions Russ. Chem. Rev. 1981 50 615–640.
A. Weller, Photoinduced electron-transfer in solution - exciplex and radical ion-pair formation free enthalpies and their solvent dependence Z. Phys. Chem. 1982 133 93–98.
R. A. Marcus and N. Sutin, Electron transfers in chemistry and biology Biochim. Biophys. Acta 1985 811 265–322.
G. J. Kavarnos and N. J. Turro, Photosensitization by reversible electron transfer: theories, experimental evidence, and examples Chem. Rev. 1986 86 401–449.
M. A. Fox and M. Chanon (ed.), Photoinduced Electron Transfer, Elsevier, Amsterdam, 1988.
G. J. Kavarnos, Fundamentals of Photoinduced Electron Transfer, VCH Publishers, New York, 1993.
V. E. Korobov and A. K. Chibisov, Primary photoprocesses in colorant molecules Usp. Khim 1983 521 43–71 Russ. Chem. Rev. 1983 52 27–53.
A. K. Chibisov, G. V. Zakharova, V. L. Shapovalov, A. I. Tolmachev, Yu. L. Briks, Yu. K. Slominskii, Flash-photolysis of polymethine dyes with various counterions in nonpolar media Khim. Vys. Energii. 1995 29 211–218 High Energy Chem. 1995 29 192–198.
A. K. Chibisov, S. V. Shvedov, H. Görner, Photosensitization processes in dicarbocyanine dyes induced by energy transfer: delayed fluorescence, trans → cis isomerization and electron transfer J. Photochem. Photobiol., A 2001 141 39–45.
E. K. L. Yeow, L. D. Slep, A. K. Chibisov and S. E. Braslavsky, Photoinduced electron-transfer reaction between the erythrosin dianion and Mo(CN)84− in the presence of various cations. The first example of enthalpy-enthropy compensation J. Phys. Chem. A 2003 1071 439–446.
T. H. James (Ed.), The Theory of the Photographic Processes, 4th ed., Macmillan, New York, 1977.
A. H. Herz, Dye-dye Interactions of cyanines in solution and at AgBr surfaces Photogr. Sci. Eng. 1974 18 323–335.
B. I. Shapiro, Molecular assemblies of polymethine dyes Usp. Khim. 2006 751 484–510 Russ. Chem. Rev. 2006 75 433–456.
S. Kirstein and S. Daehne, J-aggregates of amphiphilic cyanine dyes: self-organization of artificial light harvesting complexes Int. J. Photoenergy 2006 20363 1–21.
F. Würthner, T. E. Kaiser, C. R. Saha-Möller, J-aggregates: from serendipitous discovery to supramolecular engineering of functional materials Angew. Chem., Int. Ed. 2011 50 3376–3410.
A. K. Chibisov, T. D. Slavnova, H. Görner, Electron transfer reactions induced by the triplet state of thiacarbocyanine dimers Chem. Phys. 2004 299 1–10.
A. K. Chibisov, T. D. Slavnova, H. Görner, Dimerization kinetics of thiacarbocyanine dyes by photochemically induced concentration jump Chem. Phys. Lett. 2004 386 301–306.
A. K. Chibisov, T. D. Slavnova, G. V. Zakharova, H. Görner, Primary processes of photosensitized redox reaction of dimers of thiacarbocyanine dyes Khim. Vysok Energ 2007 41 395–401 High Energy Chem. 2007 41 344–349.
A. K. Chibisov, G. V. Zakharova, H. Görner, Photoprocesses of thiamonomethinecyanine monomers and dimers Phys. Chem. Chem. Phys. 2001 3 44–49.
D. W. Whillans, The reactions of p-nitroacetophenone with H and OH radicals Radiat. Phys. Chem. 1977 10 335–340.
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This article is published as part of a themed issue in honour of Professor Kurt Schaffner on the occasion of his 80th birthday.
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Chibisov, A.K., Zakharova, G.V. Pathways of electron transfer photosensitized by thiacyanine dimers. Photochem Photobiol Sci 11, 893–897 (2012). https://doi.org/10.1039/c1pp05273j
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DOI: https://doi.org/10.1039/c1pp05273j