Photoinduced electron transfer in a phenothiazine-riboflavin dyad assembled by zinc-imide coordination in water

Journal of the American Chemical Society

Volumn 121, Issue 8, 1999, Pages 1681-1687

  König, Burkhard ^a   Pelka, Mario ^a   Zieg, Harald ^a   Ritter, Tobias ^a   Bouas Laurent, Henri ^b   Bonneau, Roland ^b   Desvergne, Jean Pierre ^b  

^a TECHNICAL UNIVERSITY OF BRAUNSCHWEIG   (Germany)

^b CNRS   (France)

Author keywords

[No Author keywords available]

Indexed keywords

10 ( PHENOTHIAZIN 1 YLPROPIONYL) 1,4,7,10 TETRAAZACYCLODODECANE 1,4,7 TRICARBOXYLIC ACID TRI TERT BUTYL ESTER; 3 PHENOTHIAZINE 10 YL 1 (1,4,7,10 TETRAAZA CYCLODODECAN 1 YL)PROPAN 1 ONE ZINC PERCHLORATE; 3 PHENOTHIAZINE 10 YL 1 (1,4,7,10 TETRAAZACYCLODODECAN 1 YL)PROPAN 1 ONE; METHANOL; PHENOTHIAZINE DERIVATIVE; RIBOFLAVIN; UNCLASSIFIED DRUG; WATER;

ARTICLE; CARBON NUCLEAR MAGNETIC RESONANCE; ELECTRON TRANSPORT; HIGH PERFORMANCE LIQUID CHROMATOGRAPHY; HYDROGEN BOND; OXIDATION REDUCTION REACTION; PH; POTENTIOMETRY; PROTEIN ASSEMBLY; PROTEIN SYNTHESIS; SPECTROSCOPY; THERMODYNAMICS;

EID: 0038762769     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9836693     Document Type: Article

References (97)

1. (a) Marcus, R. A. Angew. Chem. 1993, 105, 1161-1172; Angew. Chem., Int. Ed. Engl. 1993, 32, 1111-1122.
2. (a) Marcus, R. A. Angew. Chem. 1993, 105, 1161-1172; Angew. Chem., Int. Ed. Engl. 1993, 32, 1111-1122.
3. (b) Kurreck, H.; Huber, M. Angew. Chem. 1995, 107, 929-947; Angew. Chem., Int. Ed. Engl. 1995, 34, 849-866.
4. (b) Kurreck, H.; Huber, M. Angew. Chem. 1995, 107, 929-947; Angew. Chem., Int. Ed. Engl. 1995, 34, 849-866.
5. (c) Astruc, D. Electron Transfer and Radical Processes in Transition Metal Chemistry; VCH: New York, 1995.
6. (d) Photoinduced Electron Transfer; Fox, M. A., Chanon M., Eds.; Elsevier: Amsterdam, 1988; Parts A-D.
7. (e) Kavarnos, G. J. Fundamentals of Photoinduced Electron Transfer; VCH: Weinheim, 1993.
8. (f) Topics in Current Chemistry; Mattay, J., Ed.; Springer: New York, 1989-1994; Vols. 156, 158, 159, 163, 168, and 169.
9. Recent examples: (a) Flamigni, L.; Barigelletti, F.; Armaroli, N.; Collin, J.-P.; Sauvage, J.-P.; Williams, J. A. G. Chem. Eur. J. 1998, 4, 1744-1754. (b) Wagner, R. W.; Johnson, T. E.; Lindsey, J. S. J. Am. Chem. Soc. 1996, 118, 11166-11180. (c) Osuka, A.; Marumo, S.; Mataga, N.; Taniguchi, S.; Okada, T.; Yamazaki, I.; Nishimura, Y.; Ohno, T.; Nozaki, K. J. Am. Chem. Soc. 1996, 118, 115-168. (d) Sun, L.; Hammarström, L.; Norrby, T.; Berglund, H.; Davydov, R.; Anderson, M.; Börje, A.; Korall, P.; Philouze, C.; Almgren, M.; Styring, S.; Akermark, B. Chem. Commun. 1997, 607-608.
10. Recent examples: (a) Flamigni, L.; Barigelletti, F.; Armaroli, N.; Collin, J.-P.; Sauvage, J.-P.; Williams, J. A. G. Chem. Eur. J. 1998, 4, 1744-1754. (b) Wagner, R. W.; Johnson, T. E.; Lindsey, J. S. J. Am. Chem. Soc. 1996, 118, 11166-11180. (c) Osuka, A.; Marumo, S.; Mataga, N.; Taniguchi, S.; Okada, T.; Yamazaki, I.; Nishimura, Y.; Ohno, T.; Nozaki, K. J. Am. Chem. Soc. 1996, 118, 115-168. (d) Sun, L.; Hammarström, L.; Norrby, T.; Berglund, H.; Davydov, R.; Anderson, M.; Börje, A.; Korall, P.; Philouze, C.; Almgren, M.; Styring, S.; Akermark, B. Chem. Commun. 1997, 607-608.
11. Recent examples: (a) Flamigni, L.; Barigelletti, F.; Armaroli, N.; Collin, J.-P.; Sauvage, J.-P.; Williams, J. A. G. Chem. Eur. J. 1998, 4, 1744-1754. (b) Wagner, R. W.; Johnson, T. E.; Lindsey, J. S. J. Am. Chem. Soc. 1996, 118, 11166-11180. (c) Osuka, A.; Marumo, S.; Mataga, N.; Taniguchi, S.; Okada, T.; Yamazaki, I.; Nishimura, Y.; Ohno, T.; Nozaki, K. J. Am. Chem. Soc. 1996, 118, 115-168. (d) Sun, L.; Hammarström, L.; Norrby, T.; Berglund, H.; Davydov, R.; Anderson, M.; Börje, A.; Korall, P.; Philouze, C.; Almgren, M.; Styring, S.; Akermark, B. Chem. Commun. 1997, 607-608.
12. Recent examples: (a) Flamigni, L.; Barigelletti, F.; Armaroli, N.; Collin, J.-P.; Sauvage, J.-P.; Williams, J. A. G. Chem. Eur. J. 1998, 4, 1744-1754. (b) Wagner, R. W.; Johnson, T. E.; Lindsey, J. S. J. Am. Chem. Soc. 1996, 118, 11166-11180. (c) Osuka, A.; Marumo, S.; Mataga, N.; Taniguchi, S.; Okada, T.; Yamazaki, I.; Nishimura, Y.; Ohno, T.; Nozaki, K. J. Am. Chem. Soc. 1996, 118, 115-168. (d) Sun, L.; Hammarström, L.; Norrby, T.; Berglund, H.; Davydov, R.; Anderson, M.; Börje, A.; Korall, P.; Philouze, C.; Almgren, M.; Styring, S.; Akermark, B. Chem. Commun. 1997, 607-608.
13. (a) Recent example of metal-induced self-assembly: Bodenant, B.; Fages, F.; Delville, M.-H. J. Am. Chem. Soc. 1998, 120, 7511-7519.
14. (b) Osuka, A.; Yoneshima, R.; Shiratori, H.; Okada, T.; Taniguchin, S.; Mataga, N. Chem. Commun. 1998, 1567-1568.
15. (c) Otsuki, J.; Harada, K.; Toyama, K.; Hirose, Y.; Araki, K.; Seno, M.; Takatera, K.; Watanabe, T. Chem. Commun. 1998, 1515-1516.
16. (d) Zahavy, E.; Fox, M. A. Chem. Eur. J. 1998, 4, 1647-1652.
17. (e) Ward, M. D. Chem. Soc. Rev. 1997, 365-375.
18. (f) Hunter, C. A.; Shannon, R. J. Chem. Commun. 1996, 1361-1362.
19. (g) Berman, A.; Izraeli, E. S.; Levanon, H.; Wang, B.; Sessler, J. L. J. Am. Chem. Soc. 1995, 117, 8252-8257.
20. (h) Arimura, T.; Brown, C. T.; Springs, S. L.; Sessler, J. L. Chem. Commun. 1996, 2293-2294.
21. (i) Roberts, J. A.; Kirby, J. P.; Nocera, D. G. J. Am. Chem. Soc. 1995, 117, 8051-8052.
22. (j) Osuka, A.; Shiratori, H.; Yoneshima, R.; Okada, T.; Taniguchi, S.; Mataga, N. Chem. Lett. 1995, 913-914.
23. (k) Ward, M. D.; Barigelletti, F. J. Chem. Soc., Dalton Trans. 1997, 727-735.
24. (l) Hunter, C. A.; Hyde, R. K. Angew. Chem. 1996, 108, 2064-2067; Angew. Chem., Int. Ed. Engl. 1996, 35, 1936-1939.
25. (l) Hunter, C. A.; Hyde, R. K. Angew. Chem. 1996, 108, 2064-2067; Angew. Chem., Int. Ed. Engl. 1996, 35, 1936-1939.
26. (m) Kirby, J. P.; Roberts, J. A.; Nocera, D. G. J. Am. Chem. Soc. 1997, 119, 9230-9236.
27. (n) Kimura, M.; Misawa, Y.; Yamaguchi, Y.; Hanabusa, K.; Shirai, H. Chem. Commun. 1996, 2785-2786.
28. (o) Opperman, K. A.; Mecklenburg, S. L.; Meyer, T. J. Inorg. Chem. 1994, 33, 5295-5301.
29. (a) Walsh, C.; Fisher, J.; Spencer, R.; Graham, D. W.; Ashton, W. T.; Brown, J. E.; Brown, R. D.; Rogers, E. F. Biochemistry 1978, 17, 1942-1951.
30. (b) Walsh, C. Acc. Chem. Res. 1980, 13, 148-155.
31. (a) David, E.; Born, R.; Kaganer, E.; Joselevich, E.; Dürr, H.; Willner, I. J. Am. Chem. Soc. 1997, 119, 7778-7790.
32. (b) Kropf, M.; Joselevich, E.; Dürr, H.; Willner, I. J. Am. Chem. Soc. 1996, 118, 655-665.
33. (c) Seiler, M.; Dürr, H.; Joselevich, E.; Doron, A.; Stoddart, J. F. J. Am. Chem. Soc. 1994, 116, 3399-3404.
34. (d) Seiler, M.; Dürr, H. Liebigs Ann. 1995, 407-413.
35. Kyogokuy, Y.; Sul Yu, B. Bull. Chem. Soc. Jpn. 1969, 42, 1387-1393.
36. Kalesse, M.; Loos, A. Liebigs Ann. 1996, 935-939.
37. Brandes, S.; Gros, C.; Denat, F.; Grilaud, R. Bull. Chem. Soc. Chim. Fr. 1996, 133, 3068-3076.
38. Grodefroi, E. F.; Wittle, E. G. J. Org. Chem. 1956, 28, 1163-1168.
39. Kionoya, M. S.; Kimura, E.; Ikeda, T.; Yamada, Y. J. Am. Chem. Soc. 1992, 114, 10134-10137.
40. (a) Shinoya, M.; Kimura, E.; Shiro, M. J. Am. Chem. Soc. 1993, 115, 6730-6737.
41. (b) Shinoya, M.; Ikeda, T.; Kimura, E.; Shiro, M. J. Am. Chem. Soc. 1994, 116, 3848-3859.
42. (c) Koike, T.; Watanabe, T.; Aoki, S.; Kimura, E.; Shiro, M. J. Am. Chem. Soc. 1996, 118, 12696-12703.
43. (d) Kimura E. In Top. Curr. Chem. 1985, 128, 113-141.
44. (e) For the synthesis of a redox-active zinc-tetraazamacrocycle complex, see: Tucker, J. H. R.; Shionoya, M.; Koike, T.; Kimura, E. Bull. Chem. Soc. Jpn. 1995, 68, 2465-2469.
45. (a) Koike, T.; Kimura, E.; Nakamura, I.; Hashimoto, Y.; Shiro, M. J. Am. Chem. Soc. 1992, 114, 7338-7345.
46. (b) Kimura, E.; Koike, T.; Shiota, T.; Iitaka, Y. Inorg. Chem. 1990, 29, 4621-4629.
47. (a) Kimura, E.; Aoki, S.; Koike, T.; Shiro, M. J. Am. Chem. Soc. 1997, 119, 3068-3076.
48. (b) Koike, T.; Takashige, M.; Kimura, E.; Fujioka, H.; Shiro, M. Chem. Eur. J. 1996, 2, 617-623.
49. (c) Kimura, E.; Ikeda, T.; Shionoya, M.; Shiro, M. Angew. Chem. 1995, 107, 711-713; Angew. Chem., Int. Ed. Engl. 1995, 34, 663-664.
50. (c) Kimura, E.; Ikeda, T.; Shionoya, M.; Shiro, M. Angew. Chem. 1995, 107, 711-713; Angew. Chem., Int. Ed. Engl. 1995, 34, 663-664.
51. (d) Kimura, E.; Kitamura, H.; Koike, T.; Shiro, M. J. Am. Chem. Soc. 1997, 119, 10909-10919.
52. (e) Kimura, E.; Ikeda, T.; Shinoya, M. Pure Appl. Chem. 1997, 69, 2187-2195.
53. (f) For other examples of binding by kinetically labile coordination, see: Mallik, S.; Johnson, R. D.; Arnold, F. H. J. Am. Chem. Soc. 1994, 116, 8902-8911.
54. (g) Sun, S.; Saltmarsh, J.; Mallik, S.; Thomasson, K. Chem. Commun. 1998, 519-520.
55. (h) Shih, H.-C.; Tang, N.; Burrows, C. J.; Rokita, S. E. J. Am. Chem. Soc. 1998, 120, 3284-3288;
56. Anodic peak potential. For experimental details, see Table 1 caption.
57. + coenzymes are the most important electron-transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
58. + coenzymes are the most important electron- transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
59. + coenzymes are the most important electron- transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
60. + coenzymes are the most important electron- transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
61. + coenzymes are the most important electron- transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
62. + coenzymes are the most important electron- transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
63. + coenzymes are the most important electron- transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
64. + coenzymes are the most important electron- transfer agents in biology. Moreover, several artificial receptors to intercept the photochemisty of flavins have been described in the literature: (a) Tamura, N.; Kajiki, T.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Chem. Commun. 1994, 2583-2684. (b) Tamura, N.; Mitsui, K.; Nabeshima, T.; Yano, Y. J. Chem. Soc., Perkin Trans. 2 1994, 2229-2236. (c) Deans, R.; Cooke, G.; Rotello, V. M. J. Org. Chem. 1997, 62, 836-839. (d) Yano, Y.; Tamura, N.; Mitsui, K.; Nabeshima, T. Chem. Lett. 1989, 1655-1658. (e) Shinkai, S.; Nakao, H.; Ueda, K.; Manabe, O. Tetrahedron Lett. 1984, 25, 5295-5298. (f) Shinkai, S.; He, G.-X.; Matsuda, T. Tetrahedron Lett. 1989, 30, 5895-5898. (g) Greaves, M. D.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 10569-10572. (h) Breinlinger, E. C.; Rotello, V. M. J. Am. Chem. Soc. 1997, 119, 1165-1166.
65. (a) Sun, M.; Moore, T. A.; Song, P.-S. J. Am. Chem. Soc. 1972, 94, 1730-1741.
66. (b) Rutter, W. J. Acta Chem. Scand. 1958, 12, 438-446.
67. (a) Kuhn, R.; Rudy, H. Chem. Ber. 1934, 67, 1936-1939.
68. (b) Karrer, P.; Schöpp, K. Helv. Chim. Acta 1934, 17, 1557-1558.
69. Bodanszky, M.; Bodanszky, A. The Practice of Peptide Synthesis, 2nd ed.; Springer: Berlin, 1994.
70. Jones, P. G.; Dix, I.; Pelka, M.; König, B. Unpublished results.
71. Kocienski, P. J. Protecting Groups, Thieme, Stuttgart, 1994; p 195-198. The Cbz groups were not completely removed under standard cleavage conditions, while at higher temperatures and increased hydrogen pressure the molecule decomposed.
72. Martell, A. E.; Motekaitis, R. J. Determination and Use of Stabilty Constants, 2nd ed.; VCH: Weinheim, 1992.
73. The measurements were performed in acetonitrile and methanol as solvents to allow scanning over a wide electrochemical window. The actual redox potentials in water may differ slightly, which will lead to a different value of ΔG. However, the general conclusion that photoinduced electron transfer from phenothiazine to riboflavin is a strongly exothermic process will not be affected. For details of the experimental conditions, see Table 1 caption.
74. (a) When the change in shape, size, and solvation after electronic excitation is small, the entropy difference between ground and excited state can be neglected. With this assumption the redox potential of excited molecules can be derived from their ground-state redox potential and the zero spectroscopic energy of the excited state. Julliard, M.; Chanon, M. Chem. Rev. 1983, 83, 425-506.
75. ○ ≈ - 1.27 eV (-28 kcal/ mol) can be derived.
76. Rehm, D.; Weller, A. Ber. Bunsen-Ges. Phys. Chem. 1969, 73, 834-839.
77. A measurement in buffered water is not possible, because of the very narrow electrochemical window.
78. 4 at 20°C and a scan rate of 0.1 V/s.
79. 4 at 20°C and a scan rate of 0.1 V/s. For a recent investigation of the binding properties of riboflavin and its radical anion, see: Breinlinger, E. C.; Keenan, C. J.; Rotello, V. M. J. Am. Chem. Soc. 1998, 120, 8606-9609 and cited references.
80. Reichardt, C. Solvent and Solvent Effects in Organic Chemistry: VCH: Weinheim, Germany, 1988.
81. See Supporting Information for UV spectra of compounds 1, 2, 7, and 8 in different solvents. The identical UV spectra of 1 and 8 reveal that exchange of the imide proton by methylation or deprotonation does not change the properties of the chromophore.
82. -1, derived from the Debye estimation of diffusional quenching in acetonitrile at room temperature. Turro, N. J. Modern Molecular Photochemistry; Benjamin/Cummings: Menlo Park, 1978; p 314.
83. q values is high.
84. -1. Sillen, L. G.; Warnquist, B. Ark. Kemi 1968, 31, 315-339, 377-390.
85. Complex formation and emission quenching was also studied in methanol. See Supporting Information for results.
86. To get an order of magnitude of the binding constant, it was derived by nonlinear fitting with algorithms provided by the program Sigma plot. Connors, K. A. Binding Constants; Wiley: New York, 1987. This value is underestimated as the quenching mechanism is more complex than assumed in the calculation.
87. For details of fluorescence decay measurements, see Supporting Information. Fluorescence decays were recorded with use of the single photon timing technique as already described (Desvergne, J.-P.; Castellan, A.; Bouas-Laurent, H.; Soulignac, J. C. J. Luminescence 1987, 37, 175-181); the exponential decays profiles were fitted by using the DECAN 1.0 program (De Roeck, T.; Boens, N.; Docks, J. DECAN 1.0, Leuwen, Belgium).
88. For details of fluorescence decay measurements, see Supporting Information. Fluorescence decays were recorded with use of the single photon timing technique as already described (Desvergne, J.-P.; Castellan, A.; Bouas-Laurent, H.; Soulignac, J. C. J. Luminescence 1987, 37, 175- 181); the exponential decays profiles were fitted by using the DECAN 1.0 program (De Roeck, T.; Boens, N.; Docks, J. DECAN 1.0, Leuwen, Belgium).
89. Foery, F.; Hemmerich, P. Helv. Chim. Acta 1967, 50, 1766-1774.
90. (a) Grodowski, M. S.; Veyret, B.; Weiss, K. Photochem. Photobiol. 1977, 26, 341-352.
91. (b) At 530 nm the same trace is observed with similar decay time but an amplitude twice lower in agreement with the TT absorption spectrum of 1.
92. (c) Methanol was used as solvent to achieve high complex formation.
93. (a) Lewis, G. N.; Bigeleisen, J. J. Am. Chem. Soc. 1943, 65, 2419.
94. (b) Alkaitis, S. A.; Beck, G.; Graetzel, M. J. Am. Chem. Soc. 1975, 97, 5723-5729.
95. (a) Holmström, B. Arkiv Kemi 1964, 22, 281. This paper is often quoted to justify the monitoring of the semireduced radical of flavins at 560 nm.
96. (b) Navarro, J. A.; Roncel, M.; De la Rosa, M. A. Photochem. Photobiol. 1987, 46, 965-970. In this paper, the absorption spectrum of semireduced lumiflavin appears as a very broad band, nearly isosbestic from 530 to 600 nm and slowly decaying from 600 to 700 nm.
97. +· (formed after electron transfer) will contribute to the dissociation of the complex allowing radical ions to diffuse into the solution.