Photochemistry of ketones adsorbed on size/shape selective zeolites. A supramolecular approach to persistent carbon centered radicals

Abstract

²H NMR, EPR, computational and product analyses of the photolysis of 2,4-diphenylpentan-3-one (DPP) adsorbed on MFI size/shape selective zeolites are consistent with supramolecular structural changes as a function of surface coverage that provide a novel method for the generation of persistent diffusing organic free radicals.

References

1. See, for example, R. M. Dessau, Selective Sorption Properties of Zeolties, ACS Symp. Ser., 1980, 135, 123.
2. V. R. Choudhary, V. S. Nayak and T. V. Chaudhary, Ind. Eng. Chem. Res., 1997, 36, 1812.
3. P. B. Weisz, Pure Appl. Chem., 1980, 52, 2091; P. B. Weisz, Ind. Eng. Chem. Fundam., 1986, 25, 53.
4. For a review of the photochemistry of organic molecules adsorbed on zeolites, see N. J. Turro, Pure Appl. Chem., 1986, 58, 1219.
5. (a) D. Griller and K. U. Ingold, Acc. Chem. Res., 1976, 9, 13; (b) G. D. Mendenhall and K. U. Ingold, J. Am. Chem. Soc., 1973, 95, 3422.
6. Self reaction via combination or disproportionation determines the persistence of radicals inert to rearrangement and reaction with the environment.
7. N. D. Ghatlia and N. J. Turro, J. Photochem. Photobiol. A: Chem., 1991, 57, 7; B. H. Baretz and N. J. Turro, J. Am. Chem. Soc., 1983, 105, 1309.
8. H. Fischer, J. Am. Chem. Soc., 1986, 108, 3925 and references therein.
9. The surface area of the ZSM-5 samples was determined to be ca. 15 m² g^–1 by mercury porosimetry.
10. For a discussion of the relationship between motion and line shape or ²H NMR spectroscopy, see R. J. Wittebort, E. T. Olejniczak and R. G. Griffin, J. Chem. Phys., 1987, 86, 5411.
11. R. Batra, B. Giese, B. M. Spichty, G. Gescheidt and K. N. Houk, J. Phys. Chem., 1996, 100, 1837.
12. M. S. Conradi, H. Zeldes and R. Livingston, J. Phys. Chem., 1979, 83, 633.