Flavins as modular and amphiphilic probes of silica microenvironments

Abstract

The amphiphilic and solvochromatic characteristics of flavins are utilized as a non-invasive polarity sensor for silica-based media.

References

1. For reviews, see: M. E. Davis, Acc. Chem. Res., 1993, 26, 111; P. T. Tanev and T. J. Pinnavaia, Access in Nanoporous Materials, Plenum Press, New York, 1995, pp. 13–28.
2. C. T. Kresge, M. E. Leonowicz, W. J. Roth, J. C. Vartuli and J. S. Beck, Nature, 1992, 359, 710; J. S. Beck, J. C. Vartuli, W. J. Roth, M. E. Leonowicz, C. T. Kresge, K. D. Schmitt, C. T.-W. Chu, D. H. Olson, E. W. Sheppard, S. B. McCullen, J. B. Higgins and J. L. Schlenker, J. Am. Chem. Soc., 1992, 114, 10 834; J. C. Vartuli, C. T. Kresge, M. E. Leonowicz, A. S. Chu, S. B. McCullen, I. D. Johnson and E. W. Sheppard, Chem. Mater., 1994, 6, 2070; S. Schacht, Q. Huo, I. G. Voigt-Martin, G. D. Stucky and F. Schüth, Science, 1996, 273, 768; P. T. Tanev, Y. Liang and T. J. Pinnavaia, J. Am. Chem. Soc., 1997, 119, 8616; K. M. McGrath, D. M. Dabbs, N. Yao, I. A. Aksay and S. M. Gruner, Science, 1997, 277, 552.
3. S. J. Tavener, J. H. Clark, G. W. Gray, P. A. Heath and D. J. MacQuarrie, Chem. Commun., 1997, 1147; S. Spange, A. Reuter and E. Vilsmeier, Colloid Polym. Sci., 1996, 274, 59; M. Kosmulski, J. Colloid Interface Sci., 1996, 179, 128; Z. Li and S. C. Rutan, Anal. Chim. Acta, 1995, 312, 127; C. G. Flowers, S. Lindley and J. E. Leffler, Tetrahedron Lett., 1984, 25, 4997.
4. U. Narang, J. D. Jordan, F. V. Bright and P. N. Prasad, J. Phys. Chem., 1994, 98, 8101; F. Nishida, J. M. McKiernan, B. Dunn, J. I. Zink, C. J. Brinker and A. J. Burd, J. Am. Ceram. Soc., 1995, 78, 1640; L. M. Ilharco, A. M. Santos, M. J. Silva and J. M. G. Martinho, Langmuir, 1995, 11, 2419 For reviews, see: D. Avnir, Acc. Chem. Res., 1995, 28, 328; B. Dunn and J. I. Zink, Chem. Mater., 1997, 9, 2280.
5. R. C. Chambers, Y. Haruvy and M. A. Fox, Chem. Mater., 1994, 6, 1351.
6. For a detailed UV–VIS investigation of solvent effects on flavins bearing ribose functionalities in the N¹⁰ position, see: J. Koziol, Photochem. Photobiol., 1966, 5, 41.
7. For detailed UV–VIS studies of solvent effects on flavin moieties bearing an alkyl functional group in the N¹⁰ position, see: H. A. Harbury, K. F. LaNoue, P. A. Loach and R. M. Amick, Proc. Natl. Acad Sci. USA, 1959, 45, 1708; P. F. Heelis, Chem. Soc. Rev., 1982, 11, 15; J. Koziol, Photochem. Photobiol., 1969, 9, 45.
8. UV–VIS dilution studies of isobutylflavin 1 in CHCl₃ and EtOH, and FMN 2 in H₂O demonstrated that no aggregation took place for the concentrations used in these studies.
9. EM Science Silica Gel 60: 0.040–0.063 mm particle size, 0.71–0.78 mL g^–1 pore volume and 490 m² g^–1 surface area (BET). Silica gel was suspended in chloroform for these experiments to minimize light scattering via refractive index matching during UV–VIS measurements.
10. C.-Y. Chen, S. L. Burkett, H.-X. Li and M. E. Davis, Microporous Mater., 1993, 2, 27.
11. The procedure for the preparation of this material was derived from: D. J. MacQuarrie, Chem. Commun., 1996, 1961.
12. The sample the MCM-41 was kindly provided by Professor M. Tsapatsis.
13. C.-Y. Chen, H.-X. Li and M. E. Davis, Microporous Mater., 1993, 2, 17; B. P. Feuston and J. B. Higgins, J. Phys. Chem., 1994, 98, 4459.
14. U. Narang, R. Wang, P. N. Prasad and F. V. Bright, J. Phys. Chem., 1994, 98, 17.
15. The polarity determined using FMN is similar, but higher than that found by previous researchers. This can be attributed to the hydrophobicity of the probes used in these studies: D. Avnir, D. Levy and R. Reisfeld, J. Phys. Chem., 1984, 88, 5956; K. Matsui and T. Nakazawa, Bull. Chem. Soc. Jpn., 1990, 63, 11.