Silica and Hybrid Silica Gels Revisited: New Insight by Solid State Nuclear Magnetic Resonance


The “old” 1H→29Si CP MAS (Cross Polarization Magic Angle Spinning) experiment is revisited in the frame of silica hybrid gels and silsesquioxanes. It is proved that the analysis of the CP curves can lead to erroneous interpretation in terms of quantification. We show that this results from false assumptions concerning the dynamical CP parameters THSi (cross relaxation time constant) and TH (1H relaxation time in the rotating frame). In other words, at least one parameter must be measured independently, in order to constrain the fits of the CP curves. Moreover, we demonstrate that the well-known (and universally used…) “spin bath” assumption is not always valid in the frame of 1H→29Si CP MAS NMR. This point is clearly demonstrated on model silsesquioxanes exhibiting short Si-H bonds. In this case, the transfer of magnetization (called coherent transfer) presents clearly oscillations, which can lead to the precise measurement of Si-H distances by solid state NMR! Curiously, the coherent transfer of magnetization is also demonstrated for weakly coupled spin systems, encountered in the silsesquioxane (SiO1.5CH3)8 or T units gels. In this case, a numerical simulation of the CP curves gives a deep insight in the chemical environment of the 29Si sites in terms of Si-H distances and local molecular reorientations. For weakly coupled systems, 1H-1H spin diffusion must be suppressed, in order to reveal the coherent character of the transfer: the quenching of spin diffusion is demonstrated by using a modified version of the CP MAS experiment. We introduce here the Lee-Goldburg CP MAS experiment (CPLG MAS) for that purpose. The “off resonance” 1H irradiation (at the magic angle) ensures the strong suppression of the 1H-1H homonuclear dipolar interaction and therefore the efficient quenching of spin diffusion during the CP transfer.

This is a preview of subscription content, access via your institution.


  1. 1.

    S. R. Hartmann, and E. L. Hahn, Phys. Rev. 128, 2042 (1962).

    CAS  Article  Google Scholar 

  2. 2.

    A. Pines, M. G. Gibby, and J. S. Waugh, J. Chem. Phys., 59, 569 (1973).

    CAS  Article  Google Scholar 

  3. 3.

    G. E. Maciel, and D. W. Sindorf, J. Am. Chem. Soc., 102, 7607 (1980).

    Article  Google Scholar 

  4. 4.

    D. W. Sindorf, and G. E. Maciel, J. Am. Chem. Soc., 103, 4263 (1981).

    CAS  Article  Google Scholar 

  5. 5.

    D. W. Sindorf, and G. E. Maciel, J. Phys. Chem., 86, 5208 (1982).

    CAS  Article  Google Scholar 

  6. 6.

    D. W. Sindorf, and G. E. Maciel, J. Am. Chem. Soc., 105, 1487 (1983).

    CAS  Article  Google Scholar 

  7. 7.

    K. Schmidt-Rohr, and H. W. Spiess, Multidimensional Solid State NMR and Polymers, Academic Press, New-York, 1994.

    Google Scholar 

  8. 8.

    I. Klur, J. F. Jacquinot, F. Brunet, T. Charpentier, J. Virlet, C. Schneider, and P. Tekely, J. Phys. Chem. B, 104, 10162 (2000).

    CAS  Article  Google Scholar 

  9. 9.

    C. J. Brinker, and G. W. Scherer, Sol-Gel Science, The Physics and Chemistry of Sol-Gel Processing, Academic Press, San Diego, 1989.

    Google Scholar 

  10. 10.

    L. Müller, A. Kumar, T. Baumann, and R. R. Ernst, Phys. Rev. Lett., 32, 1402 (1974).

    Article  Google Scholar 

  11. 11.

    M. Bak, J. T. Rasmussen, and N. C. Nielsen, J. Magn. Reson. A, 147, 296 (2000).

    CAS  Article  Google Scholar 

  12. 12.

    R. Sangill, N. Rastrup-Andersen, H. Bildsoe, H. J. Jakobsen, and N. C. Nielsen, J. Magn. Reson. A, 107, 67 (1994).

    CAS  Article  Google Scholar 

  13. 13.

    B. J. Van Rossum, C. P. De Groot, V. Ladizhansky, S. Vega and H. J. M. De Groot, J. Am. Chem. Soc. 122, 3465 (2000).

    Article  Google Scholar 

  14. 14.

    T. Terao, H. Miura and A. Saika, J. Chem. Phys. 75, 1573 (1981).

    CAS  Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Christian Bonhomme.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Bonhomme, C., Camus, L. & Babonneau, F. Silica and Hybrid Silica Gels Revisited: New Insight by Solid State Nuclear Magnetic Resonance. MRS Online Proceedings Library 847, 18–28 (2004).

Download citation