Molecule of the Month

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MCM-41

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Vladimir Gusev

MCM-41 (Mobile Crystalline Material) is a silicate obtained by a templating mechanism1,2,3. It is ordered to some degree, so that there are arrays of non intersecting hexagonal channels, identifiable by TEM, XRD, and vapor adsorption. By changing the length of the template molecule, the width of the channels can be controlled to be within 2 to 10 nm. The walls of the channels are amorphous SiO2. This feature, together with its exceptional porosity (up to 80%), makes MCM-41 is the least mechanically stable compared to, e.g., other porous silicas, silica gels or zeolites4. Attempts to synthesize crystalline MCM-41 are underway.

methane and ethane inside MCM41 Left: Methane and ethane inside one of the hexagonal pores of molecular sieve MCM-41 (of about 3 nm pore diameter).

Red = oxygen, Blue = silicon,
Light Blue = hydrogen, Brown = carbon



Right: Two hexagonal channels of MCM41, linked to its 3D structural pdb file. Enlarge to full page.

References:

  1. Kresge, C.T.; Leonowicz, M.E.; Roth, W.J., Vartuli, J.C.; Beck, J.S. Nature. 1992, 359, 710
  2. Monnier, A.; Schuth, F.; Huo, Q. et al. Science. 1993, 261, 1299.
  3. Beck, J.S.;Vartuli, J.C.; Roth, W.J. et al.  J. Am. Chem. Soc. 1992, 114, 834.
  4. Gusev V., Feng X., Bu Z., Haller G., O'Brien J. J. Phys. Chem. 1996, 100, 1985 

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